Abstract
Powdery mildew caused by Sphaerotheca sp. is the most serious disease of Rosa roxburghii cultivation. In this study, the foliar application of chitosan induced Rosa roxburghii Tratt. against Sphaerotheca sp. and its effects on the disease resistance, growth, yield, and quality of R. roxburghii were investigated. The results show that the foliar application of 1.0%~1.5% chitosan could effectively control Sphaerotheca sp. of R. roxburghii with the inducing control efficacy of 69.30%~72.87%. The foliar application of 1.0%~1.5% chitosan significantly (p < 0.01) increased proline, soluble sugar, flavonoids, superoxide dismutase (SOD), and polyphenoloxidase (POD) activities of the R. roxburghii leaf and decreased its malonaldehyde (MDA), as well as reliably enhanced its photosynthetic rate and chlorophyll. Moreover, the foliar application of 1.0%~1.5% chitosan notably improved single fruit weight, yield, vitamin C, soluble solid, soluble sugar, total acidity, soluble protein, flavonoids, and SOD activity of R. roxburghii fruits. This study highlights that chitosan can be used as an ideal, efficient, safe, and economical inductor for controlling powdery mildew of R. Roxburgh and enhancing its resistance, growth, yield, and quality.
Highlights
Rosa roxburghii Tratt., a Rosaceae deciduous shrub, is rich in antioxidants and nutrients, such as vitamin C, flavonoids, superoxide dismutase (SOD), and various minerals [1,2,3].Due to its high nutritional and medical value, it is widely used in improving immunity, lowering blood pressure, regulating the digestive system, protecting the liver, as well as anti-oxidation, anti-cancer, antibacterial, and anti-radiation, etc. [4,5,6,7,8]
The results here exhibit that the foliar application of 0.5~1.5% chitosan significantly (p < 0.01) reduced the incidence rate and disease index of Sphaerotheca sp
The foliar application of 0.5~1.5% chitosan effectively increased proline and soluble sugar of leaves in R. roxburghii. These results show that the application of chitosan effectively adjusted osmotic pressure in the cells by increasing proline and soluble sugar of leaves in R. roxburghii and could improve the resistance of plants to stress such as disease and drought
Summary
Rosa roxburghii Tratt., a Rosaceae deciduous shrub, is rich in antioxidants and nutrients, such as vitamin C, flavonoids, superoxide dismutase (SOD), and various minerals [1,2,3].Due to its high nutritional and medical value, it is widely used in improving immunity, lowering blood pressure, regulating the digestive system, protecting the liver, as well as anti-oxidation, anti-cancer, antibacterial, and anti-radiation, etc. [4,5,6,7,8]. As a promising fruit crop and natural medicine, R. roxburghii is widely planted in Southwest China, especially in Guizhou Province. Guizhou’s R. roxburghii industry has developed rapidly and made great contributions to rocky desertification control, poverty alleviation, and rural revitalization, and its planting area reached 170,000 hm in 2020 [3,9]. As commercial cultivation of R. roxburghii expanded, many pests became increasingly serious such as Sphaerotheca sp., Grapholita molesta, and Cercospora insulana Sacc, which seriously affect the yield and quality of R. roxburghii and frequently cause great economic losses. Is the most serious disease of R. roxburghii cultivation, which mainly damages the fresh young leaves and shoots of R. roxburghii, as well as flower buds, flowers, and young fruits [10]. Seriously affects the growth, yield, and quality of R. roxburghii, as well as often causes Sphaerotheca sp. seriously affects the growth, yield, and quality of R. roxburghii, as well as often causes
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