Black pepper (Piper nigrum) – Arachis pintoi intercropping system in the Central Highlands in Vietnam: Impact on the soil fertility and the diversity of native rhizobia

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van Nguyen, Long | Herrmann, Laetitia | Enez, Aydin | Brau, Lambert | Lesueur, Didier

Edité par CCSD -

International audience. Vietnam is leading the growth of black pepper worldwide, accounting for more than one-third of the globalproduction. However, this is achieved by the intensive use of chemical fertilizers and pesticides, causingpollution to the environment and reduction of soil health. Overall, it favors the development of soil-bornepathogens, such as Fusarium, Phytophthora, and Pythium/Phytopythium. Arachis pintoi is a legume that cancontribute to biological nitrogen fixation (BNF), due to its symbiosis with rhizobia. It is widely planted as acover crop to reduce soil erosion, suppress weeds, control several pests and soil-borne diseases. Forinstance, in Vietnam, A. pintoi has been intercropped with black pepper to enhance soil health and sustainthe yield. However, its impacts on reducing weeds, pests and soil-borne pathogens remain largely unknown.Meanwhile, limited information is available about the rhizobia nodulating A. pintoi in Vietnam.In this study, we investigated the impact of A. pintoi intercropped in black pepper plantations in Gia Lai andDak Lak provinces in the Central Highlands in Vietnam. Soil samples were analyzed, and the results showedthat plantations intercropped with A. pintoi significantly improved the total nitrogen. Besides, nodules of A.pintoi from these provinces were collected and screened for their rhizobial strains. The intergenic spacer(IGS 16-23S) region of the rhizobial DNA was amplified by PCR, and restriction was digested with twoenzymes (MspI and HaeIII) to group rhizobia based on their restriction profiles. During the initial phase ofour project, 38 strains have been isolated from 108 nodules and grouped into 13 different groups. Theobjective is to identify elite strains associated with A. pintoi and to formulate effective rhizobial inoculants toallow effective BNF by this legume, hence, reducing the need for fertilizer inputs, and assisting in soil healthrestoration of black pepper plantations

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