Tillering, Lodging and Yield under Deep Water Treatment in Direct-seeded Rice

抄録

The tillering, lodging and yield of two types of direct-seeded rice (dry and water seeding), under deep water (DW) and ordinary water treatment (OW), were compared in 1994 and 1995. The percentage of productive tillers to maximum tiller number under DW was 85% for transplanted, 60% for water-seeded and 84% for dry-seeded rice (mean 76%), while that under OW was 59, 50 and 74% (mean 61%), respectively, in both years. By DW, longer culm length and fresh weight tended to be increased, thus elevating bending moment, but the culm diameter and culm-breaking weight were increased showing the lower lodging index. In water-seeded rice, the suppression of the development of non-productive tillers by DW was relatively weak compared to that in dry-seeded or transplanted rice. Although the number of panicles was similar under DW and OW, 1000-grain weight and percentage of grain filling were significantly improved by DW. The grain yield was higher under DW, and the mean grain yields of the two years were 4.82 t ha^-1 under DW and 4.48 t ha^-1 under OW.