干旱胁迫对不同种源云南松幼苗生物量与根系形态的影响

Effects of Drought Stress on Biomass and Root Morphology of Pinus yunnanensis Seedlings from Different Provenances

通过盆栽控水,采用双因素随机区组设计研究了9个不同地理种源云南松幼苗生物量分配和根系形态对干旱胁迫的响应,比较了干旱胁迫下幼苗生物量及其分配以及根系形态在种源间的差异,并通过隶属函数法对不同种源幼苗干旱适应性进行了初步评价。结果表明:1)干旱胁迫下,各种源云南松幼苗地径下降明显,苗高未发生显著变化,各器官生物量和总生物量多呈下降趋势,干旱胁迫并没有导致幼苗根生物量分配比和根冠比的增加,但根系长、比根长、根表面积和比根面积在干旱胁迫下增加显著。2)不同种源云南松幼苗地径、苗高、生物量及其分配比和根系形态在干旱处理下均存在显著差异,其中地径和苗高分别以西昌和双柏种源最大,各器官生物量和总生物量以双柏、西昌和册亨种源较高,察隅种源各器官和总生物量较低,但该种源具有最大的根生物量分配比和根冠比;会泽种源根长、根表面积、比根长和比根面积均最大。研究发现,在土壤水分限制条件下,云南松幼苗以根系形态变化代替根系生物量增加的策略来适应干旱,各种源云南松幼苗生长对干旱胁迫响应的差异可能是由种源地理气候因子长期影响所形成的不同适应性策略所导致。经平均隶属函数值法初步评价了不同种源云南松幼苗对干旱适应性的强弱,结果显示,西藏察隅、云南会泽和四川西昌种源对土壤干旱的适应性较强,云南双柏、贵州册亨、云南云龙种源居中,而云南新平、永仁和禄丰种源适应性较弱。

In order to evaluate drought adaptability of Pinus yunnanensis seedlings from different provenances,the effects of drought stress on biomass and root morphology of the seedlings werestudied and the differences in the seedlings biomass and root morphology under drought stress among nine provenances were compared by two-factor randomized block designing under a pot experiment of artificial water control.The results showed that 1)compared to the normal water treatment,the seedling ground diameter,individual organ biomass and the total biomass declined obviously under drought stress,but no significant variation was observed in the seedling height.Drought stress did not result in the increases of seedling root bimass allocation ratio and root-shoot ratio,while the root length,specific root length,root surface area and specific root surface area increased significantly.2)There were significant differences in seedling height,ground diameter,biomass and its allocation ratio,and root morphology among provenances under drought stress.The highest seedling height and ground diameter appeared in Xichang and Shuangbai provenances,and each organ biomass and the total biomass were higher in Shuangbai,Xichang and Ceheng provenances.Chayu provenance had the lower biomass but the highest root bimass allocation ratio and root-shoot ratio.The highest root length,specific root length,root surface area and specific root surface area were all observed in Huize provenance under drought stress.The study indicated that P.yunnanensis seedlings adapted to the the drought stress by root morphological changes instead of root biomass increase under soil moisture constraint,and the different responses of P.yunnanensis seedling growth to drought stress among provenances may result from the different adaptive strategies due to the long-term influence of geographical and climatic factors in each provenance.The comprehensive evaluation on drought adaptability of the seedlings from 9 provenances by the membership function method suggested that the higher drought adaptability of seedlings emerged in the provenances from Chayu of Tibet,Huize of Yunan and Xichang of Sichuan,followed by Shuangbai and Yunlong of Yunnan and Ceheng of Guizhou,and the provenances from Xiping,Yongren and Lufeng of Yunnan had the lower drought adaptability.