紫荆光合日变化及其与环境因子的关系

在自然条件下,对紫荆光合作用日进程的研究结果表明,夏季晴天紫荆净光合速率日进程曲线为"双峰"型,光合效率午间明显降低,主要由非气孔限制引起.应用逐步多元回归方法得到紫荆净光合速率日变化的最优方程为:Y=11.0167 0.0051X1-0.0573X2 0.3690X3(复相关系数R=0.8695,F=8.2604,显著水平p=0.0078).偏相关分析和通径分析表明,光合有效辐射、空气相对湿度和空气CO2浓度与净光合速率的日变化有着密切关系,是影响净光合速率的直接主要因子,影响的大小顺序为:光合有效辐射>空气相对湿度>空气CO2浓度.

Study on Diurnal Variation of Photosynthesis for Cercis chinensis Bunge and Its Relation to Environmental Factors

The diurnal variation of photosynthesis for Cercis chinensis Bunge leaves had been studied under the natural conditions. The results were as follows: In summer clear days, the curves of diurnal variations of net photosynthetic rate ( P _n) had two peaks, which had an obvious phenomenon of midday decline of photosynthetic efficiency. The mid-depress of P_n was principally caused by non-stomatal limited elements i.e. photoinhibition and photorespiration. The optimal equation of the diurnal variation of P_n was attained by the method of stepwise multi-regression, which was: Y=11.016 7 0.005 1X_1-0.057 3X_2 (0.369 0X_3) ((R=0.869 5,)F=8.260 4,p=0.007 8 ). The analysis of partial correlation and path coefficient on P_n and factors showed that the diurnal variation of P_n had closer relations to photosynthetic active relation ( Q ), air relative humidity ( RH ), and CO_2 concentration (C_a) in the air. Q,RH and C_a were the primary direct factors affecting P_n . Their sequences were Q>RH>C_a .