Influence of abscisic acid and benzyladenine on fruit set and fruit quality of 'Bartlett' pears.

摘要

Experiments were conducted to evaluate abscisic acid (ABA) and the combination of ABA and benzyladenine (BA) as a thinner on Bartlett pears. Application of 500 mg l--1 ABA at bloom, petal fall and at the 10 mm stage resulted in significant fruit thinning at all timings. Application at the 10 mm stage nearly defruited the trees. Rates of ABA between 50 and 500 mg l--1 were evaluated at 10 mm and the thinning response was quadratic and highly significant. Rates as low as 50 mg l--1 thinned. BA at 150 mg l--1 at the 10 mm stage did not thin and when combined with 250 mg l--1 ABA, no additional thinning was observed, but extensive thinning was observed with ABA alone. When thinning with ABA was achieved, return bloom was also enhanced. Thinning with ABA generally resulted in larger fruit, greater flesh firmness and higher soluble solids. The russet seen on ABA-treated fruit was attributed primarily to the surfactant used. Extensive leaf yellowing and leaf abscission were noted after ABA application, especially with the 250 and 500 mg l--1 and this was considered commercially unacceptable. BA was unable to reverse or modify the leaf yellowing and abscission caused by ABA as it has been shown to do with other plant species.