香根草属与狼尾草属植物对土壤线虫营养类群的影响

Effects of Grasses of Vetiveria and Pennisetum on Trophic Groups of Soil Nematodes

对广州华南植物园香根草属泰国香根草(Vetiveria nemoralis)、普通香根草(V.zizanoides)的2个品种Sunshine和Karnataka以及狼尾草属象草(Pennisetum purpureum)、皇草(P.purpureum×P.thyphoides)和杂交狼尾草(P.americanum×P.purpureum)的地下土壤线虫各食性类群在根区和非根区的分布特征进行了对比研究,结果表明:线虫主要集中在0-15 cm的浅层土壤中,在不同生境下食细菌和植物寄生性线虫占优势,两类线虫的比例在香根草属植物生境下为87.7%-97.6%,狼尾草属植物生境下为88.5%-94.0%,而食真菌、捕食性和杂食性线虫数量则很少,其相应的比例分别为2.4%-12.3%和6.0%-11.5%。两属植物根区的线虫数量显著高于非根区,但不同营养类群的线虫在根区和非根区的分布有较大差异。香根草属植物和杂交狼尾草非根区植物寄生性线虫的比例高于根区,而食细菌线虫的比例低于根区;但象草和皇草非根区植物寄生性线虫的比例低于根区,而食细菌线虫的比例高于根区。除皇草外,两属植物非根区食真菌线虫的比例一般高于根区。在所选的植物中,Karnataka和杂交狼尾草在土壤改良和土壤生物学效应方面有更好的潜力。

Trophic groups of soil nematodes were investigated in the rhizosphere and non-rhizosphere of Vetiveria spp. and Pennisetum spp. in South China Botanical Garden, the Chinese Academy of Sciences, in Guangzhou, Guangdong Province. Soil nematodes were aggregated mainly in the soil layer of 0-15 cm regardless of the biomass and the length of roots of Vetiveria and Pennisetum, and the densities of bacterivores and phytophages were significantly higher than those of the other three trophic groups, fungivores, omnivores and predators in all habitats. The proportions ofbacterivores and phytophages were in the range of 87.7%-97.6% and 88.5%-94.0% and those of the other three trophic groups were 2.4%-12.3% and 6.0%-11.5% under grasses of Vetiveria spp. and Pennisetum spp., respectively. The total number of nematodes was much higher in the rhizosphere than in the non-rhizosphere of grasses of Vetiveria, but this was not so obvious under grasses of Pennisetum. The proportions ofphytophages under Vetiveria and under hybrid pennisetum （P. americanum x P. purpureum） were much higher in the non-rhizosphere than in the rhizosphere, while the proportions of bacterivores were much higher in the rhizosphere than in the non-rhizosphere. Nevertheless, the proportions ofphytophages and bacterivores under king grass （P. purpureum × P. thyphoides） and elephant grass （P. purpureum） habitats were opposite to that under Vetiveria. The proportions of fungivores were higher in the non-rhizosphere than in the rhizosphere under both genera of Vetiveria and Pennisetum with the exception ofking grass. Higher nematode densities were found under V. zizanoides cv. Karnataka and hybrid pennisetum, indicating that the two species have good potential for the improvement of soil fertility.