Weed dynamics, nutrient uptake and yield in Indian mustard ( rassica juncea) weed ecosystem as influenced by nitrogen levels, planting geometry and herbicides

Abstract

A field experiment was conducted at Jabalpur, Madhya Pradesh, during the winter seasons of 1996 97 and 1997 98, to find out the effect of nitrogen, planting geometry and herbicides on weed dynamics, yield and nutrient uptake in Indian mustard [Brassica juneea (L.) Czernj. Cosson]. Treatments comprised combinations of 4 N levels (0,40,80 and 120 kglha) and 2 planting geometry (uni and bi direction) in main plots, 2 herbicides, viz. lsoproturon 1.0 kg and Oxadiazon 0.75 kglha, as pre emergence were compared with hand weeding 30 days after sowing and weedy check in subplots. Weed population declined, whereas weed dry matter increased with advancement in age of the crop. Increasing levels of nitrogen and change in planting geometry did not influence the weed population, whereas weed dry matter at harvest declined significantly at 120 kg Nlhg compared with no nitrogen application. Seed yield and nutrient uptake also increased significantly at 120 kg Nlha. Both the herbicides significantly increased the nutrient uptake by checking the weed growth compared to weedy check. lsoproturon being at par to oxadiazon resulted in the highest seed yield. Application of 120 kg Nlhg and lsoproturon gave the highest net return and benefit : cost ratio.