Anil Dixit

Herbicide weed management on weed dynamics, crop growth and yield in direct-seeded rice

Effect of herbicide combinations were evaluated in Raipur (Chhattisgarh) on crop growth, weed suppression and rice yield in direct-seeded rice (DSR) system during 2014 and 2015. Results revealed that combination of pyrazosulfuron + pretilachlor provided wide spectrum weed control at 15 + 600 g/ha to 30 + 1200 g/ha (61.6 -81.5%), which was comparable to two hand weeding at 15 and 30 days after sowing. Weed control efficiency was recorded to the tune of 40.0 - 89.9%, with highest in two hand weeding (84.6 -89.9%) and lowest in pendimethalin and lowest dose of pyrazosulfuron + pretilachlor in 2014 (40.0%) and pyrazosulfuron alone in 2015 (48.5%). The crop growth parameters (tillers, total dry matter/hill and leaf area index), yield attributes (panicle length, panicle weight, filled grains/panicle) and grain yield were recorded highest in two hand weeding (2.69 t/ha in 2014 and 5.87 t/ha in 2015) followed by pyrazosulfuron + pretilachlor at 15 + 600, 16.88 + 675 and 30 + 1200 g/ha. However, the least rice grain yield was recorded under weedy plot (1.45 t/ha in 2014 and 2.17 t/ha in 2015). The results suggested that pyrazosulfuron + pretilachlor at 15 + 600, 16.88 + 675 and 30 + 1200 g/ha were the best broad spectrum effective herbicide in order to minimize the diverse weed flora in DSR system.

Glyphosate tolerant and insect resistant transgenic Bt maize efficacy against shoot borer, cob borer and non-target insect pests

Introducing Bt insect resistance genes into hybrid maize seems to be the most feasible and effective technique accessible to control the pest. Transgenic stack hybrid maize (MON 89034X NK 603) was developed by Monsanto for checking yield losses of maize crop to increase productivity. Transgenic stack hybrid maize was claimed to have both insect protection and herbicide tolerant traits to provide protection to the crop from target pests and also provide effective weed management. MON 89034X NK 603 is 2nd generation glyphosate tolerant with Bt maize technology effective against lepidopteron insect pests with “dual mode of action”. A field experiment was carried out at ICAR-Directorate of Weed Research, Jabalpur for two years during Kharif (rainy season) 2009 and 2010 to evaluate the efficacy of transgenic stack hybrid maize (MON 89034X NK 603) against shoot borer (Chilo partellus), cob borer (Helicoverpa armigera), non-target insect pests and beneficial insects. Treatments consisted of two transgenic stacked hybrids named ‘Hishell’ and ‘‘900M Gold’’ with two conventional hybrids namely ‘Proagro-4640’ and ‘‘HQPM-1’’. Artificial infestation of Chilo partelus revealed complete absence of stem borer infestation in all the transgenic entries of ‘Hishell’ and ‘900M Gold’ with less than one leaf injury score (LIS), while in other conventional entries, stem borer infestation was observed and LIS was more than one. Hlicovepa armigera infestation was also not observed on transgenic hybrids whereas in the remaining non-transgenic maize treatment, significant attack of Helicoverpa armigera was observed in the range of 37 to 56%. These transgenic entries were not found resistant to aphids and grass hoppers. Beneficial insects were observed to visit transgenic Bt maize and conventional maize entries with no significant difference.