Rice Yield and Grain Quality under Fluctuating Soil Moisture Stress

Abstract

In rainfed lowlands and water-saving cultivation systems, rice plants are often exposed to soil moisture fluctuation (SMF). Improving yield as well as grain quality is the main target for breeding under water-stressed environments. This study investigated the effects of different water treatment on yield, growth parameters, and grain quality under field conditions in Japan for 2 years. Two rice genotypes, Nipponbare (japonica) and G3-3 (derived from Nipponbare and KDML105, indica), were grown under continuous waterlogging (CWL) and SMF conditions. As the grain quality characteristics, grain appearance, dimension, and taste parameters were evaluated as well as yield and yield components. SMF reduced the yield, and G3-3 showed a higher yield than Nipponbare under SMF, which was attributed to the higher number of spikelets per panicle. G3-3 showed a better taste score (mark) with lower protein and amylose contents compared to Nipponbare. However, G3-3 had a higher percentage of broken grains, indicating a trade-off in grain quality traits. Non-structural carbohydrate dynamics may be involved as one of the grain quality characteristics. G3-3 demonstrated a superior yield under SMF conditions and have potential to show superior grain quality, indicating that the introgressed segments of G3-3 may be responsible for the grain quality traits associated with root plasticity.