ISHS Acta Horticulturae 527: International Symposium on Growth and Development of Fruit Crops
INTRASPUR FRUIT COMPETITION AND POSITION INFLUENCE FRUIT SIZE AT HARVEST AND RESPONSE TO CHEMICAL THINNING AGENTS IN SPUR-TYPE ‘DELICIOUS’ APPLE |
| Authors: | Brent L. Black, Martin J. Bukovac, M. Stopar |
| Keywords: | fruit thinning, benzyladenine, naphthaleneacetic acid, NAA |
| Abstract:
Fruiting in spur-type ‘Delicious’ is often characterized by fruit set of multiple fruits on a spur and on consecutive spurs, particularly on first-fruiting spurs. We studied the relationship of intra- and interspur fruit competition (FC) on fruit growth by analyzing the size of fruit produced on 3-year-old wood of non-thinned Redchief ‘Delicious’ apple trees at maturity. Fruit size was negatively correlated with intraspur FC (fruit number per spur), but not with interspur FC (fruiting vs. total spurs). We also studied, over two seasons, the effect of Accel® [50 mg (BA).L-1, 1993; 25 mg (BA).L-1, 1994] and NAA (15 mg.L-1), applied alone and in combination (at 10 mm king fruit diameter), on fruit growth in relation to intraspur competition and position on the spur (i.e. king, K; or lateral, L). NAA significantly decreased the frequency of spurs bearing multiple fruit, while the combination of NAA and Accel significantly increased the number of spurs bearing multiple fruit. In 1993, Accel increased fruit size only in the absence of intraspur FC. In both seasons, NAA and NAA + Accel reduced fruit size. These effects were related to intraspur position and FC, the greatest negative effect being on lateral fruits in the presence of intraspur FC. | |
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