ADEQUAÇÃO DO TESTE DE TETRAZÓLIO PARA SEMENTES DE ALGODOEIRO.

The tetrazolium test stands out among other tests because it allows the simultaneous evaluation of seed viability and vigor. The existing recommendation for conducting the test with cotton seeds is rather slow and presents difficulties in the way of preparing and evaluating seeds. Considering this fact, this study aimed to reduce cotton seed preparation time in order to conduct the test. Three assays were conducted initially: 1- distal cut followed by a longitudinal cut, after pre-moistening the seeds in paper and immersing them in water for six, eight, and 16 hours, respectively; 2- distal cut on dry seeds, followed by direct immersion in water for four, six, and eight hours, and in paper for 16 hours; 3- immersion - cut - immersion: after immersion for two hours, the end opposite to the embryo axis was cut, and immersion in water followed for four, six, and eight hours at 25°C. The treatment involving a distal cut on the side opposite to the embryo after immersion for two hours, followed by imbibition for a further six hours reduced the time required and facilitated seed preparation for the test. Next, tetrazolium concentrations of 0.1% and 0.075% were tested at temperatures of 30, 35 and 40°C. Later, the proposed methodology was validated using five seed lots, by comparing the results obtained with germination and first count results. From the results obtained, it was concluded that, for cotton seeds, the tetrazolium test should be conducted in the following manner: immersion of seeds in water for two hours, followed by a cut on the end opposite to the embryo axis, and then immersion for another six hours in water, followed by removal of the integument plus the inner membrane and, finally, the seeds should be placed in tetrazolium solution at 0.075% and maintained in an incubator at 40°C for 150 minutes. [ABSTRACT FROM AUTHOR]