水分胁迫对欧美I-107杨树苗生理生化特性的影响

Effects of water stress on physiological and biochemical characteristics of Populus×euramericana cv.‘Neva' seedlings

以欧美I-107杨扦插苗为试材,研究不同程度干旱胁迫处理对杨树苗叶片生理生化特性的影响。结果表明:随着水分胁迫程度的增加和时间的延长,杨树苗叶片的相对含水量、自由水含量显著降低;束缚水含量、束缚水/自由水比值在轻度胁迫下逐渐升高,而在中度和重度胁迫下先升后降;脯氨酸含量在轻度胁迫下与对照差异不显著,在中度和重度胁迫下显著高于对照;可溶性蛋白在轻度胁迫下逐渐升高,而在中度和重度胁迫下先升后降;SOD和CAT活性先上升后下降,丙二醛含量显著增加。可见,I-107杨树苗在轻度水分胁迫下具有相对较强的抗氧化防御和渗透调节机制,而在中度和重度胁迫下明显减弱。

I- 107 Populus euramericana seedlings growing in pots were subjected to four different water treatments（ normal irrigation,light drought,moderate drought and severe drought） in this experiment. The contents of tissue water,osmotic regulation substances,MDA and activities of antioxidant enzymes in leaves of poplar were tested. The results showed that with the increasing extent and duration of water stress,the leaf relative water content and free water content of I- 107 Populus euramericana seedlings decreased significantly. The bound water content and the ratio of bound water to free water in leaves rose gradually under light water stress,but had a trend of increasing firstly and decreasing then under moderate and severe water stress. With regard to praline content,it had no significant difference with the control under light stress,while was significantly higher than the control under either moderate or severe stress. The leaf soluble protein content increased consistently under light stress,however,had a trend of first up then down under both moderate and severe stress. The activities of superoxide dismutase（ SOD） and catalase（ CAT） decreased after an initial increase and the malondialdehyde（ MDA） content had a significant increase. As a result,the I-107 Populus euramericana seedlings had relatively stronger mechanisms of antioxidant defense and osmotic regulation under light water stress,but decreased significantly under both moderate and severe water stress.