Ajuste metodológico do teste de tetrazólio e a interferência de fungos e do tratamento químico na viabilidade de sementes de coentro

Abstract

Coriander is a crop of high relevance on the national scene; however, the production of high-quality seeds is hampered by the harmful interference of pathogens transmitted via seeds. These pathogens under favorable conditions can impair the performance of plants in the field and interfere with the results of analyzes under laboratory conditions, making it difficult to correctly assess the quality of their seeds. In this sense, the objective of this research work was to establish methodological adjustments in the tetrazolium test to assess the viability of coriander seeds as a complementary alternative to the germination test, in addition to evaluate the interference of fungi associated with its seeds and seed treatment with fungicide in the expression of physiological performance. The study was divided into three stages, conducted independently. In Study I, efficiency of the tetrazolium test was assessed in determining the viability of coriander seeds using two forms of pre moistening (paper and water). For this purpose, ten lots of coriander seeds, cultivar Verdão, were used. Soon after, in Study II, methodological adjustments were proposed in the tetrazolium test to assess the viability of coriander seeds. In this stage, two experiments were carried out independently, but sequentially. In experiment I, the seeds were exposed to different tetrazolium salt concentrations (0.25; 0.5; 0.75 and 1.0%). In experiment II, combinations of temperatures (35; 40; and 45 ºC) and exposure time (3; 4; 5; and 6 hours) were tested. In study III, the interference of fungi associated with coriander seeds lots and the effect of seed treatment with the fungicide on physiological performance were evaluated. It is concluded that the tetrazolium test is influenced pre-moistening for the rapid assessment of viability in coriander seeds, and pre-moistening can be performed by immersion in water or paper, using the concentration of the solution of the 0.5% tetrazolium salt for 5 hours at 40 ºC. Lots of coriander seeds showed high physiological potential, however, not all lots expressed their maximum potential in the germination test without treatment, due to the negative effect of fungi associated with seeds, mainly Alternata dauci and in association with A. alternata. There was an improvement in the physiological performance of coriander seeds treated with Metalaxil-m+ Fludioxonil fungicide.