土壤干旱胁迫对巨龙竹实生苗光合特性和抗氧化酶活性的影响

Effects of Soil Drought Stress on Photosynthetic Characteristics and Antioxidant Enzyme Activities of Dendrocalamus sinicus Seedlings

试验选取盆栽巨龙竹(Dendrocalamus sinicus)实生苗,通过控制土壤水分含量设置轻度干旱、中度干旱和重度干旱3个胁迫水平研究不同干旱胁迫处理对巨龙竹实生苗的光合参数和抗氧化酶活性的影响。结果表明:随干旱程度的增加,土壤含水量显著下降,巨龙竹实生苗叶片的叶绿素含量(SPAD值)、净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)均呈下降趋势,而胞间CO_(2)浓度(Ci)在中度和重度干旱时呈上升趋势;在3种干旱强度下,SOD活性呈现先上升后下降再上升的变化趋势,APX活性和丙二醛含量均高于对照,CAT均低于对照。由研究结果可见,干旱会引起巨龙竹实生苗光合参数下降,光合速率下降的原因表现为随着干旱强度的增加由气孔限制原因转为非气孔限制原因,并且SOD和APX是巨龙竹在干旱胁迫下起主要作用的2种酶。巨龙竹实生苗在轻度干旱环境中表现出良好的适应性,但在中度和重度干旱环境中其适应性较差。

The experiment selects potted Dendrocalamus sinicus seedlings to study the effects of different drought stress treatments on the photosynthetic parameters and antioxidant enzyme activity of D. sinicus seedlings by setting through soil water content control three stress levels of mild drought, moderate drought and severe drought. The results show that as the degree of drought increases, the soil water content decreases significantly, and the chlorophyll content(SPAD), net photosynthetic rate(Pn), transpiration rate(Tr) and stomatal conductance(Gs) of the leaves of D. sinicus seedlings also decrease, while the concentration of intercellular CO_(2)(Ci) show an upward trend in moderate and severe drought. Under the three drought intensities, SOD activity shows the change trend of increasing first, decreasing then and increasing again;APX activity and malondialdehyde content are higher than those of the control, and CAT is lower than that of the control. It can be seen from the results that drought will cause the decline of photosynthetic parameters of D. sinicus seedlings. The reason for photosynthetic rate decline is that with the increase of drought intensity, it changes from stomatal limitation to non stomatal limitation, and SOD and APX are the two enzymes that play a major role in D. sinicus seedlings under drought stress. The seedlings of D. sinicus show good adaptability in mild drought environment, but their adaptability is poor in moderate and severe drought environment.