Effect of prohexadione-calcium(Regalis) on shoot growth in Pear var. Passe Crassane

Prohexadione-calcium (Regalis) is a shoot growth retardant that inhibits gibberellins biosynthesis The aim of this study was to evaluate the efficacy of applying Regalis by foliar applications in Passé Crassane pear orchards to reduce tree vigor or shoot growth, to improve the structure of the canopy, to accelerate the earliness of fruit bearing and to control the alternate fruit production. Three different dosages were tested: 50ppm, 100ppm 150ppm. Regalis treatments ranging from 50 to 150 ppm were compared with control, without treatments. The first treatment was applied 7days after petal fall and the others every 10 days after the first treatment. The data was collected at the end of the vegetation period on 10 October. The growth vigor of the shoots and the shoot length of node was significantly difference after the treatment of 150 ppm than the application of 100ppm and 50ppm. The mean number of nodes per shoot percentage was not significantly different between different treatment (50ppm, 100ppm and 150ppm). The length of the shoots for non- treated trees was higher than for treated ones