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.

RESUMO: Inoculação com fungos micorrízicos e adubação fosfatada no crescimento, produção de óleo essencial e absorção de nutrientes em hortelã-pimenta (Mentha piperita L.). Este estudo avaliou os efeitos da inoculação de fungos micorrízicos arbusculares Glomus mosseae, Glomus intraradices A 4 e Glomus intraradices B 1 e duas doses de fósforo (10 e 40 mg kg -1 ) sobre a colonização radicular, crescimento, absorção de nutrientes e óleos essenciais em Mentha piperita L. O estudo foi conduzido em casa de vegetação no delineamento inteiramente casualizado em esquema fatorial 4x2. Sessenta dias após o transplantio, as plantas micorrizadas apresentaram massa fresca, massa seca, e área foliar significativamente maior em comparação as não-micorrizadas. A inoculação aumentou o teor de P, K e Ca na parte aérea sendo superiores em 40 mg P kg -1 de solo. As plantas cultivadas com 40 mg P kg -1 de solo aumentaram a produção de óleo essencial por planta cerca de 40-50% em relação às cultivadas com 10 mg de P kg -1 , independentemente da micorrização. Dentre as espécies fúngicas estudadas, a inoculação com G. Intraradices A 4 e com um elevado nível de P, aumentou significativamente o crescimento e rendimento de óleos essenciais em comparação com outras espécies de fungos micorrízicos estudados. Em conclusão, a inoculação dos fungos micorrízicos arbusculares em plantas de hortelã é uma alternativa viável para aumentar a produção de óleos essenciais e reduzir o uso de fertilizantes necessários para a produção econômica de hortelã-pimenta com deficiência de fósforo no solo. Palavras-chave: adubação fosfatada, Glomus mosseae, Glomus intraradices, Mentha piperita, óleo essencialABSTRACT: This study evaluated the effects of inoculation with the arbuscular mycorrhizal fungi Glomus mosseae, Glomus intraradices A 4 and Glomus intraradices B 1 and two phosphorus levels (10 and 40 mg kg -1 ) on root colonization, plant growth, nutrient uptake and essential oil content in Mentha piperita L. The experiment was carried out in a greenhouse, in 4x2 factorial arrangement, in completely randomized design. At sixty days after transplanting, the mycorrhizal plants had significantly higher fresh matter, dry matter and leaf area compared to non-mycorrhizal plants. The inoculation increased P, K and Ca levels in the shoot which were higher under 40 mg P kg -1 of soil. Plants grown with 40 mg P kg -1 soil increased the essential oil yield per plant by about 40-50% compared to those cultivated with 10 mg P kg -1 , regardless of the mycorrhizal treatment. Among the studied fungal species, inoculation with G. intraradices A 4 and a high level of P significantly increased plant growth and essential oil yield, compared to the other studied mycorrhizal fungal species. In conclusion, inoculation of arbuscular mycorrhizal fungi into peppermint plants is a feasible alternative to increase the essential oil production and reduce the use of fertilizers required to obtain economic production of peppermint under phosphorus-deficient soil condition.

Water deficits cause large yield losses in wheat. Although anthesis is generally considered the most vulnerable period, water deficit during grain filling can also cause yield losses. The objective of this study was to investigate the effect of water stress and rewatering, at three different grain developmental stages, on physiological and grain filling parameters and on yield components. Wheat plants were subjected to water deficit and rewatering at the watery ripe, milk and soft dough stages. In the flag leaf, water stress decreased the relative water content, the chlorophyll and protein content and increased the leakage of solutes, at all three studied grain filling stages. Water stress at the watery ripe and milk stages reduced the final grain dry mass by 47 % and 20 %, respectively. This reduction was due to a decrease in the grain filling period and to a significant reduction in the maximum rate of grain-fill. Water stress imposed at the watery ripe stage reduced not only the linear growth phase but also its slope; grain number per spike and the 1000-kernel weight were also significantly reduced. SDS-PAGE patterns of grain proteins at the watery ripe stage did not differ between the controls, stressed or rewatered treatments. Protein patterns at the milk stage changed substantially with water stress, mainly for the high molecular weight glutenin subunits and ω gliadins. Three new bands were observed with apparent molecular weights of 108.5 kDa, 84.8 kDa and 63 kDa. Rewatering reverted water stress effects when it was imposed at the milk stage. Water deficit at the soft dough stage did not have any effect on protein grain patterns. Key words: grain filling, growth rate, logistic model, protein profile, water stress.O estresse hídrico e a reidrataçao aplicados em três estàgios de desenvolvimento dos gräos afetam diferentemente o crescimento e a deposiçao das proteinas dos gräos em trigo (Triticum aestivum L.): O estresse hídrico provoca na cultura do trigo grandes perdas de rendimento. Apesar da antese ser considerada, geralmente, a fase mais vulnerável, o déficit hídri-co durante todo o período de preenchimento também pode provocar perdas na produtividade da cultura. O objetivo do presente estudo foi pesquisar o efeito do estresse hídrico e da reidratação durante três estágios, no desenvolvimento do grão de trigo, sob diferentes parâmetros fisiológicos e do preenchimento dos grãos, e sob os componentes do rendimento. As plantas foram submetidas ao estresse hídrico e reidratação durante as fases de grão aquoso, leitoso e pastoso. O estresse hídri-co reduziu o conteúdo relativo d' água, o conteúdo da clorofila e das proteínas nas folhas bandeiras e aumentou a liberação dos solutos, nos três estádios do grão estudados. O estresse produzido durante os estádios aquoso e leitoso reduziu o peso final dos grãos em 47 % e 20 %, respectivamente. Essa redução foi devida a um encurtamento do período de preenchimento e a uma significativa diminuição na taxa máxima de preenchimento dos grãos. O estresse hídrico no estádi...

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