An understanding of p lant morphology under water stress usually task for physiologists interested in the topic of drought tolerance. According to Al Hakimi et al, (1998) selection for morphology and physiological traits related to moisture water stress, such as root parameter, relative water content and carbon isotope discrimination was possible due to high heretability values and effective. Shoot and root growth were significantly reduced by osmotic stress (-0,6 and -1,0 MPa) induced with polyethylene glycol (PEG 6000) (El Midaout et al, 2003). Furthermore, Heschel and Rigions (2005) explained that plant height and diameter growth of stems were highly dependent on the amount of photosynthesis and were very sensitive to environmental conditions. In Indonesia, Guinea and Napier grasses are two important species of pastures being used mainly in cattle