Pollination treatment affects fruit set and modifies marketable and storable fruit quality of commercial apples.

Ulrika Samnegård,Peter A Hambäck,Henrik G Smith

doi:10.1098/rsos.190326

Ulrika Samnegård, Peter A Hambäck + Show 1 more

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https://doi.org/10.1098/rsos.190326

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Abstract

Insect-mediated pollination increases yields of many crop species and some evidence suggests that it also influences crop quality. However, the mechanistic linkages between insect-mediated pollination and crop quality are poorly known. In this study, we explored how different pollination treatments affected fruit set, dry matter content (DMC), mineral content and storability of apples. Apple flowers supplementary pollinated with compatible pollen resulted in higher initial fruit set rates, higher fruit DMC and a tendency for lower fruit potassium (K) : calcium (Ca) ratio than flowers that received natural or no pollination. These variables are related to desirable quality aspects, because higher DMC is connected to higher consumer preference and lower K : Ca ratio is related to lower incidence of postharvest disorders during storage. Using structural equation modelling, we showed an indirect effect of pollination treatment on storability, however mediated by complex interactions between fruit set, fruit weight and K : Ca ratio. The concentrations of several elements in apples (K, zinc, magnesium) were affected by the interaction between pollination treatment and apple weight, indicating that pollination affects element allocation into fruits. In conclusion, our study shows that pollination and the availability of compatible pollen needs to be considered in the management of orchard systems, not only to increase fruit set, but also to increase the quality and potentially the storability of apples.

Highlights

Insect-mediated pollination increases yields of many crop species and some evidence suggests that it influences crop quality
A few studies have suggested that apples which successfully have been cross-pollinated differ in their mineral content from less pollinated ones, suggesting that the mechanisms influencing mineral allocation into fruits are related to pollination services
The pollination treatment affected the seed set in apples (χ2 = 67.3, Δd.f. = 2, p < 0.001), with higher seed set in naturally pollinated fruits compared to fruits in the pollinator exclusion treatment, while no difference was found between naturally and supplementary hand-pollinated fruits

Summary

Introduction

Insect-mediated pollination increases yields of many crop species and some evidence suggests that it influences crop quality. Apple flowers supplementary pollinated with compatible pollen resulted in higher initial fruit set rates, higher fruit DMC and a tendency for lower fruit potassium (K) : calcium (Ca) ratio than flowers that received natural or no pollination These variables are related to desirable quality aspects, because higher DMC is connected to higher consumer preference and lower K : Ca ratio is related to lower incidence of postharvest disorders during storage. The DMC influences the firmness of apples at harvest and softening rates during storage, and is a good estimate of total soluble solids after storage [16,18,19] Another important quality aspect for producers and wholesalers is storability. Because the mineral content may be related to other quality aspects including firmness, postharvest disorders and storability, pollination service may have a more far-reaching role in the economy of apple production than has earlier been estimated

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