Abstract
Vigor tests are very important to obtain additional information to the standard germination test and can assist in decision-making. The aim of this work was to evaluate accelerated aging test methodologies for the determination of vigor in tobacco seeds. For the study, ten seed lots of tobacco were used. The initial quality of the tobacco seeds was determined through the germination test, first count of germination, germination speed index, seedling emergence at 7, 14 and 21 days after sowing, emergence speed index and the accelerated aging with water performed as proposed by the Association of Official Seed Analysts. After the determination of seed initial quality, the accelerated aging test was studied in the following methods: accelerated aging with water, saturated saline solution (40g NaCl 100mL-1 water) and unsaturated saline solution (11g NaCl 100mL-1 water), submitted to the temperatures of 45 and 41°C, for the exposure periods of 24, 48 and 72 hours. According to the results obtained, the accelerated aging test with water conducted under a temperature of 45°C combined with a 24-hour exposure period is shown as adequate for evaluating the vigor of tobacco seeds.
Highlights
The tobacco crop has major socioeconomic relevance in Brazil, as one of the most significant agroindustry activities in the southern region, comprised by the states of Rio Grande do Sul, Santa Catarina and Paraná, where the production is concentrated
The present work was performed at the Didactic Laboratory of Seed Analysis “Flávio Farias Rocha” of the Federal University of Pelotas (UFPel), and in a farm located at the municipality of Venâncio Aires – RS
Data from the initial quality evaluations of tobacco seed lots can be observed in Tables 1, 2 and 3
Summary
The tobacco crop has major socioeconomic relevance in Brazil, as one of the most significant agroindustry activities in the southern region, comprised by the states of Rio Grande do Sul, Santa Catarina and Paraná, where the production is concentrated. Crop establishment in tobacco is performed through seedling transplant, the use of good quality seedlings is essential to obtain uniform plant stands and to guarantee satisfactory yields. Both for crops that are sown directly in the field and species in which seedlings are produced on greenhouses and transplanted to the field, the use of seeds with high physiological quality is fundamental to obtain adequate plant populations (Nascimento et al 2011). Seed quality is characterized by the sum of four attributes: genetic, physic, physiological and sanitary Between these attributes, seed physiological quality, represented by germination and especially by vigor, is extremely important since this characteristic is directly related with an adequate establishment of seedlings in the field (Peske et al 2012). For tobacco seed commercialization a minimum value of 98% for purity and 80% for germination are mandatory, with an exception for foundation seeds, in which the minimum standards for germination are 60%, but may be marketed with up to 10 (ten) percentual points below the standard, provided the transaction is made directly by the producer and the user, with the formal consent of the latter (Brasil, 2013)
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