Teste de condutividade elétrica para avaliação da qualidade fisiológica de sementes de mamona

Abstract

The increasing demand for castor bean seeds in Brazil has promoted more interest in the development of tests to assess seed lots with superior quality. To investigate the possibility of using the electrical conductivity test for evaluation of the physiological quality of castor bean seed, ten seed lots from the cultivars AL Guarany 2002 and IAC 80 were used. The seeds were submitted to the bulk and individual conductivity test in four imbibition periods (6, 12, 18 and 24 hours). The lots were characterized by the germination test, first count, seedling emergency, initial emergency, emergence speed index and tetrazolium test. The moisture content of the seeds, the imbibition curve and seed health were also determined. The bulk conductivity test was carried out by using plastic cups with 25 seeds each in 75 ml deionized water, incubated in a BOD at a constant temperature of 25°C. The individual conductivity was determined by an SAD-9000S automatic seed analyzer. In contrast to the determination of seed physiological quality using the individual conductivity test, the bulk conductivity test was efficient in the detection of differences in castor seed lot quality and the period of 6 hours was the imbibition time indicated for the test.