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美洲黑杨(Populus deltoides)是长江中下游及江淮平原重要的造林树种,目前广泛栽培的美洲黑杨既有雄株品系,也有雌株品系。为了解镉(Cd)胁迫条件下美洲黑杨雌、雄株的耐受性差异,采用盆栽实验,研究Cd污染(10 mg·kg–1)条件下美洲黑杨雌、雄株气体交换速率、CO_2响应曲线、叶绿素荧光参数、渗透调节能力、激素含量的响应特征,以及接种丛枝菌根真菌(Rhizophagus intraradices)对受Cd胁迫美洲黑杨雌、雄株的生理效应。结果表明:(1)Cd胁迫下,美洲黑杨雌、雄株净光合速率、气孔导度、胞间CO_2浓度、蒸腾速率、光系统II(PSII)最大光化学量子产量、PSII有效光化学量子产量、光化学淬灭系数、最大羧化速率、最大电子传递速率、磷酸丙糖利用速率均不同程度降低,雌株的下降幅度更大,接种丛枝菌根真菌的雌株的以上参数有了不同程度的恢复,但对雄株没有明显影响;(2)Cd胁迫下,美洲黑杨雌雄株的脯氨酸含量均显著增加,接种丛枝菌根真菌进一步提高了雌株的脯氨酸含量;(3)Cd胁迫下,美洲黑杨雌、雄株叶片生长素含量下降,脱落酸含量增加,雌株的变化幅度更大,接种丛枝菌根真菌有利于恢复雌株激素的平衡。由此可见,与雄株相比,Cd胁迫对美洲黑杨雌株气体交换速率和碳固定能力的负面影响更大,植株光合机构受损更严重,激素平衡更易受到影响,表现出更弱的胁迫耐受性;接种丛枝菌根真菌有利于增强美洲黑杨雌株的渗透调节能力并在一定程度上恢复雌株的固碳能力和激素平衡,但菌根对雄株的效应并不显著。
Populus deltoides is an important afforestation species in the middle and lower reaches of Yangtze River and the Jianghuai Plain. At present, Populus deltoides has both male and female strains widely cultivated. In order to understand the tolerance of female and male plants under the stress of cadmium (Cd), the pot experiment was conducted to study the gas exchange rate of male and female plants under Cd pollution (10 mg · kg -1) CO_2 response curve, chlorophyll fluorescence parameters, osmoregulation ability and hormone content, as well as the physiological effects of inoculating arbuscular mycorrhizal fungi (Rhizophagus intraradices) on female and male plants exposed to Cd stress. The results showed as follows: (1) Under Cd stress, net photosynthetic rate, stomatal conductance, intercellular CO 2 concentration, transpiration rate, maximum photochemical quantum yield of PSII, PSII effective photochemical quantum yield, The photochemical quenching coefficient, the maximum carboxylation rate, the maximum electron transfer rate and the utilization rate of triosephosphate all decreased to a lesser extent, and the decline of the female plants was larger. The above parameters of the female plants inoculated with arbuscular mycorrhizal fungi had different degrees of (2) Under Cd stress, the proline contents of male and female Populus tomentosa populations increased significantly. Inoculation of arbuscular mycorrhizal fungi further increased the proline content of female plants; (3) Under cadmium stress, the content of auxin in the leaves of male and female plants decreased, the content of abscisic acid increased, and the change range of female plants was greater. The inoculation of arbuscular mycorrhizal fungi could restore the balance of female plant hormones. Thus, compared with male plants, Cd stress had a greater negative impact on the gas exchange rate and carbon fixation ability of the female Populus breaupeauensis. The photosynthetic apparatus of the plants suffered more serious damage and the hormone balance was more easily affected, showing a weaker Inoculation with AM fungi could enhance osmotic adjustment of female plants and restore the carbon sequestration and hormone balance of female plants to some extent, but mycorrhizal effect on male plants was not significant .