11 November 2016. A review of studies evaluating techniques for producing seedless fruit concludes these techniques can contribute to higher yields that help ensure the security of food supplies. The findings from researchers at University of Exeter in the U.K. appear in today’s issue of the Journal of Applied Ecology.
A team from the lab of applied ecology professor Juliet Osborne, on Exeter’s Cornwall campus in Penryn, U.K., assessed the potential usefulness of parthenocarpy, the growing of fruit plants with neither seeds nor the need for pollination. A key factor in this review was the role parthenocarpic crop plants can play in improving yields to meet food security challenges from climate change and other causes.
Parthenocarpic fruits are often sought out by farmers since they do not require pollination, making them easier to grow, and in some cases like grapes or watermelons, are favored more by consumers. These varieties also produce pollen and nectar, thus can still support pollinators, such as bees. Growers traditionally achieved parthenocarpy through selective breeding, but more recently added such techniques as growth hormones and genetic modification.
Osborne and colleagues searched public databases for published studies of parthenocarpy between 1945 and March 2016, but also included patents and requested unpublished studies to counter any publication bias. From an original return of 161 articles, the researchers gleaned a total of 69 outcomes showing parthenocarpic effects on 18 pollinator-dependent crop species. Of the 69 outcomes, 31 represented applications of hormones, 29 used genetic modification, and 9 applied selective breeding. Tomatoes, sweet peppers, and eggplant were the species most studied.
The team aggregated the results of the studies and calculated their combined effects. The results show all of the studies with outcomes reported larger quantities of fruit produced with parthenocarpy, but the differences in yields from specific techniques, e.g. genetic modification or hormones — were not large enough to be statistically reliable. In addition, the extent to which the species studied were experiencing limited availability of pollen could not be determined, thus the absolute benefits of parthenocarpy compared to optimum pollination conditions could not be calculated.
Enough of the results from the review, however, show parthenocarpic techniques can produce higher yields, without compromising quality or nutritional value. These findings enable the authors to conclude that these techniques can be applied to improve yields where normal pollination methods are interrupted, as in recent cases of bee colony collapse.
Parthenocarpy can also be considered where climate change affects pollination patterns, or to improve food security by extending the growing season. Osborne notes in a university statement that, “Food security is a pressing global challenge and environmental and technological solutions should be used in tandem to ensure the best possible crop yields where they are needed most.”
The authors caution, however, that parthenocarpy is not a panacea for all problems with fruit yields, and should be used with conventional pollination methods to preserve the ecosystem supporting the crops. “It is of course vital,” says Jessica Knapp, a doctoral candidate in Osborne’s group and the paper’s first author, “that we still encourage and increase our native pollinator populations to ensure crops and wild plants can thrive as much as possible.”