Chin J Plan Ecolo ›› 2002, Vol. 26 ›› Issue (6): 647-651.

• Research Articles • Previous Articles     Next Articles

Pigments Content, Net Photosynthesis Rate and Water Use Efficiency of Two Superhigh-Yield Rice Hybrids at Different Developmental Stages

WANG Qiang, ZHANG Qi-De, LU Cong-Ming, KUANG Ting-Yun and LI Cheng-Quan   

  • Published:2002-06-10
  • Contact: WANG Qiang

Abstract: In the 1970s’, by exploiting the poorly understood phenomenon called heterosis (first generation of hybrid plants is typically more vigorous and productive than either parent) in rice, China had improved the yield of rice in F1 hybrid 20%-30% more than either parent and has since then played the leading role in hybrid rice research and production. In order to further improve rice yield to feed the increasing population, China had carried out the “super high-yield rice project” since 1996. Tremendous progress was made during the “ninth five-year plan” and several new varieties of the rice hybrids with “super-high” yield released. Liang-youpeijiu (Pei-ai64S × 9311) and Hua-an3 (X07S × Zihui100) were two of such varieties, both with a yield of more than 10 500 kg·hm-2, compared with the traditional rice hybrid Shanyou63 (Zhenshan97A × Minghui63) with a yield of about 7 500-8 250 kg·hm-2. The two super high-yield rice hybrids had a 20%-30% higher yield. The photosynthetic characters, pigments content, net photosynthesis rate and water use efficiency of the different developmental stages of Liangyoupeijiu and Hua-an3, and the traditional hybrid rice Shanyou63 were studied. The results showed that at the seedling stage, no significant difference in the content of chlorophyll per leaf area was observed among the three rice hybrids, while the carotenoid content of Shanyou63 was the highest. The chlorophyll content and carotenoid of the two super high-yield rice hybrids were higher than that of Shanyou63 at the tillering stage, especially in the flag leaves of the heading stage. The net photosynthesis rate (Pn) of the two super high-yield rice hybrids were higher than that of Shanyou63 from seedling stage to heading stage, especially under the midday strong sunlight of the seedling stage and under the twilight of tillering and heading stages. The water use efficiency of the Shanyou63 was slightly higher than that of the super high-yield rice hybrids at seedling stage, but was lower at tillering and heading stages. The physiological basis of their higher yield in the super high-yield rice hybrids could be attributed to the fact that they had a higher net photosynthesis rate, higher resistance to photoinhibition, and also used the dim sunlight effectively, as seen in our results. The higher water use efficiency of the super high-yield rice hybrids at tillering and heading stages indicates economical use of water.