Ph.D. Dissertation:

Effect of integrated nutrient system on yield and yield components of cotton in conventional and ultra-row narrow spacing in direct and transplanting methods

In order to investigate the effect of various nutrient systems on the yield and yield components of cotton in conventional (CR) and ultra-row spacing cultivation (UNR) in two planting method a split plot factorila experiment was conducted in a randomized complete block design with three replications during two cropping seasons of 2019 and 2020 in a private farm in Rudab city (Razavi Khorasan) .The type of fertilizer used includes chemical, organic, chemical+organic and control (without fertilizer consumption) as the main plot and the planting method including common cultivation and cultivation in very narrow row spacing and the planting method including seedling cultivation and direct cultivation in a factorial arrangement were considered sub-plots. The results showed that in the first and the second year, the highest number of lateral branches was achieved in seedling cultivation and the use of chemical+organic and chemical fertilizers, respectively. The chemical+organic treatment increased the number of bolls by 19.64% compared to the control treatment. In the second year, the chemical fertilizer treatment achieved the highest number of bolls per plant with an average of 9.6 bolls and followed a 50% increase in the number of bolls compared to the control treatment. chemical+organic treatment increased the average weight of 20 bolls by 76.3% compared to the control treatment, and plants planted with common row spacing produced more average weight of 20 bolls compared to very narrow row spacing. The highest amount of seed cotton and lint yield in both methods of cultivation (direct and transplanted) was in the combined fertilizer treatment and cultivation with ultra-row spacing. In all the treatments, except for organic fertilizer and direct cultivation, the seed cotton yield in cultivation with ultra-row spacing was higher than that of common cultivation. The qualitative characteristics of cotton were less affected by the experimental treatments, however, the longest fiber length in both years of the experiment belonged to the integrated fertilizer treatment and cultivation with narrow rows. The highest fiber index was obtained in the combined fertilizer treatment and cultivation with ultra-row spacing. In comparison with direct cultivation, seedling cultivation showed superiority in terms of fiber strength, and the uniformity of fiber index was higher in conventional cultivation than in cultivation with narrow rows. Absorption efficiency in all feeding systems (except chemical) was higher than direct cultivation in germination culture. The highest absorption efficiency was observed in germination culture and in the control treatment, while direct cultivation and integrated feeding system had the lowest nitrogen absorption efficiency. The highest agricultural efficiency was observed in the chemical control treatment. The efficiency of nitrogen productivity in common cultivation was 25.49 kg of biological yield per kg of consumed nitrogen, while this value in cultivation in ultra-row spacing was 22.63 biological yield per kg. The highest physiological efficiency was observed in seed culture and with chemical nutritional system, which did not have a statistically significant difference with the same nutritional method in culture. In total, the results of this experiment showed that by replacing 50% of organic fertilizer in the integrated system, with a 50% reduction in the use of chemical fertilizers and cultivation in very narrow row spacing, good yield and fibers can be produced in cotton. The highest nitrogen harvest index was observed in the seedling cultivation method and in the control treatment, while the direct cultivation and integrated system had the lowest nitrogen harvest index . The highest nitrogen utilization of agronomy efficiency was observed in the chemical control treatment. The nitrogen utilization of agronomy efficiency in common cultivation was 25.49 kg biomass kg N, while this value in cultivation in ultra-row spacing was 22.63. The highest physiological efficiency was observed in seedling cultivation method with chemical fertilizer application, which did not have a statistically significant difference with the same nutritional method in common cultivation system. Overall, the results of this experiment showed that by replacing 50% of organic fertilizer in the integrated system, by reducing 50% of the chemical fertilizers and cultivation in ultra-row spacing, it is possible to produce suitable seed cotton yield.

Keywords: Industrial crop, Integrated nutrient management, Planting method, Seed cotton yield