Resumo

HUERTA MUNOZ, Elena et al. Organic fertilizer toxicity estimated by a lettuce germination bioassay. Terra Latinoam [online]. 2015, vol.33, n.2, pp.179-185. ISSN 2395-8030.

Even though there is a large amount of research on phytotoxicity of organic fertilizers, few have assessed livestock waste, or more specifically cattle manure. The main objective of this work was to determine the germination index (GI) as a phytotoxicity parameter of two organic fertilizers made from cow and rabbit manure, as well as one of a commercial brand. Phytotoxicity was measured in lettuce germination bioassays by germinating ten lettuce seeds in 10 mL of aqueous extract with 0.5, 1.0 and 1.50 parts of organic fertilizer and 5 parts of distilled water (v:v); distilled water was used as the control. After six days in a 25 °C controlled environment for seed germination, we calculated the relative seed germination percentage (RSG), as well as relative root growth (RRG) for the GI in the later process. The results showed germination indexes above 80% in 18 of the 19 treatments. Moreover, interactions between different factors indicated that manure, rather than its proportion, determines the presence of phytotoxins. The results of this study allow us to assert that the organic fertilizers assessed have a moderate to low degree of phytotoxicity.

Palavras-chave : Lactuca sativa L.; manure; phytotoxicity; sterilization.

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