Effect of temperature on cone bursting, seed extraction and germination in five provenances of Pinus roxburghii from Garhwal Himalaya in India

Abstract

Pinus roxburghii (chir pine or long-needle pine) is considered to be a fire-hardy species. In this study the effect of a wide range of elevated temperatures (from 40 °C to 150 °C) on cone bursting and subsequent seed germination was examined in five provenances of P. roxburghii in comparison to sun drying. The maximum germination percentage (88.6 ± 1.46%; mean ± SE) was recorded with seeds from the Jasholi provenance extracted from cones dried artificially at 40 °C and germinated at 25 °C. At bursting these cones retained 6.9 ± 0.83% moisture content and the seeds retained 8.8 ± 0.32% moisture content. The germination percentage of the seeds from the Jasholi provenance extracted at 150 °C, at which temperature cone bursting occurred within 45 min, was only 22.2% when germinated at 30 °C. These cones retained 4.8 ± 0.54% moisture content and the seeds retained 7.0 ± 0.42% moisture content after bursting. In general, increasing temperature above 40 °C was inversely proportional to seed germinability.