Residual effect of sulfonylurea herbicides applied to wheaton succeeding maize

摘要

The field experiment was conducted to assess the residual effects of sulfosulfuron (25, 37.5 and 50 g/ha) and mesosulfuron + iodosulfuron (12, 18 and 24 g/ha) herbicides applied to wheat on maize (Zea mays L.) grown in sequence at Ludhiana, Punjab (India). None of the sulfonylurea herbicides (sulfosulfuron and mesosulfuron + iodosulfuron) applied to wheat at different doses affected the emergence of maize crop during both the years. But the effect was evident on growth characters and yield during 2005 whereas in 2004, plant height and dry matter at all stages of maize was not affected significantly. This might be due to difference in rainfall received at different stages of the crop growth in both the years. The rainfall received from April to June(optimum sowing time) was 137 mm and 54.2 mm in 2004 and 2005, respectively, however, in July rainfall was more in 2005 but the earlier status of rainfall was more responsible for the residual effect in 2005 as the reduced rainfall presumably left the soil dry for long time and might have resulted in slow dissipation rate of the herbicides. Again in August, rainfall was more in 2004 (+45.7 mm departure from normal rainfall in 2004) than 2005 so this might have enhanced the movement of the herbicide to lower surface and thus no residual effect was observed on the crop. Hence, it is not safe to grow maize in rotation after application of these sulfonylurea herbicides on wheat, as significant effect on the growth and yield of maize was recorded during theyears of less rainfall.