BEAN15
Phaseolus vulgaris L., family Leguminosae
The common bean includes the edible fresh, and processed, green snap,
green-shelled, and dry beans. In 1969, about 1,872,000 acres were devoted
to the many types and scores of cultivars of beans, which had a farm value
of more than $243 million. Fresh snap beans are primarily produced in Florida
and along the eastern seaboard; processed beans, in New York, Oregon, and
California, and along the eastern seaboard. Dry beans are produced in two
main areas, in the West (Idaho, Colorado, and New Mexico) and in north
central U.S. (in and around Michigan).
__________
15 See also: "Broad Bean and Field Bean,"
pp.117; "Lima Bean," p. 244; and "Scarlet Runner Bean,"
p. 332.
Plant:
The vast majority of P. vulgaris cultivars are bush type annuals that reach a height of about 2 1/2 feet and are grown in rows about 3 feet apart. The leaves are dense, heart-shaped, and 3 to 6 inches long. The fruit is a pod, straight or slightly curved, 4 to 8 inches long, with a prominent beak. The seeds may be white to red, brown speckled, or blue-black; globular to oblong; and from l/4 to 1 inch long. Pods may contain from one to a dozen seeds.
Inflorescence:
The bean flower is of the typical legume shape; usually whitish, but may be tinged to deep violet, purple, or red; and is l/2 to 3/4 inch long. The keel is prolonged in a spirally twisted beak. The style follows the spirals of the keel. There are the usual 10 stamens, the upper one free while the other nine are united into a tube enclosing the long ovary and part of the style. The blooms are loosely scattered along a 2- to 3-inch rachis (stem). They usually open between 7 and 8 a.m., and never close. The corolla sheds after a few days. The anthers dehisce the evening of the day before the flower opens (Jones and Rosa 1928*). Weinstein (1926) reported that many pollen grains germinate in the anther, but whether such pollen plays a part in fertilization is unknown. Knuth (1908*, p. 339) stated that although the anthers surround the style and the pollen is released before the flower opens, the pollen does not get onto the stigma before tripping occurs. When pressure, for example, the weight of a large bee, is applied to the wing petals, the style, with pollen adhering to the brush of hairs on it, projects from the tip of the keel. When pressure is released, the style retracts into the keel, sometimes leaving some pollen exposed.
When the stigma is first exposed, it is free of pollen, and may touch a pollen-coated bee during its brief period of exposure. If this happens, cross-pollination can occur. As the stigma retracts into the keel, it comes in contact with the pollen released by the anthers and selfing may also occur. Bean breeders state that beans excluded from insect visitors set a full complement of pods and seeds, although there seems to be no data on the relative time interval required for isolated plants and for bee-visited plants to accomplish this.
Pollination Requirements:
Bean breeders state that they plant different lines and cultivars alongside each other without fear of cross-pollination, indicating very reliable self-pollination. The flowers of most bean cultivars are capable of self-pollination although cross-pollination can and does occur to varying degrees, depending upon the cultivar and the pollinator population (Hawthorn and Pollard 1954*, Mackie and Smith 1935, Barrons 1939). Much of the research on bean pollination has been concerned only with the impact of the cross-pollination on varietal seed contamination, not on quantity or quality of fruit set. Rutger and Beckham (1970) stated that P. vualgaris is primarily a selfing species, but studies of controlled insect pollination are needed. Free (1966) concluded that the pollination requirements of different species of beans could not be predicted so they must be studied individually. Thorough studies on the possible benefits of maximum pollinator activity on the various types and cultivars would appear to be highly worthwile.
Darwin (1857) noted that the movement of the pistil by the bee would appear to aid in the fertilization of the flower by its own pollen. When he tested this effect, he found that flowers not disturbed in any way set no seed, but flowers manipulated by the wing petals set a great number of seeds. From this, he deduced that "if every bee in Britain were destroyed, we should not again see a pod on our kidney beans." Just what species or cultivar he dealt with is not clear.
Knuth ( 1908 *, p. 339) stated that the anthers surround the style and shed their pollen upon it, but the stigma is never dusted until the keel is depressed. Then the style, with its pollen-covered brush, springs out of the opening. If the stigma is touched by the bee, coated with pollen from other plants, before being contacted by its own pollen, cross-pollination results. However, Taylor ( 1919) stated that the flowers are entirely self-fertile as is abundantly proved by their productiveness when grown in greenhouses where bees are not present. Yet, he stated that they can be cross-fertilized by bees, although the percentage of crossing is not great. Mackie and Smith (1935) and Barrons (1939) indicated that cross- pollination may amount to more than 8 percent. The pollinator population associated with the crossing was never measured.
Jones and Rosa (1928*) stated that because the stigma and the anthers are enclosed within the keel, insects reach them only with difficulty; however, visitation occurs and crossing results. They considered the- amount negligible. They also stated that selfing occurs freely when flowers are enclosed. Kristofferson (1921) reported 0 to 1.4 percent crossing, and Emerson (1904), 0 to 10 percent crossing. Free (1966) working with 'Processor' cv. of P. vulgaris concluded that "honey bees are unlikely to have much effect on the yield." His data, however, showed that the plants in the cages with bees produced 21 percent more seed weight, with 6 percent more pod weight than plants from which bees were excluded.
Beans are visited only sparingly by honey bees, and beekeepers do not consider this crop of significance as a source of nectar or pollen. What the visitation or its effect on beans might be under a high concentration of bees is unknown, but the information would be of interest and possibly of considerable value to bean growers.
Pollinators:
Mommers (1971 ) studied the pollination of beans grown under glass and concluded that bees do not influence development of P. vulgaris.
Diwan and Salvi (1965) stated that beans in India are eagerly visited by Apis dorsata, A. florea, and Trigona spp., but the flowers are generally ignored by A. cerana. Those who have studied the problem agree that bumble bees and honey bees are the most frequent visitors to bean flowers in the United States. Darwin (1858) and Palmer (1967) indicated that bees are of benefit to beans, but the kind of bean they referred to is not clear. The data indicate that, if pollinating insects are of benefit, the bumble bee is the best pollinator. Honey bees are apparently next in importance. The latter can be increased in numbers where desired. They visit the blossom for both pollen and nectar. The exact effect on the flower or value to the different cultivars of P. vulgaris has not been well established.
Pollination Recommendations and Practices:
There are no recommendations on the use of bees as pollinators of beans. In fact bean breeders, knowing the plants will set fruit in greenhouses where bees are excluded, feel that pollinating insects are entirely unnecessary. On the other hand, some growers "like to see bees around," believing that their activity results in fuller pods. For such an important crop, more precise information should be obtained on its pollination requirements, and the possible value of pollinating insects. The effect of saturation pollination, as practiced on other crops, might be effective.
LITERATURE CITED:
BARRONS, K. C.
1939. NATURAL CROSSING IN BEANS AT DIFFERENT DEGREES OF ISOLATION. Amer.
Soc. Hort. Sci. Proc. 36: 637-640.
DARWIN, C. [R.]
1857. BEES AND FERTILIZATION OF KIDNEY BEANS. Gard. Chron. 45: 725.
____ 1858. ON THE AGENCY OF BEES IN THE FERTILIZATION OF PAPILIONACEOUS FLOWERS AND ON THE CROSSING OF KIDNEY BEANS. Gard. Chron. 46: 828-829.
DIWAN, V. V., and SALVI, S. R.
1965. SOME INTERESTING BEHAVOURIAL FEATURES OF APIS DORSATA FAH. Indian
Bee Jour. 27(1): 52.
EMERSON, R. A.
1904. HEREDITY IN BEAN HYBRIDS (PHASEOLUS VULGARIS). Nebr. Agr. Expt. Sta.
Ann. Rpt. 17: 33-68.
FREE, J. B.
1966. THE POLLINATION OF THE BEANS PHASEOLUS MULTIFLORUS AND PHASEOLUS
VULGARIS BY HONEYBEES. Jour. Apic. Res. 5: 87-91.
KRISTOFFERSON, K. B.
1921. SPONTANEOUS CROSSING IN THE GARDEN BEAN, PHASEOLUS VULGARIS Hereditas
2: 395-400.
MACKIE. W. W., and SMITH, E. L.
1935. EVIDENCE OF FIELD HYBRIDIZATION IN BEANS. Amer. Soc. Agron. Jour.
27: 903-909.
MOMMERS, J.
1971. [THE POLLINATION OF BEANS UNDER GLASS (PHASEOLUS)]. Maandschr. v.
de Bijent. 73(5): 79-80. [In Dutch, English abstract.]
PALMER, R.
1967. BEES AID BEAN POLLINATION. So. African Bee Jour. 39(4): 12-13.
RUTGER J. N., and BECKHAM, L. S.
197O. NATURAL HYBRIDIZATION OF PHASEOLUS VULGARIS X P. COCCINEUS L. Amer.
Soc. Hort. Sci. Proc. 95: 659-661.
TAYLOR, W. H.
1919. BEES AND FLOWER FERTILIZATION. New Zeal. Jour. Agr. 18: 203.
WEINSTEIN, A. I.
1926. CYTOLOGICAL STUDIES ON PHASEOLUS VULGARIS. Amer. Jour. Bot. 13: 248-263.
BROAD BEAN AND FELD BEAN18
Vicia faba L., family Leguminosae
Broad bean and field bean, also known as faba, fava, horse, spring (pigeon),
tick, and windsor beans (Robinson 1968), are relatively unimportant in
the United States, but they are important in England, parts of western
Europe, and Australia. Yields vary considerably for these crops. Hawthorn
and Pollard (1954*) stated that broad beans yielded an average of 1,300
to 1,700 lb/acre in England. Bond et al. (1966) reported yields of about
700 lb/acre. Scriven et al. (1961) reported field bean yields of 4,520
kilograms per hectare (3,978 lb/acre). Watts and Marshall (1961) reported
yields of 3,377 kg/ha (2,971 lb/acre) from plots caged with bees as compared
to yields of 2,687 kg/ha (2,365 lb/acre) on plots caged to exclude bees.
