Cultivo de pimentão em sistema hidropônico com água de reúso em diferentes níveis de disponibilidade de água no substrato
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Data
2019-02-01
Autores
Carvalho, Renata da Silva Cuba de
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Universidade Estadual Paulista (Unesp)
Resumo
O interesse em aplicar águas residuárias na agricultura tem sido crescente, pelo fato de representarem uma fonte alternativa de água e nutrientes para as culturas. Além disso, há a necessidade de buscar sistemas de produção que proporcionem o uso mais eficiente da água. Neste contexto, esta pesquisa foi desenvolvida com o intuito de cultivar o pimentão (Capsicum annuum L.) e determinar o seu desenvolvimento vegetativo, fisiológico, estado nutricional e produção, em sistema hidropônico utilizando substrato fibra da casca de coco e água de reúso para preparar a solução nutritiva, além de realizar a reposição dessa solução nutritiva no substrato em diferentes percentuais da evapotranspiração da cultura (100, 75 e 50%), medida através de lisímetros de lençol freático constantes. As plantas foram cultivadas em vasos de polietileno, com volume de 15 litros, preenchidos com fibra de coco de granulometria fina, com distribuição da solução nutritiva através de um sistema de irrigação por gotejamento. O delineamento experimental envolveu dois fatores, tipos de água (potável e reúso) e lâminas de reposição de solução nutritiva no substrato (100, 75 e 50% da evapotranspiração da cultura), distribuídos inteiramente ao acaso com dez repetições, totalizando 60 parcelas. O manejo da irrigação foi feito a partir de medições diretas da evapotranspiração da cultura em três lisímetros de lençol freático constante. Avaliou-se a altura e o diâmetro da base caulinar das plantas a cada 30 dias, ao longo do período experimental. Aos 115 dias após o transplante, fez-se as análises fisiológicas de trocas gasosas e fluorescência da clorofila a, e também a coleta de amostras de folhas e frutos de cada planta para determinação dos teores de nutrientes. Os frutos foram colhidos verdes, semanalmente a partir dos 80 dias após o transplante. Ao final do cultivo determinou-se altura e diâmetro final, massa fresca e seca da parte aérea. As plantas cultivadas nos lisímetros também foram submetidas as mesmas avaliações dos tratamentos. Após a colheita das plantas foram coletadas amostras do substrato e feito a caracterização química e física. Os lisímetros de lençol freático constantes proporcionaram desenvolvimento satisfatório para a cultura do pimentão, podendo ser usados para medir a evapotranspiração da cultura. A água de reúso associada a lâmina de 100% da evapotranspiração proporcionaram aumento na taxa de assimilação e concentração interna de CO2. As lâminas de 75% e 50% da evapotranspiração da cultura reduziram as trocas gasosas, o coeficiente de extinção fotoquímico e a taxa de transporte de elétrons. O desenvolvimento vegetativo, os teores foliares e a produção da cultura não foram alterados para os tratamentos cultivados com água de reúso, mostrando-se tecnicamente viável para esta finalidade. A reposição de solução nutritiva através da evapotranspiração da cultura proporcionou aumento no substrato dos teores de nutrientes, condutividade elétrica, CTC do substrato e densidade, sendo os maiores valores para os tratamentos cultivados com solução nutritiva preparada com água de reúso.
