风沙流频繁吹袭对樟子松幼苗光合水分代谢的影响

为了解风沙流频繁吹袭对樟子松幼苗光合水分代谢的影响，2013年在内蒙古科尔沁沙地研究了0（对照），6，9，12，15和18 m／s 等6个风速处理风沙流（风沙流强度相应为1．00，28．30，63．28，111．82和172．93 g／cm·min）4次吹袭下3龄樟子松幼苗光合速率、蒸腾速率、水分利用效率等指标的变化规律。结果表明，1）频繁的风沙流吹袭，可以改变樟子松幼苗蒸腾速率、气孔导度、胞间 CO2浓度和水分利用效率的日变化规律，但对光合速率日变化规律影响较小；2）随着风沙流强度的增加，其叶片相对含水量、叶面温度和日均光合速率、日均水分利用效率趋于下降，18 m／s 处理和对照相比分别下降4．6％，1．8％，52．6％和56．3％；日均蒸腾速率、日均气孔导度和胞间 CO2浓度趋于增加，18 m／s 处理和对照相比分别增加31．6％，75．0％和30．9％；3）随着风沙流强度的增加，其日最大光合速率和日最大水分利用效率趋于下降，日最大胞间 CO2浓度趋于增加，15 m／s 以下风沙流吹袭其日最大蒸腾速率降低，15 m／s 以上风沙流吹袭其日最大蒸腾速率显著增加；4）在风沙流吹袭下，樟子松光合能力的降低主要源于叶片含水量和叶片温度的下降以及叶片的机械损伤，而蒸腾速率的增加主要源于气孔导度的大幅度提升。

Effects of frequent uind-sand flow on photosynthesis and water metabolism of Pinus sylvestnis var.mongolica seedlings

In order to understand effects of frequent wind-sand flow on photosynthesis and water metabolism of Pinus sylvestnis var.mongolica seedlings,a field wind-sand flow experiment with a gradient wind speed treat-ments of 0 (CK),6,9,12,15 and 18 m/s (wind sand flow intensity are 1.00,28.30,63.28,111.82 and 172.93 g/cm·min,respectively)was conducted in the Horqin Sand Land of Inner Mongolia in the Spring, 2013.The photosynthetic rate (P n ),transpiration rate (T r )and water use efficiency (WUE)were investiga-ted.The results showed that,1 )frequent wind sand flow could change diurnal variation pattern of the T r , stomatal conductance (G s ),intercellular CO2 concentration (C i )and WUE in the Pinus sylvestnis var.mon-golica seedlings,but had litter effects on diurnal variation pattern of the P n ;2 )With increase of wind-sand flow strength,the RWC and leaf temperature,average daily P n ,WUE tended to decrease,which decreased by 4.6%,1.8%,52.6% and 56.3% in the 18 m/s treatment than that in the CK,respectively;and the average daily T r ,G s and C i tended to increase,which increased by 31.6%,75.0% and 30.9% in the 18 m/s treatment than that in the CK,respectively.3 )With increase of wind-sand flow strength,the daily maximum P n and WUE tended to decrease,the maximum daily C i tended to increase,the maximum daily T r decreased when wind-sand flow was below 15 m/s and increased when wind-sand flow was in 15 m/s and 18 m/s.4)In wind-sand flow stress,decline of photosynthetic ability in P .sylvestnis var.mongolica scapling mainly due to de-crease of the relative water content (RWC)and leaf temperature and the leaf mechanical damage,and increase of the T r was attributed mainly to significant increase of the G s .