Abstract
Typhoon 15 passed through the Sea of Japan on August 20,2004. The typhoon caused salt-wind damage on rice plants in the Sea of Japan coast part. To investigate the effect of root activity on the salt-wind damage, we examined the bleeding rate of rice plants in puddled (PD) and no-tilled (NT) paddy fields of heavy clay soil in the Hachirogata reclaimed land. The silicon contents of the bleeding sap and rice plants before the typhoon were also examined in relation to the rate of leaf death after the typhoon. The bleeding rate was higher in the NT plot than in the PD plot, suggesting higher root activity in the NT plot. Before the typhoon, the silicon contents of the bleeding sap and the leaves were higher in the NT plot than in the PD plot. After the typhoon, the rates of leaf death and leaf decoloration were lower in the NT plot than in the PD plot. The percentage of filled spikelets in the NT plot was higher than that in the PD plot. The brown rice yield in the NT plot was 49 % higher than that in the PD plot, and the ratio of the thick brown rice was also higher in the NT plot than in the PD plot. These results suggested that the higher yield in the NT plot than in the PD plot under water stress was mainly due to the high root activity that allowed the maintenance of leaf nitrogen level.
