红豆草幼苗叶片光合和叶绿素荧光对干旱胁迫的响应

Effects of drought stress on the leaf photosynthetic characteristics and chlorophyll fluorescence of sainfoin seedlings

为探究红豆草(Onobrychis viciaefolia)幼苗叶片光合及叶绿素荧光在不同干旱胁迫下的响应和适应能力,以国内外20份红豆草为试验材料,用PEG-6000模拟干旱胁迫环境,在不同渗透浓度(0、−0.5、−1.0、−1.5和−2.0 MPa)处理下,研究干旱胁迫对红豆草幼苗光合作用、荧光参数及叶绿素含量的影响。结果表明:干旱胁迫抑制了红豆草株高,随胁迫程度增加,叶绿素含量、类胡萝卜素含量、蒸腾速率、净光合速率和气孔导度均降低,水分利用效率上升,气孔限制值先升后降,在−1.0 MPa时最大,胞间CO_(2)浓度先降后升,在−2.0 MPa时最高,说明此时非气孔因素限制了光合作用;除非光化学猝灭系数上升外,其余荧光参数(潜在光化学活性、最大光化学效率、表现光合电子传递速率、光化学猝灭系数和光化学量子产量)均降低。经主成分分析及综合指标评价可知,新品系P1、GS和1626的耐旱性较强,材料1668、6和2049的耐旱性较弱。本研究结果为抗旱红豆草新品种选育提供了理论依据和种质材料。

To explore the effects of drought stress on the responses and adaptability of leaf photosynthesis and chlorophyll fluorescence in sainfoin(Onobrychis viciaefolia)seedlings,twenty different sainfoin seedling genotypes,derived from national and international strains,were used in this study.Water deficit stress was simulated with PEG-6000 at four osmotic potentials(−0.5,−1.0,−1.5 and−2.0 MPa,respectively),alongside a nil-PEG(CK)control treatment.Corresponding results demonstrated that drought stress inhibited the plant height of sainfoin seedlings.Additionally,with increasing drought stress,chlorophyll content,carotenoid content,transpiration rate,net photosynthetic rate,and stomatal conductance were reduced,while water use efficiency was improved.Initially,the stomatal limitation value increased with increasing drought stress,and then decreased,with a maximum value being observed at−1.0 MPa.Intercellular carbon dioxide concentration initially decreased and then increased,reaching a maximum value at−2.0 MPa;this indicated that non-stomatal factors limited photosynthesis.Although the non-photochemical quenching coefficient increased,the actual photochemical efficiency,maximum photochemical efficiency,electron transport rate,photochemical quenching coefficient,and photochemical quantum yield decreased with increasing drought stress.According to principal component analysis and comprehensive index evaluation the novel P1,Onobrychis viciaefolia‘Gansu’sainfoin line and the 1626 genotype possessed the strongest drought tolerance,whereas genotypes 1668,6,and 2049 possessed the weakest drought tolerance.Therefore,P1,GS and 1626 sainfoin lines could be used for a variety of regional and production analyses in the future.