Early sowing increases grain yield of machine-transplanted late-season rice under single-seed sowing

摘要

The shift from hand transplanting to machine transplanting has increased seed sowing rates and hence shortened seedling age and delayed sowing for late-season rice. The development of a single-seed sowing system for machine-transplanted rice can reduce seed sowing rates and provides a possible way to determine the performance of machine-transplanted late-season rice with early sowing. In this study, field experiments were conducted in two years with two rice cultivars to compare seedling shoot biomass at transplanting (TP), crop growth characteristics, and yield attributes in machine-transplanted late-season rice under single-seed sowing between two sowing dates, i.e., 30 June (SD30) and 15 June (SD15). Averaged across two cultivars and two years, seedling shoot biomass at TP under SD15 was 352% higher than those under SD30. Specific leaf weight (SLW) at heading (HD), crop growth rate (CGR) and biomass production during TP to HD, harvest index, and translocation of biomass accumulated before HD to the grain were higher under SD15 than under SD30 by 4-21%. SD15 had a 5-6% higher spikelet-filling percentage and grain yield than SD30. These results suggest that early sowing can improve the CGR during TP to HD by enhancing seedling growth and increasing SLW, and consequently, increase the biomass production during TP to HD, biomass translocation, and grain yield in machine-transplanted late-season rice under single-seed sowing.