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茶园土壤水分有效性及抗旱调控研究进展

Water Availability of Soil and Drought Management for Tea Plantations – A Review

  • 摘要: 针对茶园土壤含水量难以表征茶树实际可利用水分的问题,本文以“水分输入-储存与释放-根区传输与吸收-植株响应与供需匹配-过程调控”为框架,界定土壤含水量、潜在有效水容量与根区动态供水能力的层级关系,综述降雨入渗、剖面再分布、非饱和传输、根际水力阻力、根系垂直分布及坡地水分异质性对根区供水的影响,分析其与茶树水势、气孔、光合及产量品质响应的关系。现有证据表明,覆盖、根区改良与精准灌溉可通过影响降雨入渗、根区储存与水分传输以及供水时机和湿润深度等过程改善根区供水;但根际水力阻力、补偿吸水、中深层水利用和地下侧向流在茶园中的定量贡献仍不明确。未来需加强土壤-根系-植株-大气同步观测,建立具有明确生物学终点的多维水分胁迫阈值体系和标准化水力参数数据库,并以独立观测校验过程模型,推动茶园抗旱管理由静态水量评价转向限制环节诊断与根区动态供水调控。

     

    Abstract: Content of water in soil per se does not equate the actual available amount of moisture for the tea plants grown on the land. What counts is the quantity of water that can be properly stored and released from the soil for transporting and absorbing by the roots of the plants at a rate meeting the demand of the canopy. In other words, as far as availability is concerned, seamless matching of the “storage–release–transport–uptake–supply–demand” of water in soil is the key to the usefulness of it. Thus, to thoroughly analyze and understand the critical issue in tea cultivation this article summarizes the effects of rainfall infiltration, water redistribution profile, unsaturated water transporting, root system structure, and heterogenic property of hillslope water on the dynamic water supply in rhizosphere as well as their relationships with the water status, stomatal regulation, photosynthesis, yield, and quality of the plants. Approaches for efficient water management, such as surface mulching, rhizosphere improvement, precision irrigation, utilization of middle- and deep-layer water, integrated monitoring, and multi-facet modelling, are reviewed. At present, quantified rhizosphere hydraulic resistance, compensatory water uptake of roots, deep-water utilization, and subsurface lateral flow remain insufficiently available. It would foster further progress in research if studies focusing coordinated observations on soil, roots, and plants as well as establishments of water-stress thresholds, standardized soil hydraulic parameter databases, and process-based rhizosphere water supply regulation are conducted in the future.

     

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