The interest in utilizing wastewater in agriculture has increased because it represents an alternative source of water and nutrients for crops. Furthermore, there is a need to seek production systems that can provide the most efficient usage of water. In this context, the object of the present research is to cultivate bell peppers (Capsicum annuum L.) and determine its vegetative, physiological, nutritional status and production development in a hydroponic system using as a substrate coconut shell fiber and recycled water to prepare the nutrient solution, as well as replenishing such nutrient solution in the substrate in different percentages of crop evapotranspiration (100, 75 and 50%), measured by constant water table lysimeters. The plants were cultivated in 15 liter polyethylene pots, filled with coconut fiber resulted from granulometry of fine aggregates with distribution of the nutrient solution through a drip irrigation system. The experimental design involved two factors, water types (potable and recycled) and nutrient solution replacement leaf blades into the substrate (100, 75 and 50% of crop evapotranspiration), randomly distributed with ten replications, totaling 60 plots. Irrigation management was based on direct measurements of the crop evapotranspiration in three lysimeters of constant water table. The height and diameter of the plants stem base were evaluated every 30 days, during the experimental period. On the 115th day after transplantation, the physiological analyzes of gas exchange and fluorescence of chlorophyll “a” were carried out, as well as the collection of leaf and fruit samples from each plant to determine nutrient contents. At the end of the crop, it was determined the height and final diameter, fresh and dry mass of the aerial part. The plants grown in the lysimeters were also submitted to the same treatments evaluations. After the plants were harvested, samples of the substrate were collected and the chemical and physical characterization was done. The constant water table lysimeters provided satisfactory development for the pepper crop, and can be used to measure crop evapotranspiration. The recycled water associated to the 100% evapotranspiration blade, provided an increase in the rate of assimilation and internal CO2 concentration. The 75% and 50% blades of the crop evapotranspiration reduced the gas exchange, the photochemical extinction coefficient and the rate of electron transport. The vegetative development, foliar contents and crop production were not altered for the treatments cultivated with reuse water, proving to be technically feasible for this purpose. The nutrient solution replacement through crop evapotranspiration provided an increase in nutrient content, electrical conductivity, substrate cationic capacity and density, and the highest values for treatments cultivated with nutrient solution prepared with recycled water.
The interest in utilizing wastewater in agriculture has increased because it represents an alternative source of water and nutrients for crops. Furthermore, there is a need to seek production systems that can provide the most efficient usage of water. In this context, the object of the present research is to cultivate bell peppers (Capsicum annuum L.) and determine its vegetative, physiological, nutritional status and production development in a hydroponic system using as a substrate coconut shell fiber and recycled water to prepare the nutrient solution, as well as replenishing such nutrient solution in the substrate in different percentages of crop evapotranspiration (100, 75 and 50%), measured by constant water table lysimeters. The plants were cultivated in 15 liter polyethylene pots, filled with coconut fiber resulted from granulometry of fine aggregates with distribution of the nutrient solution through a drip irrigation system. The experimental design involved two factors, water types (potable and recycled) and nutrient solution replacement leaf blades into the substrate (100, 75 and 50% of crop evapotranspiration), randomly distributed with ten replications, totaling 60 plots. Irrigation management was based on direct measurements of the crop evapotranspiration in three lysimeters of constant water table. The height and diameter of the plants stem base were evaluated every 30 days, during the experimental period. On the 115th day after transplantation, the physiological analyzes of gas exchange and fluorescence of chlorophyll “a” were carried out, as well as the collection of leaf and fruit samples from each plant to determine nutrient contents. At the end of the crop, it was determined the height and final diameter, fresh and dry mass of the aerial part. The plants grown in the lysimeters were also submitted to the same treatments evaluations. After the plants were harvested, samples of the substrate were collected and the chemical and physical characterization was done. The constant water table lysimeters provided satisfactory development for the pepper crop, and can be used to measure crop evapotranspiration. The recycled water associated to the 100% evapotranspiration blade, provided an increase in the rate of assimilation and internal CO2 concentration. The 75% and 50% blades of the crop evapotranspiration reduced the gas exchange, the photochemical extinction coefficient and the rate of electron transport. The vegetative development, foliar contents and crop production were not altered for the treatments cultivated with reuse water, proving to be technically feasible for this purpose. The nutrient solution replacement through crop evapotranspiration provided an increase in nutrient content, electrical conductivity, substrate cationic capacity and density, and the highest values for treatments cultivated with nutrient solution prepared with recycled water.
Descrição
Palavras-chave
Capsicum annuum L., Efluente, Solução nutritiva, Evapotranspiração, Fibra de coco, Effluent, Nutritional solution, Evapotranspiration, Coconut fiber