__________
18 See also: "Bean," p. 100; "Lima
Bean," p. 244; "Scarlet Runner Bean," p. 332 and "Vetch,"
p. 369.
Plant:
Broad bean and field bean are coarse, erect, smooth-stemmed annuals, 2 to 6 feet tall, with pods 2 to 10 inches long, producing two to four flat brown seeds l/2 inch to 1 1/2 inches across. They are cool-season crops, tolerant to light frost, that are planted in the fall in areas of mild winter climate or in early spring in areas of cold winters.
Extrafloral nectaries are on the underside of the stipules, the small leaflike parts at the base of the leaf. Koreshkov (1967) showed that these nectaries function throughout the vegetative period of the plant, and that repeated removal of the nectar stimulates further production.
Inflorescence:
There are two to four white, blotched, deep maroon or blackish- violet flowers, each an inch or more across in clusters at the base of the leaf. Free (1970*) stated that a normal field bean plant has 50 to 80 flowers, bul a large proportion of these flowers or the young pods shed - 86.7 percent according to Kambol (1969). Sope, (1952) stated that less than a dozen pods per plant are harvested, although isolated plants may set over 60 pods. He concluded that this heavier set on the exposed plant was associated with better insect pollination Rowlands (1960) recorded an average of 24 percent sel in the open but only 7.3 percent set in the glass house He concluded that some plants are highly self-sterile and some cross better than others. Free (1970*) stated that the amount and concentration of field bean floral nectar was relatively low, so the flowers are not overly attractive to nectar collecting insects.
In discussing the field bean inflorescence, nectar secretion, and bee visitation, Free (1970*) stated that bee visitors to extra-floral nectaries were more numerous at midday, whereas those visiting the flowers were most numerous from 2 to 4 p.m., when pollen was available. He concluded that pollen was more attractive to bees than the floral nectar.
Pollination Requirements:
The pollination of broad bean and field bean was studied by Free (1966) who concluded that insect pollination greatly increased production of broad beans but had little effect on production of field beans. Later, Free (1970*) concluded that the pollination requirements of broad bean and field bean were similar although inadequate pollination limited seed production in broad beans more so than in field beans. Darwin (1889*) showed that 17 broad bean plants covered with a net to exclude pollinators produced only 40 seeds, whereas 17 exposed plants produced 135 seeds.
Probably the most important observation concerning the pollination of field bean was that by Drayner (1956,1959) and confirmed in more elaborate detail by Bond and Fyfe (1962) who showed that continued inbreeding causes a progressive loss in the ability of the plant to set selfed seed, but upon hybridization (cross-pollination) this ability is restored. This means that the plant can survive several generations (not indefinitely) without cross-pollination although production continually decreases. A similar situation apparently exists in many other so-called self-pollinated crops; continued inbreeding leads inevitably to elimination of the strain.
Holden and Bond (1960) concluded that 30 to 40 percent cross- pollination may represent an equilibrium point in a balanced breeding system in which the cross-pollinated third of the flowers self and the selfed flowers produce one-third selfed and one-third crossed seed. Such a system, they concluded, would be self-perpetuating, yielding one-third cross-breds and two-thirds inbreds each generation. They also observed that the pollen is in contact with the stigma 24 hours before the flower opens, therefore the cross-breds are capable of selfing.
The value of hybrids or cross-pollinated plants within the cultivar as shown by Bond (1968), is in their ability to self in the absence of bees, whereas inbreds would not set seed. However, Rowlands (1958) showed that only 2.3 percent of flowers set if they were not tripped or manipulated, whereas 12.4 percent set if they were gently hand manipulated but not tripped. This indicated that insects or the elements can influence the set of fruit without actually crossing the flowers. His open-pollinated flowers set 23.1 percent, showing that cross-pollination was more beneficial than mere manipulation.
Free (1966) showed that plants caged with bees produced about twice as many seeds as similar plants caged without bees. Scriven et al. (1961), Cooper (1966), Mart'yanova (1967), National Agricultural Advisory Service (1964, 1967), and Oschmann (1957) showed similar results. Fyfe and Bailey (1951) reported about 30 percent cross-fertilization of field bean in eastern England. Hua (1943) reported an average of 32.9 percent cross-pollination over a 3-year period in China.
The grower wants the plant to set its crop of seeds as soon as possible and to produce as much as possible. Bees can contribute in this respect. Wafa and Ibrahim (1960) excluded insects from some plants by use of cages and included bees in other cages over plants. At harvest time, the bee cage had ceased flowering and most of its pods were ripe. The plants from the cages without bees had many green pods when the cages were removed. This showed that bee pollination accelerated the rate of set of bean pods. Hanna and Lawes (1967) showed that the percentage of crossing was higher on the lower nodes (51 percent below, 33 percent at upper ones), showing that the plant strives first for cross-pollination then for survival.
Pollinators:
Bond and Hawkins (1967) and Free (1962) have studied the behavior of bees on field bean. Free (1962) concluded that the activity of the honey bees may vary. They may visit only the extrafloral nectaries, they may visit only the holes cut in the bases of the corollas by bumble bees, or they may visit the corolla for nectar and pollen. Only in the latter case are the bees of value to the beans as a pollinating agent. Bond and Hawkins (1967) placed two colonies by an acre of field bean, and the bees collected sizeable amounts of pollen. However, these workers concluded that bumble bees were primarily responsible for the cross-pollination that occurred. Wafa and Ibrahim (1960) concluded that the carpenter bee, Xylocopa aestuans (L.), was the most important wild pollinating insect in the Gaza region. Free (1959) concluded that better visitation to the bean flowers resulted when the honey bee colonies were moved to the crop after it started to flower.
Watts and Marshall (1961) showed about 26 percent increase in seed production due to the presence of bees. They also showed the value of bees in setting the seed early. In their plots caged with bees and also in their open plots, they found an average of nine, nine, and two pods, respectively on the bottom, mid- and top portion of the plant, but in the no-bee cage three, five, and four pods were in the same areas.
Free (1970*) concluded that only insects with long tongues could reach the nectar in the bean flower and that honey bees and short-tongued bumble bees that enter the flower probably obtain only pollen most of the time. However, some bumble bee species with short tongues, male carpenter bees (Xylocopa aestuans), and certain ants (Cataglyphis bicolor (F.)) bite holes in the base of the corolla and "rob" the nectar without contributing to pollination. Honey bees do not make holes, but they will rob nectar from holes made by other insects.
Pollination Recommendations and Practices:
Allen and Scriven (1957) concluded that one colony of honey bees per acre should give adequate coverage of field beans, but that most of the work by these insects resulted in self-pollination. In this respect, honey bees are no different from bumble bees. Brandenburg (1961 ) reported that the placement of colonies on the bean plots doubled the yield of seed. He suggested the bringing in of a new group of bees every 7 to 14 days.
Riedel and Wort (1960) studied set of pods in relation to their location on the plant and concluded that uniform set along the body of the plant was an indication of inadequate pollination.
Because bees collect pollen from beans mostly between 2 and 4 p.m., a study of the degree of collection might be used to determine the degree of pollination anticipated. For example, a grower might observe the number of bees per unit of flowers, then, later, the set of beans along the stalk, and, finally, the volume of seed harvested. In this way, he could determine the bee population needed for maximum production of both broad bean and field bean. This information should be determined experimentally also.
LITERATURE CITED:
ALLEN, H., and SCRIVEN. W. A.
1957. NOTES ON THE POLLINATION OF FIELD BEANS BOTH IN THE OPEN AND IN CAGES.
Brit. Bee Jour. 85: 288-290.
BOND, D. A.
1968. HYBRID FIELD BEANS. Natl. Agr. Advisory Serv., East Midlands Reg.
[England] Quart. Rev. 81: 1-6.
______and FYFE J. L.
1962. BREEDING FIELD BEANS. Plant Breed. Inst. [England] Rpt., 1960-61,
pp. 4-26.
______and HAWKINS, R. P.
1967. BEHAVIOR OF BEES VISITING MALE-STERILE FIELD BEANS (VICIA FABA).
Jour. Agr. Sci. [England] 68: 243-247.
______FYFE, J. L., and TOYNBEE-CLARK, G.
1966. YIELDS OF MIXTURES OF SINGLE-CROSS HYBRIDS WITH ONE OF THE PARENTAL
INBRED LINES. Jour. Agr. Sci. [England] 67: 235-237.
BRANDENBURG, W.
1961. BROAD BEANS: CAUSES OF POOR YIELDS SOUGHT. New Zeal. Jour. Agr. 102:
277, 279-280.
COOPER, B. A.
1964. POLLINATION OF FIELD BEANS. 2d Internatl. Symposium on Pollination,
London, 1964. Bee World 47(supp.): 199-206.
DRAYNER, J. M.
1956. REGULATION OF OUTBREEDING IN FIELD BEANS (VICIA FIBA). Nature 177
(4506): 489-490
______ 1959. SELF- AND CROSS-FERTILITY IN FIELD BEANS (VICIA FABA LINN.). Jour. Agr. Sci. [England] 53: 387-402
FREE, J. B.
1959. THE EFFECT OF MOVING COLONIES OF HONEYBEES TO NEW SITES ON THEIR
SUBSEQUENT FORAGING BEHAVIOR. Jour. Agr. Sci. [England] 53: 1-9.
FREE, J. B.
1962. THE BEHAVIOR OF HONEYBEES VISITING FIEBD BEANS (VICIA FABA). Jour.
Anim. Ecol. 31: 497-502.
______ 1966. THE POLLINATION REQUIREMENTS OF BROAD BEANS AND FIELD BEANS (VICIA FABA). Jour. Agr. Sci. [England] 66: 395-397.
FYFE, J. L., and BAILEY, N. T. J.
