| The control effect and mechanism of bacillus subtilis against postharvest fruits diseases have been studied on basis of the test that Botrytis cinerea Pers.,Colletotrichum gloeosporioides and Penicillium italicum were controlled by bacillus subtilis after being radiated in magnetic field.We also studied the biological trait of the bacillus subtilis.The results are as follows:1.The screening of the high efficiency antagonistThe test showed that 7 strains as magnetic antagonists provided better inhibition of pathogens than others which were not radiated in magnetic field.They are BS0.05-1, BS0.25-4,BS0.25-5,BS0.25-7,BS0.25-1,BS0.10-1 and BS1.25.Among these 7 strains, BS0.25-1,BS0.10-1 and BS 1.25 were high efficiency antagonist after the significant test. And the inhibitory rates of these 3 strains were 61.20%,61.59%,and 61.97%after being stored 5 days at 25℃.And the results are much better than the control.2.The control effect of high efficiency antagonist on postharvest fruits disease.2.1 The control effect of high efficiency antagonist on Apple anthracnoseThe test showed that no matter at 10℃or 20℃the control effect of all the treatments went down.The control effect at 10℃is better than the one at 20℃.The treatments' control effect which inoculated antagonist first is better than the one which inoculated pathogens first.The treatment that inoculated BS1.25 provided the best control effect,its' control effect of both inoculation is 30.45%and 14.16 at 20℃.The treatment that inoculated BS 1.25 first is the best one at 10℃,its' control effect is 82.46%.The temperature has a great influence on the control effect.The control effect at 10℃is better than the one at changed temperature.The control effect at 20℃is the lowest.2.2 The control effect of high efficiency antagonist on Tomato grey mold.The temperature has a great influence on the control effect.The fruits' incidence rate at 20℃is lower than the rate at 10℃.The incidence rate of the treatment that inoculated BS1.25 is 17%and 100%at the two temperatures.Also the lesion diameter will be also influenced by the temperature.2.3 The control effect of high efficiency antagonist on Orange penicilliosis.The control effect at 10℃is better than the control effect at 20℃.It shows that the lower temperature is beneficial for growth of the pathogens.Both kinds of inoculation at 20℃,the treatment that inoculated BS1.25 is the best one,its' control effect is 44.51%and 32.08%.And the same situation occurred at 10℃,its' control effect is 59.79%and 38.10%. 3.Major Defense Enzymes of HostBy means of mensuration the enzyme activity,the changes of activities of peroxidase (POD),polyphenoloxidase(PPO)and phenylalanine ammonia-lyase(PAL)on apples and oranges were studied.Results showed that the enzyme activities of the hosts raised after inoculation,and during the storage there will be a peak of the enzyme activities.But the relationship between the enzyme activities and the resistance of the host should be studied further more.4.The study of the biological trait of the bacillus subtilisThe strain of BSCK and BS1.25 are in the logarithm growth time during the first 36 hours.The quantity of the bacterium is at maximum after being cultivated for 36 hours.At the condition of PH=6.5 and PH=7,the strain of BSCK and BS1.25 can grow better severally.Maltose as a source of carbon can be utilized better by the two strains,but D-sorbierite and D-levulose are can't be utilized easily.Yeast is the best nitrogen source, the peptone and jerk cream take second place.But the salmiac and carbamide can't be utilized by the two strains.5.The mechanism of bacillus subtilis against postharvest fruits diseases.Using the different kinds of liquid of bacillus subtilis to control the development of the diseases,the test showed that:the liquid of the antagonist can provide a better control that proved the antagonists themselves and its' metabolite both can control the development of the diseases.And the control effect of BSCK is better than BS1.25.The control effect of the soliquoid is better than filtrate and sterilization. |
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