三峡库区濒危植物疏花水柏枝的生理生化特性研究

Physiological and biochemical characteristics of Myricaria laxiflora,an endangered species in the Three Gorges Reservoir Area

关键词:  光合作用  蒸腾作用  水分生理  抗逆性  消落带

Key words:  photosynthesis  transpiration  water physiology  endurance  water-fluctuating zone

摘要:

对三峡库区特有濒危植物疏花水柏枝的光合作用、蒸腾作用、水势等生理特性以及丙二醛(MDA)、过氧化物酶(POD)和多酚氧化酶(PPO)活性等进行分析测定。结果显示,疏花水柏枝在水淹胁迫后,能快速地恢复其光合与蒸腾生理作用。植株在秋季和夏初的光合作用和蒸腾作用的日动态呈单峰曲线,最高值出现在中午。夏初的光合强度与蒸腾强度一般高于秋季,表明夏初是该物种的生长旺季。该物种10月份水势的日动态在-0.97～1.82 MPa之间变动,水势与光合作用与蒸腾作用呈显著负相关。该物种虽是一种对水淹和干旱胁迫适应能力较强的物种,但土壤水分状况仍对植物的生长有较大影响。植株的生长发育阶段对疏花水柏枝的抗逆性有影响,在花前的抗逆性总体高于花后。还对疏花水柏枝的迁地保护提出了相应的建议。

Abstract:

In order to discover the physiological and biochemical characteristics in Myricaria laxiflora,an endangered species in Three Gorges Reservoir Area,the transpiration,photosynthesis,water potential of plant planted in two kinds of soils were tested in different growing seasons. Results showed that changes of transpiration,photosynthesis and water potential in a day all showed “single curve”. Transpiration and photosynthesis could reach the maximum of a day at noon whereas water potential fall to the minimum. Transpiration changed with the fluctuation of photosynthesis. The photosynthesis and transpiration of plants in May were higher than that in October due to the plants in October just recover from the dormancy induced by flooding. PV-curve and relative water parameters,including Ψ₁₀₀(maximum osmotic potential at water saturation point),Ψ₀(osmotic potential when a plasmolysis just emerge),ROWC(relative osmotic water content),RWC(relative water content),AWC(relative water content in apoplast)and RDW(relative dry weight)of the plants grown in sandy soil,red soil and submerged soil were measured. Plants at submerge sandy soil having low Ψ₁₀₀,Ψ₀,AWC and high ROWC and RDW implied that submersion could promote plants to develop a good ability resisting dry stress. The biochemical contents related with stress resistance were tested in different growing seasons. Mlondialdehyde(MDA)content,peroxidase(POD)activity,Polyphenol oxidase(PPO)activity and total soluble sugar content decreased after flower and fructification. It suggested that the plant resistance declined after fruit. Some suggestions finally were put forward for the population transplant to conserve this species according to its physiological and biochemical characteristics.