1951. PLANT BREEDING STUDIES IN LEGUMINOUS FORAGE CROPS. 1. NATURAL CROSSING
IN WINTER BEANS. Jour. Agr. Sci. [England] 41: 371-378.
HANNA, A. S., and LAWES, D. A.
1967. STUDIES ON POLLINATION AND FERTILIZATION IN THE FIELD BEAN (VICIA
FABA L.). Ann. Appl. Biol. 59: 289 - 295.
HOLDEN, J. W. H., and BOND, D. A.
1960. STUDIES ON THE BREEDING SYSTEM OF THE FIELD BEAN, VICIA FABA (L.).
Heredity 15(2/3): 175-192.
HUA, H.
1943. [NATURAL CROSSING IN VICIA FABA.] Chin. Jour. Sci. Agr. 1: 63 - 65.
[In Chinese, English summary. ]
KAMBOL, A. E.
1969. FLOWER DROP AND FRUIT SET IN FIELD BEANS, VICIA FABA L. Jour. Agr.
Sci. [England] 72: 131-138.
KORESHKOV, V. M.
1967. [SECRETION OF NECTAR BY EXTRAFLORAL NECTARIES OF THE FIELD BEAN (VICIA).]
Vest. Nauchno-Issled. Inst. Pchelovodstvo 15: 40-57. [In Russian.] AA-730/69.
MART'YANOVA, A. I. 1968. [EFFECT OF THE POLLINATION METHOD ON THE QUALITY, AND PRODUCTIVITY OF FIELD BEAN SEED.] Byull. mosk., Obshch. Ispyt. Prlr. 72(2): 83-92. [In Russian.] Abstract in Field Crop Abstracts 21(1): 308. 1967.
NATIONAL AGRICULTURAL ADVISORY SERVICE.
1964. POLLINATION OF FIELD BEANS. Ent. Dept., N.A A.S., Shardlow, Derby
[England], East Midlands Reg. [England] Ent. Leaflet 12, 4 pp.
______ 1967. POLLINATION OF FIELD BEANS. Ent. Leaflet 21, 5 pp.
OSCHMANN, H.
1957. [IMPORTANCE OF HONEY BEE VISITS FOR THE SEED YIELD OF FIELD BEANS.]
Deut. Landwirt. 8: 302-303. [In German.] AA-340/62.
REIDEL, I. B. M., and WORT, D. A.
1960. THE POLLINATION REQUIREMENT OF THE FIELD BEAN (VICIA FABA). Ann.
Appl. Biol. 48: 121-124.
ROBINSON, R. G.
1968. FABABEANS - A NEW CROP FOR MINNESOTA? Minn. Agr. Expt. Sta. Misc.
Rpt. 83: 1-8.
ROWLANDS, D. G.
1958. THE NATURE OF THE BREEDING SYSTEM IN THE FIELD BEAN (V. FABA) AND
ITS RELATIONSHIP TO BREEDING FOR YIELD. Hereditas 12: 113-126.
______ 1960. FERTILITY STUDIES IN THE FIELD BEAN (VICIA FABA L.). 1. CROSS- AND SELF-FERTILITY. Heredity 15(2/3): 161 - 173.
SCRIVEN, W. A., COOPER, B. A., and ALLEN, H.
1961. P0LLINATION OF FIELD BEANS. Outlook Agr. 3(2): 69 - 75.
SOPER, M. H. R.
1952. A STUDY OF THE PRINCIPAL FACTORS AFFECTING THE ESTABLISHMENT AND
DEVELOPMENT OF THE FIELD BEAN (VICIA FABA). Jour. Agr. Sci. [England] 42:
335-346.
WAFA A. K., and IBRAHIM, S. H.
1960. THE EFFECT OF THE HONEYBEE AS A POLLINATING AGENT ON THE YIELD OF
BROAD BEAN. Bul. Fac. Agr. Cairo Univ. 205,36 pp.
WATTS, F. H., and MARSHALL, P. R.
1961. POLLINATION OF FIELD BEANS. YIELD RESPONSE DUE TO BEES. Rpt. Field
Expts. Observ. Studies Hort., Natl. Agr. Advisory Serv., E. Midlands Reg.
[England]: 76-79.
COWPEA
Vigna sinensis Savi (L.) ex Hassk., family Leguminosae
The cowpeas inculde the blackeyes, cream, crowders, purplehull, and some other less common types. They are grown primarily in the South and in California. Production of cowpeas decreased from 899,000 acres in 1954 to 93,000 acres in 1967 when the USDA ceased including the crop in the annual Agricultural Statisti report. The farm value also decreased from $8,600,000 in 1954 to $3,150,000 in 1967.
Plant:
Cowpeas may be prostrate, erect, or climbing to about 3 feet. They are sensitive to cold and are killed by frost, but are tolerant to heat and drought conditions. The seeds are planted after all danger of frost is past. The plants flower in midsummer, and the seeds or forage are harvested before frost. The trifoliate leaves, 2 to 5 inches across, form a dense canopy that covers the ground. The seeds are in slender pods 8 to 10 inches long with eight to 20 seeds;vary in size (2 to 12 mm), shape (globular to kidney shaped), texture (smooth or wrinkled), and color (white, green, buff, red, brown, or black; and are variously speckled, mottled, blotched, or eyed). The type of cultivar grown depends upon whether it is to be used to produce forage, green pods, or the dry seeds as a pulse crop.
Inflorescence:
The inflorescence consists of two to eight whitish, yellowish, or violet papilionaceous flowers in pairs crowded together on the tip of a slender peducle or stem, 1 inch to 6 inches long. The 3/4- to 1-inch flower has a bent style, bearded on the inner curve immediately below the oblique stigma, and uniform anthers in two fused groups around the style (fig. 97).
The flower has a single ovary with eight to 20 ovules. Extrafloral nectaries are located at the base of the corolla. Whether floral nectar is secreted is not clear, but most likely it is.
The flower is attractive to bumble bees and various other insects that forage upon both the nectar and pollen.
[gfx]
FIGURE 97. - Longitudinal section of blackeye cowpea flower, x 7.
Pollination Requirements:
Purseglove (1968*) stated that the flowers open early in the morning and close before noon of the same day. Warnock and Hagedorn (1954) stated that the stigma is receptive only one day at 68 deg to 72 deg F but slightly longer at 60 deg. Robbins (1931 ) stated that the cowpea is capable of self-fertilization, and this is probably the common occurrence, although the flowers are often visited by honey bees or bumble bees, attracted chicfly by the extrafloral nectar. However, Warnock and Hagedorn (1964), after detailed study of the stigma of the cowpea, learned that receptivity is limited to only the very tip of the stigma, which in appearance somewhat resembles the sensitive end of the trunk of the elephant. They also found that from 14 pollinations made in the greenhouse, 59 seeds set when pollen was placed on the end of the stigma but only seven set when pollen was rubbed on the style. It was interesting that they never got more than an average of 5.4 seeds per pollination when pods normally produce eight to 20 seeds, which would indicate that their method was not as efficient as the natural method.
Pollinators:
Purseglove (1968*) stated that a heavy insect is required to depress the wings of the flower and expose the stamens and stigma. The pollen is sticky and heavy, indicating that the plant is not wind-pollinated (Mackie 1946). Cross-pollination seems to be associated with areas where bumble bees are numerous. Mackie and Smith (1935) stated that bumble bees are the primary pollinators.
The actual value of frequent visitation by pollinating insects to blossoms of cowpeas has not been determined; however, the study by Warnock and Hagedorn (1954) would indicate that such activity is beneficial in increasing the number of pod set, the number of seeds per pod, or both.
A male-sterile mutant cowpea has been reported (Sen and Bhowal 1962). It has not been utilized in hybrid seed production, but if such a mutant were used, since cowpeas are not wind pollinated, insects large enough to operate the floral mechanism would be required to carry pollen from fertile to male-sterile plants.
Pollination Recommendations and Practices:
There are no recommendations for the use of pollinating insects on cowpeas.
LITERATURE CITED:
MACKIE, W. W.
1946. BLACKEYED BEANS IN CALIFORNIA. Calif. Agr. Expt. Sta. Bul. 696, 56
pp.
____ and SMITH, F. L.
1935. EVIDENCE OF FIEBD HYBRIDIZATION IN BEANS. Amer. Soc. Agron. Jour.
27: 903 - 909.
ROBBINS, W. W.
1931. THE BOTANY OF CROP PLANTS. Ed. 3, 639 pp. P. Blakiston's Son &
CO., Inc., Philadelphia.
SEN, N. K., and BHOWAL, J. G. A.
1962. A MALE-STERILE MUTANT COWPEA. Jour. Hered. 53(1): 44-46.
WARNOCK, S. J., and HAGEDORN, D. J.
1954. STIGMA RECEPTIVITY IN PEAS (PISUM SATIVUM B.). Agron. Jour. 46: 274.
KIDNEYVETCH
Anthyllis vulneraria L., family Leguminosae
Kidneyvetch, also known as sand clover or wound-wart, is not grown to any appreciable extent in this country.
Plant:
Kidneyvetch is a deep-rooted perennial herb about a foot tall. It is a forage plant of some value on poor, light, sandy soil of the more northern latitudes (Graham 1941*).
Inflorescence:
The yellow to deep red flower heads are attractive to bees for both their nectar and pollen. The stigma and stamen are enclosed in the sheath of the keel petal. The pressure of a bee visiting the flower squeezes out a string of pollen from the opening in the keel petal. When the pressure is removed, the tips of the anthers return to their former position, and, when pressure is renewed, fresh pollen masses are extruded. At a later stage, the stigma elongates and also projects through the cleft.
Pollination Requirements:
Even though surrounded by its own pollen grains, the stigma is unreceptive to them. After the pollen is carried away or no longer viable, the stigma becomes receptive to pollen brought from other flowers. Thus, it is an entirely cross-pollinated plant (Knuth 1908*, pp. 297-298; Todd 1957*; Muller 1833*, pp. 172-173).
Pollinators:
Bees are primary pollinators of kidneyvetch.
