Studies on the Seedling Emergence in Crops : On the relation between the strength of plumule-elongation and emergence vigor or emergence ability in some cereals

摘要

Data presented in the previous paper have demonstrated that the strength of plumule-elongation at the stage of 5.0-6.0 cm long measured with unbonded gauge type transducer was the strongest in corn; oats comes second; next in order are wheat, barley, rye, sorghum and rice; the weakest was italian millet. In this paper, relation between the strength of plumule-elongation and emergence vigor or emergence ability was studied. Results were as follows. 1. No positive correlation between the strength of plumule-elongation and emergence ratio or emergence rate index under hardened texture of convering-soil of 5.5 cm depth was obtained (Table 1-a, b). On the other hand, partial correlation was obtained between the strength of plumule-elongation per unit cross section in the largest portion of plumule and emergence ratio (Table 2, Fig. 2). 2. From the above results following relationship is expected. EV=R·St EV: Emergence vigor. R: coefficient of resistance elimination at the time of emergence. St: Strength of plumule-elongation measured with unbonded gauge type transducer. In this case, shape of plumule and ecological and physiological character of plumule are involved in R. From Table 1 and Table 2, it is thought that R is greater in italian millet, sorghum and paddy rice in indica type than in barley and rye. Under the condition of none or a few hardened, however, it is probably that R is negligible in EV and St is highly correlated with EV. 3. In field condition, length from seeding to emergence is very important. So the following relationship is suspected. EA=R·St·SP EA: Emergence ability. Sp: Speed of plumule-elongation under covering-soil. From the above result, it is thought that EA is the greatest in corn and sorghum; oats, wheat and paddy rice in indica type comes second; next are upland rice in japonica type, rye and barley (normal); the weakest are paddy rice in japonica type, naked barley (uzu) and italian millet under condition of 5.5 cm depth of covering-soil at 25°C in this experiment. As the shape of plumule and ecological and physiological character is almost the same in each cereal, it is probable that EA is highly correlated with St and Sp.