短期干旱对黄连叶片光合作用限制因素的研究

Research on limiting factors of photosynthesis in Coptis chinensis leaves under short-term drought

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 Thepurpose of thisexperimentwas to study the limiting factors on photosynthesis in Coptis chinensis leaves, which could provide a theoretical basis for its planting under drought condition. Methods Four groups of drought conditions, control （CK, normal moisture content）, light drought （LD）, moderate drought （MD）, and heavy drought （HD）, were set in the experiment through measuring the relative moisture content of soil. The rapid light response curves, stoma conductance （Cond）, transpiration rate （Tr）, and intercellular CO2 （Ci） in the leaves of C. chinensis under different degrees of short-term drought were determined. Results With the increase of photosynthetically active radiation （PAR）, the declined range ofFm＇and rised range ofqNin the LD, MD, and HD groups were less than those in CK group. Moreover, the lowest declined range of Fm＇ in the HD group was about 54.2% and the lowest value of qNwas 0.595. On the contrary, the rised range of Ft and declined range ofqN and ФPSII in the LD, MD, and HD groups were higher than those in CK group. Furthermore, the values of Cond and Tr in CK group were higher than those in LD and MD groups, but the values of Cond, Tr, and Ci in CK group were lower than those in HD group. Conclusion The decrease of photosynthesis is mainly due to non-stoma under the short-term HD stress （PSII reaction centre becomes inactive, the ability of heat dissipation decreases, and photosynthetic electron transport rate decreases）, while the limiting factors for photosynthesis of C. chinensis leaves are due to the stoma and non-stoma combined restriction under the short-term LD and MD stresses.