Effect of Native and Commercial Arbuscular Mychorrizal Fungi on the Development, Fruit Yield, and Phytochemicals of Pepper Plants under a Range of Salinity Conditions

Arbuscular mychorrizal fungi (AMF) have been shown to benefit plant growth and productivity and improve plant tolerance to abiotic environmental factors such as salinity.

Native AMF (isolated from the Chihuahuan desert) and commercial AMF were evaluated in a greenhouse to determine their efficacy in the alleviation of salinity stress on the growth and yield of Capsicum annuum (chili pepper) ‘Jalapeño M’ and ‘NuMex 6-4’. A factorial experiment design with AMF [native AMF (AMF1), commercial AMF (AMF2), and no AMF] and salinity [electrical conductivity (EC) of 1.4, 4.0, or 8.0 dS·m^-1] with nine plants per treatment was employed. Chili pepper seedlings were transplanted in 7.6-L pots containing Metro-Mix 360 growing medium. While transplanting, twenty-seven seedlings were inoculated with AMF1 or AMF2, 40,000 spores per plant. To facilitate root colonization, Long Ashton solution with 44 mg·L^-1 KH₂PO₄ was applied weekly to control plants, whereas Long Ashton solution with 22 mg·L^-1 KH₂PO₄ solution to inoculated plants. Salinity treatments were initiated 17 days after AMF inoculation and applied weekly for a total of seven times. AMFs had no effect in the leaf area and dry weight of both chili pepper cultivars, but salinity at EC of 8 dS·m^-1 negatively affected the leaf area and dry weight. Despite the reduction in exogenous phosphorous application, AMF1 inoculated ‘Jalapeño M’ and ‘NuMex 6-4’ plants had similar number of fruit compared to non-inoculated plants. AMF1 inoculated ‘Jalapeño M’ plants also had similar fruit fresh weight to that of non-inoculated plants.