Document Type : Scientific - Research
Authors
1
Assistant Prof, Department of Agriculture, Faculty of Agriculture, Payame Noor University, Tehran, Iran
2
Assistant Prof., Department of Plant Production and Genetics Engineering, Faculty of Agriculture, Lorestan University, Khorramabad, Iran
10.22092/jsb.2026.371597.1402
Abstract
The current research aimed to evaluate the effects of two transplanting ages (35 and 45 days) and direct-seeded sowing on growth indices and root yield of sugar beet across three cold semi-arid regions: Ardebil, Tabriz, and Urmia. Crop growth was simulated using the SUCROS model based on long-term climatic data (1980-2020) and soil physical-hydrological characteristics. Growth indices including TDW, LAI, RGR, and CGR were derived using functional growth models and compared across planting systems. Transplanting markedly improved early crop establishment. In transplant treatments, LAI peaked around 120 days after planting at 7.4 in Ardebil, 6.6 in Tabriz, and 7.05 in Urmia, whereas corresponding values under direct-seeded sowing were approximately 6.1, 3.3, and 3.8, respectively. Maximum CGR in the 45-day transplanting treatment reached 19.2 g m-2 day-1 in Ardebil, 21 g m-2 day-1 in Tabriz, and 22.3 g m-2 day-1 in Urmia. In contrast, RGR was naturally lower in transplant treatments due to higher initial dry weight and elevated respiratory costs; nevertheless, this reduction did not hinder the superior final dry matter accumulation of transplants. TDW was also higher under 45-day transplanting, reaching 1902 g m-2 in Ardabil, 2001 g m-2 in Tabriz, and about 2471 g m-2 in Urmia by day 170, all substantially exceeding the values under direct sowing. Root yield followed the same trend: the highest root yield (108 t ha-1) occurred in the 45-day transplanting treatment in Urmia, whereas the lowest (68 t ha-1) was observed under direct sowing in Tabriz. Overall, the results indicate that transplanting can serve as an effective strategy to enhance growth indices and achieve higher sugar beet productivity in cold semi-arid environments.
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