Effect of spacing and fertilizer levels on physiological parameters in relation to productivity of ashwagandha (Withania somnifera)

A field experiment was conducted during rabi seasons of 2004 and 2005 at Agricultural Research Station, Annigeri, Karnataka, to study the effect of spacings and fertilizer levels on physiological parameters in relation to productivity of ashwagandha (Withania somnifera Dunal) in Vertisols. Sixteen treatments comprising 4 spacings (15 cmx5 cm, 15 cmx10 cm, 30 cmx10 cm and 45 cmx10 cm) and 4 fertilizer levels (control, 12 and 24, 18 and 36 and 24 and 48 kg N and P/ha) were undertaken in factorial design. A spacing of 15 cmx10 cm proved superior over the other spacings in enhancing physiological parameters, viz leaf area index (4.254), leaf area duration (80.6 days), net assimilation rate (0.404 g/dm(2)/day) and yield attributes resulting in increased dry root yield (1.42 tones/ha). The higher fertilizer level of 24 kg N and 48 kg P/ha increased the physiological growth parameters, viz. dry matter production (14.987 g/plant), leaf area index (3.918), leaf area duration (72.8 days) and net assimilation rate (0.359 g/dm(2)/day); yield attributes, viz. root length (53.7 cm), root diameter (1.06 cm), fresh root weight (7.945 g/plant), dry root weight (3.295 g/plant), harvest index (15.1%) and consequently dry root yield (1.16 tonnes/ha).