Influence of crop load and canopy position on fruit maturity and quality in nectarine

The effects of different crop loads and canopy zones on fruit growth, maturity and fruit quality were studied in nectarine, Prunus persica L. Batsch LSQUORose BrightRSQUO. High, medium and low crop loads were tested representing 5, 8 or 12 fruit m^-1 of bearing shoot. Position of tagged fruit in the canopy was recorded as high or low, which represented the top half or lower half of the tree canopy. Under the conditions reported here, crop load plays a pivotal role in regulating fruit yield and quality at harvest, but not shelf-life or fruit quality during simulated marketing. Similar yields per tree were obtained for high and medium crop loads, which were greater than yields from low crop load trees. Fruit position within the canopy had a greater effect in regulating SSC than crop load. Both crop load and fruit canopy position affected the ripening time of fruit on the tree, but not the ripening rate: once fruit ripening commenced, it proceeded at the same rate irrespective of crop load or fruit position in the canopy. Fruit grouped into different maturity classes after harvest using I_AD values displayed different ripening dynamics during shelf life. This work confirms the importance of the DA-meter for quantifying physiological maturity of fruit which is fundamental to optimizing postharvest management of stone fruit and reinforces the importance of fruit thinning in nectarine to manage fruit quality.