RELATIONSHIP BETWEEN VIGOR 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 easte rn Australia. The seed from each cultivar had greater than 80% germina tion and a range in vigour. Vigour tests consisted of the accelerated aging (with or without a seed protectant, Thiram), cold, saturation an d hypocotyl length tests. Results were compared with seedling emergenc e 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 sa turated for 48 h, planted then allowed to dry to field capacity). The modified accelerated aging test with Thiram was significantly (P < 0.0 1) correlated with emergence in all 3 seedbed moisture conditions. Hig h 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 co nditions was the modified accelerated aging test with thiram.