| چکیده انگلیسی مقاله |
Introduction: There is always a gap between the actual grain yield in farmers’ fields and potential grain yield (yield gap), which is often caused by suboptimal agronomic management (Silva et al., 2021). This inappropriate management practices are partially related to non-agronomic and financial reasons including; the level of access to agricultural machineray and equipment as well as and financial facilities. It is hypothesized that farmers managing larger fields have access to financial facilities and are better equipped to address these challenges and manage their fields more effectively (Priyadarshini et al., 2022). Therefore, this study was carried out to identify the role of field size in the grain yield gap and factors contributing to it.
Materials and Methods: This study was conducted during the 2020-21 growing season in wheat growing areas of Gomishan region, Golestan province, Iran. To identify the limiting factors of grain yield of rainfed wheat, a field survey was carried out across 95 farmers’ fields using field visits and face-to-face interviews with farmers. Fields were randomly selected to ensure variability in cultivated areas, management practices, and grain yield, allowing for the identification of factors contributing to grain yield gap. The studied variables included; field size, farmer experience, and all operations from soil preparation, seed sowing, crop management, harvesting, and actual yield. Fields were categorized into three size groups: small size fields with areas ranging from 1 to 5 ha, medium size fields with areas ranging from 5 to 10 ha, and large size fields with areas more than 10 ha. Management practices, grain yield, and then yield gap (%) were determined for each group. To analyze the factors contributing to the grain yield gap, the Comparative Performance Analysis (CPA) method was used to identify major yield-limiting factors.
Results: The results showed that the yield gap was 83%, 64%, and 62% for small, medium, and large fields’ groups, respectively. The actual grain yield of rainfed wheat was 1392, 1770.5, and 2032.5 kg ha-1 for small, medium, and large fields’ groups, respectively. Contributing factors to grain yield gap in small fields included; sowing date (3.4%), topdressing fertilizer (11.2%), Atlantis + Bromaiside (48.5%), Atlantis + Granstar (14.1%), Atlantis (17.4%), and weed issues (5.4%). In medium fields, key factors were seed treatment with humic acid (14%), sowing date (12.8%), topdressing fertilizer (43.2%), micronutrients foliar application (6.9%), Atlantis + Bromaiside (13.3%), and weeds (9.8%). For large fields, factors such as crop rotation (9.3%), plant density (30.2%), split application of topdressing fertilizer (15.9%), Atlantis + Bromaiside (20.1%), Tilt fungicide (9.5%), diseases (11.8%), and harvesting (3.2%) were significant.
Conclusion: The results of this study showed that the factors contributing to the yield gap varied in some management practices across field size groups, while others remained consistent. The contribution of Atlantis + Bromaiside herbicided to the yield gap was 48.5% in small fields, 13% in medium fields, and 20% in large fields. Considering the contribution of crop management practices, it appears that the use of Atlantis + Bromaiside herbicides in small size fields, the amount of topdressing fertilizer in medium size fields, and plant density in large size fields, which had the greatest effect on reducing grain yield, should be prioritized in agronomic management practices for closing the yield gaps in rainfed wheat growing areas of Gomishan region, in Golestan province, Iran.
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