【摘要】 【目的】以群众杨为对照,探讨干旱胁迫下碧玉杨的叶形态、结构和光合、水分生理特性的关系及其影响植株生物量积累的内在成因,进一步揭示碧玉杨和群众杨的抗旱机制,为区域造林绿化杨树的抗旱生理研究和品种推广提供参考。【方法】以碧玉杨与和群众杨1年生扦插苗为研究对象,应用盆栽控水法模拟干旱条件,对比分析不同干旱胁迫程度下2个品种的叶面积、叶脉密度、叶氮素利用效率、光合特性及叶水分输导能力的响应,及其对植株生物量和抗旱能力的影响。【结果】干旱胁迫程度加剧,2个杨树品种的叶脉密度（LVD）和单位干质量叶氮含量(N_mass)上升,碧玉杨的LVD增幅大、N_mass增幅小;净光合速率（P_n）、植株总光合速率（PTL）、最大净光合速率(P_nmax)、光合日累积量、蒸腾日累积量、叶导水率(K_leaf)、水分利用效率（WUE）、光合氮利用效率（PNUE）、叶面积（LA）以及植株生物量（TB）均下降,碧玉杨的降幅均小。相较群众杨而言,碧玉杨的LA、LVD、PNUE、TB和日均耗水量在干旱胁迫前后均高,P_n、K_leaf、WUE和N_mass在干旱胁迫前后均低,PTL和Tr日累积在中度和重度干旱胁迫下高,P_nmax、P_n日累积和Tr在重度干旱胁迫下高。PTL较Pn与TB相关关系更紧密,PNUE较N_mass与TB相关关系更紧密。【结论】干旱胁迫下碧玉杨的叶形态结构与生理特性呈现出低效水分利用、高效叶形态结构调整、高效氮素利用和高效光合固碳的平衡制约关系。2个品种的抗旱机制不同,抗旱能力强的碧玉杨其叶结构调整更高效,抗旱能力弱的群众杨其光合特性对干旱更敏感,叶结构与抗旱性关联最大,其次是光合特性。更多还原

【Abstract】 【Objective】This study aimed to explorethe relationships between leaf morphological structure,photosynthetic characteristics and water physiological characteristics,and the internal causes affecting plant biomass accumulation of Populus euramericana cv. ‘BYu’in comparison with P. popularis ’35-44’ and further reveal the drought-resistant of P.euramericana cv.‘BYu’and P. popularis ‘35-44’,which could lay foundations for the drought physiology research and the promotion of poplar varieties in regional afforestation.【Method 】A pot experiment with one-year-old cuttings of P.popularis‘35-44’ and P.euramericana cv.‘BYu’was conducted to investigate the effect of different drought stress on leaf area（LA）,leaf vein density（LVD）,leaf nitrogen use efficiency,photosynthetic characteristics and leaf hydraulic conductance（LHC）,and their influence on plant biomass accumulation and drought-resistant ability.【Result】With the increase of drought stress,LVD and leaf nitrogen content per mass(N_mass) of two poplar varieties increased,and LVD increased more and Nmasincreased less for P.euramericana cv.‘BYu’.Net photosynthetic rate（P_n）,photosynthetic rateper plant（PTL）,maximum net photosynthetic rate(P_nmax),daily accumulation of P_n and Tr,K_leaf,water use efficiency（WUE）,photosynthetic nitrogen use efficiency（PNUE）,LA and plant total biomass（TB） all decreased,with decreased less for P. euramericana cv.‘BYu’. Compared with P. popularis ‘35-44’,P. euramericana cv.‘BYu’had higher LA,LVD,PNUE,TB,and daily water consumption,lower P_n,K_leaf,WUE,N_massbefore and after drought stress,higher PTL,P_nmax,and daily accumulation of Tr under moderate and severe drought stress,and higher P_nmax,daily accumulation of P_n,and Tr under severe drought stress. PTL was more closely related to TB than P_n,and,PNUE was more closely related to than N_mass.【Conclusion 】Under drought stress,the leaf morphological structure and physiological characteristics of P.euramericana cv.‘BYu’presented a balanced constraint relation between inefficient water utilization,efficient adjustment of leaf morphological structure,efficient nitrogen utilization,efficient assimilation of carbon.Drought resistance mechanism of these two varieties wasdifferent,P. euramericana cv.‘BYu ’ with strong drought-resistancehad more efficient leaf structure adjustment,P.popularis ‘35-44’with weak drought-resistancehad more sensitive photosynthetic characteristics to drought. Leaf structure was most associated with drought resistance,followed by photosynthetic characteristics.更多还原