Abstract

HERNANDEZ, Orlando L et al. Humates isolated from vermicompost as growth promoter in organic lettuce production. Rev Cie Téc Agr [online]. 2013, vol.22, n.1, pp.70-75. ISSN 2071-0054.

The rising market for organic products has attracted attention of new farmers. One of the main problems related to the transition from conventional to organic production management have been the changes on production cycles of traditional cultivars in response to plant adaption to new tillage systems. This field work was conducted with the objective to evaluate the possibility to accelerate lettuce crop cycle with foliar application of humic substances associated with changes on enzymatic activity related to the nitrogen metabolism. To perform it, humates obtained from vermicompost produce with cattle manure were applied by leaf spray at 300 L·ha^-1 rate under 1,6; 1,3 and 1,2 mmol C/L concentrations on the lettuce plantlets with x days after transplantation. It was observed that leaf spray with humate at 1,2 mmol C/L dose reduce the ontogeny cycle of lettuce production in 21 days, while both 1,6 and 1,2 mmol C/L doses had shown a reduction of 15 days over the yield cycle. Also, it was noted an increased number of leaves per plant. The plant growth promotion observed was followed by changes in plant metabolism, since humate application reduced total foliar carbohydrates content while increased protein contents, nitrate reductase and phenylalanine ammonialyase. Such metabolic activation promoted by humates resulted in increased lettuce yields and reduced time cycle with benefits to lettuce under organic system of production.

Keywords : humic substances; physiological effects; organic agriculture; nitrogen metabolism.

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