In agriculture practiced in Brazil, the branch of the horticulture is one of the prominences, in production and in exportation, being melon one of the more produced fruits, especially in Brazil¿s northeast. In this context, the use of a good quality substrate is essential for the development of the plants. In this study it was evaluated the growth of melon seedlings and the role of Arbuscular Mycorrhizal Fungi (AMF),Glomus clarum, associated to the use of coconut dust, as an alternative substrate, at 100, 80, 60, 40, 20, 10 and 0% concentrations, as a soil mixture (grayish Argissol). The plants were cultivated under greenhouse conditions and, at the end of a 35 days period, were analyzed the diameter of the stem, number of leaves, height of plants, shoot dry weight, microbial biomass carbon content, basal soil respiration, metabolic quotient, colonization with AMF and shoot nutrient content (N, P, K, Ca and Mg). It was observed that 100% and 80% concentration of coconut dust were the more restrictive treatments for plant development. Microbial carbon and mycorrhizal colonization were higher when the substrate was composed by 10 and 20% of coconut dust. The basal soil respiration and the metabolic quotient (2,07) were higher when 100% coconut dust was used, while the smallest value (0, 96) was found in treatment without coconut dust. The use of concentrations higher than 40% of coconut dust decreased AMF activity and growth of the melon plants.

The tebuthiuron residue, used in the sugar-cane culture, can be found in soil until two or more years after its application. Recent researches are being done using the phytoremediation in the attempt of removing it from the soil. The purpose of this work was to evaluate the effectiveness of the green manure use in the phyitoremediation of the tebuthiuron herbicide. The evaluated species were: Cajanus cajan, Canavalia ensiformis, Dolichos lablab, Pennisetum glaucum, Estizolobium deeringianum, Estizolobium aterrimum and Lupinus albus. These were sown and cultivated in pots containing soil treated with different doses of tebuthiuron (0.0; 0.5; 1.0; and 1.5 kg.ha-1). A control treatment without green manure, submitted to the same dosages, was kept. Sixty days after planting, green manure aerial part of all plants were harvested and soybean was sowed in the same pot, to bioassay accomplishment. Sixty days after sowing, the soybean plants were harvested, being the following evaluations carried out: height of plants, phytotoxicity symptoms and plants above ground dry biomass and leaf area. Until 0.5 kg.ha-1 tebuthiuron dosage, the species that better phytoremediated this herbicide was L. albus. When the soil was treated with tebuthiuron at 1.0 kg.ha-1, the C. ensiformis, followed by L. albus and S. aterrimum, they were the treatments that better phytoremediated tebuthiuron because results in highest plant height, above ground dry biomass and lesser phytotoxicity symptoms and still the biggest foliar area of the soybean plants. When the tebuthiuron was applied at 1.5 kg ha-1 dosage, it was impossible to evaluate the phyitoremediation, as the tested plants were eliminated.

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