PHYSIOLOGICAL RESPONSE OF BROCCOLI AND CAULIFLOWER AS AFFECTED BY NACL SALINITY

In the present investigation we studied the effects of NaCl on growth and physiological response of broccoli and cauliflower. A control nutrient solution and two saline treatments with different NaCl concentrations (20 or 40 mM L^-1) were assayed under greenhouse conditions. Plants were cultivated by using an open soilless system. The rise of the NaCl concentration in the nutrient solution caused a similar decrease in plant dry mass of broccoli and cauliflower (from 238.7 to 214.9 g plant^-1 and from 229.0 to 204.4 g plant^-1, respectively) regardless the NaCl level. The reductions of plant dry mass were not related to the assimilation rate of the plants being the net photosynthesis not influenced by NaCl salt stress. The total water potential of leaves decreased significantly at the increase of NaCl concentration in broccoli. Under salt stress, broccoli plants lowered the osmotic potential for maintaining the turgor pressure. The exposure to NaCl salinity determined an increase of Na⁺ and Cl^- concentrations on plant tissues. Moreover, the old leaves showed the highest concentrations of Na⁺ and Cl^- to preserve the integrity of the young leaves and reproductive organs. The accumulation of Cl^- in the broccoli’s roots as other defense mechanism under salt stress could enhance its salinity tolerance compared to cauliflower under more severe salinity conditions.