【摘要】 苜蓿和沙棘是西北干旱荒漠区重要的植物,然而,二者的节水和抗旱机理仍有不被理解之处。为揭示植物叶片气孔导度(G_s)、叶水势(ψ_L)对水分胁迫的响应规律,将苗期苜蓿与沙棘分别进行了水分胁迫的盆栽试验,根据土壤含水量占田间持水量的比例设置了充分供水(CK)、轻度水分胁迫(LD)、中度水分胁迫(MD)和重度水分胁迫(HD) 4个处理。结果表明:在不同胁迫梯度下,沙棘G_s与ψ_L日变化规律一致,分别为近"M"和近"V"型曲线;而苜蓿的日变化规律不一致。两种植物的G_s与ψ_L日平均值均随水分胁迫程度的加剧而降低,且沙棘G_s、ψ_L日均值均大于苜蓿。2种植物G_s、ψ_L与叶片相对湿度(RHL)均呈显著正相关关系。沙棘Gs与光合有效辐射(PAR)呈显著的负二次相关关系,且G_s最大值为(CK:432. 02,LD:384. 32,MD:335. 94,HD:307. 73 mmol/(m2·s));苜蓿Gs仅在CK时与PAR呈显著正相关关系,而在胁迫处理下与PAR无显著相关性。不同水分条件下沙棘ψ_L与叶片温度(T_L)均呈显著负相关关系,而苜蓿则均无显著相关性。沙棘G_s、ψ_L随RH_L、T_L、PAR变化率比苜蓿大87%～203%。综上,沙棘对干旱胁迫环境有更强适应性,苜蓿对水分胁迫的响应规律更为复杂。本研究有助于深入了解沙棘与苜蓿苗期对干旱胁迫环境的适应性,为荒漠地区植被恢复建设提供技术支撑。更多还原

【Abstract】 [Background]Medicago sativa and Hippophae rhamnoides are two of most important plants in the arid desert areas of northwest China. However, the mechanisms of water-saving and drought resistance of M. sativa and H. rhamnoides remain poorly understood,and the corresponding techniques need to be further studied. [Methods] The potted trials of water stress were carried out to understand the response mechanisms of stomatal conductance( Gs) and leaf water potential( ψL) to water stress for M. sativa and H. rhamnoides at seedling stage. Sufficient water supply( CK),light water stress( LD),moderate water stress( MD),and severe water stress( HD) were set up according to the percentages of soil water contents in field moisture capacity. [Results] Under different stress gradients,the diurnal variation of Gsand ψLfor H. rhamnoides was similar with M-shaped and V-shaped curve,respectively,while the counterparts of M. sativa was different. The daily average Gsof H. rhamnoides was higher than that of M. sativa. And the average of Gsand ψLof two plants decreased with the increase of water stress.The correlation between Gs,ψL,and relative humidity( RHL) were significantly positively correlated for two plants. The Gsof H. rhamnoides increased at first and then decreased with the increase of photosynthetic active radiation( PAR). The Gsof M. sativa increased with the increase of PAR only when sufficient water was supplied. However,there was no correlation between Gsand PAR under stress.The ψLand leaf temperature( TL) of H. rhamnoides were significantly correlated with different water stress treatments,but not for M. sativa. The Gsand ψLof H. rhamnoides were 87% ～ 203% higher than that of M. sativa with the change of RHL,TL,and PAR. Therefore,the response of H. rhamnoides to meteorological factors was more sensitive than M. sativa. [Conclusions] It is more adaptable for H.rhamnoides to drought stress environment,while the response mechanism of M. sativa to water stress is more complicated. This study will help to understand the mechanism of H. rhamnoides and M. sativa adapting to drought stress environment at seedling stage and provide a theoretical support for vegetation restoration in desert areas.更多还原