【摘要】 杏树(Prunus armeniaca L.)叶水势的日变化主要受控于一天中水汽压饱和亏(VPD)(或相对湿度)、大气温度和光照强度的变化。光照强度决定了一天中叶水势最低值的大小。在日进程中,随着水汽压饱和亏的逐渐增大和气温的逐渐升高,叶水势逐渐下降。当 VPD 和气温达到一定值时,叶水势达到一天中的最低值。此后,叶水势保持稳定,直到 VPD 和气温述到一天中的最大值后,叶水势最低值结束,并开始回升。在生长季节前期,每日叶水势最低值出现时的 VPD 值为4—7 mbar,后期为12—15 mbar,而气温始终是19℃左右。在其他条件相同时,叶水势的大小与叶片在树冠和枝条中所处位置无关。地膜覆盖和灌水虽可显著提高土壤水势,但对叶水势影响不大。更多还原

【Abstract】 Diurnal changes of water potential in apricots were mainly controlled by changes of saturation vapour pressure deficit(VPD)(or relative humidity),air temperature and light in- tensity in a day.The daily minimum value of leaf water potential was determined by light intensity.During the course of a day,leaf water potential decreased gradually with increas- ing VPD and air temperature.Daily minimum value of leaf water potential was reached at a VPD of 4—7 mbars early in the growing season and 12—15 mbars late in the growing season, and at an air temperature of about 19℃ in the whole growing season.Thereafter leaf water potential stayed constantly until air temperature and VPD reached daily maximum value,at the same time,the minimum value of leaf water potential at the different parts of a shoot and a canopy showed no difference,if other conditions were the same.Plastic film cover and irrigation were able to increase soil water potential,but have few effects on leaf water potential.更多还原