大豆连作障碍研究Ⅰ．大豆连作土壤紫青霉菌的毒素作用研究

Study on soil sickness by soybean continuous cropping I. Effect of mycotoxin produced by Penicillium purpurogenum

研究分析了大豆连作、轮作土壤微生物区系，发现连作大豆根际土壤真菌富集，以其优势真菌回接大豆．紫青霉菌（Ｐｅｎｉｃｉｌｌｉｕｍｐｕｒｐｕｒｏｇｅｎｕｍ）能强烈抑制大豆生长发育．在实验室条件下分离获得该菌产生的毒素粗结晶，５μｇ·ｍｌ－１水培液中即可观察到大豆根系受害，根毛很少生长；３０μｇ·ｍｌ－１水培液中大豆主根褐变严重，侧根几乎不再生长；２００μｇ·ｍｌ－１导致一些大豆品种幼苗在２周内死亡这些结果表明，连作大豆土壤中该菌的大量存在及其产生的毒素是大豆连作障碍产生的主要因素．

Microbial comunlty in soil of soybean continuous cropping was analyzed, soil fungi were found to be abundant. soybean was inoculated with dominant fungi. The soybean growth is strongly inhibited by Penicillin m Purpuroggnum Stoll 891. Crude crystals of Rubratokins of P.purpurogenum Stoll 891 were extracted. The inoculation experiment with Rubratoxin Ashows that its concentration in water culture actives at 5 μg·ml-1, the soybean root system is injured. At 30 μg· ml-1, the primary roots are seriously necrosised and the secondary roots are almost stunted. At 200 μg·ml-1, some seedlings of soybean varieties are died within a couple of weeks. It is suggested that Pedologic mycotoxin generated by P. Purpu￣um Stoll which is abundant in soybean continuous cropping soil may be one of major factors leading to soil sickness.