Qualidade de sementes de canola classificadas por densidade em diferentes condições de déficit hídrico e de profundidade de semeadura

Abstract

The aim of this study was to evaluate the effect of different density classes of canola seeds over the physiologic quality, as well as the effects on different depth of sowing and in conditions of water deficit. Also, the hydration curve was employed as auxiliary element on identification of better quality classes. Seeds of two hybrids of canola, Hyola 61 and Hyola 401, were separated into six classes of density. These classes were submitted to tests to characterize their physiological potential: germination, fist count of germination test, length and seedling dry mass. Also was determined the germination evaluation and vigor in water deficit condition into potencies, zero, -0,25, -0,5 and -1MPa, simulated with polyethylene glycol (PEG 6000) and, also in different depth of seeding (1, 2, 3 and 4 cm). According to results presented by the hybrids Hyola 61 and 401, we can conclude that there is an association between seed density and the characteristics of physiological quality (first count of germination test, germination, seedling length and index of emergency speed). The osmotic potentials reduction, from -0,25 MPa on, reduces the germination and vigor of all hybrid seed classes evaluated, being the vigor more affected than the germination. The critical potential for germination is of -1,0 MPa, regardless of the seeds densities. There is a different behavior by the hybrids about the tolerance of stress conditions caused by the PEG 6000, and Hyola 401 was more tolerant than Hyola 61. The physiologic quality affects the water content reached by the canola seeds during hydration, for both hybrids, being that the seeds with less vigor present higher water uptake and water content until 15 hours, when compared to seeds with higher vigor. At last, sowing deeper than 2 cm reduces drastically the germination and vigor of the all class in both hybrids seeds. In this way, was not verified the interaction between seeds density with the depth of sowing.