樟子松幼苗生长及光合特性对强风沙流吹袭的响应

为了解樟子松幼苗对不同时间强风沙流吹袭的生理生态响应,2013年春季在内蒙古科尔沁沙地研究了8级大风风沙流(风速18m·s-1,风沙流强度173g·cm-1·min-1)吹袭10、20和30min下樟子松幼苗生长与光合特性的变化。结果显示:(1)随着风吹时间的增加,樟子松的株高生长量减少、茎粗生长加快,落叶数量增加,其中30min处理与CK相比的株高生长量下降52.63%,茎粗生长量增加233.30%,落叶指数增加466.70%。(2)风沙流吹袭没有改变樟子松幼苗的净光合速率、蒸腾速率、气孔导度和胞间CO2浓度的日变化规律,但日光合峰值下降,日最大蒸腾速率增加;与CK相比,30min处理的日最大光合速率下降22.69%,日最大蒸腾速率增加11.89%。(3)随风吹时间增加,其叶片温度、叶片相对含水量、日均光合速率、水分利用效率下降,30min处理较CK依次下降0.60%、4.37%、28.57%和31.58%,且日均蒸腾速率、气孔导度和胞间CO2浓度增加,30min处理较CK依次增加6.25%、6.67%和12.60%。研究表明,在持续风沙流胁迫下,樟子松幼苗光合作用受到抑制,蒸腾耗水增加,水分利用效率降低;樟子松幼苗生长速率降低主要源于光合面积减少和光合作用受到抑制,而其光合速率下降主要因幼苗叶片叶温和叶片含水量下降所致,蒸腾速率的增加主要源于气孔导度的增加;为了适应风沙流持续吹袭的胁迫,樟子松幼苗采取了降低株高生长速率,加快茎粗生长速率的适应策略。

Response of the Growth and Photosynthetic Properties of Pinus sylvestris var.mongolica Saplings to Strong Wind-sand Flow Blowing

In order to understand effects of strong wind-sand flow blowing on growth properties of Pinus sylvestris var.mongolica seedlings and its photosynthetic responses,we conducted a field wind-sand flow blowing experiment with 18 m·s^-1 wind speed (wind-sand flow intensity 173 g·cm^-1·min^-1) and a time gradient of 10 min,20 min and 30 min in the Spring,2013 in the Horqin Sand Land of Inner Mongolia.The results showed that:(1)With increase of wind-sand blowing time,amount of plant height growth slowed down,amount of stem diameter growth accelerated,number of fallen leaves increased.The amount of plant height growth decreased by 52.63%,amount of stem diameter growth increased by 233.30%,and fallen leaves index increased by 466.70%,respectively,in the 30 min treatments compared to the CK.(2)Wind-sand flow blowing did not changed the diurnal variation pattern of photosynthetic rate,transpiration rate,stomatal conductance and intercellular CO₂,but resulted in decrease of the daily maximum photosynthetic capacity and increase of the maximum daily transpiration rate,which decreased by 22.69% and increased by 11.89% in 30 min treatments compared to the CK,respectively.(3)With the increase of wind blowing time,the leaf temperature,RWC,daily mean photosynthetic rate and WUE tended to decline,which decreased by 0.60%,4.37%,28.57% and 31.58%,respectively,in 30 min treatments compared to the CK.The daily mean transpiration rate,stomatal conductance and intercellular CO₂ concentration tended to increase,which increased by 6.25%,6.67% and 12.60%,respectively,in 30 min treatments compared to the CK.The results suggested that the photosynthesis was inhibited,transpiration water consumption increased,and water use efficiency decreased while P.sylvestris var.mongolica seedlings were stressed by continuous sand flow blowing.The decrease of photosynthetic rate resulted mainly from decrease of leaf temperature and leaf water content,and the increase of transpiration rate was mainly due to increase of stomatal conductance.In order to adapt to the continuous blowing sand flow stress,P.sylvestris var.mongolica seedlings reducded the height growth rate,speeded up growth rate of stem diameter.