Aperfeiçoamento metodológico do teste de tetrazólio para avaliação da viabilidade de sementes de arroz

Abstract

Calibration methodologies able to identify quickly and efficiently the quality of a lot of seeds through viability and vigor tests is constantly searched by seed technology. One of the most widely used tests for this purpose is the tetrazolium test, which methodological procedure for the rice crop still needs adjustments. This research aimed to study the preparation of alternatives, preconditioning and staining of rice seeds to evaluate the viability and establishing classes of viability to estimate the vigor of rice seed. The experiment was conducted in three stages: a) adjustment preparation procedures of rice seeds for conducting the tetrazolium test for both irrigated and upland plant varieties, were used four irrigated rice plant variety and two of upland plant variety, each consisting of two lots. It is tested on the need for removal of the shell (palea and lemma) and cut the seeds; b) study tetrazolium salt concentrations, preconditioning period and staining to evaluate the viability of rice seeds. At this stage, we used the same cultivars of the first stage, each consisting of a lot being used methodologies that showed the best results in the previous step. They were evaluated different concentrations of tetrazolium salt (0.1, 0.25, 0.5 and 1.0%) three times of staining (0.5, 1 and 2h), five periods of hydration seeds (0,5; 1, 2, 3 and 4h) and two soaking temperatures (35 and 40 ° C); c) estimate of seed vigor by the tetrazolium test, using ten seed lots of plant variety Irga 424 were established four viability classes (viable seeds of high vigor, viable medium vigor, viable low vigor and no viable and dead). The results indicated for the evaluation of viability of rice seed by tetrazolium testing is recommended to remove palea and lemma thereof and slitting the distal half of the embryonic axis is more efficient. The tetrazolium test execution period for rice seeds can be reduced to three hours using seed hydration for 1h at 40 ° C, for 1h cutting and evaluation activities and staining for 1h at 0.25% concentration. Thus, it leads to conclude that the proposed methodologies in this research to allow to evaluate the viability of rice seeds by the tetrazolium test; in order to evaluate vigor the test showed promise but needing methodological improvement.