Caracterização qualitativa de castanha-do-Brasil (Bertholletia excelsa H. B. K) nativa e enxertada

Abstract

fruits, fallen in the soil in the middle of a forest. The native chestnut trees begin their fruiting after 8 years, and can reach heights up to 60 m. In order to make the cultivation of the nut more productive and to allow control at the time of harvest, some producers have invested in the system of nut production by grafting in open areas. In this system there is an expressive reduction of the height of the trees, and with 3,5 years the production starts. In spite of the importance, little is known about the quality of the product produced by grafting, in this sense, the aim of this work was to evaluate the characteristics of Brazil nut produced under grafting comparing with the native chestnut by means of physical, chemical analyzes and sanitary. Samples of the native fruits were obtained with chestnut trees from the municipality of Itaúba - MT, and samples of chestnut grafted on property located in the municipality of Santa Carmem - MT. After collection, the samples were stored under refrigeration until the preparation and analysis. The following hedgehog variables were determined: size and shape (circularity, sphericity, volume) calculated from the three characteristic dimensions obtained with pachymeter (0.01 mm) and the weight of the hedgehog in a semi analytical balance. After the breakage of the hedgehogs, seed counting and weighing were performed. From the seeds, the water content was determined, by direct method, in a greenhouse with forced circulation of air, at 95 ºC for six hours. Seeds and almonds were then prepared for determination of the variables: size and shape, individual mass of the nut in analytical balance (0.01 g); real density by the Archimedes principle; porosity by the volume complementation method; bulk density indirectly calculated by that of the relation between unit specific mass and porosity; mass of 100 seeds according to recommendations in Brazil (2009); color of the seeds and almonds, obtained by means of the coordinates L *, a * and b * measured with the aid of a tristimulus colorimeter; identification of fungi by the blotter test, and to evaluate the chemical composition, it was estimated: ashes content by calcination; oil content by the Goldfisch method; protein content by the Kjeldahl method and the digester block. The data were submitted to analysis of variance (5% F test) and the means were compared by the Tukey test at 5% probability. The main results are that: the native hedgehog is more circular; the nut produced under grafting has a higher yield and the almonds have a larger volume and size than the native one; in relation to the format, one has the more regular native nut, that is, with values of greater circularity and sphericity; the mass of 100 grained chestnut almonds is practically double the native chestnut; the nuts produced by grafting are little darker than the native ones. In relation to fungal infestation, it was verified that the grafted chestnut has a higher incidence. The main genotypes of fungi found in Brazil nuts, for both cropping systems, were: Fusarium, Rhizopus, Aspergillus, Penicillium and Cercospora. The oil content of the grafted chestnut is higher than that of the native one.