Effects of different bioregulator applications of crop load, fruit quality, storability and shoot growth of the apple cultivars 'Elstar' and 'Gala'.

摘要

Effects of treatment of apple trees with various plant growth regulators (NAAm+GA4 +7, ethephon, paclobutrazol, phytohormones) on growth, regular fruit set and fruit quality and storage life were investigated using apple cv. Gala and Elstar. Over the 4 yr trial period, only 2 of the growth regulators improved yield of Elstar; although vegetative growth decreased. In contrast yield of Gala apples decreased. Apple quality (size, colour and internal quality) increased with application of the thinning agents for both cultivars. Paclobutrazol had a negative effect on size and calibration of Gala apples; it also retained ripening, and thus increased firmness and TSS content. Inner quality was independent of growth regulator treatment, and was determined only by crop load of the tree. Trinexapac-ethyl increased ripening rate and hence decreased storage life. AVG increased inner quality of the fruits but decreased colouring markedly. Ethephon enhanced colouring via increased ethylene activity; however, since ethylene induces fruit ripening, this would decrease firmness and storage life. It is concluded that effects of the growth regulators are cultivar dependent, and results are discussed in this context.