红叶石楠在干旱胁迫下的生理响应

Physiological Response of Photinia fraseri to Water Stress

以1 a生红叶石楠苗木为材料,设置正常供水75%~80%(占土壤最大持水量的百分数)、轻度胁迫55%~60%、中度胁迫40%~45%、重度胁迫30%~35%4个处理,通过盆栽试验研究干旱胁迫对红叶石楠膜透性与丙二醛含量、净光合速率、蒸腾速率、根系生长特性与活力的影响。结果表明:干旱胁迫程度和作用时间与红叶石楠膜伤害有一定相关性,但对照、轻度、中度胁迫间差异不显著,随着胁迫程度的加重,丙二醛含量呈上升状态,第20 d达峰值,以后处于相对稳定状态;干旱胁迫程度与光合速率下降成正比,但净光合速率在较长时间维持在较高水平,而蒸腾速率日变化呈先升后降的单峰曲线,重度胁迫处理蒸腾速率变化幅度不大,下降趋势不明显;干旱胁迫可抑制红叶石楠主根伸长生长,侧根长度在干旱胁迫时呈增加趋势,重度胁迫〉中度胁迫〉轻度胁迫〉对照,干旱胁迫的加剧,可减少红叶石楠侧根数量,而干旱胁迫程度与根系吸收面积、根系活力成反比,重度胁迫与其他处理差异显著,轻度胁迫、中度胁迫与对照差异不明显,以上指标表明红叶石楠在干旱胁迫下有较强的耐受能力。

The annual seedlings of Photinia fraseri were treated with four treatments including normal water supply（ 75% ~ 80% of soil maximum moisture capacity）,mild stress（ 55% ~ 60%）,moderate stress（ 40% ~ 45%） and severe stress（ 30% ~ 35%）. Through pot experiment,studies were made of the effects of water stress on membrane permeability,MDA content,net photosynthetic rate,transpiration rate,root growth characteristics and activity. The results showed that the degree and time of water stress had certain relativity with membrane permeability. Among control,mild stress and moderate stress,the difference was not significant. Along with the aggravation of stress degree,MDA content would rise and reach the peak in 20 thday,then maintain a stable state. Water stress and photosynthetic rate had positive correlation,and the net photosynthetic rate maintained a high level in a long period. But the transpiration rate presented unimodal curve with rising and then descending,the change of severe stress treatment was not significant,and the downtrend was not obvious. Water stress could inhibit the main root growth with the branch root growing,the order of growth quantities was severe stress moderate stress mild stress the control. The intensification of water stress could reduce the number of branch root,but the degree of water stress was negatively related to root absorption area and root activity. The treatment of severe stress had a significant difference with the others,the treatments of moderate stress and mild stress hadnot significant difference with the control. The analyses above indicated that Photinia fraseri had strong tolerance to water stress.