The effect of row spacing of different cultivars on populations density of Helicoverpa armigera (Hübner.)

Cotton Planting in rows of less than 40 cm is called ultra-narrow row (UNR). In this study, we compared the effect of narrow row spacing and prevalent row spacing on the bollworm pest population. The varieties studied in this study including Sahel, Sepid variety, and Golestan variety as the first factor and two methods of planting distance of 20×80 and 20×25 cm was considered as the second factor the experimental design was a randomized complete block design with 3 replications and was performed at Hashemabad Cotton Research Station, Gorgan. The results of the analysis of variance of data for two years of the experiment showed that the effect of varieties on crop row spacing was significantly different in terms of crop yield and population of cotton bollworm. The highest mean was obtained for Golestan variety with common cultivation distance (80×20 cm) at 3855 kg per hectare and the lowest average was obtained for Sahel variety with commonly cultivated row spacing with an average yield of 1052 kg per hectare was obtained. The results of the comparison of means on the effect of variety on cultivation distance on bollworm population density showed a significant effect on variety row spacing. The highest population density of this pest was related to Golestan variety with average cultivation distance, with average 0.65 is the number of growth stages per plant. Also, the lowest population density of this pest was related to Sahel variety with 20×80 and 20×25 cm varieties with mean of 0.25 and 0.23 growth stages per plant, respectively.