During vegetation period of cotton heating of the air temperature and over dry humidity consequences shortage of water at soil and in the air. At the period of increased water demand,ie, at flowering and yield harvest period, unfavorable environmental factors like hot wind, air and soil drought will lead to destruction of morpho-physiological and biochemical processes and spill of yield elements. Therefore, precise determination of the plant’s water requirements, irrigation periods, number and norms plays important role to the cultivation of high yields.