PDF(Pubmed)
Abstract：
Drought and salinity are two abiotic stresses that affect plant productivity. We exposed 2-year-old Platycladus orientalis saplings to single and combined stress of drought and salinity. Subsequently, the responses of physiological traits and soil properties were investigated. Biochemical traits such as leaf and root phytohormone content significantly increased under most stress conditions. Single drought stress resulted in significantly decreased nonstructural carbohydrate (NSC) content in stems and roots, while single salt stress and combined stress resulted in diverse response of NSC content. Xylem water potential of P. orientalis decreased significantly under both single drought and single salt stress, as well as the combined stress. Under the combined stress of drought and severe salt, xylem hydraulic conductivity significantly decreased while NSC content was unaffected, demonstrating that the risk of xylem hydraulic failure may be greater than carbon starvation. The tracheid lumen diameter and the tracheid double wall thickness of root and stem xylem was hardly affected by any stress, except for the stem tracheid lumen diameter, which was significantly increased under the combined stress. Soil ammonium nitrogen, nitrate nitrogen and available potassium content was only significantly affected by single salt stress, while soil available phosphorus content was not affected by any stress. Single drought stress had a stronger effect on the alpha diversity of rhizobacteria communities, and single salt stress had a stronger effect on soil nutrient availability, while combined stress showed relatively limited effect on these soil properties. Regarding physiological traits, responses of P. orientalis saplings under single and combined stress of drought and salt were diverse, and effects of combined stress could not be directly extrapolated from any single stress. Compared to single stress, the effect of combined stress on phytohormone content and hydraulic traits was negative to P. orientalis saplings, while the combined stress offset the negative effects of single drought stress on NSC content. Our study provided more comprehensive information on the response of the physiological traits and soil properties of P. orientalis saplings under single and combined stress of drought and salt, which would be helpful to understand the adapting mechanism of woody plants to abiotic stress.
摘要：
干旱和盐度是影响植物生产力的两种非生物胁迫。我们将2岁的侧柏树苗暴露于干旱和盐分的单一和综合胁迫中。随后，研究了生理性状和土壤特性的响应。在大多数胁迫条件下，叶和根植物激素含量等生化性状显着增加。单一干旱胁迫导致茎和根中非结构性碳水化合物（NSC）含量显着降低，而单一盐胁迫和联合胁迫导致NSC含量的不同响应。在单一干旱和单一盐胁迫下，侧柏木质部水势显著下降，以及综合压力。在干旱和严重盐的共同胁迫下，木质部导水率显著下降，而NSC含量不受影响，表明木质部水力破坏的风险可能大于碳饥饿。根茎木质部管胞腔直径和管胞双壁厚度几乎不受任何应力的影响，除了茎管胞腔直径，在综合应力下显著增加。土壤铵态氮,硝态氮和速效钾含量只受到单一盐胁迫的显著影响,而土壤有效磷含量不受任何胁迫的影响。单一干旱胁迫对根瘤菌群落α多样性有较强的影响，单一盐胁迫对土壤养分有效性的影响更大，而综合应力对这些土壤特性的影响相对有限。关于生理特征，在干旱和盐的单一胁迫和综合胁迫下，侧柏树苗的反应是多样的，联合应力的影响不能直接从任何单一应力中推断出来。与单一压力相比，联合胁迫对植物激素含量和水力性状的影响对东方紫杉树苗是负的，而综合胁迫抵消了单一干旱胁迫对NSC含量的负面影响。我们的研究提供了更全面的信息，说明了在干旱和盐的单一和联合胁迫下，侧柏树苗的生理性状和土壤特性的响应。这将有助于了解木本植物对非生物胁迫的适应机制。
