大豆连作障碍研究 Ⅱ.大豆连作减产机理及对土壤紫青霉菌毒素的调控对策

Obstacles of soybean continuous cropping Ⅱ. Mechanism of soybean yield decline and control strategies for toxin of Penicillium purpurogenum in soils.

研究分析了土壤紫青霉菌分泌毒素对连作大豆全生育过程的危害．结果表明，在大豆种子萌动期毒素致毒作用已经开始；在大豆幼苗期及分枝期，较高浓度毒素（×１０３倍稀释）使大豆完全不结瘤，极低浓度（×１０５倍稀释）仍然抑制４０％结瘤，致使重茬大豆光合固氮能力显著降低．而大豆残根、凋落物等通过刺激紫青霉菌的增长，造成对大豆进一步的危害．对连作大豆土壤紫青霉毒素的调控研究表明，使用土壤放线菌ＭＢ生物防治，可使重茬大豆增产８．４～１８．９％；使用海洋放线菌ＭＢ９７生物防治可使重茬大豆增产３０．５％．应用ＭＢ９７制剂对连作大豆全生育过程的防病、减毒控制的综合调控，可使重茬５年大豆田间微区试验折合大豆产量达到４５７５ｋｇ·ｈｍ－２．

Analysis on the harmfulness of toxin produced by Penicillium purpurogenum in soil in the whole growth and development period of continuous cropping soybean shows that the toxicity began at the stage of seed germination. At the seedling and branching stages, high toxin concentration (1000 delution folds) could entirely result in non nodulation, and even low concentration (100000 delution folds) could still inhibit 40% of nodulation, resulting in an obvious decrease of photosynthetic and nitrogen fixing capacities of continuous cropping soybean. By stimulating the growth of P.purpurogenum , the root residue and litter of soybean could cause further harmfulness of soybean. Studies on controlling toxin of P.purpurogenum in soils of continuous cropping soybean show that soil actinomyces MB antibiotic control could make continuous cropping soybean have a yield increase of 8.4～18.9%; and marine actinomyces MB 97 biotic control could make a yield increase of 30.5%. With the application of MB 97 bio fertilizer and comprehensive control on disease precaution and toxicity reduce in the whole growth and development period of continuous cropping soybean, the yield of continuous cropping for 5years in micro plot field experiment could reach 4575kg·hm -2 .