| Author | Bhandari, Deepak |
| Call Number | AIT Diss. no.AS-10-01 |
| Subject(s) | Wheat--Diseases and pests
|
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. AS-10-01 |
| Abstract | Spot blotch disease of wheat caused by Bipolaris sorokiniana (Shoem.) occurs every year at moderate to severe form in South Asia causing considerable losses of grain yield. Some micro-organisms possessing natural antagonistic ability against the target pathogens can be exploited against B. sorokiniana as safe, economic and most sustainable bio-control method of disease management. A series of studies was conducted to explore the natural antagonists against B. sorokiniana from the naturally existing fungi on wheat foliages , and to study the interactions between B. sorokiniana and well adapted saprophytic and parasitic fungi of wheat leaves to develop biological management methods for spot blotch disease in wheat. The study comprised of three separate experiments. Spot blotch infected leaves of more than 30 wheat genotypes were collected from Bhairahawa, Nepal, where the disease severely affects wheat production in South Asia. Pu re cultures of isolates were prepared following frequent plate transfers and single spore isolation methods. Screenings of collected isolates, comparison of the antagonistic ability of the selected isolates and effects of time of inoculation on antagonistic ability were assessed following the dual culture techniques. The experiments were conducted under in vitro conditions following Completely Randomized Design (CRD). For screening, the interactions between isolates and B. sorokiniana were observed and rated in to five categories after 14 days of incubation. Similarly, radial growth of B. sorokiniana in dual culture with selected isolates was measured, and percent growth inhibition of the pathogen was calculated to compare the antagonistic ability of the selected isolates . Effects of interaction on viability of mycelium and on sporulation ability of the pathogen were assessed. The in vivo experiments were consisted of a polyhouse seedling assay and a field experiment. The polyhouse seedling assay was conducted under partially controlled conditions following factorial experiment in CRD. The selected isolates were the first factor and inoculation times of the isolates as the second factor. Disease scoring was done 21 days after the inoculation of B. sorokiniana. Similarly, a field experiment was conducted to evaluate the antagonistic ability of s elected isolates under natural epiphytotic conditions following Randomized Complete Block Design (RCBD). Four disease scores were recorded following the percent leaf area infection methods, and area under disease progressive curve (AUDPC) was calculated. Data on yield attributes were also compared. |
| Year | 2010 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. AS-10-01 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural and Aquatic Systems(AS) |
| Chairperson(s) | Ranamukhaarachchi, S.L.; |
| Examination Committee(s) | Shipin, Oleg;Shrestha, Rajendra;Shrestha, Sundar Man; |
| Scholarship Donor(s) | Ministry of Foreign Affairs, Norway; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2010 |