Document Type : Research Paper
Authors
1 aPh.D. in Crop Ecology and Postdoctoral Researcher, Iran National Science Foundation (INSF).
2 Head of Department, Dryland Agricultural Research Institute (DARI), Maragheh, Iran ,
Abstract
Introduction: Wheat, as one of the strategic agricultural products, plays a significant role in ensuring global food security. The proper selection of tillage systems and wheat varieties is a key factors in optimizing performance and ensuring sustainable production under rainfed (dryland) conditions. While conventional tillage faces challenges such as soil moisture depletion and structural degradation, conservation tillage, through residue retention and improvements in soil physical and biological conditions, provides better yields, particularly under water stress. On the other hand, the response of different wheat genotypes to varying tillage conditions varies, and identifying varieties that are compatible with conservation tillage systems plays a crucial role in increasing productivity and production sustainability. This study aims to select suitable rainfed wheat lines under tillage methods conditions in the North Khorasan region.
Methodology: This experiment was conducted in a strip plot design based on a randomized complete block design (RCBD) with four replications during the 2023-24 cropping season at the Dryland Agricultural Research Station in Shirvan. The study included four main plots including tillage treatments: 1) Conventional tillage (involving plowing with a moldboard plow to a depth of 30 cm, followed by disking, leveling with a roller, and sowing with a row planter), 2) Minimum tillage without residue retention (using a chisel plow to a depth of 15 cm, leveling with a roller, and sowing with a row planter), 3) Minimum tillage with 30% residue cover (plowing with a chisel plow to a depth of 15 cm and sowing with a row planter), and 4) Direct seeding (direct sowing of seeds), which were applied as vertical plots. In addition, seven wheat varieties representing common rainfed wheat varieties in North Khorasan Province as subplots (Nafis, Dehghan, Sadra, Kamal, Hashtrood, Baran, and Varan) were evaluated as horizontal plots. In this study, the traits examined included physiological characteristics such as leaf area, SPAD index, as well as yield-related traits and components like plant height, number of seeds per spike, thousand-grain weight, number of spikes per unit area, biological yield, harvest index, and grain yield.
Research findings: Analysis of variance showed that the effect of genotype was significant for most traits, except the number of grains per spike, while the effect of tillage was significant for all traits except thousand kernel weight. Although direct seeding increased biological yield and leaf area, it led to a decrease in harvest index and grain yield. The cultivar ‘Baran’ under conventional tillage achieved the highest grain yield (2032 kg/ha), while ‘Dehghan’ and ‘Nafis’ showed the best performance under minimum tillage and direct seeding systems with 1797 and 1694 kg/ha, respectively. Moreover, minimum tillage with residue retention outperformed residue-free treatments across most traits. Overall, under the conditions of this study, selecting cultivars with high genetic potential played a more decisive role in optimizing rainfed wheat yield than tillage management.
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