K. PrasadNargis Kumari2024-07-122024-07-122000https://krishikosh.egranth.ac.in/handle/1/5810211896Among the factors responsible for drastic reduction in grain yield, weed occupies top most position. Weed is a serious problem in general and during rabi season particular. The problem have intensified due to increase in irrigation facilities, fertilizer use and adoption of high yielding cultivars and changed agrotechniques. Recently, there has been a rapid growing interest in adopting intercropping system as a most potential tool for enhancing the crop production over space and time. The yield advantages through intercropping over sole cropping are achieved not by means of costly inputs but by simple expedient of growing crops together. Weed management research in India has been mostly confined to sole cropping and the information pertaining to weed control in intercropping is rather meagre, specially in winter crops. Wheat crop often suffers from severe weed competition. Keeping the above fact in mind, a field experiment was conducted in split plot design with three replications. Five cropping systems (viz. sole wheat (20 cm), sole linseed (25 cm), sole sunflower (60 cm), wheat+ sunflower (3:1) and wheat + linseed (3:1) were kept in main plot and five weed management practices were kept in sub-plots [Weedy control, Weeding (20, 40 and 60 DAS). Pendimethalin (1.5 kg a.i. ha" pre-emergence), Isoproturon (1.5 kg a.i. ha post emergence) and Pendimethalin + isoproturon (1.0 kg a.i. ha pre-emergence + 1.0 kg a.i. har¹ post-emergence). The results revealed that intercropping of wheat either with sunflower or linseed in 3:1 rows ratio proved superior to their sole cropping in respect of yield attributes, yield and economic advantages. Intercropping of wheat with sunflower in 3:1 rows ratio produced significantly higher wheat equivalent yield (8605.67, 9272.76 and 8939.15 kg ha) in respective years and on pooled basis. Wheat + sunflower (3:1) intercropping system recorded lesser competitive ratio (0.58 and 0.53) and higher value of relative crowding coefficient (10.21 and 15.29) in respective years. Negative value of aggressivity (-0.41 and -0.44) were obtained in wheat + sunflower (3:1) intercropping system, which indicates that the wheat was dominated by the sunflower in the system. Wheat + sunflower intercropping system in 3:1 rows ratio recorded maximum nitrogen uptake (92.70 and 102.70 kg ha), net return (Rs.41722.52 and 48214.15 ha) and benefit: cost ratio (4.87 and 5.47) in respective years than sole cropping of either of the crops. The effect of manual weeding at 20, 40 and 60 days after sowing was comparable with combined use of pendimethalin as pre-emergence + isoproturon as post-emergence each @ 1.0 kg a.l. ha in reducing weed density and weed dry matter. Weeding thrice (20, 40 and 60 DAS) produced maximum wheat equivalent yield (6017.18, 6701.15 and 6359.17 kg ha-¹) in respective years and on pooled basis, which was comparable with combined use of herbicides. Pre emergence application of pendimethalin @ 1.5 kg a.i. ha recorded minimum competitive ratio (0.42) in 1997-98, whereas in 1999-2000 minimum competitive ratio was recorded under weeding (20, 40 and 60 DAS). Combined application of pendimethalin, pre-emergence + isoproturon, post-emergence each @ 1.0 kg a.i. ha¹ in wheat intercropped either with sunflower or linseed gave minimum value of aggresivity (-0.40 and -0.41) in respective years, whereas maximum value of relative crowding coefficient was recorded under combined application of pendimethalin as pre-emergence+ isoproturon as post-emergence each @ 1.0 kg a.i. ha¹¹ in 1997-98 and under weeded plots in 1999-2000. Weeding at 20. 40 and 60 days after sowing recorded maximum nitrogen uptake by crops (82.47 and 89.23 kg ha) in respective years which was comparable with post-emergence application of isoproturon @ 1.5 kg a.i. ha¹ and combined use of herbicides. Manual weeding (thrice) at 20, 40 and 60 days after sowing recorded highest gross return in both the years while combined use of pendimethalin as pre emergence + isoproturon as post-emergence each @ 1.0 kg a.i. ha recorded highest net return (25783.14 and 30638.23 Rs ha') and benefit: cost ratio (3.42 and 3.87) in respective years.EnglishThesis