Effect of spacing, rhizome weight and time of harvest on the yield and quality constituents in Costus speciosus

Abstract

An experiment conducted at the College of Horticulture, Vellanikkara, during 1981 –’82 to study the influence of spacing, weight of planting material and duration of the crop on the yield and quality factors in Costus speciosus revealed that low density planting (75 x 75 cm) enhanced the overall vegetative growth. However, the per hectare yield of rhizomes and diosgenin were found to be significantly higher at the closest spacing (50 x 50 cm). The higher the weight of the planting material, the better was the vegetative and rhizomatous growth. The yield of rhizomes and diosgenin were proportionately higher when heavier planting materials were used. Planting of 100 g rhizome pieces was found to be significantly superior to planting of rhizomes weighing 50 g and 75 g. Increasing the crop duration significantly increased some of the rhizome and finger characters. Though the yield of green rhizome and diosgenin content were higher at six months after planting, the dry matter content was low at that stage. The yield of dry rhizomes and diosgenin were higher at nine months after planting, due to the high dry matter content. Quadratic response functions showed the eighth month to be the optimum stage of harvest for obtaining maximum yield of diosgenin per unit area. The treatment combination D2S1W3was found to be the economic optimum. A maximum yield of 157.65 kg/ha of diosgenin, giving a net profit of Rs. 6270 per ha, could be expected by planting 100 g rhizome pieces (W3) at 50x50 cm spacing (S1) and harvesting the crop at nine months after planting (D2). The studies indicated that Costus speciosus could be groomed as a commercial crop under Kerala conditions.