Pollination Recommendations and Practices:
None.
KUDZU
Pueraria thunbergiana S. & Z. Benth. [=P. lobata (Willd.) Ohwi], family Leguminosae
Kudzu is a perennial, coarse, rapid-growing, long-lived twining plant. It is grown in the southeastern States for forage, pasture, soil improvement, and erosion control. Two decades ago, 300,000 acres were planted to kudzu in this area (Wheeler 1950). It is most frequently used along roadsides for erosion control (fig. 119). Interest in kudzu has decreased in recent years, probably because the species is not tolerant to grazing, and because its tendency to spread and crowd out other plants makes it undesirable in many places.
[gfx] FIGURE 119. - Kudzu, growing upon a steep slope, controls erosion and affords grazing for cattle.
Plant:
Kudzu has roundish trifoliate leaves, 2 to 4 inches across, and runners that may reach 60 feet in length. These runners frequently engulf large standing dead trees. Kudzu can be established by seeds, cuttings, or young transplants. The crowns of old plants will transplant, but their size and bulk limit their use. For this reason, seeds are preferred. Its propagation has been somewhat handicapped because of its poor seed setting ability (Dabadghao 1949).
Inflorescence:
Kudzu flowers are purple to reddish, and are produced in relative abundance in some areas and on some vines (fig. 120), but many that open will wilt and shed. Turner (l 959) stated that flowering is unknown in Texas. Mes (1953) stated that in Africa flowering occurs during the second season, and the flowers produce a sweet aroma. E. A. Hollowell (personal commun., 1971) stated that the plant must climb before it flowers. Wheeler ( 1950) stated that large purple flowers are produced in relative abundance, and precede the clusters of densely hairy pods, which are about 2 inches long and with usually few or no seed. Tabor (1942) noted that more seed set on old vines. Dabadghao (1949) also studied seed setting and recorded the appearance of flowers at 3 years of plant age. Mes (1953) stated that ripening required 21/2 to 3 months after the flower opened and that pollen was on the stigmas of some of the flowers that shed. Mes (1953) also noted that fruit setting took place at intervals on all inflorescences simultaneously, followed by a general period of flower shedding. He stated that when the wings and keel are depressed by the weight of a bee, the style, stigma, and anthers emerge through the gap at the tip of the keel; when the weight is removed they recede into the keel. The stigmatic surface is slightly above the top of the anthers. The stamens are all the same length. Pollen is shed when the flower opens.
[gfx] FIGURE 120. - Kudzu vine with flower clusters.
Pollination Requirements:
Wheeler and Hill (1957*) noted that three to five seeds per pod frequently mature, but there may be as many as 12. Mes (1953) caged a number of inflorescences and all flowers shed; he concluded that cross- pollination is necessary. Wheeler and Hill (1957*) concluded that a way will eventually be found to produce seed commercially, then the demand will increase. It would seem that if a method can be found to properly handle the pollination of this crop, then increased seed production will result.
Pollinators:
Bees are the only insects mentioned as pollinators of kudzu.
Pollination Recommendations and Practices:
Although planting seed is preferable to setting young plants or cuttings, the scarcity of seeds precludes this. An appropriate bee population might enable seed production to be practical, but no such usage has been developed. No recommendation currently exists on the use of insect pollinators on this crop.
LITERATURE CITED:
DABADGHAO, P. M.
1949. SEED SETTING IN KUDZU VINE (PUERARIA THUNBERGIANA) Current Sci. 10:
379 - 380. 238
MES, M. G.
1953. STUDIES ON GROWTH AND REPRODUCTION OF THE BUDZU VINE. So. African
Jour. Sci. 49(11): 335 - 339.
TABOR, P.
1942. SEED PRODUCTION BY KUDZU (PUERARIA THUNBERGIANA) IN THE SOUTHEASTERN
UNITED STATES DURING 1941. Amer. Soc. Agron. Jour. 34: 389.
TURNER, B. L.
1959. THE LEGUMES OF TEXAS. 283 pp. University of Texas Press, Austin.
WHEELER, W. A.
1950.FORAGE AND PASTURE CROPS. 752 pp. D. Van Nostrand Co., Inc., New York.
LIMA BEANS
Phaseolus lunatus L., family Leguminosae
In 1970, 70,630 acres of lima beans were grown for processing. The crop was valued at $14.5 million. USDA Agricultural Statistics no longer reports the fresh market acreage.
Plant:
The majority of the acreage is devoted to the bush type of lima beans, an annual with a somewhat woody stem and determinate type of growth, about 2 feet high. The vining, climbing, or pole type may grow to 10 feet and has indeterminate flowering habits, so that fruit is continually produced as long as climatic conditions favor plant growth. With determinate types, most of the inflorescences develop about the same time, which results in a more or less uniform set of fruit. In fact, satisfactory yields are dependent upon obtaining a "capacity set" of pods (fig. 124) during the first 2 weeks of the blossoming period (Hawthorn and Pollard 1954*). Lima beans require a long growing season, but without excessively high temperatures, such as is found along the coast of southern California and in Delaware.
[gfx] FIGURE 124. - Lima bean pods.
Inflorescence:
The white or cream-colored, legume-type flower of the lima bean is borne at the end of a pedicel on a 2- to 4-inch-long raceme. Usually, only a small percentage of the flowers on a raceme set. Various reasons for this failure have been given, including high temperature and low humidity (Cordner 1933), improper soil moisture (Lambeth 1950), and inadequate pollination (Amos 1943). In the flower itself, the keel is elongated into a spirally twisting beak. The style, which follows the spirals of the keel, is also twisted. It is bearded below the stigma (fig. 125). Knuth (1908*, pp. 339 - 340) stated that the stigma, and a portion of the spirally twisted style with pollen adhering to the brush of hairs, projects from the tip of the keel petal when this is depressed and returns again when the pressure is removed. The anthers surround the style and shed their pollen upon it, but the stigma is never dusted before it is exserted. If the stigma is pollinated by the insect visitor before it is touched by its own pollen, cross-pollination can result.
Anthesis occurs between 7 and 8 a.m. The flower never closes, but the corolla is shed after a few days. Nectar is secreted at the base of the corolla and is the source of a fine quality honey. Bees also visit the plant for its pollen. Nectar secretion seems to be greatest when plants first come into bloom, and it remains intense for about a week - then tapers off.
[gfx] FIGURE 125. - Longitudinal section of 'Murphy' lima bean, x 7. Inset shows tip of keel and stigma protruding, enlarged.
Pollination Requirements:
Magruder and Wester (1942) caged plants and concluded, without taking data, that set of pods on most families under the cloth was as good as, if not better than, on uncovered plants. However, Amos (1943) caged plots to exclude bees, and compared production with plots that were shaded, but otherwise left open to bee visitation. He reported about a 30 percent increase in yield due to the presence of bees. He stated that 30 colonies were within 1 mile of the test plots, but the acreage of beans in bloom was not given. Because the observations were made in an area of commercial lima bean production, there could have been hundreds of acres of beans and the honey bee colony per acre ratio could have been quite low. The increase was in numbers of pods, beans per pod, and total weight of beans. He gave no indication as to the pollinator density in the field.
Wester and Jorgensen (1951) found hybrid vigor in all lima bean crosses tested, with production exceeding the best parent in all cases. They stated that a high percentage of crossing was needed. Others have noted that this occurs naturally in some areas now (Magruder and Wester 1940, Barrons 1939, Welch and Grimball 1951, Magruder 1948).
Allard (1954) caged plants with and without bees to obtain a measurement of bee activity in terms of hybrid beans produced. He obtained 2.38 percent hybrids from caged plants visited by bees, and 1.06 percent in cages from which bees were excluded. In open plots dusted with DDT, he obtained 0.21 percent hybrids; but in other plots not dusted, he obtained 1.48 percent hybrids. These experiences and observations indicate that the lima bean, like other beans, is capable of self- pollination but cross-pollination can and does occur. The amount of crossing and its value seem to depend upon the number and species of insect pollinators present or the degree of insect visitation to the crop.
Boswell (1961) stated that the lima bean does not benefit from the intervention of insects; however, other works are not in complete agreement.
Pollinators:
Allard (1954) gave thrips credit for the cross-pollination he obtained. In the light of other research on lima beans, as well as on thrips as pollinators, his data are quite open to question. Incidentally, Mackie and Smith (1935) also gave thrips credit for cross-pollinating beans. Jones and Rosa (1928*) noted that honey bees, bumble bees, and other insects visit the flowers and cause cross-pollination.
Vansell and Reinhardt (1948) compared production from caged and open plots and also from areas of high and low general bee activity throughout the flowering period. They noted that 34.4 percent of the flowers set in the area where bee activity was high and continuous, but only 5 to 22 percent set where insecticides were applied. Because of the insecticide applications, most of the colonies were moved away during part of the flowering period, resulting in low pollinator activity. In fact, they recorded one bee per yard of row before the evacuation of the colonies began, but only one bee per 33 yards of row afterwards. Yet even with this low bee activity, they reported a greater yield in both number and weight of beans from open than from the caged plants. Wester and Jorgensen (1950) stated that bumble bees and honey bees were responsible for most of the lima bean crossing in the field. Anderson (1959) reported that lima bean plants caged with bees set more beans during early blooming period, and the beans were larger than in cages where bees were excluded. He reported that bees visited lima beans in abundance.
Pollination Recommendations and Practices:
Despite the rather promising results on the value of ample insect pollination on the increased production of lima beans by Amos (1943) and Vansell and Reinhardt (1948) and the intriguing study by Drayner (1956) on the value of cross-pollination to increased production of subsequent crops, there has been no follow-up. Beekeepers move their bees to lima bean fields to obtain honey crops, and some growers encourage placement of apiaries in the vicinity of their crops, because they feel that the bees "help." The number of pollinators supplied to crops in this manner is probably not sufficient for maximum activity on the blossoms. The use of bees as pollinators of lima beans is not recommended by the States in which these crops are grown, nor are there data to indicate the appropriate pollinator population desired for maximum production. Studies leading to such a recommendation are needed. In the interim, the meager data available would indicate that growers would materially benefit if they arranged for placement of numerous colonies in and adjacent to their lima bean fields at flowering time and took steps to protect these pollinators from harmful pesticides
LITERATURE CITED:
ALLARD, R. W.
