Increased Salinity Tolerance of Cowpea Plants by Dual Inoculation of an Arbuscular Mycorrhizal FungusGlomus clarumand a Nitrogen-fixerAzospirillum brasilense

Abstract

Pot greenhouse experiments were carried out to attempt to increase the salinity tolerance of one of the most popular legume of the world; cowpea; by using dual inoculation of an Am fungus Glomus clarum and a nitrogen-fixer Azospirillum brasilense. The effect of these beneficial microbes, as single- or dual inoculation-treatments, was assessed in sterilized loamy sand soil at five NaCl levels (0.0~7.2 ds/m) in irrigating water. The results of this study revealed that percentage of mycorrhizal infection, plant height, dry weight, nodule number, protein content, nitrogenase and phosphatase activities, as well as nutrient elements N, P, K, Ca, Mg were significantly decreased by increasing salinity level in non-mycorrhized plants in absence of NFB. Plants inoculated with NFB showed higher nodule numbers, protein content, nitrogen concentration and nitrogenase activities than those of non-inoculated at all salinity levels. Mycorrhized plants exhibited better improvement in all measurements than that of non-mycorrhized ones at all salinity levels, especially, in the presence of NFB. The concentration of Na+ was significantly accumulated in cowpea plants by rising salinity except in shoots of mycorrhizal plants which had K+/Na+ ratios higher than other treatments. This study indicated that dual inoculation with Am fungi and N-fixer Azospirillum can support both needs for N and P, excess of NaCl and will be useful in terms of soil recovery in saline area.

Growth and nutrition of cowpea (Vigna unguiculata) under water deficit as influenced by microbial inoculation via seed coating

“…Cowpea is considered to be highly mycotrophic (Molla & Solaiman, ) which leads to enhancement of below and above ground biomass, nutrients accumulation, protein content and grain yield under different water regimes (Kwapata & Hall, ; Oliveira et al., 2017a; Oruru, Njeru, Pasquet, & Runo, ; Rabie, Aboul‐Nasr, & Al‐Humiany, ). However, our results showed that association between AM fungi and cowpea did not result in increased plant growth or seed yield (Tables and ).…”

New Insights on Plant Salt Tolerance Mechanisms and Their Potential Use for Breeding

“…Compared to control treatments, dual inoculation of Rhizobium bacteria and mycorrhizal fungi under salt stress, enhanced plant nutrition, growth parameters and proline concentration in Acacia saligna (Soliman et al, 2014), Lathyrus sativus (Jin et al, 2010), Acacia auriculiformis , and Acacia mangium (Diouf et al, 2005). Co-inoculation with Rhizobium and PGPR including Azospirillum brasilense and Pseudomonas species showed the same beneficial effects in Z. mays (Bano and Fatima, 2009), Vigna sinensis (Rabie et al, 2005), and Vicia faba (Rabie and Almadini, 2005), which were more pronounced in plant inoculated with AMF, in addition to Rhizobium and PGPR (Rabie and Almadini, 2005; Rabie et al, 2005). In Cowpea plants, dual inoculation with AMF and nitrogen-fixing bacteria such as A. brasilense increased plant nitrogen content by 230% against 151 and 94% in plants inoculated separately with nitrogen-fixing bacteria and AMF, respectively, at 7.2 dS/m salinity (Rabie et al, 2005).…”

“…Thus, a screening of both symbiotic partners is necessary for obtaining an efficient N 2 -fixing symbiosis under saline soils (Zahran, 1999). Salinity tolerance of legumes could be better improved by associated Rhizobium with mycorrhizal fungi (Diouf et al, 2005; Jin et al, 2010; Soliman et al, 2014) and/or plant growth promoting rhizobacteria (PGPR; Rabie and Almadini, 2005; Rabie et al, 2005; Bano and Fatima, 2009). Compared to control treatments, dual inoculation of Rhizobium bacteria and mycorrhizal fungi under salt stress, enhanced plant nutrition, growth parameters and proline concentration in Acacia saligna (Soliman et al, 2014), Lathyrus sativus (Jin et al, 2010), Acacia auriculiformis , and Acacia mangium (Diouf et al, 2005).…”

Role of some rhizospheric Pseudomonas on the growth and physiology of broad bean (Vicia faba) under salt stress conditions

“…Several studies have proven the inhibitory effect of salt stress on the association of plants with symbiotic bacteria. Salt stress inhibits the growth, nodulation, and nitrogen fixation of several legumes, such as soybean (Glycine max) and common bean (Phaseolus vulgaris) [47,48]. An explanation for reduced legume growth may be that salt stress causes failure of the infection and nodulation processes [49].…”