摘要:针对淡水资源匮乏制约盐碱地改良利用难题，自1982年以来，中国科学院遗传与发育生物学研究所农业资源研究中心在环渤海低平原和滨海平原开展了缺水盐渍区盐碱地改良利用研究与示范工作，取得了以下研究成果：1）研究明确了低平原缺水盐渍区盐碱地改良的浅层地下水埋深调控深度，建立了井灌代排、蓄雨淋盐的盐碱地改良技术模式；2）揭示了咸水结冰融水咸淡水分离在滨海盐土的入渗规律，发明了冬季咸水结冰灌溉改良滨海重盐碱地技术；3）提出了耦合盐碱区土壤水盐运移-气候条件-植物生长发育规律的盐碱地改良思路，建立了微域降盐、秸秆隔盐的盐碱地农艺改良技术模式；4）探讨了盐生植物适应盐渍环境的机理，建立了滨海盐碱地盐渍资源高效利用技术模式。形成了以咸水、雨水、耐盐植物高效利用为核心的工程措施、农艺措施与生物措施相结合的盐碱地改良利用技术体系，为环渤海缺水盐渍区农业发展和生态环境建设提供了科技支撑。
关键词:环渤海/
缺水/
盐碱地/
井灌代排/
微域降盐/
咸水灌溉/
盐生植物
Abstract:Freshwater scarcity is one of the main constraints to the reclamation of saline soils. Research and demonstration studies on the reclamation and utilization of saline soils in water-scarce regions of Bohai Sea started since 1982 in Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences. The experiments had included regulation of shallow groundwater table via well-water irrigation and rainwater recharge, soil salt leaching via saline water irrigation, root-zone soil desalination via agronomic methods and utilization of halophytes. The major achievements were as follows:1) the regulating levels of shallow groundwater table were determined and the patterns of management by well-water irrigation and rainwater leaching to control soil salinization in lowland plains established. Through well-water irrigation, the critical level of shallow groundwater table was kept at >2-3 m during the dry season to reduce soil evaporation and control soil salinization. This was further reduced to 4-6 m before the rains to enhance rainwater recharge and in turn leaching of soil salts and dilution of saline groundwater. Next the groundwater table was kept at >0.5-1.0 m during the rains again to assure healthy crop growth. After the implementation of this method in Changzhuang Town (Nanpi County in Hebei Province) for the period 1983-1988, soil salt content decreased from 3.86 g·kg-1 to 1.36 g·kg-1, and the area of saline Chao soil and saline groundwater dropped by 76.2% and 42.8%, respectively. 2) The separation process of saline water and freshwater by melting saline ice and its infiltration into saline soil were revealed and the method of reclamation of coastal saline soils by freezing saline water in winter invented. Lab experiments showed that saline ice was desalinized efficiently by melting, which produced about 60% low salinity (< 4 g·L-1) water from melting saline ice (< 15 g·L-1). Also the infiltration of saline ice melt-water reduced surface soil salt content. Field experiments indicated that by freezing saline water (< 15 g·L-1) irrigation in winter (< -5℃) combined with plastic film or straw mulching and rainwater leaching improved coastal saline soil. The soil salt content in 0-20 cm was less than 3.0 g·kg-1 during the growing season under freezing saline water irrigation, while it exceeded 10 g·kg-1 under control (no irrigation) treatment. 3) Trough coupling of the dynamics of soil salt and water, climate and plant growth, the agronomic patterns of soil salinization control in the root zone was established via ridging, mulching and straw incorporation into the deep soil layer. In monsoon climate regions, there was soil salinization in spring due to low rainfall and high evaporation, and then soil desalinized in summer due to high rainfall. Seed germination and seedling growth were the salt-sensitive stages, which usually occurred in spring. Therefore, it was important to create low salinity in the root zone for health growth of plant in spring. In order to desalinize the root zone soil, field ridging in spring and straw incorporation in autumn were studied. The results showed that field ridging, combined with plastic film and straw mulching, reduced soil salinity to 2.0 g·kg-1 and straw incorporation into deep soil layer controlled the soil salinity in spring at < 3 g·kg-1. 4) The adaptive mechanisms of halophytes to saline soils were explored and the pattern of efficient utilization of saline resources established. For the utilization of saline soils and saline water, salt tolerant plants and halophytes were collected and screened. The effects of salt stress, combined with those of water and nutrient application, on seed germination and plant growth were studied. The results showed that seed germination required low salinity, moderate salinity alleviated drought stress on seed germination and seedling growth, NO played a very important role in the regulation of salt tolerance of seedlings derived from dimorphic seeds of Centralasiatica atriplex, and N application increased the growth of halophytes under salt stress, etc. Based on the characteristics of salt tolerance of different plants, the method of growing plants in saline soils was established. This included land plowing, holing cultivation, fertilizer application, frozen saline water irrigation, mulching, etc. The application of the above results has supported crop production and ecological rehabilitation of saline soils in water-scarce regions of Bohai Sea.
Key words:Bohai Sea/
Water scarcity/
Saline soil/
Well-water irrigation/
Root-zone soil desalinization/
Saline water irrigation/
Halophyte
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