盐分和干旱对沙枣幼苗生理特性的影响

以沙枣(Elaeagnus angustifolia L.)幼苗为实验材料,分别对其进行轻度干旱(土壤含水量7%—9%)、重度干旱(土壤含水量3%—5%)、100 mmol/L NaCl以及100 mmol/L NaCl处理下不同程度的盐旱共胁迫处理,处理2周后测其生理指标,包括生长指标、光合指标、渗透调节指标以及复水后生长指标,研究盐旱共胁迫对沙枣幼苗生理特性的影响。结果表明:和对照相比,轻度干旱对沙枣幼苗的生物量没有显著影响,重度干旱处理明显降低了沙枣的生物量,无论是轻度干旱还是重度干旱,都显著降低了沙枣幼苗的净光合速率、K~+含量,显著增加了Na~+含量、脯氨酸含量、可溶性糖含量、有机酸含量、总酚和类黄酮含量;和对照相比,100 mmol/L NaCl处理显著降低了沙枣幼苗的生物量、净光合速率和K~+含量,显著增加了Na~+含量、脯氨酸含量、可溶性糖含量、有机酸含量、总酚和类黄酮含量;和盐处理相比,轻度干旱和盐分共胁迫对沙枣幼苗的各项指标没有显著差异,而重度干旱和盐分共胁迫明显降低了沙枣幼苗的生物量、净光合速率;复水一周后,只有轻度干旱可以回复到对照水平。以上结果表明,盐分和干旱处理明显抑制了沙枣幼苗的生长,轻度干旱和盐分共胁迫条件下,沙枣幼苗表现出一定的交叉适应现象,而重度干旱却加重了盐害。

Effects of salt and drought on the physiological characteristics of Elaeagnus angustifolia L. seedlings

The problem of soil salinization is becoming more and more serious, and the area of saline land is increasing, which seriously affects the sustainable development of agriculture. The Yellow River Delta (YRD) of China not only has highly saline and alkalized soil but also drought in spring or autumn. Coupled with salt in the soil, the plants growing here are often subjected to double stress from salinity and drought, resulting in a decline in plant yields and economic benefits. Elaeagnus angustifolia L. is a tree species that can tolerate salt and drought. In recent years, research on the stress resistance of E. angustifolia has been abundant, but most of them focus on a single stress factor. There are few studies on the physiological characteristics of E. angustifolia seedlings under double stress from salinity and drought. An experiment was carried out to investigate the effects of drought and salt stress on the growth and physiological characteristics of E. angustifolia seedlings to provide the theoretical basis for the introduction of E. angustifolia to the YRD. In this study, the seedlings of E. angustifolia were used as experimental materials and subjected to mild drought (7%-9% of soil moisture content), severe drought (3%-5% of soil moisture content), 100 mmol/L NaCl, the salt and drought stress treatments. The physiological indexes were measured after two weeks of treatment, which included growth, photosynthesis, osmotic adjustment index, and growth index after re-watering, in order to study the effects of salinity and drought interaction on the physiological characteristics of E. angustifolia seedlings.The results showed that compared with the control, mild drought had no significant effect on the biomass while the biomass of E. angustifolia seedlings significantly decreased under severe drought. Irrespective of the drought condition, the net photosynthetic rate and K⁺ content were significantly (P < 0.05) reduced, and the content of Na⁺, proline, soluble sugar, organic acid, total phenol, and flavonoid of the E. angustifolia seedlings were significantly (P < 0.05) increased. Compared with the control, the biomass, the net photosynthetic rate, and K⁺ content were significantly (P < 0.05) decreased, and the content of Na⁺, proline, soluble sugar, organic acid, total phenol, and flavonoid of E. angustifolia seedlings significantly (P < 0.05) increased under 100 mmol/L NaCl treatment. Compared with NaCl treatment, the indexes of E. angustifolia seedlings showed no significant (P > 0.05) change under mild drought and salt treatment. Compared with NaCl treatment, the biomass, the net photosynthetic rate, and K⁺ content were significantly (P < 0.05) reduced, and the content of Na⁺, proline, soluble sugar, organic acid, total phenol, and flavonoid of E. angustifolia seedlings significantly (P < 0.05) increased under salinity and severe drought treatment. After one week of re-watering, only the E. angustifolia seedlings under mild drought can return to the control level. The findings of this study suggested that salt and drought treatment significantly inhibited the growth of E. angustifolia seedlings. Under mild drought and salt stress, the E. angustifolia seedlings showed some cross-adaptation, while severe drought exacerbated salt damage.