Peach fruit growth in relation to the leaf-to-fruit ratio, early fruit size and fruit position

To study the influences of assimilate availability, early fruit size and fruit position on fruit growth, experiments were conducted on an early-maturing peach (Prunus persica) cv. 'Alexandra' in 1992 and a late-maturing peach cv. 'Suncrest' in 1993. Leaf-to-fruit ratio (LFR) was used to manipulate assimilate availability. For each LFR, the distribution patterns of fruits along the fruit-bearing shoot were adjusted to one of four situations: 1) fruits were uniformly distributed on the leafy shoots; 2) fruits were located on the basal part of the fruit-bearing shoot with leaves on the distal part; 3) fruits were located on the distal part of the fruit-bearing shoot with leaves on the basal part; or 4) half of the fruits were distributed along the leafy shoots and the other half on the distal part of the fruit-bearing shoot. The fruit-bearing shoot base was girdled and the apical bud was removed. Fruit growth was expressed as dry weight calculated from continuously measured diameter. The effects of LFR, fruit position and early fruit size were analysed using a linear mixed-effects model. The results showed that LFR increased fruit dry weight and advanced fruit maturity date. Early fruit size had a significant influence on fruit growth. Fruit position slightly influenced its growth. Fruit closer to leafy shoots appeared to have higher fruit growth than more distal fruit, especially when there was intense assimilate competition. However, in most cases, the effect of fruit position was not significant.