Published online by Cambridge University Press: 20 January 2017
Field experiments were conducted in Punjab, India, in 2011 and 2012 to studythe integrated effect of planting pattern [uniform rows (20-cm spacing) andpaired rows (15-, 25-, and 15-cm spacing)], cultivars (PR-115 andIET-21214), and weed control treatments (nontreated control, pendimethalin750 g ai ha−1, bispyribac-sodium 25 g ai ha−1, andpendimethalin 750 g ha−1 followed by bispyribac-sodium 25 g ha−1) on weed suppression and rice grain yield in dry-seededrice. In the nontreated control, IET-21214 had higher grain yield thanPR-115 in both planting patterns. However, such differences were notobserved within the herbicide treatment. IET-21214 in paired rows, even innontreated control, provided grain yield (4.7 t ha−1) similar tothat in uniform rows coupled with the sole application of pendimethalin (4.3t ha−1) and bispyribac-sodium (5.0 t ha−1). In uniformrows, sequential application of pendimethalin (PRE) and bispyribac-sodium(POST) provided the highest grain yield among all the weed controltreatments and this treatment produced grain yield of 5.9 and 6.1 t ha−1 for PR-115 and IET-21214, respectively. Similarly, inpaired rows, PR-115 in paired rows treated with sequential application ofpendimethalin and bispyribac-sodium had highest grain yield (6.1 t ha−1) among all the weed control treatments. However,IET-21214 with the sole application of bispyribac-sodium produced grainyield similar to the sequential application of pendimethalin andbispyribac-sodium. At 30 days after sowing, PR-115 in paired rows coupledwith pendimethalin application accrued weed biomass (10.7 g m−2)similar to the sequential application of pendimethalin and bispyribac-sodiumcoupled with uniform rows (8.1 g m−2). Similarly, IET-21214 withbispyribac-sodium application provided weed control similar to thesequential application of pendimethalin and bispyribac-sodium. Our studyimplied that grain yield of some cultivars could be improved by exploringtheir competitiveness through paired-row planting patterns with less use ofherbicides.