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The tomato cultivation in the Amazon is not feasible mainly due to the natural infestation of Ralstonia solanacearum in the soil. Preventive control through grafting has been one of the main alternatives to manage this problem. This study aimed to evaluate the compatibility of Solanaceae genotypes as rootstocks for 'Santa Clara' tomato, aiming to control the bacterial wilt. Five rootstocks were evaluated: cubiu; red jurubeba; jurubebão; commercial hybrid tomato rootstock Guardião; and 'Santa Clara' tomato (self-grafting). In the seedling phase, characteristics of rootstock survival rate and compatibility were evaluated; while, in the field, that happened for survival rate, compatibility and fruit yield. In the seedling phase, Guardião and red jurubeba showed the best performances. In the field, red jurubeba presented a low compatibility, although it obtained the best productive performance among the wild rootstocks. Guardião obtained the best compatibility and yield among the studied rootstocks. Grafting is a viable technique for tomato production under soil-borne disease conditions.

RESUMOO presente estudo teve como objetivo realizar um levantamento das propriedades químicas do solo submetido a diferentes tipos de uso: cultivo de cacau, sistema agroflorestal e pastagem. As coletas foram realizadas no primeiro semestre de 2016 na comunidade Recreio, que faz parte da zona III do Município de Almeirim, no estado do Pará. Foram coletadas 13 amostras retiradas aleatoriamente em ziguezague a uma profundidade de 20 cm, abrangendo toda a área. A partir dos resultados, foram observadas diferenças importantes entre as áreas com as práticas tradicionais e com atividades conservacionistas, com destaque para o sistema agroflorestal.

This research aimed to study the effects of the nanosilica supply on Si absorption and the physiological and nutritional aspects of beet plants with N and P deficiencies cultivated in a nutrient solution. Two experiments were performed with treatments arranged in a 2 × 2 factorial scheme in randomized blocks with five replications. The first experiment was carried out on plants under a N deficiency and complete (complete solution with all nutrients), combined with the absence of Si (0 mmol L−1) and the presence of Si (2.0 mmol L−1). In the other experiment, the plants were cultivated in a nutrient solution with a P deficiency and complete, combined with the absence (0 mmol L−1) and the presence of Si (2.0 mmol L−1). The beet crop was sensitive to the N and P deficiencies because they sustained important physiological damage. However, using nanosilica via fertigation could reverse the damage. Using nanotechnology from nanosilica constituted a sustainable strategy to mitigate the damage due to a deficiency in the beet crop of the two most limiting nutrients by optimizing the physiological processes, nutritional efficiency, and growth of the plants without environmental risks. The future perspective is the feasibility of nanotechnology for food security.

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