product of the action of promoter regions for this purpose the following were measured a relative water content it was determined according to equation rwc pf u2212 ps ph u2212 ps u00d7 100 where pf corresponds to the fresh weight of the leaf when collecting the tissue ph corresponds to the weight of the leaf after 24 hours of hydration in distilled water and ps corresponds to the dry weight alter 24 hours of drying at 60 u00b0 c b quantum performance of ps ii it was measured by emission of chlorophyll fluorescence and this parameter was used as an indicator of damage to photosynthetic apparatus fluorescence of chlorophyll was measured with a portable fluorometer fluorpen pam 2000 walz effeltrich germany efficiency of quantum performance of psii was calculated by qypsii fm 0 u2212 ft fm 0 genty et al 1989 biochim biophys acta 990 1 87 92 six measurements were done during the morning in the third and fourth leaf of nine leaves of every plant c chlorophyll determination to determine chlorophyll content of leaves a chlorophyll meter ccm 200 opti sciences inc tyngsboro mass was used readings were carried out in the third and fourth leaves of plants under hydrological stress for 15.