基于GIS的南方根结线虫在陕西省越冬区划分析

Abstract

土壤温度是影响南方根结线虫（<em>Meloidogyne incognita</em>）越冬的重要因子。通过自动温度记录仪，从2009-2012年的每年冬季（11月至次年3月），对陕西省延安、商洛、杨凌和大荔4个生态区的气温和不同种植模式下的土壤温度进行数据采集和模拟统计，建立土温与气温关系的数学模型，根据模型将陕西省96个气象站点的气温数据转换为土温数据。利用GIS的克里金（Kriging）空间插值功能，结合实验室测得的南方根结线虫存活的最低温度，生成南方根结线虫在拱棚、地膜覆盖和露地3种种植条件下的越冬区划图并进行分析。研究表明，（1）0℃以下低温对南方根结线虫有明显抑制作用，南方根结线虫在低于-1℃低温持续32 d以上时无法越冬。（2）土壤温度和气温呈线性相关关系，4种种植条件下土壤温度（<em>Y</em>）与气温（<em>X</em>）的关系方程分别为露地：<em>Y</em>=0.8125<em>X</em>+1.9325，<em>R</em>=0.934；地膜覆盖：<em>Y</em>=0.7943<em>X</em>+1.8563，<em>R</em>=0.918；拱棚：<em>Y</em>=0.7046<em>X</em>+6.2685，<em>R</em>=0.907；温室：<em>Y</em>=0.302<em>X</em>+14.519，<em>R</em>=0.597。（3）最冷月土壤均温低于-1℃的概率在70%-80%的区域可以认为是南方根结线虫的越冬界线，越冬界线在露地、地膜覆盖和拱棚条件下依次北移，在温室条件下可在全省范围内越冬。;Southern root-knot nematode, <em>Meloidogyne incognita,</em> is an important pathogen of vegetables, and was first observed in South China. With the development of indoor agricultural facilities, it was found for the first time in Shaanxi in 2000, and now is widely distributed through different ecological vegetable growing zones in Northern and Southern Shaanxi, and the Guanzhong area. <em>M. incognita</em> has become a devastating soil-borne disease, causing great economic losses in vegetable production. It survives at soil depths of 5 to 15 cm, and overwinters in the soil as eggs or second instar larvae. Soil temperature is an important factor affecting its overwintering, and this is dependent on climate and plant conditions. Air and soil temperature data for open fields can be obtained from meteorological stations, but soil temperature data for indoor agricultural facilities is not available, and thus mathematical models need to be established to simulate soil temperatures under different cultivation conditions. Each winter (November to the following March) from 2009 to 2012, air and soil temperatures in four agricultural systems in four ecological regions (Yanan, Shangluo, Yangling, and Dali) in Shaanxi Province were automatically recorded. Mathematical models relating air temperature to soil temperature were then developed, and air temperatures from 96 meteorological stations were converted to soil temperatures. Based on the lowest survival temperature of <em>M. incognita</em> measured in the laboratory, a regional map of nematode overwintering was developed, and analyzed for different planting conditions using the Kriging Interpolation of GIS. We found the following: (1) Overwintering of <em>M. incognita</em> was significantly restricted below 0℃. If the temperature was less than -1℃ over 32 days, the nematode was not able to overwinter. (2) The relationship between soil temperature and air temperature is linear. We used the following relationship equations between soil temperature (<em>Y</em>) and air temperature (<em>X</em>) in four planting conditions: <em>Y</em>=0.8125<em>X</em>+1.9325, <em>R</em>=0.934 (open field); <em>Y</em>=0.7943<em>X</em>+1.8563, <em>R</em>=0.918 (mulched field); <em>Y</em>=0.7046<em>X</em>+6.2685, <em>R</em>=0.907 (plastic tunnel house); <em>Y</em>=0.302<em>X</em>+14.519, <em>R</em>=0.597 (greenhouse). (3) The areas where P values are between 70% and 80% (probability of the average soil temperature of the coldest month being less than -1℃) could be considered the overwintering boundary line for <em>M. incognita.</em> The order of different planting conditions from south to north is: open field, mulched field, and plastic tunnel house. In open fields, the north boundary is through Linyou-Yongshou-Chunhua-Yaozhou-Tongchuan-Baishui-Chengcheng-Hancheng; in mulched fields, the boundary is through Binxian-Xunyi-Yijun-Luochuan-Huanglong-Yichuan; and in plastic tunnel houses is Zhidan-Ganquan-Ansai-Yanan-Yanchuan-Qingjian. However, in greenhouse conditions the nematode can overwinter throughout the whole province. Using GIS and geostatistics methods, we have analyzed the northern boundaries of <em>M. incognita</em> overwintering sites and provided regional classification for open fields, mulched fields, plastic tunnel houses, and greenhouses. Our work makes clear the response of the nematode to low temperature stress, so that rapid and effective monitoring as well as theoretical and technical support for prevention and control can be developed in Shaanxi Province.