||Accumulation efficiency of degradable matter during the early grain-filling period in rice
INOUE, Naoto ,
KASAJIMA, Shinya ,
YANG, Zhongfa ,
KASUGA, ShigemitsuHAGIWARA, Motoyuki
11 , 2015-03-31 , 信州大学農学部附属アルプス圏フィールド科学教育研究センター
The dry weight of cellular contents in the whole rice plant (dWc/dt) is partitioned from the crop growth rate (dW/dt), and the resulting rate represents the accumulation efficiency of degradable matter (dWc/dW). The grain yielding ability and stability are significantly affected by the dry matter partitioning to cell wall during grain filling stage. Comparative studies for dWc/dW during the early grain-filling period were conducted using diverse genotypes of rice varieties in eight experimental fields in Japan, China, and Thailand for 2 yr to develop a simplified process model with submodels for partitioning. Nine rice varieties-2 japonica, 3 indica, indica×japonica, indica×javanica, javanica, and NERICA-were used. dWc/dW was measured by enzymatic analysis. The relationship between dW/dt and the accumulation rate of cellular contents per unit ground area (dWc/dt) was described using a linear regression equation, and the proportionality factor k (slope), which represents accumulation efficiency, was estimated using data from each variety. The k values varied from 0.570 for the traditional indica cv. Ch86 (CH) to 0.765 for the WAB450 line (WA), which is a NERICA variety. High values of dWc/dW were observed in the modern varieties developed by remote crossing [Takanari (TA) and WA]. The average k value from the results of multi-site experiments was 0.681.TA and WA showed high accumulation efficiency by high sink activity under various dW/dts that fluctuated according to environmental conditions at the cultivation sites. Conversely, CH, classified as a "grassy rice" phenotype, formed a cell wall during the early grain-filling period.