Effects of prohexadione-calcium with three rates of phosphorus and chlormequat chloride on vegetative and generative growth of tomato

Abstract

The aim of this study was to analyze the effects of prohexadione-calcium [(Regalis^®)(100 mg L^-1)] and chlormequat chloride (2000 mg L^-1) on vegetative and generative growth of tomato plant. An underlying aim was to evaluate the growth of plants treated with pro-Ca with three phosphorus rates (40, 80 and 120 mg L^-1). Pro-Ca was applied to plants either as a spray or medium drench, while chlormequat chloride was applied only as a spray. Results show that inhibiting effect of pro-Ca and chlormequat chloride applications on seedling height were significant and these two chemicals produced smaller seedlings compared to the control. Height reduction with chlormequat chloride was 56%, while with pro-Ca treatments it varied from 46 to 55%. Effects of chemicals on total weight of two trusses were not significant, although spray of pro-Ca together with the 40 mg L^-1 phosphorus rate was promising in relation to chlormequat chloride and control plants. Based on the results of this study, it seems likely that pro-Ca, having an inhibiting effect on stem elongation without a negative effect on total weight of two trusses would be sufficient to control stem elongation. However, further researches are needed to suggest a strong opinion whether the pro-Ca treated tomato plants give same responses in every independent application of this chemical.

Key Words: Prohexadione-calcium, chlormequat chloride, growth rate, seedling height, tomato.