【作者】 赵勇钢；

【导师】 吴普特； 汪有科；

【作者基本信息】 中国科学院研究生院（教育部水土保持与生态环境研究中心） ， 土壤学， 2011， 博士

【摘要】 水土流失与干旱缺水并存是影响黄土高原地区生态建设和经济可持续发展的关键问题。近10年来,陕北地区大面积种植山地红枣林,在此基础上结合具有节水、增产和生态综合功能的集雨微灌技术已被证明可有效、同步解决该问题。同时,陕北也是我国主要缺硒地区之一。硒是人和动物体内的必需营养元素,可通过施入外源硒经食物链吸收、转化后有效、健康地进行补充。因此,将硒和红枣结合研究对于促进红枣产业发展和人体健康十分重要,但目前关于富硒红枣的吸收机理、品质方面的研究及相应的生产技术标准还很缺乏。本研究针对陕北红枣富硒果品缺乏的生产现状,在调查土壤和红枣背景值的基础上,以外源硒（亚硒酸钠）为供体,以红枣作为硒载体,采用3种方式生产富硒红枣,对枣树的生长发育和品质指标进行测定,分析红枣的富硒效应并探讨其机制,结合不同土壤水分管理措施和施肥处理下的富硒试验,最终初步提出富硒红枣生产规范,达到“节水、增产、生态、优质”的生产模式,以期为相关的理论研究和技术标准制定提供科学依据和实践指导。经连续两年的试验,取得如下主要结果:（1）试验区红枣和土壤硒含量的本底值较低。红枣果实中未测得硒含量,表明枣树可能是非聚硒植物。0⁶0 cm土层全硒含量平均值为73.37μg kg^-1,属低硒环境,且有在0²0 cm土层“表聚型”分布的特征。土地利用方式对土壤中全硒、水溶态硒和有效硒含量有极显著（P < 0.01）影响,表现为人工草地>农地>有灌溉枣树地>无灌溉枣树地,且主要影响0⁴0 cm土层。利用逐步回归法得出影响土壤全硒和水溶态硒含量的主要土壤因子为有机质含量,而影响土壤有效硒含量的主要为有机质含量、pH和阳离子交换量。（2）不同富硒方式和硒肥浓度对枣树中硒的累积与分配有重要影响。以一年生枣树为对象,硒肥由土壤施入后主要在根中累积,而由叶面喷施后主要在叶中累积,且随着施入浓度的增加各器官硒含量呈逐渐增大趋势。以十年生枣树为对象,3种富硒方式均显著（P < 0.05）提高了红枣果实的含硒量,表现为叶面喷施>树干注射施入>土壤施入,随着施入硒肥浓度的增加红枣果实含硒量也增大。在施入总量一致条件下,叶面喷施1次和2次对红枣果实含硒量的影响没有显著差异,但喷施3次时有显著提高。与开花期喷施相比,坐果期喷施可提高果实含硒量1.3¹.7倍。（3）硒对枣树生长表现出两面性:适宜浓度促进枣树生长,但过高浓度则抑制其生长。在试验硒肥浓度内,土壤施入和树干注射施入方式对果实和新枝生长没有显著影响,但叶面喷施方式下适宜浓度对红枣果实纵径、横径、新梢、叶面积生长及叶面积指数、果形指数有显著（P < 0.05）促进作用,过量则产生相反效应,其阈值为300 g ha^-1。土壤施入和树干注射施入硒肥能提高叶片叶绿素含量,而叶面喷施下叶片叶绿素含量随着施硒浓度增加先增加后降低。与之对应,叶面喷施的枣树叶片光合特性也有相似的变化趋势。（4）适宜的富硒方式和硒肥浓度可提高红枣的品质和产量。总体上,在试验硒肥浓度内,随着土壤施入和树干注射硒肥浓度增大,红枣果实营养品质表现出Vc、可溶性固形物、可溶性蛋白和可溶性总糖含量提高,有机酸含量降低的趋势,红枣产量有小幅提高但没有显著性（P > 0.05）差异。而随着叶面喷施硒肥浓度的增加,红枣果实营养品质和产量体现出“两面性”,均表现出先提高后降低的趋势,且变化曲线呈抛物线型。本试验中叶面喷施硒肥300 g ha^-1是提高红枣果实品质的最佳浓度,同时红枣产量达最大值17.70 t ha^-1（2009年）、16.94 t ha^-1（2010年）,比对照提高了14.9%、19.9%。（5）土壤水分管理措施和施肥处理对红枣含硒量、品质和产量有显著影响。对滴灌措施、秸秆覆盖措施和无保墒3种土壤水分管理措施和不同施肥处理的组合研究发现,优化土壤水分环境和肥力可显著提高土壤贮水量,有效增强枣树对硒肥的吸收,从而提高红枣果实营养品质和产量。其中以滴灌措施和N1P3K3组合(尿素0.78 t ha^-1、过磷酸钙3.75 t ha^-1、氯化钾0.81 t ha^-1)配施的处理效果最好,叶片喷施硒肥(300 g ha^-1)后,红枣产量达到20.59 t ha^-1,果实含硒量达到46.97μg kg^-1,此水肥管理措施可作为山地枣树富硒红枣生产的推荐方案。综合上述研究结果,初步提出了《陕北山地富硒枣种植技术规范（草案）》。更多还原

