Cluster illumination differentially affects growth of fruits along their ontogeny in highbush blueberry ( Vaccinium corymbosum L.)

Abstract

A B S T R A C TShading highbush blueberry plants generally leads to a delayed fruit development. Experiments have been performed to study the effects of light on fruit growth independently from the rest of the canopy. Clusters were shaded during different fruit growth periods. The equatorial diameter of the fruits as a function of days after full bloom followed a double-sigmoidal growth pattern, being fitted using a Gompertz II nonlinear mixed model, and absolute growth rates were obtained from each fitted model. Both whole-cycle shaded and second-stage shaded fruits showed a delayed peak in absolute growth curves with respect to both first-stage shaded and whole-cycle unshaded controls. Our results suggest that deficiency of light during the last stage of highbush blueberry fruits may lead to a substantial delay (of about 10-16 days) in harvest as compared with well-illuminated fruits.In order to estimate the contribution of intrinsic fruit photosynthesis to its own growth at different stages, clusters were subjected to girdling on their peduncles at different times. Girdling just before the second-stage resulted in fruits gaining between 35 and 40% of dry weight in comparison with the controls. This suggests that fruit photosynthesis may play a relevant role in fruit growth during the second sigmoidal stage, which in turn may contribute to explain the delayed growth observed in shaded fruits.

Adverse Effects of Long-Term Continuous Girdling of Jujube Tree on the Quality of Jujube Fruit and Tree Health

“…However, the results of this study showed that after continuous girdling for many years, the quality of jujube fruit not only did not improve, but also decreased to a certain extent. The test results showed that the weight, hardness and geometric-mean diameter of jujube fruit from non-girdled jujube trees were significantly greater than the corresponding index value of girdled jujube trees, which was quite different from the general conclusions, such as that girdling can increase the weight of a single fruit, and so on [28,29]. What is more, the observation results of microscope and scanning-electron-microscope images showed that there were a large number of big porous structures in the pulp of the girdled jujube fruit compared with the non-girdled jujube fruit.…”

A physiological and metabolomic analysis reveals the effect of shading intensity on blueberry fruit quality

“…In addition, this study showed that ABC transporters, pyrimidine metabolism, and purine metabolism pathways were common in the three comparison groups, indicating that these three metabolic pathways of blueberry fruits are vulnerable to shading treatment, which led to the differences in DAMs in these pathways, thus suggesting that they may have an important impact on fruit quality. Several studies have shown that shading of blueberry plants usually leads to delayed fruit development ( Godoy et al, 2018 ) and may be considered a promising tool to delay harvest for commercial purposes ( Beraud & Ulloa, 2015 ). Blueberries, as shrubby plants, can readily be shaded for agricultural purposes, and Kim et al (2011) showed that to achieve the best photosynthesis and blueberry growth, we must avoid shading levels exceeding 60 % of the full light level.…”