Weed Management in Direct Seeded Rice under Different Row Spacing

A field study to evaluate the weed management in direct seeded rice under different row spacing was carried out at Agronomic Research Area, University of Agriculture, Faisalabad during summer 2018. Two herbicides Butachlor @ 118.61 g a.i. ha-1 (pre-emergence) was applied within 24 hours of sowing of direct seeded rice and combination of two herbicides Butachlor @ 118.61 g a.i. ha-1 (pre-emergence) within 24 hours after sowing sequentially followed by Bispyribac Sodium + Bensulfurin Methyl @ 26.7 g a.i. ha-1 + 17.8 g a.i. ha-1 (post-emergence) was applied 15 days after sowing. Bispyribac Sodium @ 26.7 g a.i. ha-1 was applied 15 days after sowing. A weedy check and weed free treatment were also run for comparison. A fine rice cultivar (Basmati 515) was sown during the last week of June in 22.5 cm and 11.25 cm spaced rows using a seed rate of 29 kg ha-1. To fulfill the requirement of nutrients 135 kg N, 88 kg P and 61 kg ha-1 K were applied. The experiment was replicated thrice in a randomized complete block design under split plot arrangement. The net plot size was 3 m × 2.25 m. Date regarding weed density (15, 30 and 45 DAS), weed biomass before harvesting and yield components of rice were recorded by following standard procedures and statistically analyzed by applying Fisher’s analysis of variance technique. Least significant difference test (LSD) at 5% probability was used to compare treatments means. Results of the study showed that total weed density and weed dry weight were significantly influenced by different row spacing and weed control treatments. Significantly lower weed density and weed biomass were observed under narrow row spacing (11.25 cm) as compared to wider row spacing (22.5 cm). Among weed control treatments application of Butachlor @ 118.61 g a.i. ha-1 (pre-emergence) within 24 hrs after sowing of DSR and Bispyribac Sodium @ 26.7 g a.i. ha-1 (15 DAS) reduced the total weed density and weed dry weight. Similarly, paddy yield was also significantly influenced by different row spacing and weed control treatments as weed free at 11.25 cm row spacing gave maximum paddy yield (4.0 t ha-1).