Soybean Seed Aging and Environmental Factors on Seedling Growth

The effect of seed vigor on seed emergence depends on the type of environmental stress present at the time of seed germination and establishment. Therefore, the aim of this study was to assess the interaction of environmental stresses and aging on soybean (Glycine max L.) seed emergence. A factorial arrangement of treatments imposed on a randomized complete block design with four replications was conducted. Treatments of seed aging for 12, 24, 36, and 48 h at 41°C, salinity (6 and 12 ds/m2), water deficiency (–4 and–9 MPa), and sowing at depths of 3 and 7 cm were selected. Growth measurements were completed 21 and 55 days after planting. Analysis of variance was performed using the regression method for quantitative treatments such as seed aging, and if interactions were significant, interaction slicing was utilized and means compared with least significant difference tests (0.05). For quantitative treatments, regression analysis was conducted and path analysis was performed on growth traits. Results showed that aging had a significant effect on maximum emergence and rate of emergence. The ranking of the stress factors from most to least injurious for maximum emergence were severe salinity, severe drought, medium salinity, sowing depth of 7 cm, and medium drought. Harmful stress conditions on the plant leaf area and seedling dry weight were severe salinity, medium salinity, severe drought, medium drought, and sowing depth of 7 cm (only for seedling dry weight). Relative growth rate, net absorption rate, and leaf area ratio were not affected by aging but were affected by environmental conditions. These findings indicate that the impacts of environmental conditions are at least partially controlled by seed vigor.