中文摘要：

以山地长寿沙田柚成年果树为对象,研究不同生境和季节对丛枝菌根（Arbuscular mycorrhiza,AM）真菌侵染以及根围土壤中AM真菌孢子密度的影响.试验结果表明,不同生境下,菌根侵染率和AM真菌孢子密度都是以梯田最高,坡地次之,洼地最低;在坡地和洼地生境下,生草区均高于清耕区.两块试验地AM真菌的菌丝侵染率均为夏季最高（16.8%±1.9%和16.0%±1.8%）,秋季次之,冬季最低;丛枝和泡囊的形成也是夏/秋季较高,春/冬季较低;而根围土壤中AM真菌孢子密度则是秋季最高[（159±19）个/100 g和（167±17）个/100 g],夏季次之,冬季最低.总之,对于长寿沙田柚成年果树,AM真菌的菌根侵染率在夏季梯田最高,根围土壤中的AM真菌孢子密度在秋季梯田最高;在坡地和洼地生境中,生草处理均可显著提高菌根侵染率和AM真菌孢子密度.图4参27

英文摘要：

The effects of different habitats and seasons on arbuscular mycorrhizal（AM） colonization of adult pomelo（Citrus grandis cv.Changshou Shatian You） trees and AM fungal spore density in rhizosphere soil were investigated.The results showed that the highest AM fungi colonization rate and spore density were recorded in terraced field,and followed by sloping fields and lying land.In sloping fields or lying land,grassland had a higher AM fungal colonization rate and spore density than no-tillage area.In different seasons,the highest mycorrhizal colonization rates,16.8% ± 1.9% and 16.0% ± 1.8% in two trials,were recorded in summer,and followed by autumn and spring,while the lowest was in winter.Both the arbuscule and vesicle percentages were higher in summer/autumn than in spring/winter.While the number of AM fungi spores in rhizosphere soil reached its peak,159 ± 19 and 167 ± 17 spores/100 g dry soil in autumn,and followed orderly by summer,spring and winter.In conclusion,for adult pomelo trees,in terraced field,AM fungi infection rate reached its peak in summer,whereas the highest AM fungal spore density was noted in autumn.In sloping fields or lying land,both AM fungi colonization rate and spore density were improved significantly by sod culture.Fig 4,Ref 27