干旱胁迫对不同种源沙柳苗木水势和水分利用效率的影响

通过人工模拟方式对5个种源沙柳苗木进行干旱胁迫处理,研究干旱处理不同阶段苗木小枝水势日变化、叶片相对含水量、水分饱和亏缺、保水力及水分利用效率。结果表明:干旱胁迫下5个种源的沙柳苗木小枝水势和叶片相对含水量均下降,而水分利用效率在轻度干旱时呈上升趋势,随干旱胁迫的加剧而下降。干旱处理15天后,民勤种源的沙柳日平均小枝水势下降幅度最大为0.77 MPa,然后依次为达拉特旗0.57 MPa、盐池0.36 MPa、榆林0.25 MPa和乌审旗0.12 MPa,其中民勤种源的苗木在充分供水和干旱胁迫下小枝水势差异达到显著。干旱处理18天后叶片相对含水量分别下降:民勤1.68%、盐池7.03%、达拉特旗7.25%,榆林9.35%和乌审旗11.07%,水分饱和亏缺民勤<盐池<达拉特旗<榆林<乌审旗。结果表明,民勤种源的沙柳抗旱的能力较强,而盐池和达拉特旗沙柳苗木在受到水分胁迫时水分利用效率下降幅度较小,即水分胁迫对苗木干物质的积累影响较小,因此具有更高的经济价值。

Effect of Drought Stress on Water Potential and Water Use Efficiency of Salix psammophila Seedlings of Different Provenances

Diurnal variation of water potential,leaf relative water content,water saturated deficit,water-holding capacity and water use efficiency of Salix psammophila seedlings from 5 provenances were studied with water stress in the greenhouse.Water potential and leaves relative content of seedlings of all 5 provenances decreased,however water use efficiency increased in light drought,then decreased in severe drought.The decreased extent of water potential for different provenances was as follows: Minqin 0.77 MPa,Dalate 0.57 MPa,Yanchi 0.36 MPa,Yulin 0.25 MPa and Wushenqi 0.12 MPa when the seedlings were treated with water stress for 15 days;Variance analysis indicated that the difference of Minqin water potential between under normal and water stress condition was significant.When the seedlings were treated with water stress for 18 days,the decreased extent of leaf relative water content was Minqin 1.68%,Yanchi 7.03%,Dalate 7.25%,Yulin 9.35% and Wushenqi 11.07%,leaf water saturated deficit of seedlings from 5 provenances was Minqin>Yanchi>Dalate>Yulin>Wushenqi.The results showed leaf water saturated deficit of seedlings from Minqin was the least under severe water and water use efficiency ofseedlings from Yanchi and Dalate was higher under water stress,suggesting that S.psammophila seedlings from Minqin were the most drought-tolerant and economic values of Yanchi and Dalate seedlings were higher.