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Two experiments were carried out in order to verify the effect of the herbicide metsulfuron-methyl on the initial growth of maize hybrids (AS 1560, DAS 2B710, AG 9010 and P 30F98). First, the hybrids were submitted to a germination test modified by addition of the herbicide in the soaking solution, using the doses 0 (control), 1.8, 3.6 and 5.4 g ha-1. After conditioning, normal and abnormal seedlings (%), dead seeds (%) and seedling length were evaluated. In the second experiment, hybrids were sown in pots after herbicide application at doses 0 (control), 3.6 and 7.2 g ha-1. The seeding was done at 0, 30, 60 and 90 days after application (DAA) of herbicide. Shoot and root dry mass were evaluated 20 days after sowing (DAS). The phytotoxicity of the herbicide metsulfuron-methyl was evidenced in the early development of plants, particularly when sowing was closer to herbicide application. The permanence of the herbicide in the soil may influence seed vigour what can be confused with low physiological quality of the lot. Although presenting different responses, all hybrids s were sensitive to metsulfuronmethyl at the analyzed periods.

Abstract: Adoption of a standard procedure to perform the germination test allows comparison of results between laboratories. Thus, the aim of this study was to evaluate the germination process of rangpur lime (Citrus limonia Osbeck) seeds conducted under different temperatures. The germination test was carried out in five seed lots under three temperatures (25, 30 and 35 °C). The dynamics of the germination process was studied through the following variables: germination (%), time to first germination (days), time to last germination (days), time interval between first and last germination (days), time required to reach 50% of germination (days), mean speed of germination (day-1), synchrony of the germination process (dimensionless), and uncertainty of the germination process (bits). The experimental design was completely randomized, and analysis of variance was performed in a 5 (lots) x 3 (temperatures) factorial arrangement, with four replicates of each treatment. Means were compared using Tukey’s test (p < 0.05). The germination process in rangpur lime seeds is slow, homogenous, and asynchronous; and the temperature of 30 °C is the most favorable for conducting the germination test, with the first count at 21 days and the last at 30 days.

Abstract: Rangpur lime is the most commonly used rootstock in Brazil, and its propagation occurs through seeds. Currently, no methodology is described in the prescriptions of the Rules for Seed Testing to perform the germination test of Rangpur lime. Thus, this research aimed to study the dynamics of germination in Rangpur lime seeds according to the Weibull distribution under the effect of different temperatures and lots. The experiment was conducted in a completely randomized design, with treatments arranged in a 3 × 5 factorial scheme (temperatures of 25, 30 and 35 °C for the germination test and five seed lots, respectively) and four replications. The percentage of germination, the number of days required obtaining 50% of germination, and the parameters of the Weibull equation were determined. The optimum temperature for germination of Rangpur lime seeds was 30 °C, with the first and last counts at 21 and 30 days after test installation, respectively. The germination process can be described by the three-parameter Weibull cumulative distribution function.