1954. NATURAL HYBRIDIZATION IN LIMA BEANS IN CALIFORNIA. Amer. Soc. Hort.
Sci. Proc. 64: 410-416.
AMOS J. M.
1943. A MEASUREMENT OF THE VALUE OF BEES IN THE POLLINATION OF LIMA BEANS.
Amer. Bee Jour. 83: 240 - 241.
ANDERSON, E. J.
1959. TWO PART POLLINATION PROGRAM CARRIED OUT ON UNIVERSITY FARMS. Penn.
Beekeeper 34(3): 4 - 8.
BARRONS, K. C.
1939. NATURAL CROSSING IN BEANS AT DIFFERENT DEGREES OF ISOLATION. Amer.
Soc. Hort. Sci. Proc. 36: 637-640.
BOSWELL, V. R.
1961. FLOWERING HABITS AND PRODUCTION OF SEEDS. U.S. Dept. Agr. Yearbook
1961: 57 - 64.
CORDNER, H. B.
1933. EXTERNAL AND INTERNAL FACTORS AFFECTING BLOSSOM DROP AND SET OF PODS
IN LIMA BEANS. Amer. Soc. Hort. Sci. Proc. 39: 571 - 576.
DRAYNER, J. M.
1956. REGULATION OF OUTBREEDING IN FIELD BEANS. Nature 177: 489-490.
LAMBETH, V. N.
1950. SOME FACTORS INFLUENCING POD SET AND YIELD OF THE LIMA BEAN. Mo.
Agr. Expt. Sta. Res. Bul. 466, 60 pp.
MACKIE, W. W., and SMITH, F. L.
1935. EVIDENCE OF FIELD HYBRIDIZATION IN BEANS. Amer. Soc. Agron. Jour.
27: 903-909.
MAGRUDER, R.
1948. NATURAL CROSSING OF LIMA BEANS IN SOUTHERN CALIFORNIA IN 1946. Amer.
Soc. Hort. Sci. Proc. 51: 471-474.
______and WESTER, R. E.
1940. NATURAL CROSSING IN LIMA BEANS IN MARYLAND. Amer. Soc. Hort. Sci.
Proc. 37: 731-736.
______and WESTER, R. E.
1942. PREVENTION OF FIELD HYBRIDIZATION IN THE LIMA BEAN. Amer. Soc. Hort.
Sci. Proc. 60: 413-414.
VANSELL, G. H., and REINHARDT, J. F.
1948. DO HONEY BEES HELP POLLINATE BABY LIMA BEANS? Gleanings Bee Cult.
76: 678-679.
WELCH, J, E., and GRIMBALL, E. L.
1951. NATURAL CROSSING IN LIMA BEANS IN S. CAROLINA. Amer. Soc. Hort. Sci.
Proc. 58: 254 - 256.
WESTER, R. E., and JORGENSEN, H.
1950. EMASCULATION UNNECESSARY IN HYBRIDIZING LIMA BEANS. Amer. Soc. Hort.
Sci. Proc. 55: 384 - 390.
____ and JORGENSEN, H.
1951. HYBRID VIGOR IN lIMA BEANS. Amer. Soc. Hort. Sci. Proc. 57: 305-309.
LUPINES
Lupinus angustifolius L., family Leguminosae
Blue lupines are grown for grazing, soil improvement, and cover, primarily in southern Georgia and northern Florida. Two decades ago, more than a million acres of lupines were grown. Since then, the acreage has dropped sharply and so have the number of species because of virus infection of the plants. Presently, some 300,000 to 400,000 acres of blue lupines are grown mostly for forage or in citrus groves (Edwardson 1963; J. R. Edwardson, personal commun., 1971).
Plant:
Blue lupines usually have upright branches, 1 to 4 feet tall, with nitrogen-fixing Rhizabium nodules on the roots, as occurs with most other legumes. The stems are relatively coarse. The seeds are relatively large, and the flowers are in large terminal or lateral racemes. The leaves may consist of 5 to 11 leaflets arising at a common point. The dense foliage will provide as much as 40,000 pounds of green manure per acre (McKee 1948).
Inflorescence:
The flower cluster is a 6- to 12-inch upright raceme, and each floret is l/2 to 1 inch in size. The petals may be shades of blue, purple, or pink. They are supposed to be nectarless but fragrant (Knuth 1908*, pp. 271 - 272; Edwardson et al. 1963), although Pellett (1947*) stated that some lupines are honey plants. The blue lupine is not a honey plant, but the pollen is attractive to bees.
The anthers dehisce before the flower opens, and after they release the pollen they shrivel, leaving the pollen in the hollow cone of the flower. When insects visit the flower, their weight causes the stamens to extrude pollen through the opening in the keel, ahead of the stigma, where pollen- carrying insects can effect crossing. Automatic self-pollination does not occur (Knuth 1908*, pp. 271 - 272). To protect the bee visitors, Edwardson et al. (1963) recommended the use of insecticides only when the bees were not visiting the plants.
Pollination Requirements:
McKee et al. (1946) and McKee and Ritchey (1947) stated that most flowers of blue, white, and yellow lupines are self-fertilized, but some crossing within (but not between) species occurs. Julen and Akerberg (1948) stated that even in some plant species considered to be self- fertilizing, seed setting is improved by insect visits This applies particularly to yellow lupine.
Kozin (1967) found that visits by honey bees substantially increased the number of pods set in three of five cultivars, the length of pod in 7 of 13 cultivars, the number of seed in all cultivars tested but three, and the weight of seed for all cultivars but two. The visits also increased the germination qualities of the seed Wallace et al. (1954) quoted Troll (1948) as saying that cross-pollination is always more frequent in yellow lupine than blue and that the extent varies with the distance to the nearest apiary. They showed practically no hybrids resulted from bee activity on blue lupines but 19.9 percent from plants of yellow lupine, both oi which were only a quarter of a mile from an apiary They also noted that honey bees work the sweet yellow lupines. Forbes et al. (1971) concluded that blue lupine is highly self-compatible, and fully capable of self-poll) nation in closed flowers independent of insect pollina tion. However, their data show that both 'Rancher' and '65G-251' selections produced more seed when there was no barrier to pollinating insects than when either poultry wire of 2.5 cm mesh or fine screen enclosed the plants. This would indicate that insects have a beneficial effect.
Pollinators:
Kozin (1967) showed that honey bees represented 83 percent, bumble bees 9.6 percent, and other insects 7.4 percent of the visitors to "fodder" lupine. He further noted that 56.5 percent of the bees collected pollen and inserted their proboscis into the flower. Leuck et al (1968) also considered the honey bee to be the most important pollinator on blue lupine. Forbes et al (1971) considered neither bumble bees nor thrips of consequence and attributed the range of crossing the observed (from 0 to 12.0 percent) to known honey bee population densities.
The honey bee, then appears to be the primary flora visitor. Kozin (1967) recommended that honey bees be widely used for increasing the seed crop of lupines, but the species of lupines involved was not given. Thorp (1957*) listed white, yellow, and blue lupines under the heading "Seed Production Increased by Bees." Horovit and Thorp (1970) considered the bumble bee to be better than the honey bee in the pollination of L. nanus Dougl.
Pollination Recommendations and Practices:
None.
LITERATURE CITED:
EDWARDSON, J. R.
1963. RITCHEY- AN IMPROVED SEED PRODUCING VARIETY OF BITTTER BLUE LUPINE.
Fla. Agr. Expt. Sta. Cir. S-143, leaflet.
_____WELLS, H. D., and FORBES, I., JR.
1963. BLUE LUINES FOR GRAZING AND FOR SOIL IMPROVEMENT IN FLORIDA. Fla.
Agr. Expt. Sta. Cir. S-146, 7 pp.
FORBES, I., LEUCK, D. B., EDWARDSON, J. R., and BURNS, R. E.
1971. NATURAL CROSS-POLLINATION IN BLUE LUPINE (LUPINUS ANGUSTIFOLIUS L.)
IN GEORGIA AND FLORIDA. Crop Sci. 11: 851-854.
HOROVITZ, A., and THORP, R. W.
1970. BEES AS TOOLS IN STUDIES OF REPRODUCTIVE BIOLOGY OF PLANTS.] Amer.
Midland Nat. 84: 560-563.
JULEN, G., and AKERBERG, E.
1948. [INSECTS AND SEED SETTING IN AGRICULTURAL PLANTS.] Svensk Jordbr.
Forsk. Arsbok: 86-97. [In Swedish.] Abstract in Herbage Abs. 18(4): 899,
Aug. 1948.
KOZIN, R. B.
1967. INFLUENCE OF BEE (APIS MELLIFERA) POLLINATION OF LUPINE (LUPINUS
L.) ON SEED YIELD AND QUALITY. In 21st Internatl. Apic. Cong. Proc., Aug.,
College Park, Md., p. 481.
LEUCK, D. B., FORBES, I., BURNS, R. E., and EDWARDSON, J. R.
1968. INSECT VISITORS TO FLOWERS OF BLUE LUPINE (LUPINUS ANGUSTIFOLIUS).
Jour. Econ. Ent. 61: 573.
MCKEE, R.
1948. THE LEGUMES OF MANY USES. U.S. Dept. Agr. Yearbook 1948: 701-726.
_____HYLAND, H. L., and RITCHEY, G. E.
1946. PRELIMINARY INFORMATION ON SWEET LUPINES IN THE U. S. Amer. Soc.
Agron. Jour. 38: 168-176.
