Browsing by Author "Jeena, Himani"

Now showing 1 - 2 of 2
  • Thumbnail Image
    ThesisItemOpen Access
    Molecular characterization, epidemiology and management of Rhizoctonia aerial blight of soybean
    (G.B. Pant University of Agriculture and Technology, Pantnagar-263145, 2023-08-01) Jeena, Himani; Singh, K. P.
    Rhizoctonia aerial blight caused by Rhizoctonia solani is a one of the most serious diseases affecting the yield and quality of soybean (Glycine max (L.) Merrill). The aim of the present investigation was to understand the prevalence, epidemiology, and management of Rhizoctonia aerial blight in soybean cultivation in Uttarakhand, India. A three-years survey conducted in major soybean growing areas of the state revealed that the disease is widespread in the Kumaon region, with an average disease incidence of 14.75 percent. Among the districts, the highest disease incidence and severity were observed in Udham Singh Nagar (30.40% and 25.78% respectively), followed by Nainital and Almora. To assess the cultural, morphological, and molecular variabilities, thirty-five isolates of R. solani were collected from different areas of Uttarakhand. These isolates exhibited significant variation in terms of colony characteristics and morphological traits. Molecular variability was examined using ISSR, RAPD, and URP markers, which all exhibited 100 percent polymorphism. The average PIC values for these markers were 0.367, 0.429, and 0.310 respectively. UPGMA cluster analysis grouped the isolates based on their geographical location, although there were a few exceptions. The mean percent disease index (PDI) and infection rate ranged from 9.29 to 65.82 percent and 0.028 to 0.058 units per day, respectively, in highly resistant and highly susceptible varieties. Disease severity showed a significant negative correlation with minimum temperature and a positive correlation with evening relative humidity. Multiple regression models utilizing weather variables successfully predicted disease severity, with coefficient of determination above 0.82 for all varieties. The logistic and Gompertz models were deemed suitable for explaining the temporal dynamics of the disease under field condition. These models can prove valuable in developing disease prediction models for timely adoption of disease management strategies. Among the tested fungicides, Tebuconazole 50% + Trifloxystrobin 25% WG exhibited maximum inhibition of mycelial growth, up to 88.24 and 100 percent at 50 μg/ml and 100 μg/ml respectively, in vitro. It also found effective disease control of up to 72.61 per cent under field conditions. Additionally, five nanoparticles were evaluated for their efficacy against Rhizoctonia solani. Among them, ZnO nanoparticles at 500 μg/ml successfully inhibited 100 percent of the fungus radial growth. In greenhouse conditions, ZnO NPs treated plants showed a 66.77 % reduction in disease incidence at 100 μg/ml. Evaluation of 53 soybean genotypes revealed that nineteen genotypes exhibited moderately resistant to Rhizoctonia aerial blight, although none of the genotype was found free from disease. Sixteen SSR markers, including Sat 281, Satt 245, Sat_ 076, Sat_246, Satt 277, Satt 463, Satt_195, Sat_276, Sat_127, Sat_196, Sat_105, Sat_124, Sct_199, and SOYHSP176, showed differential amplification between resistant and susceptible genotypes, and were found promising for validation of field level screening. The significant findings from this investigation can be utilized to optimize management strategies for Rhizoctonia aerial blight disease. (
  • Thumbnail Image
    ThesisItemOpen Access
    Studies on yellow leaf disease of sugarcane
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2018-06) Jeena, Himani; Sahu, R.K.
    Sugarcane (Saccharum officinarum L.) is one of the most important commercial crop. It is grown in tropical and subtropical region of the country. It provides sugar, fodder, manure and myriad of by product with bagass, molasses, jaggery pulp and paper and viscose etc. It is being cultivated about 26.9 million hectare with a world wide harvest of 1910 million tones. Presently, India is the second largest country after Brazil in sugar and sugarcane production. In India, area under sugarcane cultivation is 4.92 million hectare and production is 348.44 million tones in 2016- 17. Being sugar rich crop it is more prone to many diseases. Among them Yellow Leaf Disease is an emerging threat to the sugarcane cultivation. It is a viral disease and caused by Sugarcane Yellow Leaf Virus (polerovirus). Its losses were recorded upto 60 per cent in Venezuela and upto 30 per cent in India. The present investigation conducted for confirmation of causal organism of Yellow Leaf Disease, screening and evaluation of promising 11 sugarcane varieties against Yellow Leaf Disease and its epidemiological studies and also the evaluation of different insecticide and their impact on various yield attributes and on disease incidence. On the basis of observations it was concluded that causal organism of Yellow Leaf Disease in sugarcane is a virus and was recovered from the midrib of leaf. Among the 11 varieties viz., CoPant3220, CoS767, CoPant90223, CoPant5224, CoPant84212, CoS8436, CoPant97222, CoPant84211, Co1148, CoJ64 and CoPant99214, only two varieties (CoPant99214 and CoJ64) were showing resistant reaction with low disease incidence 10.67 per cent and 12.14 per cent, respectively where as variety CoPant90223 having susceptible reaction and rest were moderately resistance viz., CoPant5224, CoS8436, CoPant84212, CoPant97222, Co1148, CoPant84211 and some were moderately susceptible viz.,CoS767, CoPant3220. Epidemiological studies of the two varieties CoPant90223 and CoS767 had shown negative correlation of minimum temperature with disease incidence i.e. -0.904 and - 0.807 respectively and also gave negative correlation with disease severity i.e. -0.853, -0.829, respectively. These both varieties gave positive correlation of morning humidity with disease incidence (0.509 and 0.563) and also gave positive correlation with disease severity (0.520 and 0.585). Among the different insecticides tested, fipronil 40% + imidacloprid 40% ( Lesenta 80 WG ) was best in reducing the disease incidence (61.82%) followed by fipronil 5SC (55.17%), imidacloprid 17.8SL (47.88%), acetamaprid 20SP (42.28%), thiomethoxam 25WG (31.40%) and imidacloprid 600FS (16.10%) in comparison the control. Fipronil 40% + imidacloprid 40% also gave highest yield (41.63 kg/plot) followed by fipronil 5 SC (40.06 kg/plot), imidacloprid 17.8 SL (33.25 kg/ plot), acetamaprid 20 SP( 32.88 kg/plot), thiomethoxam 25 WG (32kg/plot), imidacloprid 600 FS (30.35kg/plot) as compared to check ( 27.56kg/plot).