摘要
在适宜水分(田间持水量为80%)、轻度干旱(60%)、中度干旱(40%)和重度干旱(20%)4种土壤水分条件下研究了油松的生理生态特征,结果显示;油松各器官(根、茎、叶)的干物质积累量、干物质积累总量、相对生长率、株高和基径均表现为适宜水分>轻度干旱>中度干旱>重度干旱,而根冠比大小顺序与其相反.气体交换参数(净光合速率、气孔导度、蒸腾速率)随干旱程度的加剧显著下降,并且净光合速率的下降主要受气孔因素限制.油松的瞬时水分利用效率和长期水分利用效率(稳定碳同位素含量,δ13C)表现适宜水分<轻度干旱<中度干旱<重度干旱,而且中度和重度干旱显著提高油松的水分利用效率.另外,单位干重叶片氮元素含量(N%)随胁迫增加呈下降趋势,而单位干重碳元素含量(C%)却与之相反,从而导致碳氮比随胁迫增加而增加,并且我们的结果显示光合速率与氮含量存在显著正相关.结果表明,油松可以通过调节自身生长特征、生物量分配模式和叶片营养元素的含量及提高水分利用效率而增强应对干旱胁迫的能力.
In our present study, seedlings of Pinus tabulaeformis were subjected to four levels of soil water content：80 % maximum field capacity （FC）, 60 % FC, 400% FC and 20% FC, respectively regarded as well- watered,mild, moderate and severe water stress. Our results showed that water stress significantly decreased dry matter accumulation （including leaf, shoot, root and total dry matter production）, relative growth rate,plant height and basal stem diameter except that root/shoot ratio showed an increasing trend with increasing water stress. Also, leaf gas exchange parameters （net photosynthetic rate, stomatal con- ductance and transpiration rate） were significantly decreased with the increase of water stress and the reduction in net photosynthetic rate was mainly due to the stomatal closure. Furthermore,when severe water stress was imposed, both instantaneous water use efficiency and long term water use efficiency, indicated by stable carbon isotope composition （δ^13 C） significantly increased. In addition, leaf nitrogen concentration （per mass,N%） showed a decreasing trend with increasing soil water stress while leaf carbon concentration （per mass,C%） showed an opposing trend,which directly resulted in an increase in C/N ratio with decreasing soil water content. We also found a positive correlation between photosynthetic rate and leaf nitrogen concentration in our study. In conclusion,our results indicated that changes in growth and structural char-acteristics,leaf nitrogen and carbon concentrations and improving water use efficiency with increasing soil water stress in P. tabulaeformis may facilitate its adaptation to low soil water availability conditions.
出处
《西北植物学报》
CAS
CSCD
北大核心
2009年第3期548-554,共7页
Acta Botanica Boreali-Occidentalia Sinica
基金
国家自然科学基金资助项目(30600041
30430560)
关键词
油松
气候变化
气体交换参数
生长特性
水分利用效率
叶片元素含量
Pinus tabulaeformis
climate change
leaf gas exchange parameters
growth traits
water use ef ficiency
leaf elements
