圃場栽培したベトナム産水稲品種（Oriza sativa L.）の乾物生産，収量と玄米の外観品質

Light intensity is one of the most important environmental factors to determine the growth and yield of rice. However, little information is known about the response of indica cultivars, especially Vietnamese cultivars to shading conditions. In this study, a field experiment was conducted in 2015 to determine the response of Vietnamese cultivars to shading condition during the grain filling period. Fourteen Vietnamese cultivars were covered by black cloth (50% shading treatment) after the heading stage in the field conditions. Grain yield of fourteen Vietnamese cultivars in shading condition fell to about 32.2–65.0% of the natural light condition. The most sensitive cultivars to shading are ‘Jasmine 85’ and ‘OM2395’, of which the grain yield decreased to 65.0 and 59.8% of natural light condition, respectively. The shaded yield decreased corresponding to the reduction in crop growth rate (CGR) and yield components, especially in the percentage of filled grain due to the increase in spikelet sterility. Shading increased the percentage of immature grains in all cultivars. Shading induced an increase in the percentage of chalky and green grains, which was largest in ‘OM2517’ and ‘OM5451’, respectively. Clearly, shading depressed both grain yield and the appearance quality of brown rice in Vietnamese cultivars, similarly reported in previous studies with Japanese cultivars.

原著論文 (Original paper)