Uso da vermiculita no teste de germinação de sementes tratadas de soja: implicações na avaliação e a validação metodológica

Abstract

In germination tests of soybean seeds treated with insecticidal phytosanitary products, especially neonicotinoids, it has been common to report abnormalities in the seedlings, especially in some substrates, such as paper roll (PR). In addition to the substrate, another factor that affects the assessment of soybean seed germination is the use of the seed preconditioning technique before the test, as this can mitigate the damage caused by soaking the seeds. The combination of soybean seeds with low humidity and treated with phytosanitary products has generated some inconsistencies in the results of the germination test in PR. In order for the results of this test to be representative, it is crucial to use an appropriate methodology that favors the true expression of germination and minimizes possible phytotoxic effects and/or soaking damage. New methodologies should therefore be developed and evaluated, such as paper rolls with vermiculite added between the leaves (PR+V). Three studies were carried out with the following main objectives: to assess the speed of soaking using the PR+V substrate in soybean seeds and the phytotoxic effect of neonicotinoid insecticides; to assess the need for preconditioning when using the PR+V substrate depending on the humidity of the seed batches; to assess the viability of the PR+V substrate and statistically validate its use in seed analysis laboratories. The PR+V substrate provided an increase in the speed of soaking and seedling development; greater expression of batch germination, regardless of seed treatment; attenuation of the phytotoxic effects of neonicotinoid insecticides compared to the traditional PR and sand (BS) substrates; and the possibility of counting germination at 7 days. The use of preconditioning increased the expression of quality in batches of soybean seeds, both treated and untreated, from batches with a moisture content of between 12 and 8%, with the effect being more evident for batches with a moisture content of less than 10%. Without the use of preconditioning. Even with the use of PR+V, preconditioning was necessary for batches of soybean seeds between 8 and 12% moisture. The PR+V substrate promoted greater expression of quality compared to PR and BS, with greater development of strong seedlings, which facilitates evaluation of the germination test, thus eliminating possible subjectivity. The data on normal soybean seedlings evaluated with the PR+V substrate showed repeatability, reproducibility, precision and accuracy within the critical parameters of 1% and 5% significance. Therefore, the methodology proposed with the PR+V substrate is suitable and reliable for routine implementation in assessing the germination of soybean seeds, especially those treated with phytosanitary products.