Regulation of growth and flowering in tuberose (Polianthes tuberosa Linn)

Abstract

A study was undertaken at the College of Horticulture, Kerala Agricultural University, Vellanikkara, Thrissur to determine the effect of nutrients and bioregulators on the growth and flowering of tuberose. The treatments in general, significantly influenced all the vegetative characters, duration, most of the spike characters and yield of bulbs and bulblets in one season or the other. Both nitrogen at 30 g m-2 as well as GA3 at 50 and 100 ppm gave maximum plant height in both the seasons. Nitrogen 20 g m-2 and GA3 100 ppm produced maximum number of leaves, followed by ethrel 50 ppm. In number of tillers, nitrogen 30 g m-2 caused a significant increase. Increasing rate of applied nitrogen and GA3 at 100 ppm reduced the days required for the emergence of spike. The effect of GA3 50 ppm and !AA 25 ppm were also found to be significantly superior. Nitrogen 20 and 30 g m" as well as GA3 50 and 100 ppm were superior in increasing the spike length. The longest rachis was obtained with nitrogen at 30 g m-2 and GA3 50 ppm. Among the nutrients, nitrogen and among bioregulators GA3 100 ppm increased the number of florets per spike and the longevity of individual floret on a spike. However, the longevity of the spike in the field was not affected significantly by the treatments. The total crop duration was found to be reduced by nitrogen application, GA3 50 ppm and !AA 25 ppm. Among the bioregulators GA3 50 ppm and among nutrients nitrogen at 20 and 30 g m-2 recorded the maximum fresh weight of spike.

Control plot plants took maximum days in vase for opening of each floret, while GA3 100 ppm took minimum days. Higher doses of nitrogen were found to increase the number of days for floret opening. Days for complete opening of florets in vase were shortest and the number of florets opening at a time was the maximum with GA3 100 ppm. Higher doses of nitrogen as well as !AA 25 ppm were able to enhance the vase life, followed by GA3 50 and GA3 100 ppm. Nitrogen and phosphorus at 20 g m? and 15 g m" respectively were responsible for increased weight of bulbs and bulblets per hill. Bioregulators did not influence this character significantly. Nitrogen and potassium content of the leaves increased with increasing levels of respective fertilizers, but application of phosphorus did not influence the leaf phosphorus content.