Qualidade fisiológica de sementes de aveia preta (avena strigosa) submetidas a dessecação com herbicidas

Abstract

In the physiological maturity of a seed is the moment when it exhibits the greatest vigor, germination potential and accumulation of dry matter. However due to having a high percentage of moisture, makes mechanical harvesting unfeasible, requiring the application of desiccant herbicides to expedite harvesting and achieve higher quality. With this in mind, the aim of the study was to evaluate the effect of applying desiccant herbicides, In physical quality, physiological, and sanitary quality of black oat seeds harvested at two different times. The experimental design used was a randomized complete block design arranged in a 2 x 8 factorial scheme (application timings x herbicides), with four replications, also including a control without herbicide application for each desiccant application timing, as well as a control where no herbicide was applied throughout the entire cycle. Factor A allocated the application timings of the products (E1 and E2 with 28% and 18% of moisture, respectively) and in Factor B, the herbicides (diquat – 400 g ha-1, amônio-glufosinate – 400 g ha-1, quizalofop-p-ethyl – 100 g ha-1, clethodim – 72 g ha-1, MSMA – 1580 g ha-1 e glyphosate – 480 g ha-1). To assess the physical, physiological and sanitary quality of black oat seeds, cultivar Embrapa 139, first germination count analyses, germination, percentage of dormant seeds, dead and hard, electrical conductivity, incidence of fungi, thousand seed weight and seed productivity. The herbicides that showed seeds with higher physiological quality were clethodim and quizalofop-p-ethyl applied at time E1. The controls from both tested seasons showed high germination rates, With high electrical conductivity, Indicating seeds of low vigor. The clethodim used in E2 presented one of the highest numbers of abnormal seedlings and dormant seeds. Meanwhile diquat applied to E1 and the end-of-season control showed the highest numbers of hard seeds. The use of amônio-glufosinate proved detrimental in both application seasons regarding dead seeds, not differing from MSMA in E1 nor from glyphosate in E2. The fungi, Fusarium spp. and Alternaria spp. they had a higher incidence in the treatments in both application periods, well Penicillium spp. and Ustilago spp. they showed reduced incidence, not occurring in both periods. The tested herbicides resulted in an increase in the weight of a thousand seeds compared to the controls in each periods, however, ended up causing a significant reduction in productivity. Among all the treatments tested, there is a possibility of using the clethodim in E1 in black oat farming.