【摘要】 研究了大豆光合午休过程中有关生理生态因素与光合速率的函数关系,并对叶温、叶片-大气水汽压亏缺(VPD)、气孔导度与光合速率之间的关系进行了通径分析.结果表明在光合午休的13:00时与15:00时这两个时刻,光合速率与VPD、叶温和气孔阻力呈极显著负相关,15:00时光合速率随VPD和叶温上升而下降的速率要大于13:00时的下降速率,但随气孔阻力上升而下降的速率却要小于13:00时的下降速率.通径分析的结果表明,午休的不同时刻影响光合的主要因素是不同的,11:00时光合的下降主要是由气孔导度下降造成的,VPD和温度对光合的直接影响微不足道,但在13:00—15:00时VPD和叶温过高却成为午休的最主要因素,气孔因素不再是午休的限制因素,15:00时气孔导度对光合的直接影响已微不足道,但这两个时刻里气孔导度通过对VPD和叶温的影响对光合的下降起着重要的间接作用.更多还原

【Abstract】 The relationship between related physiological and ecological factors and photosynthesis during midday depression of photosynthesis in soybean leaves were studied. The path analysis was also used to estimate the effects of Leaf temperature (TL),leaf to air vapour pressre deficient (VPD) and stomatal conductance (Cs) on photosynthesis (A). The TL, VPD and stomatal resis-tance (Rs) are significantly nagatively correlated with photosynthesis at 1:00 PM and 3:00 PM during midday depression of photosynthesis. At 3:00PM as VPD and TL increase photosynthetic rate decrease more pronouncely than that at 1:00PM, however as Rs increase photosynthetic rate decrease more pronouncely at 1:00PM than that at 3:00PM. The path analysis indicate that at different times during rnidday depression of photosynthesis the dominant factors of depression of photosynthesis are different. At 11:00AM the decrease of Cs is the main cause of the depression of photosynthesis, while the direct effects of VPD and TL on A are almost ineffec-tive. At 1:00PM and 3:00PM the high VPD and TL become dominant factors of depression of photosynthesis. The direct effect of Cs on A is almost ineffective at 3:00PM, however, the stomatal coductance has remarkable indirect effect on depression of photosynthesis by influencing VPD and TL at 1:00 PM and 3:00 PM.更多还原