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杂优水稻“汕优6号”在抽穗期经低温(16℃)处理后,剑叶的净光合速率、叶绿素含量、FBP 酶(1,6-双磷酸果糖酯酶)活性明显降低;叶绿素 a/b 比值、气孔阻力、蔗糖和淀粉含量明显升高,叶绿体中含有大淀粉颗粒;但叶片水势却无明显的变化。当低温处理过的水稻移至正常自然条件下后,剑叶净光合速率逐渐上升,5天后接近对照水平。然而,气孔阻力却下降得很快,1天后就降到对照水平。在常温下5天后,叶绿素含量、FBP 酶活性也几乎上升到对照水平;同时,叶绿素 a/b 比值,蔗糖和淀粉含量也下降到接近对照水平;叶绿体内大淀粉颗粒也消失了。讨论了上述各种变化与净光合速率之间的关系。认为在低温胁迫下,叶片光合速率的降低是水稻减产的原因之一。
The net photosynthetic rate, chlorophyll content and FBPase (fructose-1,6-diphosphate) activity of flag leaf were significantly lower in hybrid rice “Shanyou 6” after heading at low temperature (16 ℃). Chlorophyll a / b ratio, stomatal resistance, sucrose and starch content were significantly increased chloroplasts containing large starch granules; but no significant changes in leaf water potential. After the low temperature treated rice moved to normal natural conditions, the net photosynthetic rate of flag leaf increased gradually and approached the control level after 5 days. However, stomatal resistance dropped rapidly and dropped to control level after 1 day. After 5 days at room temperature, chlorophyll content and FBPase activity increased almost to the control level. At the same time, the chlorophyll a / b ratio, sucrose and starch content also dropped to near the control level; large starch granules in chloroplast also disappeared. The relationship between these changes and net photosynthetic rate was discussed. It is considered that the decrease of leaf photosynthetic rate is one of the reasons for the decrease of rice yield under low temperature stress.