Cross-pollination affects fruit colour, acidity, firmness and shelf life of self-compatible strawberry

Abstract

Cross-pollination affects the fruit characteristics of many crops but the effects of cross-pollination on fruit quality of strawberry (Fragaria × ananassa Duch.) are poorly known. This study determined how cross-pollination affects fruit quality of the strawberry cultivar, Redlands Joy, under controlled environment conditions. Plants were allocated to one of four treatments, with all flowers on each plant receiving either: (1) unassisted self-pollination (Autogamy); (2) hand-pollination with Redlands Joy pollen (Self); (3) hand-pollination with cross-pollen from a small-fruited cultivar (Sugarbaby); or (4) hand-pollination with cross-pollen from a large-fruited cultivar (Rubygem). Cross-pollination did not significantly affect plant yield or fruit mass, size, shape, firmness or shelf life. However, cross-pollination affected fruit colour and taste attributes. Cross-pollinated fruit were 3%–5% darker than self-pollinated fruit. They also had 26%–34% lower acidity and 43%–58% higher Brix:acid ratio. Cross-pollination by Sugarbaby increased fruit P, K, Ca, Fe and Mn, but decreased B, Cu and Zn, concentrations. Cross-pollination by Rubygem increased fruit Mn, but decreased K and Na, concentrations and reduced shelf life. Fruit mass, length, diameter and firmness within all treatments increased with increasing numbers of fertilized seeds per fruit. Hand self-pollinated fruit had a higher percentage of fertilized seeds than fruit arising from autogamy and they were also darker, redder, firmer, and had a longer shelf life, higher protein concentration, and lower Al and Na concentrations. The results indicate that strawberry fruit quality can be affected by both the source of pollen and the number of stigmas pollinated.

Biomass and mineral nutrient partitioning among self-pollinated and cross-pollinated fruit on the same strawberry plant

“…Fruit size is possibly regulated by the amount of water uptake, which may be affected by sugar concentrations as sugar contributes significantly to osmotic strength and water uptake. We have shown in our two previous studies that cross-pollinated ripe fruit often have higher Brix:acid ratio, but not higher Brix, than self-pollinated fruit [ 15 , 16 ]. However, sugar levels in the young developing fruit require further investigation.…”

“…Xenia effects on blueberry, strawberry and pear fruit size [ 17 – 19 , 34 ] were evaluated when self-pollinated fruit and cross-pollinated fruit developed on different plants. We have recently demonstrated that xenia effects on the size of mature fruit of self-compatible Redlands Joy do not occur when self-pollinated and cross-pollinated develop on different plants [ 15 ]. However, xenia effects on mature fruit size become apparent when self-pollinated and cross-pollinated fruit compete on the same Redlands Joy plant [ 16 ].…”

“…Self or Cross) was rotated successively from one experimental plant to the next, so that the first flower of five plants in each experiment was self-pollinated while the first flower of the other five plants was cross-pollinated. Details of the pollen collection and hand-pollination methods have been provided previously [ 15 , 16 ]. Briefly, each flower on each experimental plant had its anthers removed before the flower opened and was then covered with a fine-mesh bag until the stigma was receptive.…”

“…Most strawberry cultivars are considered self-compatible although some cultivars possess some degree of self-incompatibility [ 15 ]. Cross-pollinated and self-pollinated mature fruit of the self-compatible strawberry cultivar, Redlands Joy, do not differ significantly in size when they develop on different plants [ 15 ].…”

“…Most strawberry cultivars are considered self-compatible although some cultivars possess some degree of self-incompatibility [ 15 ]. Cross-pollinated and self-pollinated mature fruit of the self-compatible strawberry cultivar, Redlands Joy, do not differ significantly in size when they develop on different plants [ 15 ]. However, xenia effects on mature fruit size become apparent when cross-pollinated and self-pollinated Redlands Joy fruit compete on the same plant, and these xenia effects are amplified when calcium is in shortest supply [ 16 ].…”