Effect of seed rates, irrigation intervals and weed pressure on productivity of direct-seeded rice (Oryza sativa)

A field investigation conducted during rainy seasons 2000 and 2001 on sandy loam soils of Gurdaspur, Punjab showed that seed rate of 100 kg/ha caused significant reduction in dry matter of weeds and significantly increased the grain yield over seed rate of 50 kg/ha in both years. Increasing irrigation interval from 2 to 3 days though increased die grain yield by 0.2 tonne/ha the effect was not significant. Integrated weed management comprising 2 hand-weedings in addition to application of 0.75 kg/ha pretilachlor caused significant reduction in dry matter of weeds and significantly increased grain yield through marked improvement in yield attributes over that of chemical control of weeds alone in bom the years. Interaction of seed rates and methods of weed control revealed that dry matter of weeds in case of integrated weed control with 50 kg/ha seed rate was significantly lower man that of chemical weed control with seed rate of 150 kg/ ha. Panicles/m and grains/panicle were significantly higher with 50 kg/ha seed rate in integrated compared to seed rate of 100 kg/ha in chemical weed control. Mean grain yield with seed rate of 100 kg/ha in integrated weed control (6.47 tonnes/ha) was significantly higher than with 150 kg/ha in chemical weed control (5.91 tonnes/ha).