【作者】 耿贵；

【导师】 汪景宽；

【作者基本信息】 沈阳农业大学 ， 土壤学， 2011， 博士

【摘要】 作物根际分泌物是新兴的研究热点,土壤肥力是古老而且始终研究的重要课题。作物根际分泌物对土壤,尤其是根际土壤肥力有重要影响。本论文重点研究作物根系分泌物对土壤碳、氮组分及含量、微生物数量和酶活性的影响。试验材料选用玉米、大豆、甜菜三种作物及其根系分泌物,以及位于哈尔滨市的中国农业科学院甜菜研究所试验地的黑土。首先利用水浸提法提取玉米、大豆、甜菜根系分泌物,随即对提取的根系分泌物利用旋转蒸发仪浓缩和制备,并对根系分泌物浓缩液中碳、氮含量和主要成分进行分析测定；然后研究根系分泌物对土壤碳、氮组分与含量、土壤微生物数量以及一些酶活性的影响,获得了以下试验结果：1.采用水浸提法可获得到作物根系分泌物。玉米、甜菜、大豆根系分泌物浓缩液碳、氮总含量分别为554.415、292.488、347.766和98.249、64.164、73.074μg/mL;玉米、甜菜、大豆根系分泌碳、氮速率分别为9.1007、5.7722、5.6177μg/rfw-g-h和1.6127、1.2663、1.1807μg/rfw·g·h。检测发现甜菜根系分泌草酸、丙二酸、苹果酸、乙酸、琥珀酸五种有机酸,总有机酸分泌量0.02999 mg/rfw·g·h;分泌Asp、Gln、Lsy三种氨基酸,总氨基酸分泌量0.2573 mg/rfw·g·h;分泌蔗糖量0.01573 mg/rfw·g·h。检测发现玉米根系分泌草酸、丙二酸、酒石酸、苹果酸、乙酸、富马酸、琥珀酸七种有机酸,总有机酸分泌量0.03865mg/rfw·g·h;分泌Asp、Glu、Ser、Arg、Trp、Phe、Leu和Lsy八种氨基酸,总氨基酸分泌量0.3628 mg/rfw·g·h;分泌蔗糖量0.00697mg/rfw·g·h。检测发现大豆根系分泌草酸、丙二酸、苹果酸三种有机酸,总有机酸分泌量0.01353 mg/rfw·g·h;分泌Asp、Asn、Arg、ALa、Met、Val、Trp、Phe、Leu、Lsy十种氨基酸,总氨基酸分泌量0.6013 mg/rfw·g·h,分泌蔗糖量0.01620 mg/rfw·g·h。2.三种作物(玉米、大豆和甜菜)的根系分泌物未明显提高土壤有机质含量,但提高土壤呼吸、微生物量碳和水溶性碳数量。试验结果表明三种作物根系分泌物提高土壤呼吸释放二氧化碳量,分别为23.4%、19.7%和20.8%；提高土壤微生物量碳含量,分别为43.6%、10.9%和9.3%；提高土壤水溶性碳含量,分别为35.8%、34.4%和58.5%。因此,三种作物的根系分泌物加到土壤后土壤活性有机碳含量明显提高。3.玉米、大豆和甜菜根系分泌物对土壤全氮含量作用不明显,但是均提高土壤微生物量氮(分别为180.1%、78.3%和40.7%)、土壤水溶性全氮(分别为46.4%、39.5%和12.3%)、土壤水溶性无机氮(分别为1150.7%、238.8%和113.8%)、土壤水溶性有机氮(分别为7.5%、32.4%和8.8%)和土壤交换性无机氮含量(分别为19.8%、61.3%和53.5%)。作物根系分泌物提高了土壤氮素供给能力,玉米根系分泌物提高的作用最大,其次为大豆,甜菜作用最小4.甜菜、玉米、大豆三种作物根系分泌物均增加了微生物数量,增加量最大的是土壤真菌量,而对土壤细菌和放线菌数量的增加程度相近。5.不同作物根系分泌物对土壤磷酸酶、脲酶、蔗糖酶和过氧化氢酶活性影响不同。加入玉米根系分泌物后磷酸酶活性提高3%,加入大豆根系分泌物后磷酸酶活性几乎无变化(降低1%),而加入甜菜根系分泌物后磷酸酶活性反而降低7%。大豆根系分泌物对土壤脲酶活性的影响最大(提高9%),可能是大豆根系与根瘤菌共生固氮的作用导致的。玉米根系分泌物(提高3%)、甜菜根系分泌物(提高1%)对土壤脲酶活性影响较小。甜菜根系分泌物提高土壤蔗糖酶的活性幅度最大(提高37%),其次是大豆根系分泌物(提高17.9%)和玉米根系分泌物(提高10.4%)。加入甜菜根系分泌物后过氧化氢酶活性提高10.6%,玉米根系分泌物使过氧化氢酶活性提高4.8%,而大豆根系分泌物的添加反而使过氧化氢酶活性降低5.9%。本试验结果证明了甜菜、玉米、大豆根系分泌物富含有氨基酸、有机酸、糖分等营养物质,补充或增加了土壤尤其是根际土壤的活性碳、氮,提高了细菌、真菌、放线菌数量,影响了土壤碳、氮代谢和酶活性。但是甜菜、玉米、大豆根系分泌物三者作用差异较大。因此,现代农业应重视作物根系分泌物对土壤肥力的影响,合理轮作作物,进而持续稳定提高土壤肥力和作物产量。更多还原

