RESUMO A inoculação com fungos micorrízicos e o uso de porta-enxertos tolerantes ou resistentes aos nematoides são duas estratégias que permitem o controle e a convivência das plantas com esse patógeno. Contudo, ambas as técnicas sempre foram testadas de forma isolada, sendo seus efeitos positivos menores, se comparados com a possibilidade de suas somatizações. No presente trabalho compararam-se dois porta-enxertos em combinação com o fungo micorrízico Rhizophagus intraradices com o objetivo de avaliar seu comportamento no crescimento de plantas de tomate em solos infestados com N. aberrans, o falso nematoide das galhas. O experimento foi instalado em delineamento interiramente casualizado, com dez repetições, sob um esquema fatorial 3 x 2 x 2. Os tratamentos consistiram na combinação de três fatores: a) as composições de plantas, dois porta-enxertos (Solanum lycopersicum var. cerasiforme cv. 'Carolina' e S. lycopersicum cv. 'Maxifort'), nos quais foram enxertadas S. lycopersicum tomate 'Santa Clara'; e, a planta pé-franco, considerada controle, que foi a mesma cultivar utilizada como enxerto; b) micorrização: raízes micorrizadas ou não micorrizadas; c) substrato infestado ou não infestado com N. aberrans. Para a massa seca da parte aérea, a massa fresca radicular e o diâmetro do caule as plantas enxertadas em 'Maxifort' tiveram um crescimento significativamente maior. Os porta-enxertos testados tiveram fatores de reprodução do patógeno inferiores ao do Pé franco. A micorrização contribuiu para uma diminuição dos dias ate florescimento e uma redução da população final do N. aberrans para as três composições de plantas testadas.

ABSTRACT Inoculation with mycorrhizal fungi and the use of rootstock that is tolerant or resistant to nematodes are two strategies that allow the nematode to be controlled, and plants to coexist with the pathogen. However, the two techniques have always been tested in isolation, when their positive effects are less compared to when they are able to act together. In the present work, two rootstocks combined with the mycorrhizal fungus Rhizophagus intraradices were compared, with the aim of evaluating their behaviour on the growth of tomato plants in soils infested with N. aberrans, the false root-knot nematode. The experiment was set up in a completely randomised design with ten replications, in a 3 x 2 x 2 factorial scheme. The treatments consisted of a combination of three factors: a) plant composition: two rootstocks (Solanum lycopersicum var. cerasiform 'Carolina' and S. lycopersicum 'Maxifort'), onto which the 'Santa Clara' tomato (S. lycopersicum) was grafted, and a non-grafted plant, considered the control, which was the same cultivar as the graft; b) mycorrhization: mycorrhizal or non-mycorrhizal roots; c) a substrate infested or not infested with N. aberrans. The plants grafted onto 'Maxifort' showed significantly greater growth for shoot dry weight, root fresh weight and stem diameter. The rootstock under test had a lower pathogen reproductive factor than did the ungrafted plant. Mycorrhization contributed to a reduction in the number of days until flowering, and a reduction in the final population of N. aberrans for the three plant compositions under test.

When glyphosate is added to the soil, it is absorbed by roots and transported by xylem causing growth inhibition in plants. Mycorrhiza is the beneficial association between roots of most plants and soil fungi. The methylphosphonic group of the glyphosate could compete with inorganic phosphates for sorption sites in the soil. The aim of this work was to study the effect of phosphorus availability and glyphosate residues in soil on pepper plant growth, and on physiological parameters, in plants non-inoculated or inoculated with Glomus mosseae or G. intraradices. The phytotoxic effects of the glyphosate were assessed by a bio-indicator as shikimic acid. At high doses, glyphosate (6.32 μM) reduced root colonization, and this effect was increased by higher levels of phosphorus in the soil. The effects of herbicide on shikimic acid accumulation and on shoot growth began 24 hours after glyphosate treatments (HAT). At 24, 48, and 72 HAT, inoculated plants grown without glyphosate showed higher growth compared to the non-inoculated ones. At high glyphosate (6.32 μM) and 96 HAT, the growth was completely inhibited. The shikimic acid accumulated in the upper leaves of non-inoculated plants, treated at 3.16 μM glyphosate, was significantly higher at high P level, related to inoculated ones. These results suggest that the remobilization of glyphosate residues in the soil by the addition of phosphate should be considered a serious problem for crops in treated soils. The mycorrhization increases the pepper plant's tolerance to high glyphosate concentration in the substrate, and may allow support to this stress condition.

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 (K2Cr2O4) in soil. Pepper plants grown without Cr behaved as mycotrophic species. At the highest concentration (200 μM K2Cr2O4), 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.