EFFECT OF PLANT GROWTH REGULATORS ON GROWTH, PHYSIOLOGY AND QUALITY CHARACTERISTICS OF Cucumis Melo L.

摘要

The experiment was conducted in order to identify the effects of exogenous growth regulators (gibberellic acid (GA_3) - 100 muuM; calcium 3,5-dioxo-4-propinoylcyclohexanecarboxylate (prohexadione-calcium) - 100 mg-L~(-1); chlor-mequat chloride (Cycocel) - 100 mg-L~(-1); 2-chloroethylphosphonic acid (Ethephon) - 100 mg-L~(-1)) applied as foliar sprays, on growth, physiology and quality characteristics of Cucumis melo L. cv Galia. GA_3 promoted the elongation of the first internode and leaf, while a significant inhibition of the above length under chlormequat chloride and 2-chloroethylphosphonic acid, was observed. The maximum quantum yield of primary photochemistry (Fv/Fm), was significantly decreased under chlormequat chloride, 2-chloroethylphosphonic acid and prohexadione-calcium, showing a possible inhibition of enzymatic process in Calvin cycle. Under the application of gibberellic acid the sugars (fructose, glucose and saccharose) and the soluble solids of melon fruits remained unchanged, as compared to the control, while vitamin C content increased significantly. On the contrary, on exposure to growth retardants, a significant decrease in sugars, soluble solids and vitamin C content and a tendency to increase the titratable acidity of fruits,was induced. The so-called "maturity ratio" reflecting the ratio of soluble solids to the Acidity, was significantly reduced under prohexadione-calcium, chlormequat chloride and 2-chloroethylphosphonic acid, while under gibberellic acid was increased by36%, showing a better quality of the fruits due to that hormone.