Effects of chlormequat chloride and different rates of prohexadione-calcium on seedling growth, flowering, fruit development and yield of tomato
The aim of the study was to determine the effects of chlormequat chloride and different rates of prohexadione-calcium on seedling growth, flowering and fruit development and yield characteristics of tomato under conventionally poor growing conditions in an unheated greenhouse in Tekirdag, Turkey (40°59' N, 27°29' E). The effects of medium drench and spray applications of chlormequat chloride (2000 mg l-1) and different rates of prohexadione-calcium [(Regalis®)(50, 100, 200, 250, 300, 100 × 2, 125 × 2 and 150 × 2 mg l-1)] were evaluated. Chlormequat chloride and prohexadione-calcium effected seedling height, seedling diameter, number of leaves, chlorophyll, total and early yields, fruit diameter, percentage of fruits falling into the weight classes and flowering, and fruit development of tomato. In exception of 4 of 16 treatments, prohexadione-calcium, as well as chlormequat chloride, reduced seedling height related to control. The highest total yield was observed with chlormequat chloride and medium drench and spray applications of 100 and 300 mg l-1 and spray application of 100 × 2 mg l-1 prohexadione-calcium (pro-Ca). The lowest average fruit weight was from 150 × 2 mg l-1 and control plots. Fruit diameters were larger with the most of the pro-Ca rates in comparison to the control plants. In some pro-Ca treatments, flowers in the first florescences remained either at anthesis or fruit set stage throughout the growing period. Nevertheless, flower and fruit developments were normal in the 2nd, 3rd and 4th trusses in these treatments.
Key words: Prohexadione-calcium, chlormequat chloride, seedling height, flowering, yield, tomato.