Department of Biology, University of Essex, Wivenhoe Park, CO4 3SQ, Colchester, Essex, UK.
Photosynth Res. 1993 Nov;38(2):125-33. doi: 10.1007/BF00146411.
The effect of growth temperatures on the photosynthetic performance of field grown maize (Zea mays cv. LG11) was examined for crops sown on 1 May and 28 June 1991. During the period of growth, 2 May to 10 August, the early-sown crop experienced temperatures below 10 °C on 33 occasions compared with only one for the crop sown on 28 June. The prolonged period of low temperatures throughout May and beginning of June were associated with a marked depression in CO2 assimilation rates at all light levels in the early-sown treatment. Chill-induced depression of the photosynthetic light-response curve reflected a sustained reduction in canopy leaf photosynthesis and crop radiation-use efficiency (RUE). During the early stages of growth, RUE was 65% lower in the early- than late-sown treatment, with no marked recovery observed in the former treatment until approximately three weeks after chilling conditions had ceased. Data show a close correlation between chill-induced depression of quantum yield (Φ) and RUE, with corresponding reductions in the light-saturated rates of CO2 assimilation (Pmax). The convexity of the light-response curve recovered most rapidly from chilling temperatures, and at least three weeks before any improvement in RUE. It is concluded that photosynthetic productivity of immature maize stands is less sensitive to changes in the convexity of the light response, than to changes in either Φ or Pmax.
研究了生长温度对 1991 年 5 月 1 日和 6 月 28 日播种的田间生长玉米（Zea mays cv. LG11）光合作用性能的影响。在生长期间，即 5 月 2 日至 8 月 10 日，早播作物经历了 33 次低于 10°C 的温度，而 6 月 28 日播种的作物只有一次。5 月和 6 月初长时间的低温与早播处理中所有光照水平下 CO2 同化率的明显下降有关。低温引起的光合作用光响应曲线的抑制反映了冠层叶片光合作用和作物辐射利用效率（RUE）的持续降低。在生长的早期阶段，早播处理的 RUE 比晚播处理低 65%，在前一处理中没有明显的恢复，直到低温条件停止约三周后。数据显示，量子产率（Φ）和 RUE 之间存在密切的相关性，与 CO2 同化的光饱和速率（Pmax）相应降低。光响应曲线从低温下恢复最快，至少在 RUE 改善前三周。因此，可以得出结论，未成熟玉米植株的光合生产力对光响应凸度的变化不如对 Φ 或 Pmax 的变化敏感。
