Metabolismo primário e desenvolvimento de feijão-caupi (Vigna unguiculata) em resposta à inoculação com fungos micorrízicos arbusculares

Abstract

Arbuscular mycorrhizal fungi (AMF) are soil microorganisms that contribute to the development and growth of plants by symbiosis, also participate in the formation and assist in the stability of soil aggregates. The use of AMF in crops can decrease the need for fertilizers, reducing production costs. Because they increase the area of absorption and uptake of essential nutrients such as phosphorus and transfer them to plants, receiving carbohydrates in return. Cowpea is mostly benefited by symbiosis with AMF, but some cultivars have shown several responses (positive or null) to mycorrhizal inoculation. For Cultivar Miranda IPA 207, there is no study on its response to inoculation. In order to determine the effects of mycorrhizal association on growth, development and primary metabolism of cowpea (Miranda IPA 207), the following data were evaluated: plant height, stem diameter, shoot dry mass (MSPA) and concentration of primary metabolites (carbohydrates, amino acids, proteins, chlorophylls, and carotenoids) after inoculation with AMF: Acaulospora longula URM-FMA 07, Claroideoglomus etunicatum URM-FMA 03, and Gigaspora albida URM-FMA 11. The height, stem diameter, and MSPA of the inoculated plants did not differ from the control, except the plants inoculated with G. albida, which had smaller diameter and MSPA. Plants inoculated with C. etunicatum had lower carbohydrate and chlorophyll concentration than control. The concentration of amino acids and proteins was lower in all AMF inoculated treatments, while the carotenoid content was lower in A. longula and C. etunicatum inoculated plants compared to control plants. The absence of positive results in plants due to mycorrhizal inoculation may be associated with a possible impact on the native mycorrhizal community after the introduction of exotic fungi, directly interfering with the growth of the tested cultivar. These results demonstrate the need to verify the response of cultivars to greenhouse inoculation in order to know the feasibility of inoculation practice before field application since the expected results may not be the ones achieved. It was concluded that the inoculated AMF did not contribute more than the AMF present in the natural soil in increasing the performance of cowpea plants (Miranda IPA 207).