Late harvest and chemical treatment of cowpea seeds

Abstract

Reduced quality ofcowpea due to late harvest and therefore pathogen incidence may influence the results of the germination test, whenever losses are associated with the agentsadhered to seed coat;in that context, chemical treatmentof seeds during the evaluations may reflect more accurately physiological quality of the samples, which in turn may assurethe emergence results of healthy seedlings and establishment of appropriate plant populations inthe field. This study had the objective ofevaluating the effects of fungicide treatment on minimizing physiological quality losses of cowpea seedsdue to lateharvestin germination and seedling development tests. The experimental design was the completely randomized with four replications. Treatments consisted of cowpea, cultivar BRS Guariba, harvested at different times (0, 3, 6, 9, 12 and 15 days after physiological maturity)andtreated or not with fungicide carboxim+thiramfor seed quality tests. Seeds were initially characterized by seed moisture and mass. Afterwards, sampleswere evaluated by tests ofgermination percentage, germination first count, seedling length and dry matter. Data was submitted to variance analysisand means were analyzed as a 2x6 factorial. Means from chemical treatment and harvest times were compared by the Tukey test and regression analysis (p≤0.05), respectively, with subsequent unfolding of any significant interactions. Delayed harvest of cowpea seeds sharply reduces germination and vigor; fungicide treatment before performing physiological tests enables to establish thatseed quality losses can bein part caused by pathogen vehiculationonthe seed coat.