Germination of Seeds Subjected to Temperature and Water Availability: Implications for Ecological Restoration

Abstract

The regeneration of natural Betula platyphylla Suk., a pioneer tree and predominant species in stand forest of the northern region, China faces a challenge, i.e., population decline. One of the bottlenecks relative to the successful seedling establishment is the effectiveness of seed germination. In this study, four different families (3-4, 3-22, 3-42, and 3-43) of B.platyphylla seeds were used as research objects to explore the effects of temperature and PEG simulated drought on seed germination. The result showed that seed germination ability from different families increased first and then decreased with the increase in temperature. The germination rate (GR), germination value coefficient (GVC), and germination index (GI) at 25 ℃ and 30 ℃ were significantly higher than those at lower temperatures (15 ℃ and 20 ℃) and higher temperature (35 ℃), and the time for germination percentage to reach 50% (T50) was faster. The germination ability decreased gradually with the increase in drought stress. Seeds are more sensitive to drought stress at low temperatures, their germination is severely inhibited, and the tolerance range of PEG concentration at 15 °C (0%–10%) is less than other temperatures (10%–20%), while they can germinate well at high temperatures and the tolerance to drought stress is stronger. Our results suggested that 3-43 had better germination ability at high temperature, while 3-22 had better germination ability at low temperature. Our findings highlight low temperatures and drought stress as key factors limiting seed germination, which may be one of the bottlenecks to population regeneration. This research provides a scientific reference for the natural regeneration and population restoration of B. platyphylla.