Biofertilizers — DU B.Sc. (Hons.) Botany Previous Year Question Papers

5. Illustrate your answers with suitable diagrams wherever necessary. (i) Biological control (b) Fill in the blanks : (i) The digested waste excreted from earthworm is called (ii) AM fungus have been assigned to a new Phylum named (iii) Actinorrhizal symbiosis is a mutualistic relationship between certain non-leguminous plants and is a waste treatment process that involves combustion of substances contained in waste materials. a nitrogen fixing bacteria is closely associated with cereals and grasses. (c) True andFalse : (i) Azotobacter is a non-symbiotic biofertilizer. (ii) The bacteria responsible for biological nitrogen fixation are called diazotrophs (iii) Vesicles act as a storage site for nutrients formed inside the root cortex. (iv) Azolla is an aquatic fern. (v) Dairy products, bones and fishes can be added for biocomposting. 2. Write short notes on the following (any three) : (a) Phosphate solubilizing bacteria (b) Organic farming (c) Azolla in rice cultivation (d) Stock culture (i) Explain agricultural and industrial waste management emphasizing on various composting methods. (ii) Give a detailed account of Nitrogen-fixing biofertilizers. (iii) What are the advantages and disadvantages of using chemical fertilizers? (i) What are carrier-based inoculants? Briefly discuss the properties of an ideal carrier material. (ii) What is Green manuring? Write down the benefits of Green manuring. (iii) With the help of a diagram describe the formation of a root nodule. 5. Briefly describe the different types of mycorrhizal association. Write down the role ofmycorrhizae in growth and yield of crop plants. (15)