Resumo

HERNANDEZ, R et al. Antioxidative protection of humic acids extracted from vermicompost in rice (Oryza sativa L.) var. IACuba30. Rev. Protección Veg. [online]. 2012, vol.27, n.2, pp. 102-110. ISSN 1010-2752.

Humic substances have great importance for their effect on enzymatic activity in plants, mitigating the oxidative stress generated by water deficit. This work was aimed at evaluating the effect of humic acids (HA) extracted from vermicompost, on the germination and oxidative stress in the cultivation of rice. HA were obtained starting from bovine manure vermicompost. The treatments used respond to two HA concentrations (34 and 46mg .L^-1) under controlled conditions, besides a control treatment. Under the controlled and semicontrolled conditions, the application effect was determined via radical of HA in the germination phase, evaluating the indicators: number and longitude of roots, height of seedlings and foliate and radical dry mass. Under semicontrolled conditions the activity dynamics of peroxidases (POXs) was evaluated, besides the content of proteins and aminoacids. The results showed positive effects of HA on the indicators evaluated in the germination phase, with an increase on the emission of roots and radical hairs to a 60% superior to the control. The HA stimulated the activity of POXs when foliage was applied in plants subjected to stress due to water deficit, showing the greatest activity of POXs at the moment, an increase in the content of proteins, indicating stimulation in biosynthesis and a consumption of aminoacids. The HA showed potentialities as protective against stress due to deficit of water.

Palavras-chave : humic acids; stress due to water deficit; peroxidases.

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