EFFECT OF NH4+, NO3+, AND Cl- IONS ON ION UPTAKE AND SOLUTION pH IN HYDROPONIC CULTURE OF AGERATUM AND SALVIA

Abstract

Ageratum and salvia were grown in hydroponic solutions containing either NH4+, NO3-, or both NH4+ and NO3- with or without Cl- to study changes in solution pH and ion uptake rate. pH of both NH4+ and NH4+ + NO3- solutions was steadily decreased as time passed. A drop in pH front 6.50 to 3.57 within 3 days was recorded with NH4+. The pH changes were also affected by the presence of Cl-. The NO3- treatment maintained its initial solution pH over time regardless of the presence of Cl-. pH change by ageratum was greater than that by salvia, especially when plants were in NH4+ + NO3- solution. N uptake was maximum in NH4+ + NO3- solution with Cl-. Uptake of NO3- was suppressed by NH4+, but NH4+ uptake was not affected by NO3-. NH4+ and NO3- counteracted each other in influencing the Cl- uptake. Uptake of other ion was also affected by plant species as well as N source and Cl-. In ageratum transpiration rate was lowered by Cl- in both NH4+ and NO3- treatments.