This work aimed to assess the effect of temperature and moisture on the germination and emergence of morning glory (Ipomoea triloba) and to determine the effect of water potential and temperature on seed germination and hypocotyl and radicle elongation. Thermoperiods of 9.3 and 5 (7.5); 14.3 and 10 (12.5); 19.3 and 15 (17.5); 24.3 and 20 (22.5); 29.3 and 25 (27.5); 34.3 and 30 (32.5); 39.2 and 35 (37.5) and 44.2 and 40 (42.5) and 49.2 and 45 (47.5) ºC, which alternated for 14 and 10 hours, and water potentials of 0, -0.03, -0.06, -0.1, -0.2, -0.4, -0.6 and -0.9 MPa were evaluated. The germination of morning glory seeds occurred through temperature and water potential interaction whereas radicle and hypocotyl elongation was triggered by temperature. With regard to germination, the parameters of the model used to estimate cardinal temperatures and the baseline water potential were determined by probit analysis. As to elongation processes, cardinal temperatures were calculated by linear regression and their responses to temperature were described by a second-order regression equation. The mathematical models described the processes of seed germination and of hypocotyl and radicle elongation of this species as a function of hydrothermal time and temperature, respectively.
modeling; hydrothermal time; probit analysis
