微生物结皮对两种一年生植物种子萌发和出苗的影响

在温室中对两种一年生植物的种子在微生物结皮和流沙对照上的萌发和出苗状况进行了实验.结果表明:在湿润和干燥状况下,苔藓结皮和藻结皮对种子萌发和出苗状况的影响,完整的和破坏的苔藓结皮和藻结皮对种子萌发和出苗状况的影响,总的来说雾冰藜(Bassia dasyphlla)在完整的苔藓结皮和破坏的两种结皮中出苗率均较高.完整致密的藻结皮能阻止雾冰藜的根接触土壤从而对其出苗设置了物理屏障.小种子植物小画眉草(Eragrostics poaeoides)因其种子较大,种子植物有相对大的土壤接触面积和具有特殊的结构须根,从而较容易克服结皮造成的物理屏障,穿透完整致密的结皮层而到达土壤.在破坏的微生物结皮中小画眉的出苗率略有降低.水分处理仅对雾冰藜的出苗有显著影响.在湿润处理下雾冰藜的出苗率要高于在干燥处理下的.因此,自然状况下年降雨量和分配状况的差异可能会影响这两种植物每年幼苗出苗率的差异,进而会影响到这两个种群在人工固沙区分布格局的差异.

Effect of Soil Microbiotic Crust on Seed Germination and Emergence of Two Annual Herb Species: Bassia dasyphlla and Eragrostics poaeoides

Experiments on seed germination and seedling emergence of two annual plants in microbiotic crusts and sand (as for contrast) were conducted in greenhouse. The experiment was arranged in four treatments: soil in moist and dry situations; crusts (moss and algae) in intact and disturbed situations. Overall, \?ssia dasyphlla\% seedlings emerged better in intact moss crust and two disturbed microbiotic crusts, but intact algae crust acted as the physical barrier to \?ssia dasyphylla\% seedling emergence by preventing its root from contacting soil. The small\|seed specie, \%Eragrostics poaeoides\%, can overcome this barrier by having a greater soil contact area compared with larger seeds and having special structure such as fibre that penetrate intact algae crust into the soil. The emergence of \%Eragrostics poaeoides\% was reduced in disturbed microbiotic crusts. Moisture had a significant effect only on the emergence of \?ssia dasyphylla\% seedlings, which emerged better in the moist treatment than in the dry. Hence, it is likely that variation in rainfall causes yearly differences in seedling emergence of the two species and affects their distribution on different habitats.