Induced Resistance Of Camellia Oleifera To Anthracnose By Sodium Silicate

Camellia oleifera anthracnose is one of the main diseases affecting Camellia oleifera.Each year,the reduction in seed production caused by Camellia oleifera anthracnose ranges from 10%-30%in different regions,and in severe cases,it can even reach 50%.This has caused significant economic losses to the Camellia oleifera industry and hindered its healthy development.The most common method of prevention and control currently used is chemical control,which has the advantages of being fast and effective.However,the use of chemical pesticides can disrupt the ecological balance,cause environmental pollution,and excessive use of pesticides can lead to pesticide residues exceeding the standard,endangering human health.Therefore,it is necessary to find a new approach to prevention and control.Silicon is the second most abundant element in the earth’s crust,but the amount of available silicon in soil for plants to directly absorb and use is limited.Research has found that silicon can induce plant resistance,improve the activity of defense enzymes and the accumulation of defense-related metabolites in plants.Currently,research on the use of silicon to improve plant disease resistance has mainly focused on crops such as rice and sugarcane.However,there is still a lack of research on the induction of Camellia oleifera resistance to Camellia oleifera anthracnose using silicon.Sodium silicate is a soluble inorganic silicate that has a bactericidal effect.In this study,sodium silicate was used as the research object to investigate its inhibitory effect on the Camellia oleifera anthracnose pathogen in Camellia oleifera and to explore the mechanism by which sodium silicate induces Camellia oleifera resistance to Camellia oleifera anthracnose.This provides a theoretical basis for the effective prevention and control of Camellia oleifera anthracnose in Camellia oleifera.The main research results are as follows:1.Study on the inhibitory effect of sodium silicate on the Camellia oleifera anthracnose pathogen in Camellia oleifera:in PDA culture media containing different concentrations of sodium silicate,treatment with 20 mmol/L sodium silicate showed the most significant inhibitory effect on the Camellia oleifera anthracnose pathogen,with spore germination rate and colony growth inhibition rate of 15.98%and 77.61%,respectively;in PDA culture media containing different concentrations of sodium silicate with pH6.7,treatment with 20 mmol/L sodium silicate at pH6.7 showed the most significant inhibitory effect on the Camellia oleifera anthracnose pathogen,with spore germination rate and colony growth inhibition rate of 33.51%and 31.28%,respectively;in PDA culture media containing different concentrations of sodium silicate corresponding to different pH values,treatment with 20mmol/L sodium silicate corresponding to the appropriate pH value showed the most significant inhibitory effect on the Camellia oleifera anthracnose pathogen,with spore germination rate and colony growth inhibition rate of 26.83%and 24.80%,respectively.By comparison,it found that sodium silicate has an inhibitory effect on the Camellia oleifera anthracnose pathogen in Camellia oleifera,and the inhibitory effect is significant.2.Construction of the system of inducing Camellia oleifera resistance to Camellia oleifera anthracnose using sodium silicate:In the root irrigation treatment,the diameter of the lesions of plants without sodium silicate induction was 0.77 cm,but the diameter of Camellia oleifera spots induced by 15 mmol/L sodium silicate solution was 0.40 cm,which was significantly lower than that of the control group;in the spraying treatment,the diameter of lesions in plants without sodium silicate induction was 0.69 cm,but the diameter of Camellia oleifera spots induced by 1.5 mmol/L sodium silicate solution was 0.34 cm,which was significantly lower than that of the control group.Sodium silicate can alleviate the incidence of Camellia oleifera anthracnose in Camellia oleifera within a certain concentration range.Root-irrigation and spray treatments with different concentrations of sodium silicate induced changes in CAT activity and POD activity in Camellia oleifera.Among them,Camellia oleifera treated with a 15 mmol/L sodium silicate solution via root-irrigation showed the highest CAT activity on the first day after inoculation,reaching a maximum of 705.97 U/g·min,and its POD activity on the fifth day after inoculation was 0.02 U/g·min,significantly higher than other treatments.For plants treated with a 1.5 mmol/L sodium silicate solution via spray,their CAT activity on the first day after inoculation was 528.13 U/g·min,significantly higher than other treatments,and their POD activity on the seventh day after inoculation was 0.029 U/g·min,significantly higher than the control group.The results of the experiment showed that the reduction in the incidence of Camellia oleifera anthracnose in Camellia oleifera was induced by sodium silicate.In the interval and duration measurements after induction with sodium silicate,the diameter of the lesions on Camellia oleifera in the first 15 days after induction was lower than that of the control group,with the most significant effect on the first day after induction,with a lesion diameter of 0.38 cm.After 20-30 days of induction,there was no significant difference in the lesion diameter compared to the control group.The results showed that the optimal induction concentration of sodium silicate was 1.5 mmol/L,the optimal treatment method was spray treatment,the optimal interval period was 1 day,and the optimal duration was 15 days.3.Study on the mechanism of inducing Camellia oleifera resistance to Camellia oleifera anthracnose using sodium silicate:Inoculation with Camellia oleifera anthracnose and treatment with sodium silicate increased SOD activity,PPO activity,soluble protein content,and total phenol content in Camellia oleifera,and decreased malondialdehyde content.PPO activity and soluble protein content rapidly increased on the first day after inoculation,reaching 43.36 U/g-min and 18.61 mg/g,respectively.SOD activity and total phenol content significantly increased and reached their maximum values on the third day after inoculation,with SOD activity and total phenol content of 79.14 U/g and 22.20 mg/g,respectively.The MDA content on the third day after inoculation was 9.20 μmol/g,significantly lower than that of the control group and the inoculation-only group.PAL activity did not significantly differ from that of the control group.Camellia oleifera treated with inoculation-only showed changes in physiological and biochemical indicators,but the effect of inoculation with sodium silicate was more significant.Treatment with sodium silicate without inoculation did not have a significant effect on the physiological and biochemical indicators in Camellia oleifera.The results of the experiment showed that sodium silicate was involved in the defense mechanism of Camellia oleifera.In summary,sodium silicate has an inhibitory effect on Camellia oleifera anthracnose,and spraying sodium silicate induces changes in the defense mechanism in Camellia oleifera and improves the resistance of Camellia oleifera to anthrax.It provides a theoretical basis for the effective prevention and treatment of Camellia oleifera anthracnose.