ABSTRACT

Understanding the yield potential and yield-determining factors of recent high-yielding cultivars is essential for further increasing rice yield. In this study, a cross-locational field experiment was conducted across 3 years using ‘Hokuriku 193ʹ (H193), a high-yielding cultivar, at four sites including one in Nagano Prefecture, which is the highest-yielding region in Japan. The highest mean yields of 3 years, 1214 g m⁻² for brown rice grains and 1586 g m⁻² for rough grains, were recorded at the Nagano site. The yields from the 17 environments were strongly correlated with spikelet number per square meter while percentage of filled grain was relatively stable, suggesting that sink capacity is the primary determining factor for grain yield of H193. The climatic factors for high spikelet number at the Nagano site can be explained by the high cumulative radiation before heading associated with longer duration until heading by low night temperature. In addition, a large increase in shoot dry weight during grain filling (ΔW) and high radiation use efficiency (ΔW/rad) at the Nagano site could satisfy large source demand by the large sink size. The high ΔW/rad at the Nagano site associated with low night temperature. This study demonstrated high yield potential of H193 and revealed an environment that achieves extra-high yields in H193, which provided insight to attain further increase in rice yield.

摘要

了解近期高产品种的产量潜力和产量决定因素对于进一步提高水稻产量至关重要。在这项研究中，使用高产品种“北陆 193”（H193）在包括日本最高产地区长野县在内的四个地点进行了为期 3 年的跨地区田间试验。3 年平均单产最高，糙米谷物1214 gm ^{-2和 1586 gm -2}对于粗粒，在长野现场记录。17个环境的产量与每平方米小穗数密切相关，而灌浆率相对稳定，表明库容量是H193粮食产量的主要决定因素。长野地区小穗数高的气候因素可以解释为抽穗前的高累积辐射与较长的持续时间相关，直到抽穗的夜间温度低。此外，在长野地区，灌浆期间枝条干重（ΔW）的大幅增加和高辐射利用效率（ΔW/rad）可以通过大水槽尺寸来满足大源需求。长野站点的高 ΔW/rad 与低夜间温度有关。