Investigation of the Effect of N Form in the Response of Snap Bean (Phaseolus vulgaris L. cv. Alpha) to NaHCO3 in Hydroponic System

Regarding to this issue that nitrogen is one of the main essential elements for plant that growth and efficiency of plant is related to it, and on the other hand most of the water and soil resources in Iran are alkaline; in order to evaluation of the interactive effect of different concentrations of sodium bicarbonate and nitrogen form on snap bean in hydroponic system, this research was done in factorial design with two factors, sodium bicarbonate (0, 1, 5 and 15 mM) and nitrogen form (ammonium and nitrate). Results showed that ammonium decreased vegetative growth compared to nitrate, and on the other hand bicarbonate caused increase of the effect of ammonium toxicity and reduced the plant growth. Ammonium increased flower and pod production compared to nitrate. In the presence of nitrate in nutrient solution, addition of bicarbonate caused reduction in reproductive growth of snap bean plants that can be due to the cumulative effect of bicarbonate and nitrate on the pH increase in nutrient solution.