N is the most important plant nutrient. In plants, N is present as proteins including amino acids and chlorophyll. A shortage of N can  cause a reduction in plant growth  due to inhibition of cell division resulting in stunted plant growth. Since shortage of such protein compounds can cause excess production of carbohydrates, thickening of  the cell membranes due to increase in the content of cellulose and lignin is noticed under N deficiency. Thus a plant suffering from N deficiency often looks small, dry and non succulent.

N deficient cassava plants normally show visible deficiency symptoms and they become shorter, less vigorous than normal plants. Under severe conditions, plants lack vigour, become chlorotic mostly the lower leaves becoming yellow initially and then the entire foliage  becoming chlorotic almost at the same time. The upper leaves are generally much paler than normal ie, less green.