_____and RITCHEY, G. E.
1947. LUPINES, NEW LEGUMES FOR THE SOUTH. U.S. Dept. Agr. Farmers' Bul.
1946, 10 pp.
TROLL, H. J.
1948. [PROBLEMS IN THE DEVELOPEMENT AND BREEDING OF THE MUNCHBERGER LUPINES.
Der Zucher 19: 153-177. [In German.]
WALLACE, A. T., HANSON, W. D., and DECKER, P.
1954. NATURAL CROSS-POLLINATION IN BLUE AND YELLOW LUPINES. Agron. Jour.
46: 59.
MUNG BEAN, GREEN OR GOLDEN GRAM
Phaseolus aureus Roxb., family Leguminosae
At one time the mung bean was a crop of considerable importance. Martin and Leonard (1949*) stated that in 1945 110,000 acres were grown in Oklahoma.
In 1967, when records on this crop were discontinued, 34,000 acres were harvested, yielding 400 pounds seed per acre, for which a price of only 0.06 cents per pound was obtained. Mung bean is an important crop in India where it rates as the most wholesome among the pulses. The beans are boiled and eaten whole, parched and ground into flour, eaten green as a vegetable, or used for bean sprouts (Yohe and Poehlman 1971). The crop is also grown for hay, green manure, and as a cover crop (Purseglove 1968*).
Plant:
The mung bean is an erect or suberect, deep-rooted, many-branched, rather hairy, annual herb 1 1/2 to 5 feet tall. The gray, black, or brownish pods, 2 to 4 inches long, may contain 10 to 15 small, round, usually green but sometimes yellow or blackish seed.
Inflorescence:
The inflorescence is an axillary raceme, with 10 to 25 pale-yellow flowers, 1 1/2 to 2 cm long, and clustered at the top. Pollen is shed the afternoon before the flower opens the following morning. The flower fades the same afternoon. Only about half of the flowers (64 percent) open to permit possible cross-pollination.
Pollination Requirements:
Purseglove stated, "The flowers are fully self-fertile when bagged and almost entirely self-pollinated." However, van Rheenen (1964) stated that when he alternated varieties in the row, he obtained 2.8 to 3 percent crossing.
Pollinators:
There seems to be no information on the pollinators involved.
Pollination Recommendations and Practices:
None.
LITERATURE CITED:
RHEENEN. H. A. VAN.
1964. PRELIMINARY STUDY OF NATURAL CROSS-FERTILIZATION IN MUNG BEAN, (PHASEOLUS
AUREUS ROXB.). Netherlands Jour. Agr. Sci. 12(4): 260-262
YOHE J. M., and POEHLMAN J. M.
1971. BREEDING MUNG BEANS, A FOOD GRAIN LEGUME IN INDIA. Agron. Abs. 1971,
Ann. Mtg. Amer. Soc. Agron., p. 18.
PIGEONPEA
Cajanus cajan (L.) Millsp., family Leguminosae
The pigeonpea or cajan is adapted to the tropics and subtropics where it is one of the most valuable legumes. It is cultivated as an annual for both forage and its edible beans, which are produced in abundance (Graham 1941*). It is common in India, Hawaii, and Puerto Rico and has been tried extensively in Florida and some other southern stations on an experimental basis but is not grown commercially within the continental United States (McKee and Pieters 1937). Killinger (1969) conducted tests with 'Norman' cv. in Florida and concluded that it shows promise as a seed, hay, cover, grazing, or windbreak crop.
Plant:
Pigeonpea is a pubescent, many-branched shrub (but cultivated as an annual), 4 to 10 feet or more tall, with yellow or orange papilionaceous flowers that produce brown, hairy, four- to seven-seeded, long-beaked pods, 2 to 3 inches Iong by 1/2 inch thick.
Inflorescence:
The 1 1/2 to 5-inch terminal and/or axillary raceme bears several flowers that resemble the common sweet pea in shape, but the color is yellow, red, or yellow-purple with a brownish back. The filaments elongate in the bud, and pollen is shed the day before the flower opens. Whether actual pollination of the stigma occurs before the flower opens is not clear. The majority of the flowers open between 1 a.m. and 3 p.m., and often remain open for only about 6 hours (Purseglove 1968*). Bees visit the flowers in great numbers (Wilsie and Takahashi 1934), but whether they do so to collect pollen, nectar, or both has not been reported.
Pollination Requirements:
Krauss (1932) and Wilsie and Takahashi (1934) considered the pigeon pea to be a normally self-pollinated species. However, a high degree of cross- pollination, ranging from 5 to 40 percent, has been observed (Wilsie and Takahashi 1934, Purseglove 1968*, Matta and Dave 1931, Krauss 1927, Shaw 1932, Abrams 1967).
There is no information on the need for pollinating agents in the production of seeds. Apparently, seeds can be produced when insects are excluded from the flowers (Abrams 1967), but whether production by plants where pollinating insects are excluded is equal to open pollinated plants has not been determined.
Pollinators:
Abrams (1967) stated that bees visit the flowers in large numbers. He also indicated that thrips might be of some significance. Purseglove (1968*) stated that the flowers are visited by "bees and other insects," and Wilsie and Takahashi (1934) stated that bees visit the flowers in great numbers. These references indicate that, if insect pollination is beneficial in pigeonpea seed production, there should be no problem in building up a high bee population on the crop.
There is no proven value of pollinating insects to pigeonpeas, even though the evidence indicates these insects might be of value.
Pollination Recommendations and Practices:
None.
LITERATURE CITED:
ABRAMS, R.
1967. STUDIES ON NATURAL CROSS-POLLINATION IN PIGEONPEAS (CAJANUS CAJAN).
Puerto Rico Univ. Jour. Agr. 51(1): 1-3.
KILLINGER, G. B.
1969. PIGEONPEAS (CAJANUS CAJANS (L.) DRUCE)- A USEFUL CROP FOR FLORIDA.
Soil Crop Soc. Fla. Proc. 28: 162-167.
KRAUSS, F. G.
1927. IMPROVEMENT OF THE PIGEONPEA, GENETIC ANALYSIS OF CAJANUS INDICUS
AND THE CREATION OF NEW VARIETIES THROUGH HYBRIDIZATION AND SELECTION.
Jour. Hered. 18: 227-232.
______ 1932. THE PIGEONPEA (CAJANUS INDICUS) ITS IMPROVEMENT, CULTURE AND UTILIZATION IN HAWAII. Hawaii Agr. Expt. Sta. Bul. 64, 46 pp.
MATTA, D. N., and DAVE, B. E.
1931. STUDIES IN CAJANUS INDICUS. India Dept. Agr., Mem. Bot. Ser. 19,
25 pp.
MCKEE, R., and PIETERS, A. J.
1937. MISCELLANEOUS FORAGE AND COVER CROP LEGUMES. U.S. Dept. Agr. Yearbook
1937: 999-1031.
SHAW, F. J. F.
1932. THE BREEDING OF CICER AND CAJANUS. Imp. Burl Plant Genet., Herbage
Plants Bul. 7: 14-16.
WILSIE, C. P., and TAKAHASHI M.
1934. NATURAL CROSSING IN THE PIGEONPEA. Jour. Agr. Res. 49: 923-927.
SAINFOIN
Onobrychis viciifolia Scop, family Leguminosae
Sainfoin is sometimes called esparcet or holy clover. The crop is limited to a few acres grown in Montana.
Plant:
Sainfoin is a perennial with a deep taproot and stout erect stems arising from a many-branched crown. Some plantings in Montana are 60 years old and still used for pasture (Dubbs 1967). The plant may grow from 15 to 40 inches high. It requires a soil rich in lime. Because it can withstand temperatures as low as -40 deg F., it can grow in the coldest parts of the country.
Inflorescence:
The pinkish or rose-colored flowers occur on terminal, erect, close racemes at the top of the plant, giving a field in flower a delicate rose color. The flower mechanism is essentially like that of white clover or sweetclover. The weight of a bee on the flower causes the stigma and anthers to protrude from the keel, then return after the weight is removed. The stigma projects beyond the anthers so that cross-pollination is assured should the bee visit occur. Lateral access to the nectar in the flower by the bee is impossible. The calyx tube is only 2 to 3 mm deep, so most melliferous insects can reach the nectar and pollen. The style becomes more and more erect as anthesis progresses, and ultimately projects 1 to 1 1/2 mm beyond the cleft in the keel (Knuth 1908*, p. 319). Tereshchenko (1949) stated that flowers may open throughout the day but mostly in the morning. They usually remain open only 1 day. Flowering begins at the base of the raceme and takes 2 to 3 weeks to reach the tip. The seed develops in a one-seeded pod.
Sainfoin blossoms secrete nectar excessively and are highly attractive to pollinating insects, particularly honey bees. Pollen is also produced in abundance. Dubbs (1968) stated that 20 hives placed on 4.78 acres was insufficient for bee saturation. An estimated ninetenths of all bee visitors were honey bees.
Graham (1941*), Madoc (1934), Alfonsus (1929), Dubbs (1967), and Pellett (1947*) reported that sainfoin honey is of the finest quality. Kropacova (1969) calculated the total quantity of nectar sugar produced as 32.8 to 130.3 kg/ha or 29 to 155 lb/acre.
Pollination Requirements:
Bosca and Hejja (1963) stated that self-fertility of the plants ranged from zero to 37 percent. They also found that inbred plants produced only 70 percent as many stems and weighed only 73 percent as much as crossed plants. Knuth (1908*, pp. 318-319) indicated that cross- pollination of sainfoin flowers was required because automatic self- pollination does not occur. Kropacova (1969) found that seed production of exposed plants was 10 to 25 times as great as that from plants caged to exclude bee visitors (caged plants yielded 9.75 g/m2), whereas plants exposed to bees yielded 179.13 g/m2). Sainfoin seed production is primarily dependent upon bee pollination. The most effective time for bees to visit sainfoin flowers has not been determined, nor has the effect of bee pollination on the appearance of the flower. Flowers of many other species of plants begin to fade or wilt shortly after they are pollinated.
