Induction of sprouting on bulbs of Polianthes tuberosa L. by curing and application of plant growth regulators

Abstract

Increasing flower production of Polianthes is hindered by limited supply of bulb. Newly harvested bulb shows after ripening phenomenon, in which new bulbs are not readily sprouting. Farmers usually air or sun-dried the bulbs followed by curing above the kitchen stove for 1-3 months to induce sprouting. It is therefore necessary to accelerate sprouting. The purpose of this research was to study if bulbs of different sizes will sprout at the same time and if sprouting could be accelerated. The research was conducted at the Laboratory of Seed Science and Technology, Department of Agronomy and Horticulture, IPB Darmaga during November 2010 - February 2011. The research consisted of two experiments. In the first experiment bulbs were grouped into small (0.5 < Ø < 1.5 cm), medium (1.5 < Ø < 2.5 cm) and large ( Ø > 2.5 cm) sizes and subjected to air-drying or curing for six days. Each treatment was replicated four times with 20 bulbs for each experimental unit. In the second experiment sprouting was induced using BAP, GA3 or cured as three different set of experiments. The concentrations of BAP were 0, 100, 200, 300 ppm, whereas GA3 were 0, 50, 100, 150, and 200 ppm. Curing was carried out for 0, 2, 4, 6 days. The result showed that larger bulb produced higher number of sidebulb, so did curing as opposed to air-drying. The large bulb produced higher percentage of sprouting bulb than medium and small bulb. The larger the bulb the earlier they sprout. Result from the second experiment showed that the higher concentration of BAP give higher number of sidebulbs and earlier sprouting. Bulbs treated with BAP at 300 ppm uniformly sprouted within one week after treatment. However, it was not significantly different from BAP at 200 ppm. Use of GA3 up 100 ppm affected number of sidebulb and shoot length but did not affect percentage of sprouting bulbs. Use of curing did not affect number of sidebulb, shoot length as well as percentage of sprouting bulbs.