珍稀濒危植物半日花光合作用日动态变化的初步研究

Primary Studies on Daily Photosynthetic Changes of Rare and Endangered Plant Helianthemum soongoricm

对半日花的光合生理生态特征的分析表明:在晴朗天气条件下,半日花的净光合速率曲线呈双峰型,在 9:00和15:00左右达到峰值。蒸腾速率日变化曲线呈单峰型,在 15:00 达到最大。数据分析表明:空气温度和气孔导度是半日花光合作用和蒸腾作用的主要影响因子。叶绿素荧光作用参数的日变化结果显示:半日花受中午强光和高温的影响发生光抑制,使PSⅡ系统发生可逆失活,产生光合“午休”现象。

Analysis on a series of physiological and ecological characteristics of photosynthesis of Helianthemum soongoricum during the growth season shows that the daily change pattern of net photosynthetic rate (P (n)) of Helianthemum soongoricum can be expressed as a two-peak curve. The P (n) reaches the maximum at 9:00 and 15:00. The daily change pattern of transpiration rate (E) is a one-peak curve, and the E value reaches the maximum at 15:00. Analysis also shows that the air temperature (T (a)) and the stomatal conductance (g s) are the two most influential factors on the photosynthesis and transpiration of Helianthemum soongoricum. From the diurnal variation of chlorophyll fluorescence parameter of Helianthemum soongoricum, the intensive light and high temperature have deep effect on the PSⅡ system and make it reversible, appearing the midday depression of photosynthesis.