两个主栽油茶品种对干旱胁迫的适应策略OA

To better understand the response mechanisms and adaptation strategies of two main Camellia oleif-era varieties to drought stress,providing important theoretical basis and technical support for the management mea-sures for efficient cultivation of high-quality varieties of C.oleifera,three-year-old seedlings of C.oleifera varieties Xianglin 210 and Changlin 53 were selected for investigating adaptive strategies under drought stress.A controlled pot experiment lasting 90 days was conducted with three moisture treatment levels,including mild(40％-50％of the field water holding capacity),moderate(field water holding capacity 30％-40％),and severe(field water holding capacity 20％-30％)drought stress.Quantitative assessments were conducted on carbon allocation patterns,leaf construction costs,gas exchange parameters,and dynamic water relations.Comparative analyses were performed to elucidate the differential responses of contrasting C.oleifera varieties to gradient drought stress,with particular em-phasis on characterizing their adaptive strategies and underlying physiological mechanisms.Under drought stress,2 C.oleifera varieties exhibited differentiated adaptation strategies.Under mild drought conditions,both Xianglin 210 and Changlin 53 can maintain basic growth.However,under the stress of moderate and severe drought,2 varieties showed different response strategies.Under moderate and severe drought stress,Xianglin 210 exhibited a 30.80％-47.40％reduction in plant height,with the most pronounced decrease in ground diameter reaching 82.22％after 30 days of treatment.In contrast,this genotype demonstrated adaptive morphological adjustments,showing signifi-cant increases in root-to-shoot ratio(40.00％-44.30％)and specific leaf area(36.14％-73.80％),which may con-tribute to its drought tolerance mechanism.Under prolonged drought stress,Changlin 53 plants cultivated exhibited significant morphological adjustments,with plant height reduction ranging from 29.78％to 63.06％and maximum basal diameter decrease reaching 66.77％.Notably,this genotype demonstrated dynamic regulation of specific leaf area(SLA)characterized by an initial decline followed by compensatory increase,accompanied by enhanced dry matter accumulation(elevated by up to 31.90％).Physiological responses included rapid stomatal conductance re-duction(34.69％-36.45％decrease within 15 days)and sustained water conservation mechanisms,with cumulative height reduction stabilizing at 61.23％-64.10％after 60 days.Principal component analysis revealed that Changlin 53,in contrast to Xianglin 210,maintains superior homeostasis and phenotypic plasticity under drought stress through coordinated regulation of morphological remodeling and physiological adjustments,suggesting its putative adaptive strategies for improving drought resilience in oil tea plantations.This study elucidated the divergent drought resistance strategies employed by 2 major C.oleifera cultivars.Xianglin 210 demonstrated a"dynamic accli-mation"strategy for coping with episodic drought,characterized by rapid biomass redistribution,plastic leaf mor-phology adjustment,and progressive stomatal conductance modulation.In contrast,Changlin 53 adopted a"homeo-static maintenance"strategy to address prolonged drought,exhibiting intrinsic drought-resistant traits,conservative leaf morphology,and threshold-triggered stomatal closure.This cultivar-specific strategy classification system pro-vides novel insights into the mechanistic basis of drought resilience in C.oleifera,offering theoretical guidance for differentiated breeding programs and regionalized planting schemes.