Significance of mycorrhizal network in no-tillage cultural systems

与传统耕作方式相比，免耕方式具有减少土壤侵蚀、降低生产成本等优点，也适合当前节能减排等绿色环保技术的需求。然而，减少耕作可能会导致土壤紧实度增加，这不利于作物的生长，特别是由于限制了根系的发育，抑制了养分的获取。大多数作物物种能够与丛枝菌根真菌形成共生关系，这种共生关系促进了养分的吸收，特别是磷的固定元素。这项研究表明，利用菌根共生可以恢复受限的根系功能。菌根真菌与寄主植物的根一起定植，在土壤中形成菌丝网络结构。这种结构不仅在养分从土壤向植物的运输中发挥作用，而且在探索其他寄主方面也起到了作用。在常规耕作方式下，菌丝结构受到干扰，但在免耕方式下仍能保持菌丝结构，因此菌根对促进根系功能的作用得到了极大的发挥。因此，我们发现，根瘤土壤条件下的菌根联合抵消了压实土壤的压力。还观察到，土壤干扰引起的真菌侵染势的降低在不同的真菌物种之间以及其他物种的存在下也是不同的。此外，我们还证明，植物不能仅用根分泌物来溶解稀有的可溶性来源来充分获得磷，菌根网络的作用是显著的。根际微生物和根际微生物可能会竞争来源释放的磷，而菌根真菌因其较大的表面积而提高植物的竞争能力。

No-tillage systems have several advantages reducing soil erosion and production cost comparing with conventional tilled ones, and also they would be suitable for current demand for environmental sound technologies such as saving energy inputs and carbon dioxide exhausted. However, it is pointed out that reduced tillage may cause increased soil compaction which is detrimental to crop growth, especially for inhibited nutrient acquisitions due to restricted root system development. Most species of crop plants enable to form symbiotic associations with arbuscular mycorrhizal fungi, nutrient uptake particularly immobile elements of phosphorus are enhanced with the associations. This study showed that restricted root functions could be restored by utilizing the mycorrhizal symbiosis. The mycorrhizal fungi colonize with host plant roots, establishing the hyphal network structure in soils. This structure functions not only in nutrients transport to the plants from soils but also in exploring other hosts. The hyphal structure is disturbed in conventional tilled systems, but remained in no-tillage ones hence mycorrhizal benefits to help root functions are greatly displayed. As such, we found that the mycorrhizal association under notilled soil conditions counteracts compacted soil stress for pigeon pea. It was also observed that decreases in the fungal infective potential due to the soil disturbance are different among fungal species and also with the presence of other species. Moreover, we demonstrated that the plant can not acquire phosphate sufficiently only with root exudates to solubilize sparingly soluble sources, a mycorrhizal network function as the interaction is significant. Probably, the root and rhizosphere microbes would compete for phosphate released from the sources, the mycorrhizal fungi could increase the competitive ability of the plants due to their larger surface area.