تأثیر خاک‌ورزی حفاظتی بر عملکرد و اجزای عملکرد ارقام پنبه

Background and Objective:
Cotton (Gossypium hirsutum L.) is a major industrial crop whose production in arid and semi-arid regions is increasingly constrained by water scarcity, soil degradation, and rising input costs. Conventional tillage systems, characterized by intensive soil disturbance, often aggravate these challenges by increasing evaporation losses, fuel consumption, and weed pressure. Conservation tillage, which minimizes soil disturbance and field traffic, represents a viable strategy to improve resource-use efficiency and long-term sustainability. However, crop response to conservation tillage is strongly influenced by cultivar characteristics and local environmental conditions. This study aimed to evaluate the effects of conventional and conservation tillage systems on morphological traits, yield components, weed biomass, and lint yield of several cotton cultivars under the agro-climatic conditions of Esfarayen, Iran, in order to identify optimal cultivar–tillage combinations for sustainable cotton production.
Materials and Methods:
The experiment was conducted during the 2024 growing season (1403) at the Esfarayen Agro-Industry fields in North Khorasan Province, Iran. A split-plot experiment arranged in a randomized complete block design with three replications was employed. Tillage system was assigned to main plots at two levels: conservation tillage using a Cyclo-Tiller, and conventional tillage consisting of moldboard plowing followed by discing and Cyclo-Tiller operations. Subplots comprised five cotton cultivars: Khordad, Kashmar, Varamin, Khorshidi, and Sajedi. Uniform agronomic practices were applied across all treatments. Measured variables included plant height, number of monopodial and sympodial branches, number of bolls per plant, weight of 30 bolls, weed dry biomass, and lint yield. Data were subjected to analysis of variance, and mean comparisons were performed where significant effects were detected.
Results:
Analysis of variance revealed significant effects of tillage system, cultivar, and their interaction on most measured traits. Conventional tillage generally resulted in taller plants and a higher number of monopodial branches, reflecting enhanced vegetative growth under greater soil disturbance. The maximum plant height (137.7 cm) was recorded for the Varamin cultivar under conventional tillage, whereas Sajedi and Khorshidi produced the shortest plants. Conservation tillage reduced plant height across all cultivars; however, the magnitude of reduction varied by genotype. Khordad and Varamin exhibited greater reductions, while Sajedi and Khorshidi were less affected, indicating better adaptation to reduced tillage conditions.
The number of sympodial branches was primarily influenced by cultivar and the tillage × cultivar interaction. Conservation tillage increased sympodial branch number in Varamin, Khordad, and Khorshidi by 8–15% compared with conventional tillage, suggesting improved reproductive development under enhanced soil moisture retention and reduced stress. Varamin consistently produced the highest number of sympodial branches, whereas Kashmar and Sajedi showed lower values and limited responsiveness to tillage system.
Weed dry biomass was strongly affected by tillage system, with conservation tillage reducing weed biomass by up to 56% relative to conventional tillage. The highest weed biomass (192.7 g m⁻²) was observed in Sajedi under conventional tillage, while the lowest (83.3 g m⁻²) occurred in Varamin under conservation tillage. Reduced weed growth under conservation tillage was attributed to improved soil cover and restricted weed emergence. The number of bolls per plant was significantly influenced by the tillage × cultivar interaction. Conservation tillage increased boll number in all cultivars, with Varamin producing the highest number (12.3 bolls per plant), representing a 23% increase compared with conventional tillage. Similarly, the weight of 30 bolls was significantly greater under conservation tillage, with the maximum value (173 g) recorded for Varamin, followed by Khordad (167 g), corresponding to increases of 19–27% relative to conventional tillage.
Conclusion:
The results demonstrate that conservation tillage can enhance cotton yield components and lint yield under the agro-ecological conditions of Esfarayen, while simultaneously reducing weed biomass and input requirements. Among the evaluated cultivars, Varamin and Khordad exhibited superior performance and adaptability under conservation tillage. Therefore, integrating conservation tillage with appropriate cultivar selection is recommended as an effective strategy to improve productivity, reduce fuel consumption, and promote sustainable cotton production in water-limited regions.