高产水稻光合速率的变化

VARIATION OF PHOTOSYNTHETIC RATE IN HIGH-YIELDING RICES

1998年早季于广州,测定了水稻两系高产杂交组合培矮64s/E32、地矮64s/93、粤杂122,高产品种粤香占和特三矮2号在四个主要生育期顶叶光合速率及叶绿素含量。（1）在人工气候箱的弱光下测得的分蘖期盆栽植株的非饱和光合速率在5个品种/组合间差异不大。（2）4个品种/组合的大田植株在四个生育期中以分蘖盛期到幼穗分化初期的光合速率最大,其值已达到或接近水稻品种最大光合速率30μmol m-2s-1的上限;品种/组合间差异不大。抽穗期和黄熟期光合速率较前期下降很大,但两期间变化不大。收割期光合速率进一步大幅下降。（3）4个品种/组合抽穗期叶绿素含量较前期下降或不变,黄熟期叶绿素含量又升高,收割期则大幅下降。（4）讨论了叶片光合速率在抽穗后下降的原因,并据此提出了光合保持能力的概念。认为在形态性状改良的基础上,提高群体整体光合能力,是提高水稻光合生产力和实现超高产育种目标的有效途径。

The net photosynthetic rate in top leaves and their chlorophyll content at four major growth stages of high-yielding rice varieties/combinations, Pciai 64s/E32, Peiai 64s/9311, Yueza 122, Yuexiangzhan and Tesan'ai 2, were determined in early season of 1998 in Guangzhou. (1) At tillering stage, there was little difference in photosynthetic rate in leaves of potted plants among five varieties/combinations determined under low light intensity (270 μmol m-2S-1) in phytotron. (2) The photosynthetic rate in four varieties/combinations grown in the field was the highest at active tillering to initial young panicle differentiation stages among four major growth stages, their values (27-30 μmol m-2S-1) being equal or close to the upper limit of maxium photosynthetic rate (30 μmol m-2S-1) in rice varieties. It declined greatly at heading and yellow ripening stages, but changed little between these twostages. At harvest, their photosynthetic rates were further reduced greatly. (3) The chlorophyll content in the four varieties/combinations dropped or remained unchanged at heading stage as compared to the previous stages, but it rose again at yellow ripening stage, then declined greatly at harvest. (4) The variation of photosynthetic rates at different growth stages is discussed. It is believed that improving the integrated photosynthetic capacity of rice canopy on the basis of improvement of morphological traits is a feasible approach to acquire further higher photosynthetic productivity and superhigh grain yield.