Although the general effects of drought on plant growth are fairly well known, the primary effects of water deficit at the biochemical and molecular levels are not well understood [6]. Accumulation of proline has been advocated as a parameter of selection for stress tolerance [7,8]. Proline accumulation can be met with the stresses such as temperature, drought and starvation [9]. High levels of proline enabled the plant to maintain low water potentials. By lowering water potentials, the accumulation of compatible osmolytes, involved in osmoregulationallows additional water to be taken up from the environment, thus buffering the immediate effect of water shortages within the organism [10]. Previous works revealed the changes in antioxidant metabolism of Vigna unguiculata under water deficit stress [11]. The objectives of this study were to determine the morphological traits that contribute tolerance for water deficit and to estimate the changes that occurred in the proline metabolism under water stress, which is an important strategy to abiotic stress resistance and identify the tolerant variety of Helianthusannuus for water deficit