Effect of row spacing and nutrient consumption on some morphological, physiological and agronomic responses of three cotton cultivars

In order to investigate the effect of row spacing on yield and growth of cotton cultivars uncer two conditions of fertilizer application and non-fertilization, a study was conducted in Gorgan as a split-factorial experiment based on randomized complete blocks design with three replicates in 2017. Experimental factors included three cotton cultivars (Sajedi, Kashmar and Golestan), row spacing at two levels (20 and 80 cm) and nitrogen, phosphorus and potassium fertilizers application at 350, 300 and 225 kg ha-1 and control treatment (No fertilizer), respectively. According to the results of analysis of variance, the effect of cultivar on number of reproductive branches and bolls as well as the height of first boll from ground was significant, whereas row spacing significantly affected number of vegetative branches and bolls, the height of first boll from ground, boll weight and lint yield. In all three cultivars studied, decrease in row spacing led to decreased plant height and increased leaf area index, dry matter and lint yield. Fertilization led to significant increase in plant height, leaf area index, number of reproductive branches and bolls, boll weight and yield. Among interactions, only the interaction of cultivar× row spacing on number of reproductive branches and interaction of row spacing× fertilizer on boll number, boll weight and lint yield were significant. Therefore, there is a significant interaction between row spacing and nutrient consumption in terms of growth characteristics and yield of cotton cultivars, and decreased row spacing in cotton can significantly increase lint yield.