土壤水分对幼龄桉树蒸腾和生长的影响

通过盆栽试验,研究不同土壤水分对幼龄桉树蒸腾和生长的影响.结果表明,土壤含水量越高,桉树蒸腾量越大.随着桉树增长,植株蒸腾量逐月增大,但蒸腾强度却逐月下降,说明桉树叶面积增长速度,大于蒸腾量增长速度.不同土壤水分条件下桉树的蒸腾量、蒸腾时间长短和最大蒸腾量出现的时间不同.水分亏缺对桉树的影响是多方面的,外观表现为幼嫩枝梢萎蔫,分枝少、叶片少、叶面积下降、叶色变深、变暗,植株下部叶子叶尖枯死;生理上表现为气孔导度降低,阻力增大,气孔关闭,光合速率降低,养分吸收量减少.总的影响是生长量显著降低.在试验条件下,桉树每生产1 kg干物质所付出的蒸腾耗水量与土壤水分有关,土壤干旱时桉树的水分利用效率最低.

Effects of soil water on transpiration and growth of young eucalyptus

By pot-experiment, the effects of soil water on transpiration anf growth of young eucalyptus are studied. Results show thatthe more high soil water content, the more transpiration capacity of eucalyptus. With the growth of the trees, the transpirationcapacity increases monthly, but the transpiration intensity decreases, indicating that the growth rate of foliar area is larger than theincrease rate of transpiration capacity.Under the different soil water conditions, the transpiration capacity, transpiration time lengthand the time of maximum transpiration capacity occurring are different. Soi1 water deficiency affects eucalyptus in many ways,resulting in evidently decreased growth amount in the end. The results also show that during soi1 drought, the efficiency of waterapplication of eucalyptus is minimum.