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This article in AJ

  1. Vol. 92 No. 3, p. 411-417
     
    Received: Aug 20, 1998
    Published: May, 2000


    * Corresponding author(s): kobata@life.shimane-u.ac.jp
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doi:10.2134/agronj2000.923411x

Shading during the Early Grain Filling Period Does Not Affect Potential Grain Dry Matter Increase in Rice

  1. Tohru Kobata *,
  2. Makoto Sugawara and
  3. Sadanori Takatu
  1. Dep. of Agronomy, Faculty of Life and Environ. Sci., Shimane Univ., Matsue, 690-8504, Japan

Abstract

Shortage of C assimilate supply to rice grain during approximately the first 10 days after heading (DAY10) has been believed to reduce potentiality of grain dry matter increase (GP) and decrease the final grain weight (GF). However, we suspect that assimilate shortage during DAY10 does not determine GF, if assimilate supply during the rest of the grain filling period (GPERIOD) meets subsequent requirements for realizing GP Our objective was to determine if GP is in fact affected by shortage of assimilate supply caused by shading during DAY10 Plots of rice (Oryza sativa L.) grown under paddy field conditions were subjected to three strengths of shading for DAY10 After the shades were removed, the plots were divided into two groups. Plants in the first group were thinned to half the plant population density, while the second group was left at normal spacing. GF in the unthinned group was reduced depending on the strength of the shade, but weights in the thinned group almost reached those of nonshaded control plants, except in the most heavily shaded plots, where weights were slightly reduced. In pot experiments simulating crop stand, GF all reached those of control plants when the pots were exposed to abundant radiation after being subjected to heavy shading during either the early or mid-GPERIOD These results suggest that rice plants are capable of recovering from early reduction in grain growth rate at least until the mid-GPERIOD, and shortage of available assimilate during DAY10 does not determine GP

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