Does variability in shoot carbon assimilation within the tree crown explain variability in peach fruit growth?
A three-dimensional model of radiative transfer and leaf gas exchange was used to quantify daily carbon (C) assimilation of all fruit-bearing shoots (FBS) in an early maturing 6-year-old peach tree (Prunus persica L. Batsch) with a heavy crop load. For a sample of FBS (n=36), growth of fruit and leafy shoots was measured every 1-2 weeks from 24 days after bloom (DAB) until harvest, between 93-101 DAB. The objective was to relate shoot C assimilation with harvested fruit mass for each shoot to test the hypothesis that variation in C supply contributes significantly to variation in fruit growth within and among FBS. Mean C assimilation of the sampled shoots was 0.07 g C fruit(-1) day(-1), but varied between 0.014 and 0.32 g C fruit(-1) day(-1). This indicates that C availability for fruit growth would have varied significantly among individual FBS if they were autonomous. Mean fruit dry mass on each FBS varied between 0.716 and 7.68 g C at harvest, and most of the variation originated am
