Evaluation of Weed Control Options for Herbicide Resistant Transgenic Stacked (TC 1507 X NK603) and Conventional Maize Hybrids for Higher Productivity

Abstract

Weeds are posing a serious problem in maize. The congenial climatic conditions encourage more weed growth in the widely spaced crop like maize and cause yield reduction to the tune of 29 to 70 percent. A field experiment was con ducted for two years at Tamil Nadu Agricultural University, Coimbatore during kharif seasons of 2010 and 2011 to evaluate the weed management options for transgenic stacked (TC 1507 & NK 603) and conventional maize hybrids. The experiments were conducted with the following objective to evaluate the weed control efficiency and crop produc tivity with K salt of glyphosate formulations under field conditions. Treatments consisted of two transgenic stacked hybrids named 30V92 and 30B11 applied with glyphosate as early post emergence at 900 and 1800 g a.e ha - 1 during kharif , 2010 and conventional maize hybrids named 30V92 and 30B11 applied with glyphosate by controlled droplet application method at 900, 1350 and 1800 g a.e ha - 1 during kharif , 2 011 compared with non transgenic counterpart maize hybrids applied with pre emergence atrazine at 0.5 kg ha - 1 followed by one hand weeding on 40 DAS with and without insect management. Based on the two years field experimentation, it was found that early post emergence application of glyphosate at 1800 g a.e ha - 1 gave significantly lower weed density, weed dry weight and higher weed control effi ciency at all the intervals. Higher grain yield was registered with post emergence application of glyphosate at 1800 g a.e ha - 1 in transgenic and conventional maize hybrid of 30V92 (12.21 t ha - 1 and 11.23 t ha - 1 ) during both seasons of the study. Unweeded control accounted for grain yield which in turn reflected through higher weed index