Relationship between vigour tests and emergence of soybean when grown under a range of seedbed moisture conditions

Laboratory vigour tests were performed on seed from 4 soybean [Glycine max (L.) Merr.] cultivars coming from commercial crops grown in eastern Australia. The seed from each cultivar had greater than 80% germination and a range in vigour. Vigour tests consisted of the accelerated aging (with or without a seed protectant, Thiram), cold, saturation and hypocotyl length tests. Results were compared with seedling emergence from the same cultivar when planted under growth room conditions (25/20 +/- 1 degrees C, 14/10 h day/night) at 3 seedbed moisture levels (field capacity, -0.01 MPa; dry, -0.30 MPa; and saturated soil, soil saturated for 48 h, planted then allowed to dry to field capacity). The modified accelerated aging test with Thiram was significantly (P < 0.01) correlated with emergence in all 3 seedbed moisture conditions. High vigour seed samples with high accelerated aging germinations emerged well. Overall, the vigour test which ranked the seed samples to give the best indicator of performance under a range of seedbed moisture conditions was the modified accelerated aging test with thiram.