Application of NAA and BA in chemical thinning of some commercial cultivars of apple

This paper presents the fruit thinning response to naa and ba plant regulators of apple cultivars ‘prima’,‘mcintosh’ and ‘jonathan’. the experiment was designed to evaluate the effects of naa applied at three concentrations,15,20 and 30 ppm,and ba + naa combinations (ba-60,100,120 or 140 ppm + naa 5 ppm) for fruit thinning of the assessed apple cultivars. all the applied treatments with naa and ba + naa adequately thinned fruits of ‘mcintosh’ and ‘jonathan’ cultivars,whereas application of naa at the concentration of 20 and 30 ppm and combined treatment of ba 140 ppm+ naa 5 ppm were effective fruit thinners for ‘prima’ cultivar. in terms of the average fruit weight and number of fruits categorized as large (> 75 mm or > 65 mm),as well as from the aspect of fruit number per trunk cross-sectional area,the variant of treatment with ba 140 ppm + naa 5 ppm was the most effective on ‘mcintosh’ and ‘prima’ cultivars,whereas ba 100 ppm + naa 5 ppm had the best effect on ‘jonathan’ cultivar. © 2016,university of agriculture. all rights reserved.