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以一年生实生盆栽苗为试材,用红外线 CO_2气体分析器研究了水分胁迫对龙眼光合作用的影响。结果表明,幼龄叶片对水分胁迫的反应比较敏感,老龄叶片反应迟钝;叶片光合速率(Pn)的下降与叶片含水量的下降基本同步,都明显滞后于土壤相对含水量的下降;Pn 下降的原因,既有气孔因素,也有非气孔因素;严重的水分胁迫改变了叶片光合速率的日进程;复灌后其光合作用恢复较慢,且不能恢复到胁迫前的最高水平;龙眼生长的最适土壤相对含水量为62%～84%,灌水临界期约为38%～42%。
Taking the annual potted seedlings as test material, the effect of water stress on photosynthesis of longan was studied by infrared CO_2 gas analyzer. The results showed that the response of young leaves to water stress was sensitive and the response of aged leaves was unresponsive. The decline of photosynthetic rate (Pn) of leaves was basically synchronous with the decrease of water content of leaves, which obviously lagged behind the decrease of soil relative water content. The reason is that there are both stomatal and non-stomatal factors. Severe water stress changes the daily process of leaf photosynthetic rate. After reperfusion, the photosynthesis recovery is slow and can not recover to the highest level before stress. The optimum growth of longan The relative water content of soil is 62% ~ 84%, and the critical period of irrigation is about 38% ~ 42%.