| The hydraulic failure and carbon starvation hypothesis are important in explaining the mechanism of tree death under drought.However,there is still insufficient research on the relationship between hydraulic failure and carbon starvation.To clarify the drought resistance strategies adopted by poplar clones with different growth rates under drought and the relationship between hydraulic characteristics and carbon metabolism,and to understand the physiological mechanism of poplar survival in the current drought-prone environment will help solve the problems of afforestation and cultivation of poplar in arid areas.In this study,poplar clones with different growth rates(group K,group M)were used as materials to carry out different drought(control group;moderate drought group;severe drought group)and rewatering.Various embolism vulnerability,leaf water potential,hydraulic conductivity,percent loss of hydraulic conductivity(PLC)and other hydraulic indicators and gas exchange parameters,photosynthesis,non-structural carbohydrates(NSC)before and after rehydration,etc.Comparing the changes and differences of various indexes of the same clone between differenttreatments and different clones between the same treatment,exploring the physiological and biochemical indexes and water stress of the two groups of poplar clones during drought and rewatering and the relationship between carbon metabolism and hydraulic characteristics.Main findings as follow:1.Compared with growth,embolism vulnerability,hydraulic safety threshold,etc.,the drought resistance of group K poplars with faster growth rate was weaker than that of group M with slower growth rate.2.Poplar trees adopted different drought-resistance strategies because of their different growth rates.The water regulation strategy of poplar clones in group K showed characteristics closer to isohydric behavior,and poplars in group M were closer to anisohydric behavior.3.Different drought significantly affected the hydraulic characteristics and carbon metabolism of the two groups of poplar clones,and the hydraulic failure played a dominant role in the two groups of clones,and no carbon starvation occurred in the two groups of poplars.4.There was a difference in the ability of two groups of poplars to recover from droughtafter rewatering.After rehydration,the hydraulic characteristics of the two groups of poplars can be restored to a certain extent.The fast-growing group K had stronger recovery ability,while the slower-growing group M had stronger carbon distribution capacity and was more resistant to drought even after rewatering. |
