Integrated weed management effects on the growth characteristics and yield of cotton (Gossypium hirsutum)

In 2009, an experiment carried out in a farm at Agricultural Research and Natural Resources Center of Tehran (ARNRCT) to determine the best method of integrated weed management of in cotton fields. The experimental design was a split block design with four replications by 20 treatments. The main plots were consisted four levels of weed management practices including herbicide trifluralin along with one round and two-round hand weeding, untreated control weeds and fully control of all weeds. Sub plots were five cotton cultivars including Varamin, Oltan, Mehr, Sepid and Khordad. The results showed that among the methods, trifluralin herbicide application with two-stage hand weeding were the appropriate control treatments, while weed dry weight was reduced and cotton yield was increased in all cultivars. Optimal growth conditions with increasing height, producing vegetative and reproductive shoots, leaf area and canopy resulted in increased competitiveness in the cotton plants. Sepid variety despite lower height between varieties produced more leaves and stems dry weight, reduced dry weight of weeds. Oltan gained lowest yield among the varieties, due to the canopy structure and the type of growth. In contrast, Varamin and Khordad had dominate performance in the presence of weeds because of maximum height, number of reproductive shoots, number of nodes and shoot dry weight as more extensive canopy and good leaf coverage.