水分胁迫对仁用杏苗期光合生理和生物量积累的影响

The Responses of Photosynthetic Physiology and Biomass Accumulation of Sweet Kernel-apricot(Prunus armeniaca×sibirica) Seedling to Soil Water Stress

为探讨不同水分胁迫强度对仁用杏苗期光合生理变化、生物量积累的影响,以2年生甜仁杏品种‘中仁1号’为试验材料,采用盆栽控水试验,经6个土壤含水量[土壤质量含水量（15.0±0.5）%（T1,对照）、（13.0±0.5%）（T2）、（11.0±0.5）%（T3）、（9.0±0.5）%（T4）、（7.0±0.5%）（T5）和（5.0±0.5）%（T6）]处理后,测定并分析‘中仁1号’的光合生理参数和生物量变化。研究结果表明：‘中仁1号’幼苗叶片随水分胁迫的加重,净光合速率（Pn）、蒸腾速率（Tr）、胞间CO2浓度（Ci）、气孔导度（Gs）逐渐降低,在13.0%（T2）时有最大值,而水分瞬时利用效率（WUE）在土壤含水量（8.0±0.5）%（T4）时达到最大;‘中仁1号’净光合速率的日变化曲线均为单峰型曲线,无光合＂午休＂点,并且随干旱胁迫的加剧,最大净光合效率（Pnmax）、光饱和点（LSP）逐渐减小,在13.0%（T2）时有最大值,而光补偿点（LCP）、表观量子羧化效率（AQY）则逐渐增加。PSⅡ最大光化学效率（Fv/Fm）、最大荧光（Fm）、表观光合电子传递速率（ETR）和光化学猝灭系数（q P）随着水分胁迫的加剧逐渐降低,在13.0%（T2）时有最大值,但非光化学猝灭系数（q N）逐渐上升,最小荧光（Fo）先上升后逐渐下降。‘中仁1号’的株高、地径、主根长和根系总长度以及各个生物量指标均在13.0%（T2）时有最大值,之后随干旱胁迫的加剧逐渐降低,而根冠比却逐渐上升。‘中仁1号’苗期生长的土壤水分适应范围为9.0%-15.0%,最适含水量为13.0%,下限为5.0%左右。

In order to explore the impacts of drought stress on the photosynthetic physiology and biomass accumulation of sweet kernel-apricot（ Prunus armeniaca ×sibirica） seedlings, and further to better understand the influence mechanism of drought stress on the seedling growth and development. 2-year-old seedlings of cultivar P.armeniaca ‘Zhongren No. 1＇ were used in this paper. Soil moisture content was artificially controlled in ratio as follows：（ 15.0 ±0.5）%（ T1, CK）,（ 13.0 ±0.5）%（ T2）,（ 11.0 ±0.5）%（ T3）,（ 9.0 ±0.5）%（ T4）,（ 7.0 ±0.5）%（ T5） and（ 5.0 ±0.5）%（ T6）. The results showed that the net photosynthetic rate（ Pn）, transpiration rate（ Tr）, stomatal conductance（ Gs） and Intercellular CO2 concentration dropped gradually in the leaves of ‘ Zhongren No. 1＇ with the moisture content decreasing and reached maximum at 13.0%（ T2）, while the water use efficiency（ WUE）reached maximum under（8.0±0.5）%（T4）. The diurnal variation curve of ‘Zhongren No. 1＇ showed a single apex type except under（ 4.0 ±0.5）%（ T6）, which had no photosynthesis ‘ nap＇ point. The maximum net photosynthetic efficiency（ Pnmax）, Light saturation point（ LSP） gradually decreased and reached maximum at 13.0%（ T2）, whilelight compensation point（LCP） and apparent quantum efficiency（AQY） increased along with water stress intensified.PSII maximum quantum yield（ Fv/Fm）, maximum fluorescence（ Fm）, apparent photosynthetic electron transport rate（ ETR） and coefficient of photochemical quenching（ q P） all went down along with water stress strengthened and reached maximum at 13.0%（ T2）. However, the coefficient of photochemical quenching（q N） gradually increased and minimum fluorescence（Fo） firstly increased and then declined. As the soil moisture decreased, the basal diameter,tap root length, total length of root and biomass all declined and reached maximum at 13.0%（ T2）, while root-shoot ratio opposite. Our results suggested that 9.0% -15.0% would be the suitable moisture content and 13.0%would be the optimum moisture content. At the same time, the minimum moisture content in soil for P. armeniaca‘Zhongren No. 1＇ seedlings keeping alive would not be less than 5.0%.