干旱胁迫下红麻和大麻状罗布麻水分生理及光合作用特征研究

以中国红麻和美国大麻状罗布麻为材料,采用防雨棚内盆栽控水法研究了4种土壤水分条件下2种罗布麻的水分生理及光合作用日变化特性,探讨2种罗布麻对干旱胁迫的响应和适应能力,为美国大麻状罗布麻引种栽培提供理论依据。结果显示:(1)随干旱胁迫的加剧,2种罗布麻叶片的组织含水量、相对含水量均逐渐降低,但大麻状罗布麻的降幅较小;同一水分条件下,大麻状罗布麻的组织含水量、相对含水量均高于红麻,而水分饱和亏均低于红麻;不同水分条件下,大麻状罗布麻叶片相对含水量在离体2h后仍维持高位,降幅极显著低于红麻(P<0.01),离体8h后仍能维持较高水平。(2)在饱和供水(CK)、轻度胁迫(LS)和中度胁迫(MS)条件下,2种罗布麻叶片的Pn、Tr、Gs日变化均呈相似的"双峰"型曲线,而重度胁迫(SS)下却呈单峰曲线,各胁迫条件下Pn第二峰值比CK推迟2h左右;各处理Pn和WUE日均值在大麻状罗布麻中表现为LS>CK>MS>SS,而在红麻中则为CK>LS>MS>SS,且2种罗布麻除WUE指标在处理CK与T1间差异不显著外(P>0.05),其余处理间差异均达到显著水平以上(P<0.05);同一水分条件下,大麻状罗布麻的Pn和WUE值均显著高于红麻,如大麻状罗布麻在SS条件下的Pn和WUE日均值分别为2.28μmol·m-2.s-1和1.41μmol·mmol-1,而红麻的仅为0.29μmol·m-2.s-1和0.16μmol·mmol-1。研究表明,在土壤干旱胁迫条件下,大麻状罗布麻叶片在水分生理和光合生理方面均表现出明显优势,比当地红麻具有更强的保水及光合生产能力,耐旱性更强,可在宁夏地区引种栽培。

Daily Dynamics of Photosynthesis and Water Physiological Characteristics of Apocynum venetum and A.cannabinum under Drought Stress

In order to find out the adaptability and coping strategies to arid environment of Apocynum venetum and A.cannabinum,water physiological characteristics and daily dynamics of photosynthetic characteristics were studied under drought stress.The results showed that:(1)With the advance of drought stress,the leaf water content and relative water content for both Apocynum decreased gradually,and A.venetum decreased greatly compared with A.cannabinum.In the same soil water grade,the leaf water content and relative water content of A.cannabinum were significantly higher than that of A.venetum,but water saturation deficit was lower than that of A.venetum.Under the different soil water contents,the relative water content of leaves in vitro of A.venetum sharply declined after two hours,and declined significantly higher than that of A.cannabinum(P<0.01);After 8 hours,the relative water content of leaves in vitro of A.cannabinum were maintained at higher level.(2)Under treatments of saturated water supply(CK),light drought stress(LS) and moderate drought stress(MS),the diurnal curves of the net photosynthetic rate(Pn),transpiration rate(Tr) and stomatal conductance(Gs) of A.venetum and A.cannabinum were "double-peak",while "single-peak" under severe drought stress(SS).Compared with CK,the sub-peak of Pn delayed to about 16:00 under LS and MS condition.The order of Pn and WUE of A.cannabinum were LS>CK>MS>SS,while were CK>LS>MS>SS in A.venetum,and the difference reached to the significant level(P<0.05) except for WUE index between CK and T1 of two Apocynum.The Pn and WUE of A.cannabinum were significantly higher than that of A.venetum in same soil water grades;The daily average value of Pn and WUE in A.cannabinum were 2.28 μmol·m-2·s-1 and 1.41 μmol·mmol-1,respectively.However,the A.venetum.dropped to 0.29 μmol·m-2·s-1 and 0.16 μmol·mmol-1 under SS conditions.All these reflected that A.cannabinum was with higher water conservation and photosynthetic production capacity than A.venetum,and suitable to plant in Ningxia.