【Abstract】 The main objective of this study was to evaluate the effect of root exudates in three different crops (maize, soyb soybean, sugar beet) on soil carbon and nitrogen fraction and content, the number of microorganisms and enzymes activity. Soil sample was taken from black soil experimental field at Sugar Beet Reaserch Insititute of Chinese Academy of Agricultural Sciences in Harbin, Heilongjiang Province. Firstly, root exudates of maize, soybean, sugar beet were extracted by water. Then the extraction of root exudates was concentrated by rotary evaporation apparatus and the contents of carbon, nitrogen and their main fractions were analysed in root concentrated exudates. Finally, it was evaluated that the effect of root exudates on soil carbon and nitrogen fractions and content, the number of microorganism and enzyme activity.1 Aqueous extraction was available to the crop root exudates. Total carbon concentration was 554.415,292.448 and 347.766μg/mL and total nitrogen concentration was 98.249, 64.164 and 73.074μg/mL for maize, sugar beet, soybean root exudates, respectively. The secretion rate of total carbon was 9.1007,5.7722 and 5.6177μg/rfw·g·h, that of total nitrogen was 1.6127,1.2663 and 1.1807μg/rfw·g·h, for maize, sugar beet, soybean root exudates, respectively. The total content of organic acid was 0.02999 mg/rfw·g·h which contained mainly oxalic acid, malonic acid, malic acid, acetic acid, succinic acid in sugar beet root exudates. The composition of total composition of amino acid, whose content was 0.2573 mg/rfw·g·h, was Asp, Gln, Lsy amino acids, and the amount of sucrose was 0.01573 mg/rfw·g·h in sugar beet root exudates. Oxalic acid, malonate, tartaric acid, malic acid, acetic acid, fumaric acid, succinic acid were found, and total amount of organic acid 0.03865 mg/rfw·g·h; Asp, Glu, Ser, Arg, Trp, Phe, Leu amino acids were found, and total amount of amino acid 0.3628 mg/rfw·g·h; amount of sucrose 0.00697 mg/rfw·g·h were detected in maize root exudates. Oxalic acid, malonic acid, malic acid were found, and total amount of organic acid 0.01353 mg/rfw·g·h; Asp、As、Arg、ALa、Met、Val、Trp、Phe、Leu、Lsy amino acids were found, and total amount of amino acid 0.6013 mg/rfw·g·h; amount of sucrose 0.01620 mg/rfw·g·h were detected in soybean root exudates.2 After maize, soybeans and sugar beet root exudates were added to the soil, soil organic matter content did not substantially increase. The content of CO2 from soil respiration was obviously increased 23.4%、19.7% and 20.8% for maize, soybeans and sugar beet root exudates compared to the control, respectively. Microbial biomass C content of soil was apparently increased 43.6%、10.9% and 9.3%, and soluble organic C content increased 35.8%、34.4% and 58.5% for maize, soybeans and sugar beet root exudates compared to the control, respectively. Thus three crops root exudates added to the soil significantly improved soil active organic carbon content.3 The root exudates of maize, soybeans and sugar beet added to the soil did not substantially increase soil total N content. The content of microbial biomass N distinctly increased 180.1%,78.3% and 40.7%, that of soluble total N content increased 46.4%,39.5% and 12.3%, that of soluble inorganic N increased 1150.7%,238.8% and 113.8%, that of soluble organic N content of soil increased 7.5%、32.4% and 8.8%, and that of exchange inorganic N increased 19.8%、61.3% and 53.5% for maize, soybeans and sugar beet root exudates compared to the control, respectively. Thus crop root exudates improved soil nitrogen supply capacity, which of maize is the best, followed by of soybean, sugar beet.4 Root exudates of sugar beet, corn, soybean crops have increased microbial populations, the maximum amount increased was the amount of soil fungi, and the increase was similar in the number of degrees to the bacteria and actinomycetes in the soil.5 The influence of different crop root exudates on soil phosphatases, urease, invertase and catalase activity in soil were different. After added maize, soybean and sugar beet root exudates, soil phosphatase activity increased 3%, almost unchanged (down 1%) and reduced 7% respectively. After added soybean, sugar beet and maize root exudates, soil urase activity increased 9%,3% and 1% respectively. After added sugar beet, soybean and maize root exudates, soil invertase activity increased 37%,17.9% and 10.4% respectively. After added sugar beet, maize and soybean root exudates, soil catalase activity increased 10.6%,4.8% and reduced 5.9% respectively.The results demonstrated that sugar beet, maize, soybean root exudates were rich with amino acids, organic acids, sugar and other nutrients, increasing content of active C, N and quantity of bacterium, actinomycetes and fungi in soil, influencing soil phosphatases, urease, invertase and catalase activity. But the effect of sugar beet, maize, soybean root exudates on these were very different. Therefore, we should pay attention to the crop root exudates on soil fertility, making good crop rotation, thereby improving soil fertility and crop yields steadily.更多还原