长叶红砂主要水分参数随季节和生境的变化

运用压力容积(PV)技术，研究了4种盐分生境下长叶红砂饱和含水量时最大渗透势(Ψ_s^sat) 、初始质壁分离时的渗透势(Ψ_s^tlp)、初始质壁分离时渗透水相对含量(ROWC^tlp)、初始质壁分离时的相对含水量(RWC^tlp)、质外体水的相对含量(AWC) 、束缚水与自由水的比值(V_a/V_o) ,以及饱和含水量时最大渗透势与初始质壁分离时的渗透势之差(ΔP)的季节变化.结果表明：长叶红砂的主要水分参数Ψ_s^sat、Ψ_s^tlp值为5月＞7月＞9月，AWC、V_a/V_o 和ΔP值表现为5月＜7月＜9月.说明长叶红砂在季节变化中历经了逆境锻炼，其耐水分亏缺能力随5、7、9月逐渐递增，这与植物的生长发育节律相吻合；与其他荒漠旱生植物相比，长叶红砂的Ψ_s^sat和Ψ_s^tlp值非常低，具有很强的忍耐高渗压和维持低水势的能力.以3个月份4种不同生境所测水分参数值为基础，运用模糊数学隶属函数法对不同生境长叶红砂耐水分亏缺能力进行综合评价，得出重盐土＞非盐渍土＞盐渍土.

Seasonal changes of main water parameters of Reaumuria trigyna in different habitats

By using press-volume technique,this paper studied the seasonal changes of water potential at saturated point(Ψ_s~(sat)),water potential at turgor loss point(Ψ_s~(tlp)),relative osmotic water content at turgor loss point(ROWC~(tlp)),relative water content at turgor loss point(RWC~(tlp)),relative content of apoplastic water(AWC),bound water/free water(V_a/V_o),and the difference between Ψ_s~(sat) and Ψ_s~(tlp) (ΔP) of Reaumuria trigyna growing on heavy solonchack,non-salinized soil,and saline soil.The seasonal changes of Ψ_s~(sat) and Ψ_s~(tlp) were in order of May > July > September,while those of AWC,V_a/V_o,and ΔP were in opposite sequence,indicating that the water deficit resistance ability of R.trigyna enhanced with season,being consistent with its growth rhythm.Comparing with other xerophytes,R.trigyna had very low Ψ_s~(sat) and Ψ_s~(tlp),presenting its strong ability of maintaining high osmotic pressure and low water potential.Based on the water parameters measured in three months,and by using the subordination function of fuzzy mathematics,the water deficit resistance ability of R.trigyna was evaluated,which was the strongest on heavy solonchack,followed by on non-salinized soil,and on saline soil.