Treffer: Effect of hand thinning and plant growth regulators: Thidiazuron, carbaryl and Ethrel on fruit size, yield and quality of kiwifruit (Actinidia deliciosa Chev.) Cv. Allison

In order to improve fruit size, yield and quality of kiwifruit, trials were carried out using plant growth regulator treatments of thidiazuron, carbaryl or Ethrel, with or without hand thinning at petal fall stage. At harvest, thidiazuron treated fruits were 65 to 74 per cent heavier than the control, depending on the concentrations used. It also increased fruit length by 14 to 23 per cent longer and diameter by 23 to 29 per cent wider than the control. As a result, the yield per vine was about 27 to 43 per cent higher than the control. Carbaryl application did not have positive effects on fruit size, weight and yield. The proportion of both grade 'A' and 'B' fruit was increased by thidiazuron, while carbaryl increased the proportion of grade 'B' and 'C' fruit. Thidiazuron treated fruits had higher total soluble solids and lower fruit acidity. Hand thinning followed by 600 ppm Ethrel spray caused maximum fruit thinning. Significant fruit thinning by Ethrel spray alone was also obtained at a concentration of 800 ppm. The fruit size and quality was found better under hand and chemical thinning treatments than for the controls.