engleski

Apple diameter and fruit growth rate at tree crop loads

Fruit thinning is indispensable practice in production of large sized and good quality apple fruits. Often problems are light and late thinning. Intensity and late thinning were evaluated in trail settled near Zadar, Croatia, on apple cv. ‘Cripps Pink’ grafted on M9 rootstock and cultivated at spindle-type system. Fruits were hand thinned on July 31st 2017 to standard (S), high (H) and very high (VH) crop load (levels of 6, 8 and 10 fruits per trunk cross-section area, TCSA, respectively). Fruit diameter was measurement on 1 to 3 fruits on each of four branches per tree with four trees per treatment (total of 90 fruits) using fruit sizing loop. Fruits were measured at 10 days intervals till December 30th. Fruit diameter and daily fruit growth rate (FGR) were compared at three crop loads and time of measurement. TCSA were 13.7 ± 0.681 cm2. Fruit diameter at VH was lower (67.9 mm) than at S and H (70.8 and 69.6 mm. respectively) which were not significantly different. Fruit diameter of 59.22 mm at 97th day of the year (D97) increased on D105, D125, D136, and D167, then fruit diameter remained similar until D188, being 77.1 mm. FGR was affected only by time. FGR was highest at D105 (0.388 mm/day), gradually decreased to D146, and from D157 to D188 was similar (0.092 mm/day). Interactions of crop load and time were not significant. Fruits were hand thinned at 75% of final fruit size. VH negatively affected fruit diameter, hence VH could be thinned to H. Thinning H to S was not justified.

Cripps Pink, fruit size, TCSA, thinning, time

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