CRESCIMENTO, PRODUÇÃO E CONSUMO HÍDRICO DO QUIABEIRO SUBMETIDO À SALINIDADE EM CONDIÇÕES HIDROPÔNICAS     FRANCISCO JOSÉ NUNES MODESTO1; MARIA ÂNGELA CRUZ MACÊDO DOS SANTOS1; TALES MILER SOARES2 E ELLEN PAULA MENEZES DOS SANTOS3   1 Engenheiro Agrônomo, Mestre em Engenharia Agrícola, Universidade Federal do Recôncavo da Bahia, Núcleo de Engenharia de Água e Solo, Rua Rui Barbosa, S/N, Cruz das Almas-BA, CEP 44.380-000, e-mail: fjmodesto@gmail.com; angela_macedo.08@hotmail.com 2 Engenheiro Agrônomo, Prof. Doutor, Universidade Federal do Recôncavo da Bahia, Núcleo de Engenharia de Água e Solo, Rua Rui Barbosa, S/N, Cruz das Almas-BA, CEP 44.380-000, e-mail: talesmiler@gmail.com 3 Graduanda em Engenharia Agronômica na Universidade Federal do Recôncavo da Bahia, Núcleo de Engenharia de Água e Solo, Rua Rui Barbosa, S/N, Cruz das Almas-BA, CEP 44.380-000, e-mail: ellenpaulamenezes@gmail.com     1 RESUMO   Pesquisas têm sido conduzidas com uso de águas salobras em cultivos hidropônicos e são estratégicas para o aproveitamento racional dessas águas. Nesse contexto surge o interesse em se pesquisar culturas que estão na demanda dos consumidores, como é o caso do quiabeiro. Objetivou-se com o presente trabalho analisar o consumo hídrico, o crescimento, a produção e a qualidade do quiabeiro, submetido a diferentes níveis de condutividade elétrica em sistema hidropônico. O quiabeiro foi submetido a sete níveis de condutividade elétrica da solução nutritiva (CEsol 2,08; 4,47; 7,90; 9,46; 12,84; 14,82; 18,61 dS m-1). Aos 85 dias após o transplantio foi avaliado o consumo hídrico, eficiência do uso da água (EUA), o crescimento vegetativo, a produção, a qualidade do fruto e o índice de tolerância do quiabeiro. Para a determinação da tolerância à salinidade foi utilizado, dentre outros, o modelo de platô com redução exponencial. A área foliar e o número de folhas foram as variáveis do crescimento mais afetadas com o incremento da CEsol. A EUA teve seu máximo de 7,81 Kg m-3 para a CEsol de 7,08 dS m-1. A salinidade limiar encontrada foi de 5,43 dS m-1. O aumento da CEsol até 18,61 dS m-1 não afetou a qualidade do fruto.   PALAVRAS CHAVE: Condutividade elétrica, Abelmoschus esculentus L. (Moench), qualidade da água, cultivo hidropônico.     MODESTO, F. J. N.; SANTOS, M. A. C. M. dos; SOARES, T. M.; SANTOS, E. P. M. dos GROWTH, PRODUCTION AND WATER CONSUMPTION OF  OKRA SUBJECTED TO SALINITY UNDER HYDROPONIC CONDITIONS     2 ABSTRACT   Researches have been conducted using brackish water in hydroponic crops and are strategic for the rational use of these waters. In this context the interest arises in researching cultures that are in the demand of the consumers as it is the case of the okra. The objective of this work was to analyze  water consumption, growth, production and quality of  okra submitted to different levels of electrical conductivity in a hydroponic system. Okra trees were submitted to seven levels of electrical conductivity of the nutrient solution (ECsol 2.08, 4.47, 7.90, 9.46, 12.84, 14.82, 18.61 dS m-1). At 85 days after transplanting, water consumption, water use efficiency (WUE), vegetative growth, yield, fruit quality and tolerance index of okra were evaluated. For determination of tolerance to salinity was used, among models, the plateau model with exponential reduction. Leaf area and number of leaves were the growth variables most affected with the increment of ECsol.  WUE had its maximum of 7.81 kg m-3 for ECsol of 7.08 dS m-1. Threshold salinity found was 5.43 dS m-1. ECsol increase up to 18.61 dS m-1 did not affect fruit quality.   Keywords: Eletrical conductivity, Abelmoschus esculentus L. (Moench), water quality, soilless cultivation.

