Study On Mycorrhizalization Of Major Tree Species For Afforestation In The Loess Plateau Of West Henan Province

Resource investigation of mycorrhizal fungi in major tree species for afforestation in the Loess Plateau of west Henan province was conducted and screening of superior fungal species was carried out. In addition, effects of mycorrhizalization on plant resistance were studied. The results are summarized as follows:1. Fifteen vesicular-arbuscular mycorrhiza (VAM) species belonging to 3 genera were isolated and identified from roots of major tree species for afforestation (i.e. pagodatree, elm, Chun, poplar, willow and candlenut) in the Loess Plateau of west Henan province, among which 12 species are from genus Glomus, including G. constrictum, G. diaphanum, G. caledonium, G. viscosum, G. gepsporum, G. mossea, G. microaggregatum, G. ambisporum, G. aggregatum, G. intraradices, G. desterticola, G. monosporum, G. Taiwannense and 2 unidentified species. Of the rest species, 1 belongs to Scutellospora (S. reticulata), 1 to Acaulospora (A. spinosa) and 2 to be identified with a code name of G.sp1 and G.sp2 respectively. Glomus constrictum was dominant mycorrhizal fungal species in studied area.2 Although VAM fungi were in great abundance in the rhizosphere of major tree species for afforestation in the Loess Plateau of west Henan province, soil spore density was rather low, with an average of 40.8 spores per hundred gram soil. Moreover, soil VAM fungal abundance in this area lacked consistency. In some study sites (e.g. Heyu, Luoyang City), soil spore density in the rhizosphere of target trees were relatively high, which could reach 111 spores per hundred gram soil. On the other hand, rhizosphere of target trees in some places harbored only a small amount of VAM spores. Shanmenxia People's Park is a typical example, which presented a soil spore density of 9 spores per hundred gram soil. According to our investigation, genus Glomus occurred with the highest frequency in all sampling sites.3. Distribution of VAM fungi were influenced by soil conditions in the Loess Plateau of West Henan Province, though the results lacked consistency. As a whole, soil pH values showed significant effect on VA mycorrhizal fungi occurrence, with neutral or slightly acid soils harbored much more fungal spores than others. Interspecific variances were detected in terms of soil organic matter content. According to our investigation, spore density of G.constrictum and G.diaphanum revealed a positive correlation with soil organic matter content while that of G.mosseae and G.taiwannense presented a reverse response. Unapparent negative correlation between soil spore density of VA mycorrhizal fungi and...