土壤干旱过程对裸果木荧光特性及渗透调节物质的影响

以2年生裸果木盆栽幼苗为试验材料，在土壤干旱过程中，监测叶片荧光参数和渗透调节物质的含量，揭示裸果木幼苗对水分变化的生理响应机制，以期为裸果木抗旱机理的研究提供理论依据。结果表明，初始荧光(F_o)和非光化学猝灭(NPQ-Lss)系数随土壤水分含量的减少而持续上升；最大荧光(F_m)、原初光能潜在活性(F_v/F_o)、光化学最大量子产量(F_v/F_m)、光化学猝灭(qP-Lss)系数和稳态光量子效率(QY-Lss)随土壤水分含量的减少而呈现下降的趋势；荧光衰减率(Rfd-Lss)在土壤相对含水量达到23.23%时迅速下降。土壤水分含量减少时，叶片PSⅡ反应中心的活性降低，光合作用的原初反应过程受抑制，但叶片能通过显著提高NPQ-Lss，消耗过剩的光能来减轻干旱对光合机构的伤害。随着土壤干旱程度的逐渐加剧，脯氨酸(proline，Pro)含量显著积累，增加幅度却逐渐减小；可溶性蛋白(soluble protein，SP)含量先下降，当土壤相对含水量低于31.38%时开始显著增加；可溶性糖(soluble sugar，SS)含量持续增加。在干旱过程中，裸果木叶片能够通过积累Pro、SS和SP，来降低渗透势，起到一定的抗旱作用。

Effects of Soil Drought on Fluorescence Characteristics and Osmotic Regulatory Substances of Gymnocarpos przewalskii

To provide theoretical basis for the study of drought-resistance mechanism of Gymnocarpos przewalskii,the seedlings of biennial G.przewalskii were used as experimental materials to investigate the physiological response mechanism of the seedlings to moisture variation during soil drought by monitoring chlorophyll fluorescence parameters and osmoregulation substance content.The results showed that the initial fluorescence (F_o) and non-photochemical quenching coefficients (NPQ-Lss) increased with the decrease of soil water content.The maximum fluorescence (F_m),primary light energy potential activity (F_v/F_o),photochemical maximum quantum yield (F_v/F_m),photochemical quenching coefficient (qP-Lss) and steady-state light quantum efficiency (QY-Lss) reduced with the decrease of soil water content; the fluorenscece decay rate dropped significantly when the relative content of soil reached 23.23%.With the decrease of soil water content,the activity of PSII reaction center in leaves decreased,and the primary reaction process of photosynthesis was inhibited.However,the leaves could significantly increase NPQ-Lss and consume excess light energy to reduce the damage of drought to photosynthetic apparatus.With the gradual intensification of soil drought,proline (Pro) content accumulated significantly,but the increasing range decreased gradually.The content of soluble protein (SP) decreased first,and then increased significantly when the soil relative water content was lower than 31.38%.Soluble sugar (SS) content increase continuously.In the process of drought,the leaves of G.przewalskii could accumulate Pro,SS and SP to reduce the osmotic potential and play a certain role in drought resistance.