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目的探讨短期干旱对黄连叶片光合作用的限制因素,为黄连栽培中抗旱研究提供科学依据。方法通过测定土壤相对含水量,设置了CK(正常水分)、LD(轻度干旱)、MD(中度干旱)、HD(重度干旱)4个处理组,测定了短期干旱下黄连叶片快速光响应曲线,气孔导度(Cond)、蒸腾速率(Tr)、胞间二氧化碳(Ci)随光强变化特性。结果随着光合有效辐射(PAR)强度的增加,LD、MD、HD组的最大荧光产量(Fm’)下降幅度,非光化学猝灭系数(qN值)的上升幅度均低于CK组,且HD组Fm’下降幅度最低为54.2%,qN值最低为0.595。相反,LD、MD、HD组Ft值上升幅度,qN、有效荧光产量(φPSII)的下降幅度均高于CK组,此外CK组的Cond和Tr高于LD、MD组,但低于HD组,且Ci也低于HD组。结论短期重度干旱胁迫对黄连叶片光合作用的限制主要是非气孔因素起主导作用(PSII反应中心失活,热耗散能力降低,电子传递速率降低等);短期轻度、中度干旱胁迫对黄连叶片光合作用的限制是非气孔因素和气孔因素共同作用。
Objective To investigate the limiting factors of photosynthesis of Coptis chinensis leaves under short-term drought and provide a scientific basis for the research on drought resistance of Coptis chinensis. Methods The relative water content of soil was determined by four treatments: CK (normal water), LD (mild drought), MD (moderate drought) and HD (severe drought) Curve, stomatal conductance (Cond), transpiration rate (Tr), intercellular carbon dioxide (Ci) with the light intensity. Results With the increase of photosynthetically active radiation (PAR) intensity, the decrease of maximum fluorescence yield (Fm ’) and the increase of non-photochemical quenching coefficient (qN value) in LD, MD and HD groups were all lower than CK Group Fm ’the lowest decline of 54.2%, qN minimum value of 0.595. On the contrary, the decrease of Ft value, qN, effective fluorescence yield (φPSII) in LD, MD and HD groups were all higher than those in CK group. Cond and Tr in CK group were higher than those in LD and MD groups, Ci is also lower than HD group. Conclusion The main limitation of photosynthesis in Coptis chinensis under short-term severe drought stress is that non-stomatal factors play a leading role (inactivation of PSII reaction center, decrease of heat dissipation capacity and decrease of electron transfer rate). Short-term mild and moderate drought stress can inhibit the photosynthesis of Coptis chinensis The limitation of photosynthesis is the combination of non-stomatal and stomatal factors.