苗期甜菜根系分泌物的分布特征研究

根系分泌物的量及分布特征直接影响着根际微生物的种群、结构和功能,进而间接影响着根际养分的有效性和作物的生长。本研究通过砂培盆栽培养,收集得到甜菜苗期的根系分泌物,利用高效液相色谱测定了根系分泌物中的3大类物质,包括土壤中常见的17种氨基酸、10种有机酸和4种糖类物质,并分析得到了到甜菜根表面不同距离的各种氨基酸、有机酸和糖类物质的含量及其分布特征。结果表明：总的来看,有机氮高效品种‘KWS8138’根系分泌物含量普遍高于有机氮低效品种‘Beta176’,距离根表面0~5 mm范围内降幅较大,随后逐渐趋于平缓。总氨基酸含量、甘氨酸、丙氨酸、丝氨酸、精氨酸和酪氨酸变化趋势相似。各种糖类物质的含量变化顺序为：葡萄糖>果糖>蔗糖>半乳糖。有机酸中草酸和甲酸的含量变化也是距离根表面越远越低缓。因此,沿甜菜根表面形成了根系分泌物的分布梯度,在为根际微生物提供能源和碳源的同时,对植物根际养分的有效吸收利用提供理论参考。

Distribution Characteristics of Beet Root Exudates in Seedling Stage

The content and distribution of root exudates directly affect the population, structure and function of rhizosphere microorganisms, which indirectly affect the availability of rhizosphere nutrients and crop growth. In this study, the root exudates of sugar beet seedlings were collected and cultured in a sand culture basin. The three major types of root exudates were measured by high performance liquid chromatography, including the common 17 amino acids, 10 organic acids and 4 saccharides in soil. The contents and distribution of amino acids, organic acids and saccharides were analyzed at different distances from the surface of the beet root. The results showed that: in general, the content of root exudates from the organic nitrogen efficient variety ‘KWS8138’ was higher than that from the organic nitrogen inefficient variety ‘Beta176’, which decreased greatly from 0 to 5 mm from the root surface, and then gradually became flat. The total amino acid content, glycine, alanine, serine, arginine and tyrosine showed similar trends. The order of saccharides content was: glucose>fructose>sucrose>galactose. The content changing trend of oxalic acid and formic acid in the organic acid was that the farther away from the root surface, the lower and slower it was. Therefore, the distribution gradient of root exudates was formed along the surface of beet roots, which provided energy and carbon sources for rhizosphere microorganisms. The study could be a theoretical reference for the effective absorption and utilization of plant rhizosphere nutrients.