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大针茅(Stipa grandis P.Smirn.)是我国北方典型草原上的建群种或优势种植物,具有重要的饲用价值。大针茅根系能够形成丛枝菌根(arbuscular mycorrhiza,AM)。采集围栏区的大针茅根系,根据18S r DNA序列鉴定大针茅根系中的AM真菌为球囊霉属(Glomus)的根内球囊霉(G.intraradices)。通过对轻度放牧区、中度放牧区、重度放牧区和未放牧的对照区(30年围栏草场)大针茅根系AM真菌侵染情况的分析,发现不同放牧强度下菌丝侵染率和总侵染率都不存在显著性差异。放牧利用总体降低了丛枝的侵染率。放牧强度影响AM真菌泡囊结构在大针茅根系中的发育,轻度和中度放牧促进AM真菌泡囊的形成,而重度放牧则显著抑制。放牧强度对大针茅AM真菌的影响主要体现在AM真菌营养的交换和繁殖方面,AM真菌光合产物的减少属于中性反应,对碳的需求相对较少,这可能也是大针茅具有较强耐牧性的原因之一。
Stipa grandis P.Smirn. Is a kind of dominant species or dominant species in the typical steppe of northern China, which has important value for feeding. Stipa grandis roots can form arbuscular mycorrhiza (AM). The root system of A. maxima was collected from the fenced area, and G. intraradices from Glomus was identified according to 18S r DNA sequence. Through analyzing the AM fungal infection of AMF in light grazing area, medium grazing area, heavy grazing area and non-grazing control area (30-year-old grazing grassland), it was found that mycorrhizal infection rate under different grazing intensities and There was no significant difference in the total infection rate. Grazing use overall reduced the rate of penetration of the bush. Grazing intensity affected AM fungal vesicle structure in the development of Stipa grandis roots, mild and moderate grazing promoted the formation of AM fungal vesicles, while severe grazing significantly inhibited. The effects of grazing intensity on AM fungi were mainly reflected in the exchange and multiplication of AM fungi. The reduction of AM fungal photosynthetic products was a neutral reaction and the demand for carbon was relatively low, which may also be the reason why Stipa grandis One of the reasons for resistance to pastoralism.