水分胁迫对苹果蒸腾强度和气孔扩散阻力的影响

1986年用盆栽三年生长富—2苹果作试材,研究了水分胁迫对叶片气孔扩散阻力(Rs)以及蒸腾强度(Tr)的影响,证明用LI—1600型恒态气孔计测定Rs、Tr是一种快速、灵敏、生产可行的鉴定植株缺水的方法。水分胁迫对植株的影响包括两个因素,一是缺水程度,二是缺水持续时间。一般在缺水后第二天,Rs就会显著提高,Tr显著下降,如果及时供水,一天后,Rs、Tr便迅速恢复;若继续缺水(持续四天),叶片在中午发生了萎蔫,这时补救较为困难,需要近一周才能恢复;若缺水持续10天,叶片在早上都见萎蔫,Rs、Tr在一周以上尚不恢复,有可能造成永久危害。恢复过程中的植株,对外界尤为敏感,轻微的逆境,气孔会迅速作出关闭反应。土壤含水量与Rs呈负相关、与Tr呈正相关,回归曲线均为变形双曲线,当土壤含水量在10%以下时,随土壤含水量的增加,Rs迅速下降,Tr迅速提高,当土壤含水量在10%以上时,Rs下降和Tr上升幅度都比较缓慢。

EFFECTS OF WATER STRESS ON TRANSPIRATION RATE AND STOMATAL RESISTANCE IN APPLE TREES

The effects of water stress on diffusive resistance of stomata (Rs) and transpiration rate (Tr) were studied in three-year-old apple trees (cv.Red Fuji-2) in 1986. It was shown that the method of measuring Rs and Tr by means of LI-1600 Steady State Porometer was a quick, sensitive and practicable one to determine water deficit of fruit trees. The effect of water stress was caused by two factors: the magnitude and duration of water deficit. Rs increased and Tr decreased significantly after two days of water deficit and recovered completely in two days after rewatering. If the duration of water deficit lasted for 4 days and wilting of leaves occurred at noon, the recovery would require about 7 days. If severe water stress lasted for 10 days, Rs and Tr would not be recovered completely after 7 days and might be affected permanently.The soil moisture positively correlated with Tr(r=0.9879~(**))and negatively correlated with Rs ( r=-0.9882~(**) ) . Rs decreased and Tr increased quickly as the soil moisture increased, and then they changed slowly when the soil moisture reached above 10%.