FOLIAR SALT SPRAY INFLUENCE ON GROWTH, COMPOSITION AND YIELD OF PHASEOLUS VULGARIS

Experiments were conducted to investigate the influence of long-term treatment of varied concentrations of saline aerosols and salt deposition rates applied during different developmental stages on growth, composition and yield of Phaseolus vulgaris. Bean plants were subjected to saline aerosols four hours daily during the periods of treatment. Wind-tunnel treatments: Plants were treated during the vegetative stage for two weeks starting at two weeks age, for four weeks during vegetative and flowering stages, and during the flowering stage for two weeks starting at four weeks age. A 1% NaCl solution foliar spray was applied at deposition rates of 0.52 and 1.35 ug Na(.)m('-2)(.)sec('-1). Plants harvested after vegetative stage showed growth stimulation at the lower salt deposition rate. Plants treated continuously were stimulated in the vegetative growth but decreased in dry weight of flowers. Treatment only during the flowering stage reduced growth of flowers at the higher deposition rate. Na and Cl contents of tissue were increased by all spray treatments. Treatment in sedimentation chambers with NaCl: Plants treated at deposition rates of 0.35 and 0.71 ug Na(.)m('-2)(.)sec('-1) during the vegetative-fruiting stage, three to six weeks, had reduced growth. Plants treated through the vegetative-fruiting and fruit-development stages, three to nine weeks, had maximum reduction in pod and seed growth at the higher deposition rate. Treatment of plants only during the fruit-development stage, six to nine weeks, resulted in a slight reduction of pod and seed production. Plants treated only during the vegetative-fruiting stage and placed in the control during the fruit-development stage, had reduced pod and seed production. All NaCl treatments increased Na and Cl contents in tissue. Treatments in sedimentation chambers with NaCl, N-P-K or distilled H(,2)O mists were made at a deposition rate of 5 ug Na(.)m('-2)(.)sec('-1), and nutrient solution (11-3.4-4) at solution concentrations of 2 and 1% with corresponding deposition rates of 2.5 and 1.25 ug K(.)m('-2)(.)sec('-1) during the vegetative-fruiting and fruit-development stages, respectively. Within NaCl treatments, plants harvested after the vegetative-fruiting stage had increased fresh weight of leaves, plants treated continuously had reduced seed weight 61%, those treated only during the fruit-development stage had no effect on seed weight but plants treated only during the vegetative-fruiting stage (plants placed in the control during the fruit-development stage) resulted in the most reduction in seed weight 71%. Tissue contents of Na and Cl increased and NH(,4)-N decreased. Within N-P-K treatments, continuous or only during the fruit-development stage seed weight was slightly increased, but treatment only during the vegetative-fruiting stage (plants placed in the control during the fruit-development stage) reduced seed yields 18%. N-P-K spray maintained optimum NH(,4)-N, K and P content in the tissue.