Effect of potassium sources on the antioxidant activity of eggplant¹

Abstract

SUMMARYPotassium participates in the essential processes in plant physiology, however, the effects of K sources on plant metabolism have been little studied. Also, in certain cases, K sources and concentrations may cause undesirable effects, e.g., soil salinization. The objective was to evaluate the effect of K sources and levels on the enzyme activity of the antioxidant system and protein content in eggplant (Solanum melongena L.) leaves and to determine the most suitable K sources for these physiological characteristics. The experiment was conducted in randomized blocks, in a 2 × 4 factorial design, consisting of two K sources (KCl and K 2 SO 4 ) and rates (250, 500, 750, and 1000 kg ha -1 K 2 O), with four replications. The following variables were evaluated: plant height, number of leaves per plant, superoxide dismutase (SOD), catalase (CAT), and leaf protein content. There was an increase in CAT activity with increasing K levels until 30 days after transplanting (DAT), when K 2 SO 4 was applied and until 60 DAT, when KCl was used; after this period, the enzyme activity decreased under both sources. The activity of SOD increased in the presence of KCl, but was reduced with the application of K 2 SO 4 . For both K sources, increasing rates reduced the protein content and number of leaves per plant, and this reduction was greater under KCl application. Thus it was concluded that KCl tends more strongly to salinize the soil than K 2 SO 4 . Both for KCl and for K 2 SO 4 , the increasing rates adversely affected the activities of CAT and SOD and the levels of leaf protein in eggplant. The potential of KCl to reduce the enzyme activity of SOD and CAT, leaf protein content and plant growth of eggplant was stronger than that of K 2 SO 4 .Index terms: Solanum melongena L., potassium, superoxide dismutase, catalase, protein.(1) Part of the Master's thesis of the first author. Received for publication on October 2, 2013 and approved on July 25, 2014. O potássio participa dos processos essenciais na fisiologia da planta; contudo, os efeitos de fontes potássicas no metabolismo das plantas têm sido pouco estudados. Além disso, diferentes fontes e concentrações de K podem levar a efeitos indesejados como a salinização do solo. Dessa forma, objetivou-se avaliar o efeito de fontes e doses de K sobre a atividade de enzimas do sistema antioxidante e o teor de proteínas em folhas de berinjela, bem como qual das fontes de K pode ser mais adequada em razão dessas características fisiológicas (Solanum melongena L.). O experimento foi conduzido em blocos casualizados e esquema fatorial 2 × 4, sendo os fatores duas fontes (KCl e K 2 SO 4 ) e doses de K (250, 500, 750 e 1000 kg ha -1 de K 2 O), com quatro repetições. As variáveis avaliadas foram: altura das plantas, número de folhas por planta, atividade da superóxido dismutase (SOD), catalase (CAT) e teor foliar de proteína. Observou-se aumento na atividade da CAT com a elevação das doses de K até os 30 dias após o transplante (DAT) para K 2 SO 4 e até 60 DAT para KCl; após esse pe...

Fertilization with Silicon in Sweet Pepper Improved Plants Grown under Salt Stress

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Production of groups of tomatoes in substrate at different concentrations of phosphorus

“…Although irrigation water in protected crops is of good quality, the addition of fertilizers, when using the fertigation technique, makes it saline, increasing the risk of salinization, especially potassium chloride, which has high salinity (Marques et al, 2014). This conclusion is confirmed by Fontes et al (2004), which reports the accumulation of salts, the presence of soil pathogens and allopathic substances, as a limiting factor for the tomato crop economy.…”

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Qualidade físico-química de farinhas de genótipos de berinjela (Solanum melongena L.) submetidas ao cultivo orgânico

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