Influence of Chemical Thinning of Apple Cultivars on Yield and Fruit Quality

Abstract

This experiment was designed to investigate effects of chemical thinning on fruit set, yield, return bloom and fruit quality of apple cultivars ‘Golden Reinders’, ’Gala Royal Beaut’, ’Red Cap Deliciou’' and ’Red Jonaprince’ in 2014. The orchard was established in spring 2013 with high-quality 2-year-old nursery trees that contained 7 or more lateral branches (except the cultivar ’Red Cap Delicious’). For chemical thinning the following chemicals were used: auxine naphthaleneacetic acid (NAA), cytokinin 6-benzyladenine (BA), insecticide carbaryl (‘Sevin’) and photosynthesis inhibitor metamitron (‘Brevis’) and their mix combinations. The most intensive fruit thinning for all cultivars were obtained in treatments with metamitron used either alone or in combination with NAA, and in the combination BA + NAA. Due to the decrease in the number of fruits per tree, in these treatments was recorded the largest increase in fruit weight compared with the control. Application of bioregulators in two-year old orchard depending on the cultivar had a greater or lesser effect on apple bloom in the next spring. Effect of chemical thinning on flowering in the next spring was not significant in cultivars ‘Royal Gala Beaut’ and ‘Red Jonaprince’. In the cultivar ‘Golden Reinders’ number of fruits over 6 per cm2 of trunk cross-sectional area (TCSA) resulted in absence of flowers, while in the cultivar Red Cap that number was 3 per cm2 of TCSA.

U radu je ispitivan uticaj hemijskog proređivanja plodova na zametanje plodova, prinos, kvalitet ploda i povratno cvetanje kod sorti jabuke Zlatni delišes klon Rajnders, Gala rojal bjut, Red kep i Red džonaprins u 2014. godini. Zasad je podignut u proleće 2013. godine sa „knip“ sadnicama. Hemijsko proređivanje je vršeno sledećim sredstvima: naftil-sirćetna kiselina (NAA), 6-benziladenin (6-BA), karbaril, metamitron i kombinacijom ovih sredstava. Najintenzivnije proređivanje plodova kod svih sorti bilo je kod tretmana sa metamitronom i tretmana sa kombinacijama metamitron + NAA i 6-BA + NAA. Usled smanjenja broja plodova po stablu kod ovih tretmana je zabeleženo najveće povećanje mase ploda u poređenju sa kontrolom. Primena bioregulatora u dvogodišnjem zasadu imala je efekat na cvetanje jabuke narednog proleća. Kod sorti Gala rojal bjut i Red džonaprins, efekat hemijskog proređivanja na cvetanje narednog proleća nije bio značajan, za razliku od sorti Zlatni delišes i Redkep. Kod sorte Zlatni delišes broj plodova preko šest po cm2 površine poprečnog preseka debla (PPPD) uticao je na izostanak diferenciranja cvetova, dok je kod sorte Red kep kritičan broj plodova bio tri po cm2 PPPD.