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用里查德培养液制备的棉枯萎病菌培养滤液浸养棉苗,以测定不同菌系的致萎能力。培养滤液有快速致萎能力。用 F_7培养滤液的50%稀释液浸养“517”棉苗8小时就开始萎蔫,16小时有34%的棉苗达Ⅲ级萎蔫,40—56小时100%棉苗死亡。Ⅲ级萎蔫苗在移入蒸镏水后不能恢复常态,成为汞久性的病理萎蔫,有维管束变色的内部症状。根据致萎迅速这一特点,提出了定时分级记载和统计萎蔫指数方法。以“萎蔫开始时间”,“Ⅲ级萎蔫出现时间”,24及48小时“Ⅲ级萎蔫率”和“萎蔫指数”等作为不同菌系致萎力的比较标准。作者根据稀释试验认为用30%稀释液进行测定较为合适。试验结果指出:①不同菌系的培养滤液对“517”棉苗有不同程度的致萎能力,例如 F_7及 F_8的致萎能力最强,F_9次之。③不同品种对于各菌系的反应有显著差异,侧如在24小时“52—128”品种表现对 F_7及 F_8有较低于“517”的萎蔫指数;在48小时“52—128”对 F_7的萎蔫指数同于“517”,而对 F_8则低于“517”;但“52—128”对于 F_9的反应显示其24及48小时萎蔫指数均较“517”为高。在用 F_7培养滤液对16个供试品种及杂交材料的测定中也显示不同品种对该菌系的反应具有差异。试验指出 F_7培养滤液具有下列特性:①,耐高温,在100℃下10分钟或在蒸锅内15磅压力下处理30分钟后仍具有相当的致萎能力,据测定在40小时后的萎蔫指数各为73.3%及66.6%,对照为100%。②,耐储藏,在室温下储藏1年后仍具有相当的致萎能力,据测定在48小时后的萎蔫指数为72.2—94.4%,对照为100%。③,抗污染,原液暴露在室内空气下两月之久并无其他真菌或细菌污染,未接种的里查德液在2—3日内受到严重污染。④,耐稀释,据测定2%的稀释液在120小时具有11.1%的萎蔫指数。
Cotton seedlings were inoculated with filtrate of Fusarium oxysporum f. Filtrate culture has rapid wilting ability. The 517 cotton seedlings inoculated with 50% dilution of F_7 culture filtrate began to wilt for 8 hours, 34% of the cotton seedlings reached Grade III wilt in 16 hours and 100% cotton seedlings died in 40-56 hours. Grade III wilting seedlings can not be restored to normal after they have been transferred to distilled water, becoming a long-lasting pathological wilt of mercury with internal symptoms of vascular discoloration. According to the characteristics of rapid wilting, a method of time-grade classification and statistics of wilting index was proposed. The wilting power of different strains was compared with “wilting start time”, “wilting time of grade Ⅲ”, “grade Ⅲ wilting rate” and wilting index of 24 and 48 hours. According to the dilution test, the author thinks that it is more appropriate to measure with 30% diluent. The results showed that: (1) The culture filtrates of different strains had varying degrees of wilting ability on “517” cotton seedlings, for example, F_7 and F_8 had the strongest wilting ability and F_9 times. (3) There was a significant difference in the responses of different strains to different strains. For example, the varieties “52-128” displayed the wilting index lower than “517” for F_7 and F_8 at 24 hours; The wilting index was the same as “517”, but lower than “517” for F_8; however, the response of “52-128” to F_9 showed that the wilting index was higher than “517” at 24 and 48 hours. In the F_7 culture filtrate on 16 test varieties and hybrid materials also showed different varieties of the reaction of the strains have differences. The test indicated that the F7 culture filtrate had the following properties: ① high temperature resistance, considerable wilting power after being treated at 100 ° C for 10 minutes or at a pressure of 15 pounds in a steamer for 30 minutes, and the wilting index after 40 hours was determined Each 73.3% and 66.6%, and the control was 100%. ②, resistant to storage, after storage at room temperature for 1 year still have considerable ability to wilt, it was determined after 48 hours wilting index was 72.2-94.4%, the control was 100%. ③, anti-pollution, liquid exposure to indoor air for two months and no other fungal or bacterial contamination, uninoculated Richard liquid in 2-3 days was heavily contaminated. ④, resistant to dilution, it was determined that a 2% dilution had a 11.1% wilting index at 120 hours.