Tereshchenko (1949) caged plants to exclude bees and obtained only 3.2 percent set of blooms (3.2 g seed) compared to 42.7 percent set (49.2 g seed) of those not caged. He also found a high negative correlation between distance from the apiary and seed set.
Pollinators:
The honey bee is doubtless the most populous of insect visitors to sainfoin flowers. Pellett (1947*) stated that he saw 100 bees on sainfoin for each 10 on white clover, a plant considered highly attractive to bees. Honey bees begin visiting the flowers quite early in the morning and continue to visit them throughout the entire day.
Pollination Recommendations and Practices:
Kropacova (1969) recommended two to three colonies of honey bees per hectare (about one colony per acre) located close to the field. This seems rather low when we consider Dubbs' (1968) statement that 20 colonies placed on a 4.78-acre seed field were insufficient for bee saturation. He calculated that two to three colonies per acre would provide five or six visits to every sainfoin flower. This would appear to be low, thus more colonies may be required.
LITERATURE CITED:
ALFONSUS, J.
1929 SAINFOIN NEXT TO THE CLOVERS AS A HONEY PLANT. Amer. Bee Jour. 79:
113-115.
BOSCA, I., and HEJJA, S.
1963. [DATA ON FERTILIZATION IN SAINFOIN (ONOBRYCHIS VICIIFOLIA SCOP.).]
Novenytermeles 12(2): 137-142. [In Hungarian, English summary.]
DUBBS, A. L.
1967. SAINFOIN: A NEW HONEY CROP FOR MONTANA. Amer. Bee Jour. 107: 18-19.
______ 1968. SAINFOIN AS A HONEY CROP. Mont. Agr. Expt. Sta. Bul. 627: 108-109.
KROPACOVA, S.
1969. THE RELATIONSHIP OF THE HONEY BEE TO SAINFOIN (ONOBRYCHIS SATIVA).
In 22d Internatl. Apic. Cong. Proc., Munich, pp. 476-477.
MADOC, E. W. D.
1934. SAINFOIN, FODDER AND HONEY PLANT. Amer. Bee Jour. 74: 201.
TERESHCHENKO, A. K.
1949. [POLLINATION OF SAINFOIN BY HONEYBEES ] Pchelovodstvo 26(6): 338
- 341. [In Russian.]
SCARLET RUNNER BEAN
Phaseolus coccineus L., family Leguminosae
The scarlet runner bean, or runner bean, native to Mexico or Central America (Graham 1941*) and of major importance in parts of Europe, is of minor importance in the United States, where it is sometimes called the Oregon lima bean.
Plant:
The roots of the slender, twining scarlet runner bean are tuberous and live for several years, but frost kills the aerial part; therefore, it is an annual plant above the ground, but a perennial beneath (Kooistra 1968). The plant may grow to a height of 10 to 15 feet if staked, but when grown commercially the crop is not staked. It is harvested by the same method used in harvesting lima beans, with yields of 1,200 to 1,500 lb/acre of seed (Hawthorn and Pollard 1954*).
Inflorescence:
The showy blossoms are borne on long racemes. They are attractive to various species of bees for both nectar and pollen. Darwin (1874) showed that the blossom is ingeniously contrived to insure that insect visitation results in pollination. This is brought about by a pair of nectar holes at the base of the staminal tube, almost covered by a flap on one stamen. When the bee forces this flap aside, it rubs across the staminal column and transfers pollen from anthers to stigma.
Pollination Requirements:
Darwin (1889*) covered scarlet runner beans to exclude pollinating insects and obtained only one-eighth and one-third as many beans as were obtained from open plants. In a more elaborate experiment, Free (1966) caged scarlet runner beans with and without honey bees to determine the need for insect pollination. Plants caged with bees set 1,479 g of pods per plant, compared with 180 g per plant where bees were excluded. Other factors varied correspondingly: Pods per plant, 96:11; grams of seed per plant, 356:50; number of seeds, 206: 30; and seeds per pod, 3.9 in bee cages compared to 2.7 in cages where bees were excluded. Only the mean weight per seed was unchanged. The pods in the cages without bees could not be harvested until later in the season than those in the bee cages. Tedoradze (1959) obtained similar benefits from bees.
Mommers (1971) studied the pollination of runner beans under glass and reported that bees had no effect on production of beans. He concluded that varietal differences influenced the results obtained by Free (1966), and that this accounted for the differences reported.
Pollinators:
Henslow (1878) showed that bumble bees pollinated scarlet runner beans. Free and Racey (1968) showed that honey bees were as useful as bumble bees in pollination of scarlet runner beans grown in glass houses, although Free (1968) found that individual bumble bees worked faster and visited more flowers per plant than did honey bees. Bumble bees often pierce a hole in the base of the flower and steal the nectar without contributing to pollination. Subsequently, honey bees visit this hole and again pollination is bypassed (Jany 1950).
Pollination Recommendations and Practices:
Blackwall (1964) said that adequate pollination is a must for early yields and that lack of insect pollination is the most important single cause for low yield of beans. Blackwall also stated that where lack of pollination is a recurrent problem, it may be worthwhile to hire colonies of honey bees to supplement the local pollinator population. She recommended that beekeepers supply small, rapidly expanding colonies, which have a high need for pollen.
Free (1966) stated that because honey bees are clearly effective in pollinating scarlet runner beans, their use should increase yields where pollination is a limiting factor. However, he did not make a recommendation to growers on the use of honey bees as pollinators of this crop. The evidence indicates, however, that if the grower wants to obtain maximum yields and harvest the seeds as early as possible, he should have a high pollinator population in his field, particularly during early flowering.
LITERATURE CITED:
BLACKWALL, F. L. C.
1964. RUNNER BEANS: ADEQUATE POLLINATION IS A MUST FOR EARLY YIELDS. Grower
61: 1272-1273.
DARWIN, F.
1874. BEES VISITING FLOWERS. Nature 9: 189-190.
FREE, J. B.
1966. THE POLLINATION OF THE BEANS PHASEOLUS MULTIFLORUS AND PHASEOLUS
VULGARIS BY HONEYBEES. Jour. Apic. Res. 5: 87-91.
______ 1968. THE BEHAVIOUR OF BEES VISITING RUNNER BEANS (PHASEOLUS MULTIFLORUS). Jour. Appl. Ecol. 5: 631-638.
______and RACEY. P. A.
1968. THE POLLINATION OF RUNNER BEANS (PHASEOLUS MULTIFLORUS) IN A GLASSHOUSE.
Jour. Apic. Res. 7: 67-69.
HENSLOW, G.
1878. THE FERTILIZATION OF THE SCARLET RUNNER BEAN BY BUMBLE- BEES. Gard.
Chron., n.s., 10: 561.
JANY, E.
1950. [THE PIERCING OF SCARLET RUNNER FLOWERS BY BUMBLE BEES.] Ztschr.
f. Angew. Ent. 32(2): 172-183. [In German.] AA-45/54.
KOOISTRA, E.
1968. SELECTION IN RUNNER BEANS (PHASEOLUS CONCINNUS) WITH SPECIAL REFERENCE
TO THE USE OF TUBEROUS ROOTS. Euphytica 17: 183-189.
MOMMERS, J.
1971. [THE POLLINATION OF BEANS PHASEOLUS UNDER GLASS.] Maandschr. v. de
Bijent. 73(5): 79-80. [In Dutch English summary.]
TEDORADZE, S. G.
1959. [THE ROLE OF BEES IN THE SHAPE-FORMING PROCESS OF [SCARLET RUNNER]
BEANS UNDER GEORGIAN CONDITIONS.] Pchelovodstvo 36(9): 40-42. [In Russian.]
SOYBEAN
Glycine max (L.) Merr., family Leguminosae
Soybeans comprise the most important oilseed crop grown in the United States. Approximately 41 million acres of soybeans were grown with a farm value of $2.6 billion. The crop is widely grown in all areas except New England and the West. The primary reason for growing the crop is for the beans, which are processed to obtain oil and a high protein meal.
Plant:
The soybean is a bushy, upright, annual, summer legume, 1 to 4 feet tall, with dense, alternate, and usually trifoliate oval leaves 2 to 4 inches across. The plant is not frost resistant so it must be grown after spring frosts are past and have time for the seeds to mature before the first fall frost. Many selections or cultivars are bred for production under different daylength or other environmental conditions. They range in maturity from 75 to 200 days. There are hundreds of selections under test; however, only 17 cultivars make up 88 percent of the acreage in the 14 major producing States.40
The seeds are borne, one to five (usually two or three) to a pod (Weiss
1949), the 3 to 15 pods are in a cluster on the short seed stalk in the
rachis or base of the leaf. A productive plant may have as many as 100
seed clusters. The seeds are mechanically harvested after the plant sheds
its leaves as it matures.
__________
40 UNITED STATES DEPARTMENT OF AGRICULTURE. Highlights
of U.S. Crop Report as of November 1, 1971. U.S. Dept. Agr. Crop Prod.
CrPr 2-2, 33 pp. 1971.
Inflorescence:
There may be from 1 to 35 purple or white florets, three-eighths of an inch long, on each short raceme or flower cluster. A single plant may bear as many as 800 florets, but may set only 13 to 57 percent (van Shaik and Probst 1958). The floret has the characteristics and shape of many other legume flowers - a large standard petal, two small wing petals, and a keel petal that encloses the staminal column (fig. 174). The calyx is relatively large in proportion to the flower or even to the calyx of other legumes. Each floret is capable of producing a bean pod. Southern grown cultivars stop growing when flowering begins. Flowering usually continues for 4 to 6 weeks. There may be one-half million florets per acre. There are no extrafloral nectaries (Jaycox 1970).
