盐碱胁迫对文冠果幼苗水力学特征和碳素分配的影响

以文冠果(Xanthoceras sorbifolia)1年生幼苗为研究对象,通过控制条件下的盆栽试验,研究不同盐碱胁迫条件对文冠果幼苗的水力学特征和碳素分配的影响。结果表明:(1)盐碱胁迫显著降低文冠幼苗存活率、株高和基径、不同部位生物量、凌晨水势、根水力学导度、光合速率和气孔导度;(2)随盐碱胁迫强度增加,植株各部位非结构碳含量均先升后降,且碱性盐胁迫对植株的伤害显著大于中性盐胁迫和混合盐碱胁迫,盐度和pH有显著的交互增强效应,碱性盐比例增加会加重胁迫危害;(3)盐碱胁迫显著限制幼苗根系吸水能力、植株水分状况恶化、气孔导度和光合速率下降,造成生物量和非结构碳含量降低,超出植株对低渗透胁迫的适应能力,最终影响植株存活;(4)文冠果具有一定的耐盐碱胁迫能力,在轻度盐碱条件下能正常生长,在中度和重度盐碱胁迫条件下生长和存活能力受限。通过研究进一步揭示了文冠果幼苗在水力结构和碳代谢上对不同类型和强度盐碱胁迫的生理响应模式,可为文冠果适宜立地选择、栽培范围扩展和规模化发展提供依据。

Effects of Saline-alkali Stress on Hydraulic Characteristic and Carbon Allocation in Xanthoceras sorbifolia Seedling

Saline-alkali stress is one of the significant abiotic stresses affecting plant growth worldwide. However, the adaptive capacity and physiological response mechanism of Xanthoceras sorbifolia to saline-alkali stress are still poorly understood. In this study, 1-year-old Xanthoceras sorbifolia seedlings were used. We aimed to explore the adaptability of the seedlings to saline-alkali stress, and to reveal the physiological response of hydraulic structure and carbon metabolism of the seedlings to different salinity-alkali stresses. The results showed that:(1) Saline-alkali stress significantly reduced survival rate, plant height, basal diameter, biomass of different parts, predawn water potential, root hydraulic conductivity, photosynthetic rate and stomatal conductance of the seedlings. (2) Along with the increase of saline-alkali stress degree, the contents of NSC in roots, stems and leaves increased first and then decreased. Moreover, the damage degree of saline-alkali stress was significantly higher than that of neutral salt, mirrored as lower survival rate, smaller biomass, lower water potential, root hydraulic conductivity and photosynthetic rate. (3) Saline-alkali stress limited the water absorption ability of root system, and affected the water status of plants, then influenced plant growth and NSC accumulation, even plant survival. The effect of saline-alkali stress was more severe than that of neutral salt. (4) Xanthoceras sorbifolia could adapt to mild saline-alkali environment, while moderate and severe saline-alkali stress would have a great influence on its growth and survival. The physiological response of the seedlings to different types and degrees of saline-alkali stress in terms of water structure and carbon metabolism could provide a basis for the site selection, cultivation range expansion and large-scale development of the Xanthoceras sorbifolia.