【摘要】 土壤中除无机氮外,有机态氮也是植物生长发育的重要营养来源。为探明不同基因型甜菜对根际土壤有机氮吸收利用以及有机氮组分在根际的空间分布情况,分别选取对土壤有机氮吸收效率高和低的品种各1个,采用Kuchenbuch-周氏微型盆及田间网袋法,研究了甜菜苗期及大田全生育期根际土壤有机氮各组分的变化规律,建立了土壤氮矿化及各组分在根际空间分布的数学模型。结果表明:2周苗龄的甜菜根际土壤有机氮各组分含量高低顺序为:酸解总氮(ATN)>氨基酸态氮(AAN)>氨态氮(AN)>氨基糖态氮(ASN)。其中AAN和AN在根际形成明显的耗竭面,即距离根表越远含量越高,在距根表15 mm时达到最高值,随后的变化渐趋平稳,其分布规律可用方程Y=Y0+Aln(X)拟合;ASN含量较低,随根际距离远近变化不显著;不同基因型甜菜对根际有机氮的耗竭能力各异,有机氮吸收效率高的品种均高于低的品种。田间自然条件下,甜菜根际土壤中的ATN、AAN及AN的含量在苗期增长最快,随后缓慢上升并逐渐趋于恒定。室内及田间试验结果表明,施氮处理后土壤有机氮的矿化量低于未施氮处理,其中有机氮吸收效率高的品种根际土壤有机氮的矿化量高于低的品种。更多还原

【Abstract】 Apart from inorganic nitrogen in soil, organic nitrogen is also an important nutrient source for plant growth and development. To ascertain the absorption and utilization of organic nitrogen in the rhizosphere and the spatial distribution of organic nitrogen components in the rhizosphere of different genotype sugarbeets, one of each of the varieties with high and low organic nitrogen efficiency were selected. Using the methods of Kuchenbuch-Zhou’s miniature and field net bags, the variation regularities of organic nitrogen components in the rhizosphere of sugarbeet seedling period and the whole growth period in field were studied, and the mathematical model of soil nitrogen mineralization and the spatial distribution of each component in the rhizosphere were established. The results showed that the content of organic nitrogen in the rhizosphere soil of2 weeks old seedlings was as follows: acid hydrolysis total nitrogen(ATN) > amino acid nitrogen(AAN) >ammonia nitrogen(AN) > amino sugar nitrogen(ASN). Among them, AAN and AN formed obvious depletion surface in the rhizosphere, that is, the farther away from the root surface, the higher the content. The highest value was reached at 15 mm from the root surface, and the subsequent change became more stable. The distribution law could be obtained by the equation Y=Y0+Aln(X) fitting. The content of ASN was low, and it changed not significantly with the distance of the rhizosphere. Different sugarbeet varieties had different depletion abilities to rhizosphere organic nitrogen, and the depletion ability of varieties with high organic nitrogen absorption efficiency was higher than that of the low varieties. Under natural condition in field, the contents of ATN, AAN and AN in the rhizosphere soil grew the fastest at the seedling stage, then slowly increased and gradually became constant. The results of laboratory and field experiments showed that the mineralization of soil organic nitrogen was lower than that of non-nitrogen treatment after nitrogen application,and the mineralization of rhizosphere soil organic nitrogen of variety with higher organic nitrogen absorption efficiency was higher than that of low variety.更多还原