The Effect of Planting Dates and Plant Density on Some Yielding and Qualitative Traits of Soybeans Glycine max L.) under the conditions of Deir Ezzor Governorate

Abstract

A field experiment was conducted at Saalo Research Station, Deir Ezzor Agricultural Research Center, Syria, during the 2024 growing season to investigate the effects of planting date and plant density on yield and quality traits of soybean line SB-335. The experiment was arranged as a split-plot design within a randomized complete block design (RCBD) with three replications. Three planting dates (1, 15, and 30 May) were assigned to main plots, while three plant densities (55,000, 83,000, and 166,000 plants ha⁻¹, corresponding to 30, 20, and 10 cm within-row spacing with fixed 60 cm between rows) were assigned to subplots. Measured traits included height to the first pod, number of pods plant⁻¹, 100-seed weight, seed yield, and oil percentage. Results showed that early planting (1 May) significantly increased pods plant⁻¹ (28.43), 100-seed weight (13.52 g), seed yield (3.16 t ha⁻¹), and oil content (16.44%), while decreasing height to the first pod (6.5 cm) compared to late planting dates. Increasing plant density from 55,000 to 166,000 plants ha⁻¹ significantly increased seed yield (2.82 t ha⁻¹) and height to the first pod (8.28 cm), but decreased pods plant⁻¹ (21.69) and oil percentage (14.53%). A significant interaction between planting date and density was observed for seed yield and oil content. Maximum seed yield (3.61 t ha⁻¹) was achieved with early planting (1 May) at 166,000 plants ha⁻¹, while maximum oil content (18.53%) occurred at early planting with 55,000 plants ha⁻¹. Under Deir Ezzor conditions, planting SB-335 on 1 May at 166,000 plants ha⁻¹ is recommended to maximize seed yield