Soybean flowers attract relatively few bees (Blickenstaff and Huggans 1962); however, bees do visit the flowers for both pollen and nectar. The anthers dehisce before the flower opens so that the stigma is in contact with and receptive to the pollen on the anthers. Pollination and fertilization is usually accomplished before the flower opens. Beekeepers in some areas frequently report honey crops from soybeans ( Hambleton 1936, Jaycox 1970, Pellett 1947*). Beekeepers in other areas report that bees never visit the flowers, or if they do no honey is obtained.
[gfx] FIGURE 174. - Longitudinal section of soybean flower, x 25.
Pollination Requirements:
The soybean is considered to be self-fertile and not benefited by insect pollination (Morse and Cartter 1937, Rubis 1970). Although there is no experimental evidence to support them, some soybean growers in Arkansas have indicated that bees increase production of beans, and they encourage the presence of apiaries near their fields. Tests with plants caged to exclude bees have shown no decrease in production over exposed plots (Woodhouse and Taylor 1913, Milum 1940, Piper and Morse 1910). Culter (1934) obtained an estimated 5 percent cross-pollination in open plots surrounded by 36-inch cheesecloth fences with an apiary nearby. Gordienko (1960) used honey bees in cages with two cultivars of soybeans. He fed the bees a scented sirup to stimulate the floral visitation and obtained 29 percent hybrids on one cultivar and 44 percent on the other.
Various tests have been conducted to determine the amount of cross-pollination that occurred at different locations, but the agents responsible for the crossing obtained were usually not determined, possibly because the tests were conducted by agronomists who did not consider themselves qualified to record these observations (Caviness 1966,1970; Caviness et al. 1970; Garber and Odland 1926; Woodworth 1922).
Weber et al. (1970) stated that, for a highly self-fertilizing species such as soybeans, two requirements must be met for successful production of hybrid seed. First, there must be heterosis (or an increase in production, or some other beneficial effect, of the cross over the best parent), and there must be an economical, large-scale method of producing the hybrids. Brim and Young (1971) have reported that male sterility, although not cytoplasmic, has been found and that 99 percent of the seed set on the male-sterile plants was due to cross-pollination; however, the total seed set was extremely low.
Veatch (1930) showed that hybrid soybeans out-yielded the average parent variety up to 95.9 percent and the higher parent variety up to 71.5 percent. Weiss et al. (1947) showed a range of 14.2 to 71.3 percent heterosis over the best parent in the greenhouse, and 5.9 to 38.6 percent increase over the best parent in the field. Weiss (1949) showed an increase of 19.6 to 117 percent increase of the hybrid over the best parent. Wentz and Stewart (1924) showed increases of 60 to 397 percent. Weber et al. (1970) showed an average for all tests of the hybrids over the best parents of 13.4 percent.
Mention might be made that the increased yields for hybrids are all based upon a relatively low number of widely spaced plants. Because of the problems in making a sufficient number of hand pollinations to satisfactorily evaluate F1's in a normal-type planting, essentially no such studies have been conducted. The extremely large increases that have been reported are assumed to be partly a result of the extra space allotted to the plants.
Bradner (1969) stated that all of the breeding components have been described for the production of hybrid soybean seeds, except that a suitable pollen vector has not been found, although the honey bee "looks encouraging." Piper and Morse (1923) noted that soybean flowers were "much visited by bees." They also noted that three of their varieties, when in full flower at Jackson, Tenn., were very fragrant - the odor suggesting that of lilacs. Although they gave no indication that these varieties were more attractive to bees than other varieties, the information indicates that cultivars might be selected with aroma or attractiveness that when incorporated in a hybrid seed program might efficiently attract pollinating insects. Because of the potential value of hybrid soybeans, the breeders might watch for selections that show attractiveness to bees.
Pollinators:
Little attention has been paid to the prevalence of pollinating insects on soybeans. Jaycox (1970) reported only seven honey bees per 100 yards of row, but he gave no indication as to number of honey bee colonies and the acres of soybeans in the area. Blickenstaff and Huggans (1962) recorded only one honey bee, three leafcutter bees, and nine halictids in 25,346 individual insects collected on soybeans with a sweepnet, but this is a poor method for determining pollinator populations in dense foliage such as soybeans. Culter (1934) and Gordienko (1960) showed that honey bee populations can be built up on soybeans. Beard and Knowles (1971 ) showed that crossing at different locations in California varied: 10 percent at Five Points, 1 to 5 percent at Davis, and O to 7 percent at Shafter. No studies have been made on the value of concentrating the gregarious types of wild bees on soybeans, although such insects might prove to be more efficient than honey bees.
Woodworth (1932) indicated that thrips and honey bees might be responsible for some transfer of pollen; however, Caviness (1970) showed that thrips are uneffective as pollinators of soybeans, but that honey bees were repsonsible for 7.7 percent crossing.
Pollination Recommendations and Practices:
There are no recommendations for the use of bees in pollination of soybeans. The subject is reviewed, however, because of the interest in hybrid soybeans and the possibility of using pollinating insects in hybrid soybean production.
LITERATURE CITED:
BEARD, B. H., and KNOWEES, P. F.
1971. FREQUENCY OF CROSS-POLLINATION OF SOYBEANS AFTER IRRADIATION. Crop
Sci. 11: 489-492.
BEICKENSTAFF, C. C., and HUGGANS, L. J.
1962. SOYBEAN INSECTS AND RELATED ARTHROPODS IN MISSOURI. Mo. Agr. Expt.
Sta. Bul. 803, 51 pp.
BRADNER, N. R.
1969. HYBRID SOYBEANS: FICTION OR FACT? Soybean Digest 29(7): 16-17. 338
BRIM, C. A., and YOUNG, M. F.
1971. INHERITANCE OF MALE-STERILE CHARACTER IN SOYBEANS. Crop Sci. 11:
564-566.
CAVINESS, C. E.
1966. ESTIMATES OF NATURAL CROSS-POLLINATION IN JACKSON SOYBEANS IN ARKANSAS.
Crop Sci. 6(2): 211.
____ 1970. CROSS-POLLINATION IN THE SOYBEAN. In The Indispensable Pollinators, Ark. Agr. Ext. Serv. Misc. Pub. 127, pp.33-36.
____ WALTERS, H. J., and JOHNSON, D. L.
1970. A PARTIALLY MALE STERILE STRAIN OF SOYBEAN. Crop Sci. 10(1): 107-108.
CULTER, G. H.
1934. A SIMPLE METHOD FOR MAKING SOYBEAN HYBRIDS. Amer. Soc. Agron. Jour.
26: 252-254.
GARBER, R. J., and ODBAND, T. E.
1926. NATURAL CROSSING IN SOYBEANS. Amer. Soc. Agron. Jour. 18: 967 - 970.
GORDIENKO, V.
1960. [SEXUAL HYBRIDS OF SOYA BEANS OBTAINED BY DIRECTED BEE POLLINATION.]
Pp.400-407. In Mel'nichenko, A. N., [Pollination of Agricultural Plants
by Bees.] Izd-vo Minist. Sel'sko Khoz. SSSR. [In Russian.]
HAMBLETON J. I.
1936. SOY BEAN FOR POLLEN AND NECTAR. Gleanings Bee Cult. 64: 431.
JAYCOX, E. R.
1970. ECOLOGICAL RELATIONSHTPS BETWEEN HONEY BEES AND SOYBEANS. Amer. Bee
Jour. 110(8): 306-307, (9): 343-345, (10): 383-385.
MILUM, V. G.
1940. BEES AND SOYBEANS. Amer. Bee Jour. 80: 22.
MORSE, W. J., and CARTTER, J. L.
1937. IMPROVEMENT IN SOYBEANS. U.S. Dept. Agr. Yearbook 1937: 1154-1189.
PIPER C. V. and MORSE, W. J.
1910. THE SOYBEAN: HISTORY, VARIETIES AND FIELD STUDIES. U.S. Dept. Agr.
Burl Plant Indus. Bul. 197, 84 pp.
PIPER, C.v. and MORSE, W.J.
1923. THE SOYBEAN. 329 pp. McGraw-Hill Book Co., Inc., New York.
RUBIS, D. D.
1970. BREEDING INSECT POLLINATED CROPS. In The lndispensable Pollinators.
Ark. Agr. Ext. Serv. Misc. Pub. 127, pp.19-24.
SHAIK, P. H. VAN, and PROBST, A. H.
1958. EFFECTS OF SOME ENVIRONMENTAL FACTORS ON FLOWER PRODUCTION AND REPRODUCTIVE
EFFICIENCY IN SOYBEANS. Agron. Jour. 50: 192-197.
VEATCH, C.
1930. VIGOR IN SOYBEANS AS AFFECTED BY HYBRIDITY. Jour. Amer. Soc. Agron.
22: 289-310.
WEBER, C. R., EMPTG, L. T., and THORNE, J. C.
1970. HETEROTIC PERFORMANCE AND COMBINING ABILITY OF TWO- WAY F1
SOYBEAN HYBRIDS. Crop Sci. 10: 159-160.
WEISS M. G.
1949. SOYBEANS. Adv. in Agron. 1: 77-157.
____ WEBER, C. R., and KALTON, R. R.
1947. EARLY GENERATION TESTING IN SOYBEANS. Jour. Amer. Soc. Agron. 39:
791-811.
WENTZ, J. B., and STEWART, R. T.
1924. HYBRID VIGOR IN SOYBEANS. Jour. Amer. Soc. Agron. 16: 534-540.
WOODHOUSE, E. J., and TAYLOR, C. S.
1913. THE VARIETIES OF SOYBEANS FOUND IN BENGAL, BIKAR AND ORISSA AND THEIR
COMMERCIAL POSSIBILITIES. India Dept. Agr. Mem. Bot. Ser. 5: 103-175.
WOODWORTH, C. M.
1922. THE EXTENT OF NATURAL CROSS-POLLINATION IN SOYBEANS. Jour. Amer.
Soc. Agron. 14: 278-283.
____ 1932. GENETICS AND BREEDING IN THE IMPROVEMENT OF THE SOYBEAN. Ill. Agr. Expt. Sta. Bul. 384: 297-404.