光下无CO_2气体处理对叶片光合强度的影响

小麦等C_3植物的叶片在光下经无CO_2或低CO_2气体处理后,通入高CO_2气体,光合强度出现“升、降、升”的波动,而玉米等C_4植物无此现象。不同植物的光合波动幅度不同。强光、高CO_2、低O_2等能缩短第一次光合上升时间,增大光合下降幅度;而低CO_2、高O_2等则减少光合下降幅度。此现象与RuBP及ATP的含量变化有关。

THE EFFECT OF CO_2-FREE AIR TREATMENT ON LEAF PHOTOSYNTHETIC RATE IN LIGHT

The photosynthetic rates of leaves of C_3 plants such as wheat, rice, cotton,spinach and so on present a "rising-falling-rising" wave motion, after being treatedwith CO_2-free or low CO_2 air in light, and then flushed with high CO_2 air. Thisphenomenon is called "oscillation in photosynthesis after being treated With lowCO_2 air in light". But there is not such a phenomenon in C_4 plants, e.g., maize,sorghum, etc. The magnitude of the oscillation differs with different species (Fig.1).Factors favourable to photosynthesis such as strong light, high CO_2 and lowO_2 can shorten the time of the first rising and increase the range of the falling ofphotosynthesis, while the factors favourable to photorespiration, for instance, lowCO_2 and high O_2, can decrease the amplitude of the falling of photosynthesis (Fig.2,3,4,5,6).The oscillation phenomenon is related to the changes of RuBP and ATP contentsin leaves (Table 1).