(i) Yes, we can artificially induce the property of nitrogen fixation in a plant, leguminous or non-leguminous by genetic engineering. It involves the introduction of nif genes that cause the synthesis of nitrogenase enzyme by some vector in the plant in which we have to induce symbiosis.
(ii)) Symbiotic association.
[iii) Yes, it is necessary for a microbe to be in close association with a plant to provide mineral nutrition. For example, plants that contribute to nitrogen fixation include the legume family-Fabaceae or Leguminosae, such as clover, soyabeans, alfalfa, lupines and peanuts. They contain symbiotic bacteria called Rhizobia within nodules in their root systems, producing nitrogen compounds that help the plant to grow and compete with other plants.