Effects of Mycorrhizal Fungi Inoculation on Green Pepper Yield and Mineral Uptake under Irrigation with Saline Water

Salinity in soil or irrigation water are major environmental constraints to crop productivity and are increasing steadily in many parts of the world, especially in arid and semi–arid areas (e.g., Mediterranean region). Due to low precipitation in arid and semiarid regions, in addition to overexploitation of available water resources (e.g., ground water), low quality water (e.g., saline water) has been utilize for irrigation crops grown in plastic houses as well as those planted in open fields. High salinity of the irrigation water has detrimental effects on soil fertility and reduces crop growth and yield.1–3 One of the strategies that have been used to counteract salinity stress involves growing crops that are tolerant to saline conditions.4,5 However, alleviation of salinity problem using salt tolerant crops is consider expensive and often represents only a temporary solution.6,7 Therefore, incorporating biological factors that enable plants to tolerate salt stress such as mycorrhizal fungi inoculum would be helpful in improving crop production under saline conditions.6,8 Arbuscular mycorrhizal (AM) fungi are beneficial plant symbionts that form mutualistic relationships with roots of most crop plants. This association allows plants to explore larger volumes of soil to absorb more water and nutrients uptake (especially immobile nutrients as P, Zn, and Cu) which result in enhancement of plant growth and productivity.1,9 This can be attained by increasing the surface area of soil explored via fungal hyphae, that extend into soil past zone of nutrient depletion.9 Many recent studies have indicated that AM fungi could enhance the ability of plants to cope with salt stress by improving mineral nutrient absorption, maintaining ion balance, protecting enzyme activities and increasing water use efficiency.1,10–13 AM fungi also enhance soil aggregation and water holding, both by extra radical hyphae in soil and exuding glomalin (glue like) which enhances soil structure.14 The most promising areas for practical use of AM fungi are during nursery seedlings production (e.g., horticultural crops), due to benefits that can be realize stronger growth of seedlings in nursery and improved performance after planting in the field.6,15 Green sweet pepper (Capsicum annuum L.) is one of the economic important crops produced all over the world and its seedlings are produce in nurseries. Green pepper is considered sensitive to moderately sensitive to salinity stress.16,17 However, AM fungi use in green pepper crop production is still less exploited compared to other crops of economic importance especially under field conditions.18 Therefore, the symbiotic interactions between AM fungi and host plants under saline conditions need to be studied in order to optimize beneficial effects of AM fungi in enhancing crop growth and productivity. The objective of this study was to determine the effects of pre–inoculation of seedlings with arbuscular mycorrhizal (AM) fungi on mineral uptake, growth and yield of green pepper when irrigated with different levels of water salinity.