A study was conducted in a greenhouse, to investigate the effects of arbuscular mycorrhizal fungi (Glomus intraradices), soil salinity and P availability on growth (leaf area and dry weight), nutrient absorption and ion leakage, chlorophyll, soluble sugar and proline content and alkaline phosphatase activity of pepper plants (Capsicum annuum L.). Plants were grown at four levels of salinity (0, 50, 100 and 200 mM NaCl) and two P levels (10 and 40 mg kg -1). Colonisation was 80% to 51% in non-stressed and high salt-stressed plants, respectively. The mycorrhizal dependency was high and only reduced at the higher salinity level. Mycorrhizal plants maintained greater root and shoot biomass at all salinity levels compared to non-mycorrhizal plants, regardless the P level. Interactions between salinity, phosphorous and mycorrhizae were significant for leaf area, root and shoot dry mass. Non-mycorrhizal plants accumulated higher Na and lower K and P compared to mycorrhizal plants. The cell membrane integrity was greater in mycorrhizal plants than in non-mycorrhizal ones. The proline content increases with increasing salt stress and was significantly higher in leaves than in roots The results indicate that the mycorrhizal inoculation is capable of alleviating the damage caused by salt stress conditions on pepper plants, to maintaining the membranes stability and plant growth, and this could be related to P nutrition.

In general, heavy metals interfere with several physiological processes and reduce plant growth. Plants naturally establish symbiotic associations with soil microorganisms, such as mycorrhizal fungi. The aim of this research was to determine if inoculation with mycorrhizal fungi increases tolerance to Cr, evidenced by growth and biochemical parameters and the effect on roots membranes in Capsicum annum. Plants were either non-inoculated or inoculated with Glomus mosseae or Glomus intraradices, and grown in the presence of different concentration of Cr (K 2 Cr 2 O 4 ) in soil. Pepper plants grown without Cr behaved as mycotrophic species. At the highest concentration (200 mM K 2 Cr 2 O 4 ), Cr reduced root colonization by G. mosseae or G. intraradices (to 23 and 20% respectively). Moderate and high concentrations of Cr reduced all growth parameters. The interaction of inoculation and Cr increased leaf chlorophyll and proline content while reduced the leaf protein and root proline content. Carotenoid content was not affected by treatments. High Cr concentrations increased significantly electrolytes leakage in roots, either non-inoculated or inoculated plants. At the highest Cr concentration, inoculated plants had double the biomass of non-inoculated plants. Cr content in roots of inoculated plants was significantly higher than in non-inoculated plants. Chromium accumulation was low in leaves and showed no differences between treatments. Mycorrhization increased pepper plant tolerance to Cr in the soil, modifying proline metabolism to assure a more efficient response.

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The effect of arbuscular mycorrhizal fungi (AMF) inoculation, on pepper plant growth and physiological parameters in response to increasing soil Cu concentrations was studied. Treatments consisted of inoculation or not with Funneliformis mosseae or Rhizophagus intraradices and the addition of Cu to soil at concentrations of 0, 2, 4 and 8 mM CuSO 4 . The increase in copper concentration diminished the inoculation in all treatments. The highest experimental concentration of Cu (8 mM) reduced significantly the hyphae viability and ALP activity, regardless of the inocula used. The total dry weight and the leaf area were higher for mycorrhizal plants. The mycorrhizal dependence was 30 and 50% for plants inoculated with F. mosseae and R. intraradices, respectively at 8 mM CuSO 4 . The electrolyte leakage was higher at higher Cu concentrations, in roots and leaves. Net photosynthetic rates and transpiration were lower in plants treated with Cu, regardless of the inocula. At low Cu concentration in soil no differences were observed in Cu content in the shoots and roots. At 4 mM Cu, Cu content in roots was significantly higher than in shoots. At 8 mM Cu, in non-inoculated plants accumulate more Cu than inoculated plants in the roots, leaves and fruits regardless of the inocula. Beneficial microbial inoculants such as AMF, is an attractive strategy to farmers in the context of sustainable agriculture. Pre-inoculation in transplants could be an adequate practice to alleviate the deleterious effects in stress of pepper plants. However different AMF species can differ in their ability to minimize stress effects and promote plant growth.