Effect of seed rate and row spacing on the efficacy of clodinafop for combating isoproturon resistant Phalaris minor Retz. in wheat
M.S. BhullarA and U.S. WaliaB
A Department of Plant Breeding, Punjab Agricultural University, Ludhiana, India.
B Department of Agronomy and Agrometeorology, Punjab Agricultural University, Ludhiana, India.
A field investigation to study the effect of seed rate and row spacing on the efficacy of clodinafop for combating isoproturon resistant Phalaris minor Retz. in wheat was conducted on a sandy loam soil at Punjab Agricultural University, Ludhiana, India during growing seasons of 1999-00 and 2000-01. The results revealed that the crop sown with 50% higher seed rate (i.e. 150 kg ha-1) produced more dry matter which in turn reduced the dry matter accumulation of P. minor by 35.4% resulting in increased grain yield of wheat by 12.3% over recommended seed rate. The crop planted at closer spacing of 15 cm reduced the dry matter accumulation of P. minor by 32.3% which increased the effective tillers of wheat by 20.8% leading to increase in grain yield of wheat by 10.5% compared to crop planted at 22.5 cm. Post-emergence application of clodinafop at its recommended dose (0.06 kg ha-1) gave selective control of resistant P. minor and reduced its dry matter accumulation by 79.8% resulting into 128.9% increase in wheat grain yield over recommended dose of isoproturon (0.94 kg ha-1).
Grain yield of wheat crop sown at 100 kg ha-1 with a spacing of 15 cm was at par to the crop sown at 125 kg ha-1 with a spacing of 22.5 cm during 2000-01. Further, the crop sown at closer row spacing of 15 cm and sprayed with 0.75 times the recommended dose of clodinafop produced grain yield at par to the crop spaced at 22.5 cm but sprayed with recommended dose of clodinafop (0.06 kg ha-1) during 1999-00 indicating the possibility of reducing herbicide dose through closer spacing of wheat.
Keywords: Resistance, Phalaris minor, isoproturon, clodinafop, wheat, geometry, density and management.
Plant Protection Quarterly (2004) 19 (4) 143-146.