生物土壤结皮物理因子对植物种子萌发的影响

本研究采用冗余分析的方法,探讨了生物土壤结皮物理性质对小麦Triticum aestivum L.、黑豆Glycinemax merr L.、白菜Brassica rapavar.glabra和软尾生菜Lactuca sativa萌发的作用。结果显示:1)在结皮上表面:生物土壤结皮的厚度对4种植物种子萌发率均有反作用(P0.05,n=5);生物土壤结皮的抗压强度抑制软尾生菜的萌发率呈负相关(P0.05,n=5);生物土壤结皮的厚度与黑豆种子平均萌发时间呈正相关(P0.05,n=5)。2)在结皮下表面:生物土壤结皮的孔隙度和分形维数与小麦的萌发率呈正相关(P0.05,n=5);生物土壤结皮的厚度抑制了黑豆和白菜的萌发率(P0.05,n=5);生物土壤结皮的抗压强度对黑豆和软尾生菜萌发率起反作用(P0.05,n=5);生物土壤结皮容重的增加降低了小麦的萌发速率(P0.05,n=5);生物土壤结皮厚度增加减慢了黑豆、白菜和软尾生菜的萌发速率(P0.05n=5);生物土壤结皮抗压强度的增加降低了黑豆和白菜的萌发速率(P0.05,n=5)。结果表明,在结皮上表面,结皮厚度对4种植物种子萌发率均起抑制作用,尤其能够减慢胚根较为粗壮的黑豆种子的萌发速率。在结皮下表面,胚芽尖细的小麦可以利用结皮孔隙萌发;黑豆、白菜和软尾生菜由于子叶较大,不能利用生物土壤结皮的孔隙,其萌发率和萌发速率主要受生物土壤结皮的厚度或抗压强度抑制。

Effects of physical charateristics of biological crusts on seed germination

We assessed the effects of soil physical factors of biological soil crusts (BSCs) on germinations of Triticum aestivum L.,Glycinemax merr L.,Brassica rapa var. glabra and Lactuca sativa seeds by using with redundancy analysis.Results showed that:1)On the surface of BSCs:thickness of BSCs had negative effects on germination rates of all the four species(P<0.05,n=5).Compression strength of BSCs reduced the germination rate of L.sativa (P<0.05,n=5).Thickness of BSCs had a positive effect on the mean of generation time (MGT) of G.merr L.;2) Under the surface of BSCs,porosity and fractal dimension of BSCs showed positive effects on germination rate of T.aestivum L. (P<0.05,n=5)and thickness of BSCs inhibited germination rate of G.merr L. and B.rapa var. glabra (P<0.05,n=5).Compression strength of BSCs had a negative correlation with germination rates of G.merr L. and L.sativa (P<0.05,n=5).Bulk density of BSCs inhibited seed germination speed of T.aestivum L.(P<0.05,n=5).And germination speed of G.merr L.,B.rapa var. glabra and L.sativa decreased with thickness of BSCs (P<0.05,n=5).Compression strength of BSCs restrained germination speed of G.merr L. and B.rapa var. glabra (P<0.05,n=5).Our results indicate that thickness of BSCs inhibits the germination rates of all the four species and drop the germination speed of G.merr L. on the surface of BSCs.Under the surface,seeds of T.aestivum L. can germinate through the porosity of BSCs due to their thin and straight cotyledon,while thickness and compressive strength of BSCs inhibit germination of G.merr L.,B.rapa var. glabra,and L.sativa for their big cotyledon.