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This article in AJ

  1. Vol. 94 No. 1, p. 102-109
    Received: Jan 2, 2001

    * Corresponding author(s): jzhang@hkbu.edu.hk
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Carbon Remobilization and Grain Filling in Japonica/Indica Hybrid Rice Subjected to Postanthesis Water Deficits

  1. Jianchang Yanga,
  2. Jianhua Zhang *b,
  3. Lijun Liua,
  4. Zhiqing Wanga and
  5. Qingsen Zhua
  1. a College of Agric., Yangzhou Univ., Yangzhou, Jiangsu, China
    b Dep. of Biol., Hong Kong Baptist Univ., Kowloon Tong, Hong Kong, China


Poor grain filling, as in unfilled grains, and unused carbohydrate in straws are two major problems in japonica/indica (J/I) hybrid rice (Oryza sativa L.). This study investigated if an early senescence, induced by controlled postanthesis soil drying, could enhance the remobilization of reserved C to the grains, and therefore improve the grain filling. Two J/I hybrids and one indica/indica (I/I) hybrid were field-grown. Three levels of soil water potential (ψsoil)—well watered (ψsoil = 0), moderate water deficit (ψsoil = −0.025 MPa), and severe water deficit (ψsoil = −0.05 MPa)—were imposed 9 d after anthesis to maturity. As a result of water deficit treatment, chlorophyll concentrations and photosynthetic rates of flag leaves declined more quickly, indicating an enhanced senescence. The remobilized C reserve from the culm and sheath during grain filling was increased by 47 to 61% for the J/I hybrids and 12 to 26% for the I/I hybrid. Partitioning of 14C from the flag leaves to the grains was increased by 18 to 28%. Active grain-filling period was shortened by 2.7 to 8.7 d, and grain-filling rate increased by 0.14 to 0.36 mg d−1 grain−1 Water deficits reduced the grain yield of the I/I hybrid by 2.9 to 16.4% but increased that of the two J/I hybrids by 4.4 to 13.3%. We conclude that if water deficit is properly controlled for J/I, the gain from enhanced remobilization of stored C may outweigh the loss due to shortened photosynthetic duration, leading to a fast grain filling and high grain yield in cases where senescence is unfavorably delayed.

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Copyright © 2002. American Society of AgronomyPublished in Agron. J.94:102–109.