【Abstract】 The simultaneous occurrence of severe water and soil losses and water shortage is a key problem that affects eco-environment construction and sustainable agricultural development on the Loess Plateau. Jujube trees were widely planted in the past decade for its ecological and economical benefits in the hill-gully areas of Northern Shaanxi Province. Applied with the combination techniques of dwarf, close planting and drip irrigation, jujube trees have been proved to be an effectively and simultaneously solution of the problem. At the same time, Northern Shaanxi province belongs to low-Se regions and is also one of the regions with the serious Keshan disease in China. Selenium （Se）, as an essential micronutrient for animal and human health, can be assimilated efficiently and complemented safely via food-chain. Fruit is one of the main sources of Se for humans. If we can produce Se-enriched jujube so as to meet the needs of human’s health, it will be an important way to improve the jujube’s quality and promote the industrial development of jujube. However, few studies were reported in the mechanism of Se uptake, fruit quality and production technique standard of jujube.Based on the investigation of Se background contents in soil and jujube fruit, three methods including soil addition, trunk injection and foliar application were employed with exogenous Se（Na2SeO3）to produce Se-enriched jujubes. To analyse the Se fertilizer effects and mechanism in jujube trees, the growth and development index of jujube were determined under different soil water and fertilizer managements. Finally, integrating the research results above, Se-enriched jujube production technical specification was proposed. Experiments were conducted in two consecutive years and the main conclusions are as follows:（1） Se background contents in jujube fruit and soil in experimental area were low, which indicating that jujube probably is not a Se-accumulator plant. The mean total Se content at 0⁶0 cm soil depth is 73.37μg kg^-1, so the soil belongs to low-Se soil. Se content in soil profile accumulated mostly at 0²0 cm and showed the distribution characteristic of surface accumulation. Land use effected the content of soil total Se, water solute Se and available Se at 0⁴0 cm depth significantly（P < 0.01）, and showed the trend as article grassland > cropland > jujube orchard （irrigated） > jujube orchard （non-irrigated）. Analysis by stepwise regression, the results showed that soil organic matter content was the most important soil factor affecting soil total Se and water solute Se content, and soil organic matter content, pH and CEC were the most important soil factor affecting soil available Se content.（2） Se accumulation and distribution in jujube trees was obviously affected by different Se-enrich methods and Se fertilizer concentrations. As to one year jujube trees, Se mainly accumulated in root after soil addition method, while in leaf after foliar application method. Se content in all the organs of jujube trees was increased generally with the increase of Se fertilizer concentrations. As to ten year jujube trees, three Se-enriched methods increased fruit Se content significantly which appearing foliar application > trunk injection > soil addition, and fruit Se content was enhanced with increase of Se fertilizer concentrations. Under the same Se fertilizer amount, foliar spray once and twice had no significant difference to enhance fruit Se contents, but foliar spray triple had significant effects. Compared with flowering stage, foliar application at fruit set stage increased fruit Se content 1.3¹.7 times.（3） Se displayed dual effects on growth of jujube trees, which can be promoted at or below optimal concentrations, whereas be stunted at higher concentrations. Under the Se fertilizer concentrations used in the trials, soil addition and trunk injection methods had no significant effects on growth of fruit and new shoots. Foliar application method significantly promoted vertical diameter, horizontal diameter of jujube fruit, new shoots, leaf area and leaf area index at optimal Se fertilizer concentration, however, inverse effects were found at higher concentrations. Moreover, as to foliar application method, the threshold value of Se fertilizer is 300 g ha^-1. Chlorophyll content and photosynthetic characteristics of leaves was significantly increased in three Se-enriched methods, but decreased at higher Se fertilizer concentration in foliar application method.（4） Suitable Se-enriched methods and Se fertilizer concentrations can enhance the quality and yield of jujube. With the Se fertilizer concentrations in the trials increased, soil addition and trunk injection methods enhanced fruit quality of fruit vitamin C content, soluble solid content, soluble protein content and soluble total sugar content and decreased organic acid content. Foliar application method also had similar trend when Se concentration not more than 300 g ha^-1, but had inverse effects when Se concentration more than 300 g ha^-1. Soil addition and trunk injection methods increased jujube yield but had no significant difference.（5） Soil water and fertilizer managements affected significantly jujube fruit Se content, quality and yield. Three treatments including non-moisture conserving technology, straw mulch and drip irrigation and different fertilizer treatments enhanced Se uptake of jujube tree by improving soil water storage, and then increase fruit Se content. The integrated management of drip irrigation and N1P3K3 fertilizer (urea 0.78 t ha^-1, calcium superphosphate 3.75 t ha^-1, Potassium Chloride 0.81 t ha^-1) and treatments had better effects. Applying foliar application with Se fertilizer 300 g ha^-1, jujube yield and fruit Se content were 20.59 t ha^-1 and 46.97μg kg^-1, respectively, which can be recommended for Se-enriched jujube production.These results show that Se-enriched jujube can be produced by the technologies above. Therefore,“planting technical specifications of Se-enriched jujube in the Northern Shaanxi Province”was proposed.更多还原