Question

Which one of the following is not a biofertilizer?
A. Agrobacterium
B. Rhizobium
C. Nostoc
D. Mycorrhiza

Answer 1

Hint: Biofertilizers are microorganisms that are treated to seeds, plant surfaces, or soil. Biofertilizers often encourage growth by improving the host plant's supply or availability of primary nutrients. Biofertilizers are organically vigorous products that help grow and provide plants with nutrients.

Complete answer: One of the famous species and a gram-negative bacteria is agrobacterium. It induces plant tumours. Agrobacterium is a bacterium transmitted from the soil and is used as a natural vector. Agrobacterium does not constitute a biofertilizer. Agrobacterium is a transmission agent of genes. Agrobacterium tumefaciens induces crown gall disease, in particular members of the rose family such as apple, pear, peach, cherry, almond, raspberry, and roses, in a wide variety of dicotyledonous (broad - left) plants. It induces crown gall disease in plants, which is the reason why gene transfer and its expression are most commonly used in biotechnology. Nostoc, Rhizobium and Mycorrhiza are associated with plant roots and turn nitrogen into nitrites and nitrates in the atmosphere and make it available to plants. These can turn atmospheric nitrogen into the consumable form of bacteria. So, it shows a symbiotic relationship and lives in the root of certain legumes and provides them with nitrogen. In exchange, bacteria are given food and shelter by plants. So, it's a fertilizer that works.
Hence, the correct answer option is A.

Note: Rhizobium is beneficial to farmers as it can decrease the use of nitrogen fertilizers where leguminous plants are cultivated. It allows root nodules and can also be referred to as root node bacteria. It is an aerobic bacterium that displays a leguminous symbiotic relationship.