Vigor tests in mechanically delinted cotton seeds

Abstract

A trial was carried out in Piracicaba, São Paulo, Brazil, with the purpose of determining, comparatively, the best vigor tests for mechanically delinted cotton (Gossypium hirsutum L.) seeds. It consisted of a field experiment and six monthly spaced (from November 1974 to April 1975) laboratory and field plot tests. The seeds used were of the IAC 13-1 and IAC RM 3 cultivars, stored in dry chamber and in laboratory conditions with no temperature and humidity control. The following tests were performed: emergence percentage, velocity of emergence, first count in the germination test and rapid aging. The emergence percentage test was done in field plots; the final germination percentage was calculated for each treatment. The velocity of emergence was determined in the same test and the velocity index was calculated. The data of the first count (four days) of the germination test were used as a vigor test. For each time interval (month, four rapid aging) tests were done, being the seeds kept in the rapid aging chamber for 36, 48, 60 and 72 hours. After that, germination tests were made. The analysis and interpretation of the results allowed for the following main conclusions: the emergence percentage test can substitute the velocity of emergence test; the first count of the germination test was found to be inaquate as a vigor test; rapid aging in the aging chamber for 72 hours was found to be most suitable for cotton-seeds among the various tests studied; it was not detected any influence of seed vigor on the field yield.