| In this study,Rhizopus stolonifer,a pathogen of the soft rot of the peach,was used as a test bacterium,and ACS dilution was used as an antiseptic and antibacterial agent.First,peach Rhizopus stolonifer was treated with different dilutions of ACS solution in vitro and in vivo.The isolated,purified and identified Rhizopus stolonifer was treated with ACS diluent to investigate its effect on the spore germination,mycelial growth and morphological changes of Rhizopus stolonifer.The antibacterial mechanism of ACS was preliminarily explored by measuring the cell membrane permeability,leakage of soluble sugar and soluble protein in Rhizopus stolonifer.Secondly,to further study the antibacterial activity and related mechanisms of different dilutions of ACS solution against cell wall degrading enzymes and respiratory energy metabolic enzymes of Rhizopus stolonifer.Then inoculated with Rhizopus stolonifer on the‘hujingmilu'peach,to study the effect of ACS dilutions on the virulence and the control of Rhizopus stolonifer on peaches.Finally,to explore the incidence,physiological activities and storage quality of peach during storage.The results of the study are as follows:1.The antibacterial effect of ACS dilution solution on Rhizopus stolonifer,a pathogen of soft rot of postharvest peach fruit,was significant.In vitro,observation and determination of spores,mycelial growth rate and germination morphology of Rhizopus stolonifer.It was found that ACS dilutions could inhibit the spore germination,inhibit the production of spoers and elongation of germ tubes,thereby inhibiting spore germination rate,mycelial growth and colony expansion of Rhizopus stolonifer,and its inhibitory effect decreases with increasing dilution.The ACS-10-3treatment group had the best inhibition effect,the spore germination rate,colony expanded diameter and mycelial dry weight were only 54.89%,2.58±0.23 cm and0.09±0.01 g,respectively,which was a decrease of 45.11%,69.97%and 85.48%,compared with the control group,sporulation significantly reduced.In the ACS dilutions treated with Rhizopus stolonifer had small spores,rough shoots,and short and thick mycelia with uneven distribution,the mycelia of the ACS-10-33 and ACS-10-44 treated groups even wrinkled,fractured,vacuolizated,and melanizated.In the Rhizopus stolonifer test with different dilutions of ACS in vitro,it was found that the membrane permeability of ACS-10-33 treated group was the highest at the 120thh minute of culture,reaching 52.76%,which was 39.72%higher than that of the control group.The ACS solution impairs the cell membrane of Rhizopus stolonifer,increased permeability of celsl,causes leakage of intracellular substances,metabolic disorders,and the bacteria cannot normally grow or even die.2.The dilution of ACS had a significant inhibitory effect on cell wall degrading enzymes and respiratory energy metabolizing enzymes of Rhizopus stolonifer.Studies have shown that with the increase of dilution multiple of ACS,the activity of pathogenic enzymes such as PG,PMG,CX and GLU produced by Rhizopus stolonifer,and three kinds of respiratory metabolic enzymes such as SDH,MDH and IDH decreased,the vitality of Rhizopus stolonifer weakened and the ability to infect peach fruit decreased.After the ACS soaking treatment,the‘hujingmilu'peach was inoculated with Rhizopus stolonifer and cultured at a constant temperature of 25°C,the results showed that ACS solution could significantly inhibit the incidence of peach fruit,reduce the incidence,and inhibit the expansion of lesion area.In the first day of inoculation with Rhizopus stolonifer,the fruit of the control and ACS-10-66 treated peaches had begun to develop,and the incidence rates were 46.67%and 6.67%,respectively,whereas the ACS-10-33 treatment group started on the 4thh day and the incidence was 10%,the lesion area was reduced by 99.93%compared with the control group,indicating that the ACS dilution can inhibit the growth of Rhizopus stolonifer and reduce pathogenicity.3.ACS treatment significantly promoted the quality maintenance and physiological changes during the postharvest storage of peaches.The study found that ACS is a good preservation for peach,which can significantly reduce the rot index and rot rate of peach during storage,maintain excellent appearance quality and nutritional quality,and extend the shelf life.At the 25thh day after storage,the rot of the peach fruit in ACS-10-33 treatment group was low,with a weight loss rate of15.40±0.03%,which was 54.33%lower than that of the control group.At the same time,the peach peel of the ACS-10-33 treatment group had a bright red color,and the flesh had a bright color,and the hardness was 2.98±0.05 Kg/cm2,under this condition,the soluble solids,soluble sugar,and Soluble protein and ascorbic acid content were14.32%,37.81%,35.38%and 106.90%higher than the control group,respectively.And in this treatment group,peaches had a low degree of membrane lipid peroxidation at the end of storage,and they maintained high antioxidant activity while inhibiting the activity of multi-oxidase,delaying the oxidation and aging process of peach fruit.The ACS-10-33 dilution is the best treatment for postharvest preservation and preservation of peaches. |
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