4种柳树苗木叶的PV水分参数对水分胁迫的响应

在温室内研究了瑞典能源柳C号、2号柳、4号柳和陕北红皮柳苗木的抗旱能力。对其盆栽苗木施行水分轻度胁迫、中度胁迫、重度胁迫及正常(供水)生长4种处理,应用压力室和PV技术测定4种柳树苗木在不同处理状态下的叶组织多项水分参数,以此对其苗木的耐旱能力作综合评定。结果表明,在水分胁迫条件下,2号柳苗木叶吸收水分的能力最强;4种柳树的苗木均有一定的渗透调节和保持膨压能力,4号柳、2号柳、红柳的苗木能通过增加叶束缚水的含量来实现渗透调节,但其依靠改变苗木叶束缚水的含量来实现渗透调节的作用有限,红柳、4号柳苗木在土壤相对含水量降至61%时,2号柳苗木在土壤相对含水量降至46%时,其叶由束缚水含量所引起的渗透调节作用消失;在水分胁迫条件下,红柳、4号柳苗木通过改变叶组织细胞壁的弹性来保持其的膨压,2号柳、能源柳C号的苗木主要靠叶渗透调节来维持其的膨压。水分胁迫能增强红柳、能源柳C号、4号柳苗木保持最大膨压的能力,而降低2号柳苗木维持最大膨压的能力;4号柳能通过提高苗木叶细胞原生质忍耐脱水的能力来适应干旱,能源柳C号、红柳苗木叶细胞原生质耐脱水能力对水分胁迫的适应性差,在水分胁迫条件下其耐脱水能力减弱。通过对4种柳树苗木叶组织渗透调节和维持膨压能力的综合比较,其抗旱能力由强至弱依次为能源柳C号、2号柳、红柳和4号柳。

Responses of PV Parameter to Water Stress in Four Kinds of Salix Seedlings

The drought resistance of Olof,Salix dasyclados,Salix 'Mesu Neko'and Salix purpurpea were studied in greenhouse by using pot plants as materials.Three treatments were designed,including water content of 15 %~19 %,7 %~14 % and<7 % respectively.The water parameters were calculated by using pressure-volume technique,and the drought resistance of four species were comprehensively evaluated.The experimental results showed that under dry conditions,Salix dasyclados was the best in terms of water absorbing,all the four species had some extent of osmotic adjustment and turgor maintenance abilities.Salix 'Mesu Neko',Salix purpurpea and Salix dasyclados could adjust osmosis by improving he proportion of bound water to some extent,when the soil moisture content decreased to 61 %(for Salix dasyclados and Salix 'Mesu Neko') and 46 %(for Salix dasyclados),their osmotic adjustment ability by improving the proportion of bound water disappeared.Under drought conditions,Salix purpurpea and Salix 'Mesu Neko'could maintain turgor by improving elasticity of cell wall,while Salix dasyclados and Olof maintained turgor mainly by osmotic adjustment.Water stress could increase the abilities of maintaining maximum turgor of Salix purpurpea,Olof and Salix 'Mesu Neko',but decrease the abilities of maintaining maximum turgor of Salix dasyclados.Salix 'Mesu Neko'could adapt drought stress by improving the ability of tolerating dehydration,but Olof and Salix purpurpea could not.Through integrating the osmotic potential adjustment and turgor maintaining abilities,it was concluded that ability of drought resistance of four species was Olof>Salix dasyclados>Salix purpurpea>Salix'Mesu Neko'.