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The Brazilian semiarid is historically characterized by the water scarcity of good-quality. In this region there is great availability of groundwater reserves, however, these waters has high concentrations of dissolved salts, that makes them inappropriate to be used in the irrigation of most crops. The objective of this study was to evaluate the growth, production and salinity tolerance of three cauliflower cultivars in hydroponics NFT (Nutrient Film Technique), subjected to different electrical conductivities of the nutrient solution (ECsol) prepared with saline water. The experiment was carried out in a randomized blocks design in split-plot, with six replications. The plants were subjected to six levels of ECsol (1.94 - control, 3.24, 4.10, 5.04, 5.92 and 7.01 dS m-1) in the main plots, with three cauliflower cultivars (‘Piracicaba de Verão’, ‘Sabrina’ and ‘SF1758’) in the subplots, which were grown in the same hydroponic channel. Vegetative growth, inflorescence production and salinity tolerance of cultivars were evaluated. In general, except for the number of leaves, leaf width and fresh matters of leaves and shoot, the different ECsol levels negatively influenced the vegetative growth and inflorescences yield of cultivars cauliflower. The cultivars ‘Piracicaba de Verão’ and ‘Sabrina’ were considered moderately sensitive to salinity, while cultivar ‘SF1758’ was moderately tolerant to salinity.

Most commercial citrus varieties are intolerant of salinity stress, but some rootstocks, such as Rangpur lime, tolerate moderately saline irrigation water. Development of salinity-tolerant citrus may allow for citriculture in semiarid and arid regions where salinity stress is problematic. Because salinity stress influences shoot growth in citrus, we compared the behavioral responses of Asian citrus psyllid, Diaphorina citri Kuwayama, to salinity-stressed versus nonstressed Rangpur lime seedlings. The effects of salinity stress on key physiological processes in the seedlings were also examined. Seedlings in the control group were fertilized with a solution having a salinity of 1.7 dS m−1 while seedlings in the salinity-stressed group were fertilized with a solution having a salinity of 10 dS m−1. The seedlings were exposed to salinity stress for increasing durations (15, 20, or 60 d). Seedlings presented differential physiological responses 15 d after the imposition of salinity stress, and differences in psyllid settling rate on control versus salinity-stressed seedlings were discernable within 1 h following the imposition of salinity stress. The levels of settling, oviposition, and egg survivorship were significantly lower on salinity-stressed versus control seedlings. Olfactometer tests showed that female psyllids preferred the odor from control seedlings, suggesting that the odors of control and salinity-stressed seedlings were different. The results showed that D. citri avoids salinity-stressed seedlings; this suggests the possibility of using moderate salinity stress as a management strategy to minimize psyllid settlement and reproduction and to reduce the spread of huanglongbing, especially in citrus grown in semiarid and arid areas.

The knowledge of water consumption and the efficiency of water use by crops is extremely important in the elaboration of agronomic and hydraulic projects of hydroponic systems. Thus, the present study determined the water consumption and water use efficiency of ‘Biquinho’ pepper cultivated in the hydroponic system using seven levels of electrical conductivity of the nutrient solution (ECsol) of 2.70, 3.64, 4.58, 5.28, 6.09, 6.90, and 7.77 dS m-1 and six replicates in randomized blocks. The hydroponic system used was the Nutrient Film Technique (NFT). The water consumption per plant was determined at an interval of ten days in the crop cycle (120 days after transplanting). The maximum mean daily water consumption was equal to 5.88 L plant-1 during the period 111-120 DAT, for ECsol of 4.58 dS m-1. The maximum water consumption for the crop cycle (120 DAT) was 275.66 L per plant for an estimated ECsol = 4.11 dS m-1. The highest water use efficiency (WUE), based on the total production of fruit fresh mass (ripe and unripe fruits) of ‘Biquinho’ pepper was 10.84 kg m-3 up to an estimated ECsol of 5.18 dS m-1, with an exponential reduction thereafter. The salinity of the nutrient solution, biomass production, and evapotranspiration are factors that influence the most water consumption of ‘Biquinho’ pepper.