نقش فنيل مركوريك استات PMA ماده بازدارنده تعرق در افزايش مقاومت به شوري در گياهان جو و لوبيا

Salinity reduces plant growth and development by reducing external water potential, increasing ion toxicity and interference with absorption of essential alleviate the harmful effects of excess salts on plant growth. In this investigation., effects of different concentrations of phenylmercuric acetate (PMA) applied either as spray or added to root media on barley (Hordeum vulgare, C.V. Karoon) and bean (Phaseolus vulgaris, C.V. Talash) were studied. Using PMA as spray under non - saline conditions and also adding to root media under saline conditions reduced the plant growth. However, under saline conditions (113.5 mM NaCl for bean and 227 m M NaCl for barley, corresponding to -0.5 and -1.0 Mpa osmotic potential respectively), spraying plants with PMA (100 uM for bean and 100 - 750 uM for barley) resulted in an increase in both fresh and dry weight of the plants. There was also increase in K1 Na ratio in the shoots. Applying PMA to root media at very low concentrations (0, 2, 5 and 10 uM). decreased the growth rate in both groups. It appears that PMA when applied as spray apparently by increasing stomata) resistance will reduce the rate of sodium transport to shoot in transpiration stream. This compound also by some unknown mechanism (s) improves K/Na selectivity transport to shoots. Thus, PMA by improving plants water balance, reducing the rate of sodium transport to shoot and improving photosynthetic efficiency, counteracts the harmful effects of excess salts application of PMA to root, adversely affects plant growth and damages root cell membranes probably by mercury metal present in this compound.