Among the most modern techniques of vegetables production cultivation in substrate is highlighted. In this method the substrate and the nutritive solution are main components that deliver nutrients to the crop and directly influence the performance of the plants. The objective of this study was to evaluate the reuse of substrate with several concentration of the nutritive solution in cultivation of tomato plants of the salad group 'Paronset'. The experimental design was a randomized blocks in a factorial scheme 3x5, with four replicates. The plants were grown in coconut husk fiber, in three substrate reuse levels (new substrate, reused once and reused twice) and five concentrations of the nutritive solution recommended for the culture [25%; 50%; 100% (original solution); 150% and 200%]. The chemical and physical characterization of the substrate after cultivation was done such as fruit productivity and quality and nutritional status of the plants. Physical characteristics were only influenced when substrate was reutilized. Chemical characteristics of the substrate were influenced by both the reuse of the substrate and the concentration of the nutritive solution. It was observed that the nutritional status of the plants was influenced only by the concentration of the nutritive solution. It was also noted that the productivity and fruit mass decreased after the second reuse of the substrate. The use of the original solution (100%) allowed the highest productivity; however, the largest fruit mass was obtained with the most dilute solution (25%).

This research was carried out aiming at evaluating the effects of nitrate and ammonium ions on nutrient accumulation, biochemical components and yield of Italian zucchini (cv. Caserta) grown in a hydroponic system under salt stress conditions. The experiment was carried out in a greenhouse utilizing an experimental design in randomized blocks, arranged in a 2 x 5 factorial scheme, with 4 replications. The treatments consisted of two forms of nitrogen (nitrate - NO3- and ammonium - NH4+) and 5 electrical conductivity levels of irrigation water (ECw) (0.5, 2.0, 3.5, 5.0 and 6.5 dS m-1). The analysis of the results indicated that supply of N exclusively in NH4+ form promotes greater damage to the leaf membrane and reduction in accumulation of macronutrients and higher Na+/K+, Na+/Ca++ and Na+/Mg++ ratios in the shoots of zucchini plants. Electrical conductivity of irrigation water above 2.0 dS m-1 reduces the accumulation of nutrients in shoot and yield of Italian zucchini plant. The toxicity of NH4+ under Italian zucchini plants overlap the toxicity of the salinity, since its fertilization exclusively with this form of nitrogen inhibits its production, being the NO3- form the most suitable for the cultivation of the species.

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RESUMO: O presente estudo foi conduzido em ambiente protegido do Departamento de Engenharia Agrícola da Universidade Federal de Campina Grande em Campina Grande com o objetivo de avaliar os efeitos de diferentes níveis de salinidade da água de irrigação sob a germinação e desenvolvimento inicial de porta enxertos de mangueira (Mangífera indica L.). O delineamento experimental adotado foi o inteiramente casualizado, em esquema fatorial 6x2, com quatro repetições e 13 plantas por unidade experimental. Os tratamentos consistiram de seis níveis de condutividade elétrica da água de irrigação-CEa (

RESUMO:Condições temporárias ou permanentes de alagamento ou encharcamento do solo são problemas que podem trazer sérios prejuízos para o desenvolvimento das culturas. O objetivo deste estudo foi investigar a resposta de diferentes velocidades de rebaixamento do nível freático sob a composição mineral do tecido foliar da cana-de-açúcar (Saccharum officinarum L., cv. RB867515) para diferentes estádios de desenvolvimento da planta. Um experimento em ambiente protegido foi conduzido em delineamento de blocos casualizados, arranjado em esquema fatorial (5 x 3 + 1) x 4, quais sejam, 5 velocidades de rebaixamento do nível freático (30 cm em 3, 6, 9, 12 e 15 dias) e 3 estádios de desenvolvimento (67, 210 e 305 dias após o plantio -DAP) + um tratamento controle (irrigação sem inundação do solo) com 4 repetições. A análise dos resultados indica que as velocidades de rebaixamentos do nível freático nos diferentes estádios de desenvolvimento não interferiu no acúmulo dos teores de macro e micronutrientes nas folhas das plantas de cana-de-açúcar enquanto que os períodos nos quais houve estresse pelo encharcamento interferiu nos teores dos macronutrientes cálcio e magnésio e dos micronutrientes manganês e zinco. PALAVRAS-CHAVE: drenagem, encharcamento, nível freático. MINERAL COMPOSITION OF SUGARCANE FOLIAR TISSUE UNDER FLOODING AND POSTERIOR DOWNGRADE RATE OF WATER TABLEABSTRACT: Temporary or permanent conditions of flooding or waterlogging of the soil are problems that can cause serious damages to the development of the crops. The objective of this study was to investigate the response of different downgrade rate of water table under the mineral composition of the sugarcane foliar tissue (Saccharum officinarum L., cv. RB867515) for different stages of plant development. A greenhouse experiment was conducted in a 1 Parte da tese do primeiro autor.