甜菜根系对根际土壤化学性质的影响

Effect of Sugar Beet Root System on the Chemical Properties of Rhizosphere Soil

根系在根际土壤中的分泌物为根际微生物提供了丰富的碳源,极大地改变了根际土壤的理化性质,对根系的养分状况产生重大的影响。本研究采用网袋培养法分析有机氮高效甜菜品种‘KWS8138’和低效品种‘Beta176’在不同生长阶段(苗期、叶丛快速生长期、块根糖分积累期及收获期)根际土壤中的有机物质(氨基酸、有机酸和糖)与根际土壤化学性质的相关性。研究表明,根际土壤有机氮矿化的各组分中,氨态氮(AN)在根际内的含量比非根际高0.002~0.018 g/kg,从苗期至收获期逐渐降低;氨基酸态氮(AAN)、氨基糖态氮(ASN)在根际内的含量低于非根际,分别低0.017~0.029、0.005~0.044 g/kg,从苗期至收获期逐渐升高。品种‘KWS8138’的AN、AAN含量比‘Beta176’高0.025~0.035、0.011~0.026 g/kg,而ASN含量却比‘Beta176’低0.037~0.048 g/kg,说明有机氮高效对AN、AAN的吸收少于低效品种。‘KWS8138’的根际土壤中总氨基酸、Glu、Arg、草酸、甲酸、葡萄糖均高于‘Beta176’,分别高11.25、3.08、1.77、56.80、2.55、1.55μg/(g·h);从苗期到收获期,各品种总氨基酸和Arg含量呈逐渐增加趋势,平均增幅分别为14.64%、37.74%,Glu、草酸、甲酸、葡萄糖含量逐渐降低,平均降幅分别为36.91%、92.02%、84.25%、78.11%。土壤有机质(SOM)、碱解氮(Alkali-N)和pH的含量变化与AAN、ASN相一致,在根际内的含量低于非根际。不同品种根际土壤中总氨基酸、精氨酸(Arg)与AAN、总氮(TN)、Alkali-N显著正相关(r=0.918*~0.999**),与AN和SOM显著负相关(r=0.919*~0.985**);谷氨酸(Glu)、草酸、葡萄糖与AN、SOM显著正相关(r=0.901*~0.998**),与AAN、TN呈显著负相关趋势(r=0.882~0.988**)。试验结果可以为进一步研究根际土壤中有机养分的变化特征及根系分泌物的遗传和分子机制提供参考。

Root exudates in the rhizosphere soil provide a rich carbon source for rhizosphere microorganisms,greatly change the physical and chemical properties of the rhizosphere soil,and have a significant impact on the nutrient status of the root system.In this study,the net bag culture method was used to analyze the content of organic nitrogen-efficient sugar beet variety'KWS8138'and low-efficiency variety'Beta176'in the rhizosphere soil at different growth stages(the seedling stage,the rapid growth stage of the leaf clump,the tuber sugar accumulation stage and the harvest stage)for determing the correlation between organic matter(amino acids,organic acids and carbohydrate)and the chemical properties of rhizosphere soil.Studies had shown that among the various components of organic nitrogen mineralization in the rhizosphere soil,the content of ammonia nitrogen(AN)in the rhizosphere was 0.002-0.018 g/kg higher than that in the non-rhizosphere,and gradually decreased from the seedling stage to the harvest stage.The content of amino acid nitrogen(AAN)and amino sugar nitrogen(ASN)in the rhizosphere was lower than that in the non-rhizosphere,0.017-0.029 and 0.005-0.044 g/kg lower,respectively,and gradually increased with the growth period.The content of AN and AAN of the variety'KWS8138'was higher than'Beta176'by 0.025-0.035 and 0.011-0.026 g/kg,while the content of ASN was 0.037-0.048 g/kg lower than that of'Beta176',indicating that organic nitrogen was highly effective on AN and AAN.Absorption was less than inefficient varieties.The total amino acids,Glu,Arg,oxalic acid,formic acid,and glucose in the rhizosphere soil of‘KWS8138’were all higher than‘Beta176’,by 11.25,3.08,1.77,56.80,2.55,1.55μg/(g·h),respectively.From the seedling stage to the harvest stage,the total amino acid and Arg content of each variety showed a gradually increasing trend,with an average increase of 14.64%and 37.74%,respectively;Glu,oxalic acid,formic acid,and glucose content gradually decreased,with an average decrease of 36.91%,92.02%,84.25%,78.11%,respectively.The changes in soil organic matter(SOM),alkali hydrolyzable nitrogen(Alkali-N)and pH content are consistent with AAN and ASN,and the content in the rhizosphere was lower than that in the non-rhizosphere.The total amino acids and arginine(Arg)in the rhizosphere soil of different varieties were significantly positively correlated with AAN,total nitrogen(TN)and Alkali-N(r=0.918*-0.999**),and significantly negatively correlated with AN and SOM(r=0.919*-0.985**);Glutamate(Glu),oxalic acid,and glucose were significantly positively correlated with AN and SOM(r=0.901*-0.998**),and had a significant negative correlation trend with AAN and TN(r=0.882-0.988**).The test results could provide references for further research on the change characteristics of or-ganic nutrients in the rhizosphere soil and the genetic and molecular mechanisms of root exudates.