ISHS Acta Horticulturae 732: VIII International Symposium on Canopy, Rootstocks and Environmental Physiology in Orchard Systems
NECTARINE YIELD AS A FUNCTION OF CROP LOAD AND PAR INTERCEPTION |
| Authors: | G. Reginato, V.G. de Cortázar, H. Lázaro |
| Keywords: | fruit size, yield efficiency, vegetative growth |
| Abstract:
Nectarine yield and fruit size were studied in relation to crop load and photosynthetically active radiation (PAR) interception. The trial was established in a 'Royal Glo' orchard, as 4-year-old regrafted trees, planted at 4.8 x 2.5 m, open vase trained, located 40 km south of Santiago (33.8 Lat. S, 71.7 Lon. W). Twelve trees were selected at flowering and were hand thinned 35 days before pit hardening, leaving between 121 and 242 fruits per tree (1.34-3.99 fruits per cm2 of branch cross-sectional area; BCSA). PAR interception was measured three times a day every 20 days until harvest, when fruit size and yield per tree were evaluated. Fractional PAR interception (f) after flowering was on average 20% for all trees. Twenty days after thinning, it ranged between 25 and 40%. Near harvest, fractional PAR interception stabilized between 36% and 56%. The increase in PAR interception was not clearly explained by crop load and tree size. Average fruit size varied between 95 and 131 g. Fruit size was inversely related to crop load expressed as fruits per tree (r2=0.60), but a better relationship was found when crop load was expressed as fruits per tree divided by fraction of PAR interception (fruits/f) near harvest (r2=0.78) or expressed as fruits per branch cross-sectional area at thinning (r2=0.76). Yield and fruits/f were also related, but with a parabolic model (r2=0.70). | |
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