Departmental Bulletin Paper Simplified model of dry matter partitioning in relation to grain yield stability in rice

INOUE, Naoto  ,  KASAJIMA, Shinya  ,  KATO, Futoshi  ,  MAHMUD, Rezwanul  ,  YANG, Zhongfa  ,  KASUGA, Sigemitsu

13pp.13 - 22 , 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
A new partitioning model was developed for evaluating the dynamics of physiologically degradable materials among rice plant organs. Enzymatic analysis was applied by dividing materials into the following two categories : physiologically degradable, which is regulated by the grain filling rate (dWcp/dt) and grain yield stability (cellular contents, CC), and no degradable structural material comprising the plant cell wall, which cannot be recycled. The CC in dry matter in stover (leaf blade+leaf sheath+culm) and panicle samples were determined using a mixture of α-amylase and protease. The field experiments were performed using two commercial varieties of japonica for two years from a paddy field in Japan. The percentage of physiologically degradable matter in dry matter in stover (Wcs%) decreased gradually after transplanting time and decreased quickly after heading, and that of panicle (Wcp%) increased drastically after heading. The dry weight of CC in stover (Wcs) increased gradually up to the heading stage and decreased after heading. In contrast, the dry weight biomass of CC in panicle (Wcp) increased after heading and drastically decreased 10 d after heading. The derivations of Wcs and Wcp were calculated for indicating the apparent removal rate from stover to panicle (dWcs/dt), and the grain filling rate was indicated by the term of the fractions of enzymatic analysis. The upper peak of dWcs/dt and the lower peak of dWcs/dt were observed approximately 20 d before heading and 15 d after heading, respectively. The change in dWcs/dt after heading coincided with the change in dWcp/dt. There was a significant negative relationship between dWcs/dt and dWcp/dt, and the regression coefficient (slope) and intercept were estimated at -1.47 and 8.46, respectively. Results suggested that dWcs/dt was a more important and dominant factor for determining dWcp/dt than photosynthesis-governed crop growth rate after heading.

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