Effects of Arbuscular Mycorrhiza Fungi and Salinity Stress on Morphological Characteristics, uptake of Some Nutrients and Soil Aggregate Stability in Three Different Plants

Soil salinity is an increasing problem in agricultural soils that mycorrhizal fungi in saline soils increase plants tolerance to salinity by symbiosos with their roots and improving their growth. In addition, mycorrhizae contribute to agglomerate stability through two main mechanisms, physical stabilization by trapping individual soil particles by extensive hyphae networks and chemical stabilization by adhesive-like secretions. Therefore, the aim of this study was to compare the root effects of three different plants, clover Terifoliom alexandrinum L., onion Allium cepa L. and parsley Petrocelinum crispum L. with and without mycorrhizal on soil aggregates stability in saline soils.

In order to investigate the effect of mycorrhiza fungi and different salinity levels on morphological characteristics, nutrient concentrations and soil aggregate stability in three plants: clover, parsley and onion, a factorial experiment in a completely randomized design with 3 replications were conducted in the greenhouse of Agricultural sciences and natural resources university of Khuzestan in 2018. factors were included mycorrhiza at two levels (no inoculation with mycorrhiza (NM), inoculation with mycorrhiza (M)), salinity at three levels (salinity 1 dS m-1 (S1), 3 dS m-1 (S2) and a 6 dS m-1 (S3)) and three levels of plant type (clover (TA), parsley (PC) and onion (AC)).

Accourding to the results, salinity stress caused a significant decrease in growth indices and plant colonization percentage, but inoculation with mycorrhiza fungus increased them significantly. Salinity stress in clover, parsley and onion reduced shoots dry weight 31%, 35% and 96% respectively, but inoculation with mycorrhizal faungus increased this factor 69%, 67% and 93% compared to non-mycorrhizal treatments. The increase of root dry matter of these three mycorrhizal plants compared to their non-mycorrhizal treatments was 65, 65 and 93%, respectively. Salinity stress also caused a significant decrease in the macronutrients (phosphorus and potassium) and micronutrients (iron, zinc and copper) concentration, while sodium concentration increased significantly. Mycorrhizal treatment increased phosphorus concentration significantly in clover, parsley and onion by 26, 27 and 41%, while salinity stress reduced it by 22, 24 and 26% respectively. Mycorrhizal inoculation increased iron concentratin 6, 12 and 66% in the above three plants, respectively. The results showed that the highest aggregate stability in clover, parsley and onion were seen with an average of 0.81, 0.75 and 0.93 mm in mycorrhizal low salinity level treatment and and the lowest aggregate stability by an average of 0.41 , 0.39 and 0.35 mm were obtained in non-mycorrhizal high salinity level treatment.

Based on the results of this study, salinity stress has a negative effects on plant growth characteristics and nutrient uptake by clover, parsley and onion, but mycorrhizal fungi inoculation reduces these negative effects. Also, the negative effects of salinity stress on aggregate stability in mycorrhizal treatments were less than non-mycorrhizal treatments. Among the studied plants, the highest amount of aggregate stability in mycorrhiza inoculation conditions was related to onion and the lowest amount of aggregate stability was seen in parsley. Its obvious from the results that onion, which has a higher mycorrhizal dependency, can further increase the aggregates stability. Thus, the use of mycorrhizal fungi, especially in saline soils, can increase the stability of aggregates and thus improve quality and soil physiacl properties.