Efficacy of potassium salt of glyphosate on weed control and yield in transgenic corn

A field experiment was carried out at Directorate of Weed Research, Jabalpur for the consecutive two years during kharif 2009 and 2010 to evaluate the weed control efficiency and crop productivity with K salt of glyphosate formulation in field conditions. Treatments consisted of two transgenic stacked hybrids named Hishell and 900M Gold applied with glyphosate as early post-emergence at 900, 1 800 and 3 600 g a.i./ha during kharif season of 2010 with two conventional hybrids namely Proagro-4640 and HQPM-1. Among the treatments, early post-emergence application of glyphosate at all doses registered lower weed density and higher weed control efficiency, i.e. 100% in all transgenic corn hybrids at 21 DAS and at harvest. Significantly higher numbers of cobs/plot were observed in transgenic hybrids as compared to conventional entries. While more cob length was observed with Hishell Transgenic hybrids at all doses as compared to 900 M Gold transgenic hybrids. Hishell transgenic hybrids at 3 600 g/ha registered significantly higher number of grains per row as compared to with its conventional control, 900 M Gold transgenic hybrid (1 800g/ha), 900 M Gold conventional and national checks. Significantly higher values of 20 cob weight, 20 cob grain weight and total cob weight was observed with Hishell and 900 M Gold transgenic hybrids as compared to other conventional hybrid entries and national checks. Hishell and 900 M Gold transgenic hybrids performed better with regard to grain yield ranging between 6-10 tonnes/ha which was approximately 3 to 4 times higher than the average yield of maize crop per ha, i.e. 2.30 tonnes/ha during both the years. Hishell at all rates of glyphosate application performed equally well in terms of yield but the yield of 900 M Gold decreased as the dose was enhanced from 1 800 to 3 600 g/ha during second year of experimentation.