Abstract
Dry matter production and related characteristics of rice plants cultivated in non-tillage and non-paddling paddy fields (non-tillage plants) were compared with those cultivated in conventionally tilled paddy fields (tillage plants) from 1997 to 1999. The grain yield was not significantly different between the two cultivation methods. However, the yield components were slightly different. In 1997 and 1998 non-tillage plants had fewer spiklets per m2 but larger thousand grain weight than conventional tillage plants. In 1999, both the number of spiklets per m2 and the percentage of ripened grain tended to be greater in non-tillage plants. The weight of dry matter was lighter in non-tillage plants than in conventional tillage plants until the early ripening stage. This resulted from a lower leaf area index (LAI) in non-tillage plants during this phase of plant growth. In contrast, during the later ripening period, crop growth rate (CGR) was greater in non-tillage plants due to greater net assimilation rate (NAR). As a result, there was no difference in the weight of dry matter between the tillage plants and non-tillage plants. The difference in the NAR may be attributed to the difference in photosynthetic rates during ripening. The higher photosynthetic rate in non-tillage plants was due to the maintenance of high nitrogen levels in leaves.
