几种木本植物木质部栓塞的日变化

对我国北方地区１０种树种一年生枝木质部栓塞程度及水势在不同季节的日变化情况进行了测定。结果表明，木本植物木质部栓塞化存在着日变化规律。３种针叶树木质部栓塞的日变化不明显，变化幅度较小。７种阔叶树种冬季清晨和傍晚时木质部栓塞程度大于上、下午，生长季节则为上、下午大于清晨和傍晚。生长季节水势的日变化趋势与木质部栓塞程度的日变化趋势相反，清晨和傍晚高于上、下午。并对木质部栓塞化在自然状态下的恢复状况作了一些讨论。

Diurnal Variation of Xylem Embolism in Some Woody Plants

Diurnal variation of xylem embolism and water poptential in one year old twigs of ten main afforestation tree species in North China were studied. The results showed that diurnal variation of xylem embolism was significant in broad leafed trees, but not distinct in conifers. The xylem embolism in broad leafed trees was lower in earlymorning and nightfall than that in forenoon and afternoon during the growing season, however, in winter, it was higher in earlymorning and nightfall because of the low temperature. In general, there was an inverse relationship between water pontential and xylem embolism, the lower the water potential, the higher the xylem embolism. The refilling of xylem embolism in natrual conditions was also analyzed and discussed.