Effects of High Temperatures on the Permeability and Germinability of the Hard Seeds of Rhus javanica L.

The effects of temperature, 40–85 °C, on the permeabilityand germinability of the hard seeds of the pioneer tree Rhusjavanica L. with a fire syndrome were studied. The temperatureeffective for removal of the water-impermeable coat dormancyof the seeds was 55 ± 7·4 °C. With increasingtemperature, shorter exposure became sufficient to render theseeds permeable, but at temperatures above 75 °C, heat impairmentof germinability resulted in less than 60% germinability, evenwith long exposure. The most favourable regimes among thosetested were temperatures of 65–75 °C for durationsof 30–120 min, which frequently occur on denuded groundduring the midday hours of clear spring or summer days. Rhus javanica L., water-impermeable coat dormancy, seed germination, high temperature