This research was conducted to study the effect ofwaterlogging level and duration, nitrogen feritilizer and terminal drought stress on root and shoot growth of Stevia. A screenhouse pot experiment was conducted in University of Guilan in spring, 2013. The experimental design was factorial with completely randomized design layout with three replications. Treatments included four waterlogging levels; (0, -5, -10 cm from soil surface and with normal irrigation as control), in periods of 2 and 4 days of waterlogging, two levels of nitrogen (6‰ and 0) from source of urea and two levels of terminal drought stress. Treatments were measured before flowering phase. Results showed that measured root and shoot traits include root dry weight, root length, root area, root volum, root length density, root surface area density, dry root mass density,root diameter, leaf area, plant height, number of SPAD, number of lateral shoot,number of leaves were significantly different among treatments.Root dry weight, root length and root volume in -10 waterlogging level treatment( 16.24 g, 24.8 cm and 27.7 ml, respectively) and in fertilizer treatment (17.9 g, 25.5 cm and 22.1 ml, respectively) the least decrease were seen. Moreover, interaction between drought stress treatment and nitrogen fertilizer for root dry weight and root length (18.4 g and 26.5 cm, respectively)and in shoot traits, number of leaves, leaf area and plant height (237, 64.07 cm2 and 87 cm) showed the minimum difference with control tretments. Generally, the results of this experiment showed that increase of waterlogging either level or duration decrease the amount of root and shoot characteristics. Nitrogen fertilizer was optimum for plant production and root growth, resulting in higher root and shoot traits in applying treatment. By contrast, terminal drought stress led to decrease in all root and shoot traits.

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