桑树根的分泌物和根际微生物的研究

为了解不同剪伐方式的桑树根系分泌物对桑树抗病能力的影响,进行了以氨基酸为主的根系分泌物和根际微生物的研究。在桑苗茎叶切除后的根分泌物中,除丙氨酸和苯丙氨酸外,几乎所有氨基酸的含量都增加,这种倾向在切除20d内明显,至40d后差异基本消失。将桑苗地的健全根、衰弱根和患病根根际的细菌、放线菌和真菌进行了定量分析,发现健全根的根际微生物相是细菌型的,但随着根系的衰弱与病变,逐渐由细菌型转向真菌型。分析认为,茎叶切除后根的氨基酸的分泌量增加是由于根毛死亡而释放出来的。根的分泌物有利于真菌孢子的发芽和菌丝的生长发育,促进了病菌对根系的侵入。

Study on the Secretion and the Rhizospheric Microorganisms of Mulberry Roots

To understand the influence of secretion from mulberry roots on the disease-resistent ability of mulberry, study were done on the amino acid secretion of mulberry roots and rhizospheric microorganisms. After the stem and foliage of mulberry sapling were clipped, amino acids except alanine and phenylalanine increased compared with non-clipped mulberry sapling. This tendency is quite clear within 20 days after the clipping, but vanished almost after 40 days. After quantitatively analysis of bacteria, actinomycetes and fungi of rhizosphere from healthy roots, weakened roots and diseased roots, we found that the rhizospheric microorganisms of healthy roots was bacteria type, but changed to fungi type along with mulberry roots was becoming weakened diseased. It was conduded that increase of the secreted amino acid amount is owing to dying of root hair. Secretion of the roots is favor to the fungi spores’ germination, mycelia’s growth, and make the formation of the penetration seat which prompt invasion of pathogens into the roots.