Effect of different growth regulators on flowering and fruit development in pineapple

Abstract

The present investigations were carried out in College of Horticulture, Kerala Agricultural University during the years 1976-78. The object of the study was to find out the effect of growth regulators and certain other chemicals on flowering and fruit development in pineapple. The growth regulators and chemicals included in this study consisted of ethrel and Planofix at different concentrations and combination of Ethrel, Ca CO3 and urea. Ca C2 was also included in this study. Seasonal variation in the effect of growth regulators and chemicals in two seasons was noticed. Application of growth regulators and chemicals in January resulted in earlier flowering than November application. The differential response of growth regulators in the two seasons might be attributed to the variation in leaf area. Of the different growth regulators and chemicals tried, Ethrel 250 ppm was found to be the for maximum induction of flowering. Ethrel at all concentrations was found to reduce the duration of flowering and also the time for fruit set. Ethrel in combination with urea 2 per cent and Ca CO3 0.04 per cent also showed similar effect. Time taken for fruit maturity was slightly reduced by Ethrel treatment while it was delayed by the application of Planofix. In respect of fruit size, maximum size was obtained by Planofix 20 ppm. None of the growth regulators, chemicals and combinations tried resulted in an over all improvement in quality of fruits, but the number of leaves possessed by a plant profoundly influenced the quality of fruits. While induction of flowering could be achieved by the application of growth regulators and chemicals irrespective of the morphological characters of the plant, the fruit development was found to be associated with the number of leaves possessed by the plant. The fruits produced by plants with higher number of leaves (Class IV) possessed maximum of TSS, reducing sugars, total sugars and sugar acid ratio closely followed by Class III. For a satisfactory fruit development the plant should possess around 40 leaves at the time of application of growth regulators. The nutrient status of leaves was also found to influence fruit development considerably. The largest fruits were produced by plants having leaf nutrient status of 1.40 per cent N, 0.08 per cent P and 3.43 per cent K. The application of growth regulators and chemicals was responsible for low sucker production. Ethrel at 1250 ppm retarded the sucker production to a maximum extent.