Effects of heat shock on seed germination of Turkish red pine (Pinus brutia)

Abstract

Fire plays an important ecological role in Mediterranean-type ecosystems. Many Mediterranean plant species exhibit enhanced germination capacity when exposed to heat. In the present study, the effect of high temperatures and exposure times on germination of Turkish red pine (Pinus brutia) was analyzed in order to reveal the response of seeds to fire and the implications on species regeneration. Seeds were heated to a range of temperatures (from 75 to 170 ºC) and exposure times (from 30 seconds to 30 minutes) similar to those obtained in surface soil layers during natural fires. In total, twenty treatments were performed. Seed germination percentages and germination values were calculated for each treatment. The results of ANOVA performed for germination values showed that temperature had a significant effect. Germination percentages increased in thermal treatments at 70 ºC for 10, 15, 20, 25, and 30 min; at 105 ºC for 10, 15, 20, and 25 min, and at 130 ºC for 1 and 2 min. The increase in both temperature and exposure times generally decreased the germination percentage especially at 130 °C and over in comparison with the control. Maximum germination percentage was reached in the treatment at 130 ºC for 1 min while the minimum germination was reached at 130 ºC for 10 min.