Dear Hafiz

Nitrogen plays a major role in growth and differentiation such as stem elongation and leaf morphology. Both form and amount of nitrogen in in vitro medium have significant effects on rate of cell growth and differentiation. In tissue culture medium, nitrate, ammonium salt, amino acids and complex organic products supply nitrogen. Nitrate is good source of nitrogen because it is readily taken up and metabolized by the cells and affects a number of developmental processes leading to shoot branching, breaking of seed and bud dormancy and release of apical dominance.

I also studied the effects of the nutrient medium on shoot proliferation, so that you can download the articles from the following links:

Article In vitro shoot proliferation and rooting of garnem rootstock...

Article In Vitro Propagation Of ‘Gisela 5’ Rootstock As Affected By ...