Dear student, nitrogen is essential for the plants and they can not live without nitrogen. It is a very important part of many cells and various structures like amino acids , proteins and also in the genetic material (DNA). Nitrogen is also required by the plants to make chlorohyll which is required in the process of photosynthesis to produce food and energy. It is an important component of amino acids which forms proteins and without proteins the plants withers and thus they dies. Regards.