矮沙冬青种子特性和萌发影响因素的研究

 对矮沙冬青(Ammopiptanthus nanus)种子的特性和萌发影响因素进行了初步研究，结果表明：种子不易传播；虫蛀率高，室温贮藏60 d的种子虫害率为38%；易形成硬实，含水量为7.68%的种子在30 ℃温水中浸泡90 h，只有33.33%能吸水膨胀。种子萌发时不需光，在15～30 ℃和室温（18～32 ℃）条件下，经9 d的萌发，发芽率均可达80%以上，30℃时萌发最快；在1～2 cm深的沙壤中，种子出苗率可达75%以上，超过3 cm显著降低，超过6 cm则低于20%；种子在沙壤中萌发时，沙壤的适宜湿度为19.35%～28.75%，高于32.43%或低于3.85%，很少有种子萌发；含水量分别为19.36%、10.64% 和7.68%的种子发芽率无显著差异，在-10 ℃和5 ℃下贮藏7个月，发芽率也无显著降低，但在室温和35 ℃下贮藏7个月则显著下降，发芽率下降的速度与种子本身的含水量和贮藏温度正相关；在湿度分别为7.41%、13.79%和28.57%的沙壤中播种育苗，幼苗死亡率高达77.49%、81.25%和89.49%，即使用三唑酮拌种，死亡率亦高达50.27%、69.53%和76.03%，幼苗死亡率与沙壤湿度正相关。

CHARACTERISTICS OF AMMOPIPTANTHUS NANUS SEED AND FACTORS AFFECTING ITS GERMINATION

The rare and endangered plant, Ammopiptanthus nanus is the only evergreen broad leaved plant in Xinjiang listed as a Category 1 National Protected Plant. It is a xerophytic relict species of the subtropical evergreen forests of the Tertiary and found only in the arid Tarim Basin. Previous studies have examined the anatomical characteristics and drought-resistant mechanisms of this species. In this paper, we examined seed characteristics, including germination in relation to temperature and various light regimes duration of storage, seedling emergence and survival rate in relation to soil moisture content (MC) and seeding soil depth, and effects of a fungicide treatment. Our results showed that Ammopiptanthus nanus seeds were dispersed only short distance from the parent plants due to their morphological characteristics and high predation rates. the seed germination rate reached 38% in seeds stored for 60 d at ambient temperature (AT) of 18 - 32 ℃. The dried and ripened seeds of this plant often had impermeable seed-coats, and only 33.33% of the dried seeds with 7.68% MC absorbed water and swelled up after soaking for 90 h at 30 ℃. Seed germination did not require illumination. Germination percentage (GP) was above 80% when seeds were incubated for 9 d at 15 ℃, 20 ℃, 25 ℃ , 30 ℃, 20/30 ℃ and AT, and seeds germinated most quickly at 30 ℃. The seedling emergence rates were greater than 75% when seeds were buried in 1-2 cm depth below the surface of sandy soil. Seedling emergence rates decreased with increasing soil depth and were less than 20% at 6 cm soil depth. The most suitable MC of sandy soil for seedling emergence was 19.35%-28.75%; when soil MC was above 32.43% or below 3.85%, few seedlings emerged. After seed storage for 210 d at 10 ℃ and　5 ℃, MC of 19.36%, 10.64% and 7.68% had no significant effect on GP, but GP decreased significantly at AT and 35 ℃. The decreasing GP rate had a significantly positive correlation with seed MC or storing temperature. When sowing seeds and nursing seedlings in soils of 7.41%, 13.79% and 28.75% MC, the seedling mortality rates were 77.49%, 81.25% and 89.49% respectively. When seeds were treated with triadimefon, mortality rates were still as high as 50.27%, 69.53% and 76.03% in the three soil MC treatments, respectively. The seedling mortality rate had significant positive correlation with sandy soil MC.