Significance of mycorrhizal network in no-tillage cultural systems

与传统耕作方式相比，免耕具有减少土壤侵蚀、降低生产成本等优点，同时也符合当前节能减排等环保技术的要求。然而，它指出，减少耕作可能会导致土壤压实，这是不利于作物生长，特别是抑制养分收购，由于限制根系发育。大多数农作物能与丛枝菌根真菌形成共生体，这种共生体能促进植物对养分的吸收，特别是对磷等不动元素的吸收。本研究表明，利用菌根共生可以恢复受限制的根系功能。菌根真菌与寄主植物的根定殖，在土壤中建立菌丝网络结构。这种结构不仅在营养物质从土壤向植物的运输中起作用，而且在探索其他宿主中也起作用。在常规耕作系统中，菌丝结构受到干扰，而在免耕系统中，菌丝结构保持不变，因此，菌根对根系功能的促进作用得到了极大的发挥。因此，我们发现，在免耕土壤条件下的菌根协会抵消木豆压实土壤应力。还观察到，由于土壤扰动而导致的真菌感染潜力的降低在真菌物种之间以及在其他物种的存在下是不同的。此外，我们证明，植物不能获得足够的磷只与根分泌物溶解难溶性来源，菌根网络功能的相互作用是显着的。根系和根际微生物可能会竞争磷源释放的磷，菌根真菌由于其较大的表面积可以增加植物的竞争能力。

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.