【作者】 童文杰；

【导师】 陈阜；

【作者基本信息】 中国农业大学 ， 作物栽培学与耕作学， 2014， 博士

【摘要】 土壤盐渍化是制约河套灌区农田高效利用的主要障碍因素,基于作物耐盐性评价的作物种植结构优化与栽培耕作措施优化对该区域盐碱耕地资源利用意义重大。本论文在剖析河套灌区盐碱地利用现状和存在问题的基础上,利用农户地块调查开展了该区域主要农作物耐盐性和盐碱耕地适宜种植区划,并基于田间定位试验探讨了垄作与覆膜技术提高向日葵耐盐性的机理。主要结论如下：(1)河套灌区自20世纪后半叶以来,耕地面积持续扩大,导致受土壤盐渍化耕地面积比例不断提高。尽管1990-2012年河套灌区引黄灌溉量呈显著下降趋势,但年平均积盐高达205万吨。由于节水灌溉工程与农艺节水技术发展,中、重度盐碱耕地占灌区总耕地的比例呈下降趋势。近年来,由于向日葵对盐碱地适宜性强和经济效益相对高,其种植面积快速增加,且连作现象非常普遍,小麦等传统粮食作物种植面积持续下降。(2)通过比较0-10cm、0-20cm和0-40cm土壤ECe值与作物产量相关性大小判断,河套灌区小麦、玉米、向日葵苗期土壤饱和浸提液电导率(ECe)与产量及产量构成因素之间均呈显著负相关关系,以作物苗期0-20cm土壤ECe值作为作物根层盐分来评判作物的耐盐性最有代表性。双指数函数对作物耐盐性的拟合效果优于分段式耐盐函数和S型耐盐函数。河套灌区小麦、玉米的耐盐等级为中度敏感型,向日葵耐盐等级为中度耐盐型。小麦、玉米、向日葵的耐盐指数分别为7.442、8.986和12.967,其相应的苗期0-20cm土壤ECe值如控制在3.893、3.778、4.919dS·m-1以下,可以保障作物相对产量不低于88.3%。(3)根据河套灌区作物双指数耐盐函数分析结果,以作物相对产量降低幅度小于10%、10%-25%、25%～50%和大于50%作为划分依据,作为盐碱地作物种植的最适宜区、适宜区、次适宜区和不适宜区。选择河套灌区五原县和平村的575个地块进行适宜区划分,基于耐盐函数和相对产量的适宜区区划结果与实际调查结果基本吻合；在此基础上,本文也结合经济效益、生态效益、社会效益等指标对和平村的作物结构进行了优化分析。(4)垄作覆膜种植模式能有效增强向日葵耐盐性,该模式与垄作不覆盖及垄作覆盖秸秆相比,能有效降低向日葵耕层土壤盐分含量和减小盐分变异系数,生育期间根层0-20cm土壤含盐量受降水洗淋和蒸发返盐的影响呈波浪式动态变化。同时,垄作覆膜明显增加向日葵体内K+、脯氨酸、SOD等抗逆调节物质含量,有效提高盐碱地向日葵耐盐性和产量。更多还原

【Abstract】 Root zone soil salinity is the major abiotic factors that restrict efficient utilization of the farmland in Hetao Irrigation District. It is important to optimize cropping system for land use based on crop salt tolerance. This paper investigated current situation of saline land and carried out crop salt tolerance analysis and salinity ecological zoning at farmland level. The mechanism of ridge system with plastic film mulching which enhances sunflower’s salt tolerance was investigated in a field experiment located in Hetao Irrigation District. The main conclusions were as follows:(1) The arable land in Hetao Irrigation District continually expanded which led to the increasing the proportion of saline land in the arable land. Even though the irrigation amount from the Yellow River presented a downward trend from1990to2012, the yearly mean accumulated salt reached about2.05million tons. As the development of water-saving irrigation engineering and agronomical water-saving technology, the proportion of moderate saline land and strongly saline land in the arable land was on the decline. In recent years the ecological-economic adaptability of sunflower was better than of the other main crops in Hetao Irrigation District. Therefore, the planting acreage of sunflower increased rapidly and sunflower continuous cropping was of common occurrence. The planting area of wheat and other traditional food crops showed a downward trend due to the predominance of sunflower.(2) There was a significant negative correlation between the conductivity of soil saturation extracts (ECe) and the theoretical yield as well as yield components of wheat, corn and sunflower in Hetao Irrigation District. According to the correlation coefficients between crop yield and ECe of0-10cm,0-20cm and0-40cm soil layer, ECe of0-20cm soil layer at crop seedling stage was the most representative as the root-zone salinity for crop salt tolerance analysis. The bi-exponential function had the best (close) fit to the test data than both modified discount function and three-piece linear function. Both wheat and corn were moderately sensitive to salinity, while sunflower was moderately tolerant. The salinity tolerance index of wheat, corn and sunflower were7.442,8.986and12.967, respectively. Therefore, in order to prevent yield of wheat, corn and sunflower from rapidly declining, the ECe of0-20cm soil layer should be under3.893,3.778,4.919dS·m-1, respectively. In this instance, the relative yield will be above of0.883.(3) According to the bi-exponential functions for different crops salt tolerance, the arable land in Heping Village was characterized into four salinity ecological adaptability zones:the most suitable region in which crop relative yield reaching or exceeding90%, suitable region in which crop relative yield is between75%and90%, sub-suitable region in which crop relative yield is between50%and75%and unsuitable region in which crop relative yield is lower than50%. The results of crop salinity ecological zoning were mainly consistent with the actual crop distribution. The cropping system of Heping Village was optimized based on the results of crop salt tolerance and ecological zoning.(4) The cropping pattern of ridge system with plastic film mulching could efficiently enhance sunflower salt tolerance. In comparison with the other cropping patterns of ridge system with no mulching and ridge system with straw mulching, the ridge system with plastic film mulching significantly reduced the root zone salinity and the coefficient of variation of salt content. Soil salinity of sunflower in0-20cm root zone changed all the time with the dynamics of precipitation and evaporation. Compared to flat normal system with plastic film mulching, ridge system with plastic film mulching could significantly increase the soil temperature and decrease soil density. In addition, the ridge system with plastic film mulching could also improve the content of K+, proline and SOD in the sunflower. Finally, the cropping pattern of ridge system with plastic film mulching improved sunflower growth and increased the yield.更多还原