Thumbnail Image

Theses

Browse

20181
Reset filters
Author: Manoj Kumar × End date: 2018 × Start date: 2010 × Type: Thesis × Thesis Type: Ph.D ×
Reset filters

Search Results

Now showing 1 - 1 of 1
  • Thumbnail Image
    ThesisItemOpen Access
    Ecofriendly management of Rhizoctonia solani causing black scurf of potato
    (CCSHAU, 2018) Manoj Kumar; Anil Kumar
    In recent years, among different fungal diseases of potato, black scurf disease has emerged as a serious problem caused by Rhizoctonia solani in most of the potato growing areas of India with 2-70 per cent disease incidence leading to considerable yield losses up to 50 per cent. Due to difficulties in disease management and lack of stable genetic resistance in potato cultivars against R. solani, different ecofriendly management aspects including fungicides, bioagents, organic amendments and cultural practices as well as systemic acquired resistance (SAR) activators in vitro and in vivo conditions were undertaken for effective management of the disease in present investigation. The in vitro and in vivo management study involving fungicides, bioagents or organic amendments indicated that among fungicides, Monceren, MEMC were most effective, whereas, in bioagents Trichoderma harzianum produced better results followed by T. viride. Among the organic amendments, vermicompost was found most effective followed by neem cake against black scurf of potato. Besides chemicals and biological control, cultural practices have also been used to minimize the inoculums level from the soil and tubers. Black scurf incidence is significantly influenced by irrigation level and depth of planting. As the irrigation frequency and depth of planting were increased, disease incidence and severity of potato black scurf was also increased. The delayed date of planting also affects disease incidence and severity. It was observed that soil moisture content is directly proportional to increased irrigation frequency and depth of planting. Black scurf disease incidence and severity showed a linear and negative correlation with soil temperature, whereas, a linear and positive correlation with soil moisture. Biochemical analysis indicated roles of systemic acquired resistance (SAR) inducing chemicals viz., salicylic acid, jasmonic acid, β-aminobutyric acid, γ-aminobutyric acid and hydrogen peroxide against black scurf of potato caused by R. solani. SAR activators play an important role in biochemical composition viz., total phenol, peroxidase, polyphenol oxidase and phenylalanine ammonia lyase and enhanced defense mechanism in potato crop for black scurf. It was also inferred from the study that all the biochemical constituents initially increased up to peak concentration after that, it decreased. Tubers dipping of SAR activators were found more effective to control the disease by reducing disease incidence as compared to foliar spray.