Influence of seed hardening techniques and weed management practices on weed dynamics and yield of groundnut plus castor intercropping system under rainfed conditions

Field experiments were conducted at North-West and Western Zones of Tamil Nadu during kharif season to study the seed hardening techniques and weed management for productivity enhancement in groundnut+castor intercropping system under rainfed conditions. In kharif 2003 and 2004 the effect of seed hardening in groundnut (0.5% CaCl(2) and normal seed) and weed management practices (unweeded check, hoeing and weeding on 20 and 40 DAS, weeding with star type weeder on 20 DAS+hoeing and weeding on 40 DAS, pre-emergence application of pendimethalin @ 1.0 kg a. i./ha+hoeing and weeding on 40 DAS and pre-emergence application of metolachlor @ 1.0 kg a. i. ha+hoeing and weeding on 40 DAS) in groundnut+castor intercropping system. In respect of groundnut, seed hardening with 0.5% CaCl(2) treatment recorded the highest speed of emergence, field emergence, vigour index, plant height, LAI, CGR, RGR, DMP, number of matured pods, pod yield and haulm yield. Irrespective of the locations chlorophyll content, soluble protein, 100-kernel weight and oil content were, however, not influenced by CaCl(2) seed hardening. Among the weed management practices studied, pre-emergence application of metolachlor @ 1.0 kg a. i./ha+hoeing and weeding on 40 DAS recorded the highest weed control efficiency and lowest weed dry matter production at 20 DAS, while at 40 DAS hoeing and weeding on 20 and 40 DAS recorded the highest weed control efficiency. In the overall experimental results, it was concluded that groundnut seeds treated with 0.5% CaCl(2) and pre-emergence application of metolachlor @ 1.0 kg a. i. / ha followed by one hoeing and weeding on 40 DAS increased the yields of groundnut and castor crops during kharif season.