Effect of two species of mycorrhizal-arbuscular fungi in different levels of moisture stress on some growth characteristics of Maize

Arbuscular-mycorrhizal fungi (AM) are important in sustainable agriculture because they increase the tolerance to drought stress in host plants. One of the most important aspects of the relationship between the mycorrhiza fungus and the host plant is that it’s physiological and biochemical processes should be such that the host plant can successfully deal with limiting environmental conditions.

The isolates of the fungus used in this study included two Glomus (G.) genus species, G. intraradices and G. mosseae. In this research, their efficiency was evaluated on the improvement of some quantitative traits of corn under irrigated conditions and water stress in a calcareous soil. For this purpose, soil samples were prepared from a depth of 0-30 cm in a cultivated soil with a phosphorus available concentration of less than five mg.kg-1 and its physical and chemical properties were measured according to the standards of the Soil and Water Research Institute, Iran. The experiment based on factorial completely randomized design was carried out in five replications. The first factor was related to the drought stress levels of 60%, 80% and 100% of field capacity moisture (FC) and the second one consisted of two mycorrhizal fungi species, G. intraradices and G. mosseae, and control (non-inoculated). At the beginning of flowering, traits such as plant height, leaf area, chlorophyll index (using Spad-502 Minolta chlorophyll meter), relative humidity, were measured. At harvesting time, shoot dry weight, root dry weight and root colonization percentage were measured in all treatments.

The results revealed that there was a significant difference between the drought stress levels in terms of plant height so that with increasing tension, plant height decreased. The effects of mycorrhizal fungus species were significant in terms of plant height and the highest plant height was obtained in inoculum treatment with G. intraradices. The interaction effects of drought stress and mycorrhizal fungi were also significant in terms of plant height. The highest plant height was obtained in the control treatment at field capacity, which was maintained by G. intraradices with the same moisture content and G. mosseae at 60% of soil moisture content in a statistical class, indicating the effectiveness of G. mosseae in improving Corn growth under moisture stress condition. Drought stress reduced the SPAD chlorophyll index, leaf area, root colonization percent, relative water content (RWC) of leaves, leaf area, root dry weight, and shoot dry weight of maize. In plants inoculated with mycorrhizal inoculation, the chlorophyll index, plant height, root dry weight, leaf surface area and root colonization percent and RWC of leaves were increased. Interactions between drought stress and mycorrhizal species on all mentioned parameters have a significant effect. Although, chlorophyll content was higher in plants inoculated with the fungus G. mosseae specie at 80% FC, but maximum shoot dry weight was obtained at 100% FC and inoculation with fungi G. intraradices treatment. The most root colonization was achieved in plants inoculated with the fungus G. mosseae specie at 60% FC treatment. Overall, the results of this study proved that inoculation of corn seeds with AM fungi increased leaf chlorophyll content and produced dry matter of the plant in moisture regimes less than field capacity. Further increase of the traits studied in this study such as plant height, chlorophyll index, leaf area, relative humidity, root and shoot production as a result of using G. mosseae compared to G. intraradices, suggests that G. mosseae species are more compatible and able to communicate more effectively with the root of corn in drought stress conditions. Therefore, to increase the tolerance of corn to drought stress and increase the water absorption efficiency, G. mosseae species is more efficient in similar conditions of this experiment.