Effect of variety, density and weeds interference period on morphophysiological and qualitative traits of cotton (Gossypium hirsutum L.)

In order to study the effect of variety, density and weeds interference on morphophysiological and qualitative traits of cotton, a factorial experiment was conducted in a randomized complete block design with three replications at Research Farm of Islamic Azad University, Birjand Branch in 2015. The research factors consisted of two varieties (Philistine and Khordad), two density levels (14 and 28 plants. m²) and four levels of weed interference (weed free in the whole period, interference up to 40, 60 and 80 days after emergence of cotton). The results showed that Khordad variety in comparison to Philistine variety had superior significant 17.9 and 15.1 %, in traits of seed yield and oil yield respectively. Also, increasing density from 14 to 28 plants per m², seed yield and oil yield significantly were increased by 90 and 100.3%, respectively but number branches of main stem and stomatal conductivity significantly were decreased by 28.6 and 10%, respectively. With increasing the length of period of weeds interference up 80 days, number branches of main stem, seed yield, oil yield and oil percent significantly were decreased by 61.3, 94, 96.5 and 53.1%, respectively. In general, based on the results of this research, cultivation of variety Khordad with density of 28 plants per m² and weeding in the whole growth period is suitable for maximum of oil yield in cotton cultivation in Birjand region.