M.A. Thesis:

Integrated weed management in conventional tillage and ultra narrow row spacing in cotton

In order to determine the most appropriate method of weed control in conventional and ultra narrow row cultivation system in Cotton, a factorial experiment in a randomized complete block design with three replications was conducted in Sabzevar in 2015-2016. Factors were cultivation system (conventional (75 cm row spacing) and ultra narrow row ( 20 cm row spacing) and weed control management(Weedy, Herbicide at recommended dose, three times hand weeding at 30, 45 and 60 days after emergence (DAE), two times hand weeding 30 and 45 DAE, 50% recommended herbicide dose+ hand weeding at 45 DAE and 50% recommended herbicide dose at 45 and 60 DAE. Ethalfluralin (Treflan 48% EC) at 1160 g. ai ha-1 as soil applied 7 days before planting was used in this study. At maturity, Weed dry weight, weed density, plant height, Maximum leaf area index, Light absorption percent, Number of symodial and reproductive branches, number of boll in plant, boll weight, lint weight per boll, lint yield, biological yield and lint index were measured. The results showed that ultra narrow row cultivation system had more height (15.5%), leaf area index (14.5%), the percentage of light absorbed (15.5%), yield (22.45%), lint yield (16.7%), cotton yield (25.6%), biological yield (18.5%) and less lint weight per boll (), weed dry weight (), lint index () than in conventional system. For all of the traits in this experiment, three times hand weeding most useful in increasing the characters over other control methods. 50% recommended herbicide dose at 45 and 60 DAE was increased yield and yield components but in 50% recommended herbicide dose at 45 DAE yield and yield components significantly decreased. In ultra narrow row cultivation system, reducing herbicide dose had more yield and yield components compared to conventional farming system. Overall results showed that planting system in ultra narrow row cultivation in the presence of weed competition, hand more cotton yield compared to conventional tillage systems. In this system with a 50% reduction of herbicide and twice at 30 and 40 days after emergence can suggestion for seed cotton yield.

Keywords: Cotton, Low herbicide dose, Ultra-narrow row, Weed competition