The effect of nitrogen fertilizer level on leaf chlorophyll content was significant (Table
3). Results indicated the highest and lowest leaf chlorophyll content were observed at 50
kg·N·ha-1 and control plants (at vegetative and flowering stages) but there was no
significance between nitrogen levels at the reproductive stage. Similar results have been
reported in investigations conducted by Bowen and Frey (2002), Aroiee and Omidbaigi
(2004) and Basela et al. (2008). A promotion effect of inorganic fertilizers on chlorophyll
contents might be attributed to the fact that nitrogen is a constituent of chlorophyll molecule.
Moreover, nitrogen is the main constituent of all amino acids in proteins and lipids that act as
structural compounds of the chloroplast (Basela and Mahadeen, 2008). Nitrogen is the most
important nutrient and required by the plant in largest proportion. It is the important
constituent of chlorophyll, protoplasm, protein and nucleic acids. It is most important for
preparation of starch in leaves and production of amino acids.