【作者】 李辉信；

【导师】 徐盛荣；

【作者基本信息】 南京农业大学 ， 土壤学， 1998， 博士

【摘要】 本文应用悉生培养法研究接种土壤线虫后,线虫与细菌的相互作用及其对土壤N、P转化和小麦生长的影响;利用盆栽试验,研究杀灭线虫对土壤N、P转化和小麦生长的影响,以及运用¹⁵N同位素示踪技术研究了线虫对¹⁵N吸收和损失的影响。结果表明,小麦根际土的细菌数和线虫数明显高于非根际土;食细菌线虫的引入显著增加了细菌的数量,在不种植作物条件下,增幅达103.9%至185.1%;线虫和细菌的相互作用显著增加了土壤中矿质N的含量,线虫加细菌处理培养40天时,与只有细菌处理相比其增幅达35.1%;接种线虫对土壤有效P的提高不明显,而对土壤生物量P有显著的增加。同时,土壤线虫和细菌的相互作用促进了小麦的生长和对N的吸收,40天时,线虫加细菌处理小麦生物量比只有细菌处理提高了6.5%,吸N量提高了5.8%,而吸P量则减少9.1%。但接种线虫对小麦生物量和吸N量的影响主要是促进其地上部的吸N量和生物量的积累,对根系的影响不大。 在没有小麦致病线虫的情况下,施杀线剂和干热处理杀灭土壤线虫减少了小麦对土壤N、P的吸收,其降幅分别达15.2%—16.4%和8.3%—14.4%;同时抑制了小麦的生长,其生物量减少3.4%—9.2%。杀灭土壤线虫还不利于土壤N素和P素的矿化,但对P素矿化的影响小于对土壤N素矿化的影响。 ¹⁵N同位素示踪技术研究结果表明:接种线虫促进了小麦对肥料N的吸收,增加幅度达10.3%,并有利于养分向穗部转移,同时减少了肥料N的损失,降低幅度达18.2%。更多还原

【Abstract】 The interactions between nematodes and bacteria and their effects on wheat growth and transfer of soil N and P were studied in gnotobiotic systems by inoculating nematodes and in pot culture by killing nematodes with nematocide or oven—dry. The effects of nematodes on ¹⁵N absorption by wheat and ¹⁵N loss from soil —plant system were also studied using ¹⁵N isotope tracer technique. In gnotobiotic systems, both the number of bacteria and nematodes in rhizosphere was evidently higher than that in non—rhizo-sphere. The inoculation of soil nematodes significantly promoted the bacteria population . The interactions between nematodes and bacteria evidently increased the content of soil mineral N, with about 35% more than that treatment with bacteria only at the end of incubation（40 days）. Soil available P was not affected by nematodes,while soil microbial biomass P increased obviously with the inoculation of nematodes. The wheat biomass and N absorption by wheat in nematodes+bacteria treatment increased by 6. 5% and 5. 8 % respectively at the end of incubation when compared with that in bacteriaonly treatment, but the P absorption by wheat decreased by 9. 1 %. The interactions between nematodes and bacteria mainly increased shoot bimass and shoot N absorption by wheat and had little effects on root biomass and root N absorption.In the absence of parasitic nematodes, the N and P absorption by wheat and wheat biomass evidently decreased after kiiling soil nematodes by nema-tocide and oven—dry. The mineralization of soil N and P were also restricted by killing soil nematodes, however,soil N mineralization was more sensitive to nematodes removing than soil P mineralization.The results obtained from 15N isotope tracing systems indicated that the inoculation of nematodes increased the absorption of (NH^&Oi—N by 10. 3%, favoured the transfer of N nutrient to spike, and reduced the loss of fertilizer N by 18. 2% compared with no nematodes treatment.更多还原