Crescimento inicial e produção de óleo essencial de Corymbia citriodora (Hook.) em solo suplementado com lodo de esgoto e duas fontes de potássio
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Data
2020-02-28
Autores
Zabotto, Alessandro Reinaldo
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
O crescimento populacional urbano tem promovido aumento do volume de efluentes gerados pelas estações de tratamento de esgoto. Assim, se faz necessário práticas de reciclagem apropriadas para evitar contaminação do meio ambiente. A aplicação desses resíduos como insumos em plantios florestais apresenta-se como alternativa viável, com possível reflexo na produtividade. Desta forma este trabalho teve como objetivo determinar a viabilidade de sua aplicação, associado a doses e fontes de potássio no cultivo da espécie Corymbia citriodora. A suplementação do lodo de esgoto com fonte potássicas, justifica-se pelo baixo teor do nutriente na composição do resíduo. A hipótese central do estudo considera o potencial nutricional do resíduo no crescimento e desenvolvimento da cultura, além do efeito da sua suplementação com duas fontes e doses potássicas. O experimento foi conduzido em estufa agrícola por 150 dias nas estações de verão e outono. As mudas produzidas a partir de sementes em viveiro comercial, foram transplantadas para vasos com solo e doses equivalentes a 20 e 40 Mg ha-1 de lodo de esgoto e 60 e 120 Kg ha-1 das fontes KCl ou K2SO4. Ao final do período experimental, as plantas foram avaliadas quanto a parâmetros biométricos, atividade metabólica e parâmetros fisiológicos, além do rendimento e composição do óleo essencial das folhas. A aplicação do lodo de esgoto combinado com fontes e doses de potássio alterou todos parâmetros avaliados, quando comparado às plantas do tratamento controle. Em termos nutricionais, a atividade da enzima nitrato redutase foi reprimida em plantas do tratamento com a maior dose do resíduo, denotando efeito de redução na fixação assimilatória do nitrato. Igualmente, para esse tratamento, houve redução no rendimento de óleo essencial no tecido foliar, refletindo em menores teores de citronelal, seu componente principal. O teor de nutrientes em tecidos foliares, caule e raízes variaram em função dos tratamentos, com aumento considerável de macronutrientes, reflexo da alteração da fertilidade do solo. Concluiu-se que o uso do lodo de esgoto como insumo na cultura Corymbia citriodora favoreceu o crescimento inicial das plantas, sendo necessário à sua suplementação com fonte potássica. Desta forma, a melhor combinação para o desenvolvimento inicial da espécie sem prejuízos na produção de óleo essencial é a aplicação da dose de 20 Mg ha-1 de lodo de esgoto, suplementado com 120 kg ha-1 de K na fonte de KCl.
The urban population growth has promoted an increase on effluents volume generated by sewage treatment plants. Thus, appropriate recycling practices are necessary to avoid contamination of the environment. The application of these residues as inputs in forest plantations is a viable alternative, with possible effect on productivity. Thus, this study aimed to verify the viability of its application, associated with doses and sources of potassium in the cultivation of the species Corymbia citriodora. The supplementation of sewage sludge with potassium is justified by the low content of the nutrient in the waste composition. The central hypothesis of the study considers the nutritional potential of the residue in the growth and development of the crop, in addition to the effect of its supplementation with two sources and potassium doses. The experiment was carried out in an agricultural greenhouse for 150 days in the summer and autumn seasons. Seedlings produced from seeds in a commercial nursery were transplanted into pots with soil and doses equivalent to 20 and 40 Mg ha-1 of sewage sludge and 60 and 120 Kg ha-1 from sources KCl or K2SO4. At the end of the experimental period, the plants were evaluated for biometric parameters, metabolic activity and physiological parameters, in addition to the yield and composition of the essential oil in leaves. The application of sewage sludge combined with potassium sources and doses changed all evaluated parameters, when compared to the control treatment plants. In nutritional terms, the activity of the enzyme nitrate reductase was suppressed in treatment plants with higher doses of the residue, showing a reduction effect on the assimilation of nitrate fixation. Also, for this treatment, there was a reduction in the essential oil yield in the leaf tissue, reflecting in lower contents of citronellal, its main component. The nutrient content in leaf tissues, stem and roots varied depending on the treatments, with a considerable increase in macronutrients, reflecting the alteration of soil fertility. It was concluded that the use of sewage sludge as an input in the Corymbia citriodora culture favored the initial growth of the plants, being necessary for its supplementation with potassium source. Thus, the best combination for the initial development of the species without prejudice to the production of essential oil is the application of a dose of 20 Mg ha-1 of sewage sludge, supplemented with 120 kg ha-1 of K in the KCl source.
The urban population growth has promoted an increase on effluents volume generated by sewage treatment plants. Thus, appropriate recycling practices are necessary to avoid contamination of the environment. The application of these residues as inputs in forest plantations is a viable alternative, with possible effect on productivity. Thus, this study aimed to verify the viability of its application, associated with doses and sources of potassium in the cultivation of the species Corymbia citriodora. The supplementation of sewage sludge with potassium is justified by the low content of the nutrient in the waste composition. The central hypothesis of the study considers the nutritional potential of the residue in the growth and development of the crop, in addition to the effect of its supplementation with two sources and potassium doses. The experiment was carried out in an agricultural greenhouse for 150 days in the summer and autumn seasons. Seedlings produced from seeds in a commercial nursery were transplanted into pots with soil and doses equivalent to 20 and 40 Mg ha-1 of sewage sludge and 60 and 120 Kg ha-1 from sources KCl or K2SO4. At the end of the experimental period, the plants were evaluated for biometric parameters, metabolic activity and physiological parameters, in addition to the yield and composition of the essential oil in leaves. The application of sewage sludge combined with potassium sources and doses changed all evaluated parameters, when compared to the control treatment plants. In nutritional terms, the activity of the enzyme nitrate reductase was suppressed in treatment plants with higher doses of the residue, showing a reduction effect on the assimilation of nitrate fixation. Also, for this treatment, there was a reduction in the essential oil yield in the leaf tissue, reflecting in lower contents of citronellal, its main component. The nutrient content in leaf tissues, stem and roots varied depending on the treatments, with a considerable increase in macronutrients, reflecting the alteration of soil fertility. It was concluded that the use of sewage sludge as an input in the Corymbia citriodora culture favored the initial growth of the plants, being necessary for its supplementation with potassium source. Thus, the best combination for the initial development of the species without prejudice to the production of essential oil is the application of a dose of 20 Mg ha-1 of sewage sludge, supplemented with 120 kg ha-1 of K in the KCl source.
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Palavras-chave
Adubação orgânica, Resíduo urbano, Nutrição mineral, Fertilidade do solo, Organic fertilization, Urban waste, Mineral nutrition, Soil fertility