THINNING PATTERN AND LIGHT ENVIRONMENT IN PEACH-TREE CANOPIES INFLUENCE FRUIT-QUALITY

The effects of shoot length, fruit density, thinning patterns, and light levels on crop quality of peach (Prunus persica Batsch.) were investigated. On shoots 50 and 75 cm long, fruits were thinned to produce several distribution patterns, with peaches concentrated in the bottom, middle, or distal portion of the shoot, or uniformly spaced along the shoot at two fruit densities (almost-equal-to 10 or 15 cm between fruit). The lower fruit density on the longer shoots resulted in larger fruits. At the same fruit density, fruits clustered in the distal section of the shoot were smaller, with lower soluble solids concentration (SSC) and a smaller percentage of the exocarp colored red than for the other spacing patterns. Photosynthetically active radiation (PAR) was negatively correlated with the percentage of green exocarp and positively correlated with the percentage of red exocarp. However, the low correlation coefficients (0.45 and 0.50, respectively) indicate that even low light levels can result in substantial red pigment development in peach fruit.