The Influence of No-till Farming on Durum Wheat Mycorrhization in a Semi-Arid Region: A Long-Term Field Experiment

Maintaining a reliable and sustainable agricultural production system has become one of the major concerns of producers in arid and semi-arid regions. Simplifying farming techniques and practicing Direct Seedling (DS) could contribute to insure the sustainability of agriculture, preserving the natural resources and the environment. Direct Seedling based on limiting soil plowing has a potential number of benefits, including reduced production costs and soil erosion. Associated with the organic mulch, this technique improves the soil fertility and favors the establishment of root symbioses. Given the importance of the no-till farming techniques, the present research work aims to compare the effects of DS and those of Conventional Seedling (CS) on the evolution of arbuscular mycorrhizal symbiosis in durum wheat (Triticum durum Desf) roots, cultivated in the field for five years. Soil and root samples were collected during three different cropping stages at two different treatments. The results of Arbuscular Mycorrhizal Fungi (AMF) root colonization kinetics have shown an increase in the percentage of arbuscules and a decrease in vesicles for plants sampled from a DS field compared to those from CS. Effects of the DS on the mycorrhizal parameters appears clearly in the fourth year of the experiment and continues in the fifth year, with an arbuscule percentage reaching 80% in a DS field and not exceeding 21% in a CS field. Soil phospholipid fatty acids (PLFA) C16:1ω5 (biomarker of AMF) and C18:2ω 6, 9 (biomarker of saprophytic/ectomycorrhizal fungi) demonstrate that no-till practice improves AMF biomass and saprotrophic/ectomycorrhizal fungal biomasses by 52 and 159%, respectively, in comparison with those found in a CS field. In both treatments, no-till farming and CS plots, the AMF biomass is higher than saprotrophic/ectomycorrhizal biomasses. The natural biodiversity of AMF is also enhanced in a no-till field. In addition, an increase in the relative abundance of six families of Glomeromycota (Gigasporaceae, Diversisporaceae, Scutellosporaceae, Entrophosporaceae, Acaulosporaceae, Dentiscutataceae) was observed. To summarize, the present study highlights the importance of no-till practice as an approach to restore the microbiome in soils disturbed by tillage in semi-arid regions.