Fruit production increase in Asian pear trees by use of plant growth regulators.

The low fruit set in the Southern Brazil conditions is one of the limiting factors to pear pmduction in the country. The use of plant growth regulators may minimize this problem. This study was carried out aiming to evaluate the effectiveness of different growth regulators and the combination of these substances on fruit set increase of Shinseiki Asian pears. The application of growth regulators was performed when the pears have reached the full bloom stage. The experimental design was randomized blocks with four replications of one tree, with the following treatments: I. control (no application); 2. thidiazuron (TDZ) 20mg L-1; 3. gibberellic acid (GA) 20mg L-1; 4. prohexadione calcium (PCa) 600mg L-1; 5. PCa 600mg L-1 TDZ + 20mg L'; 6. PCa 600mg L-1 + AG 20mg L-1; and 7. AG 20mg L-1 + TDZ 20mg L-1. When sprayed on full bloom stage, thidiazuron and gibberellic acid, and combinations of these substances, both at a concentration of 20mng L-1, increased significantly the fruit set and the fruit production of Shinseiki' pears. The use of prohexadione calcium, single or in combination with thidiazuron and gibberellic acid, did not increase the fruit production. [ABSTRACT FROM AUTHOR]