Effect of storage conditions and temperatures on seed germination of 4 plant species from Zygophyllaceae

Seed germination of 4 plant species from Zygophyllaceae including Nitraria sphaerocarpa, N. tangutorum, Peganum nigellastrum and Zygophyllum fabago were studied. After the seeds were separately treated with soil burial during winter (SB) and dry storage in laboratory (DSL) for 80 days, the germination rate was measured under 4 constant temperatures (10 ℃, 15 ℃, 20 ℃ and 25 ℃) and one fluctuating temperature regimes (25 ℃/5 ℃). The result showed that the seed germination rates of N. tangutorum, P. nigellastrum and Z. fabago were greatly influenced by temperature and the seed germination rates increased with the increasing temperature. The maximum germination rate of N. tangutorum seeds both in SB and DSL groups reached the highest values from 40% to 50% at 15 ℃ and 20 ℃. As for P. nigellastrum, it was closed to 0 % (SB) and 60% to 70% (DSL) at 5 ℃/25 ℃. And for Z. fabago, it was 90% to 100% (SB) and 60% (DSL) at 5 ℃/25 ℃. The seed germination rates of these three species were less than 10% at low temperature (10 ℃ or 15 ℃). The seed germination rate of N. sphaerocarpa was mainly affected by the storage methods and it was significantly higher in SB group than that in DSL group and the highest germination rate was from 60% to 70% in SB group atat 20 ℃ or 25 ℃.