INCREASED PHOSPHORUS MITIGATES THE ADVERSE EFFECTS OF SALINITY IN TISSUE CULTURE

Abstract

Interactive effects of increased phosphorus (P) with salinity were studied at the microculture level of African violet (Saintpaulia ionantha). Increased P from 0.5 to 2.0 mM in the medium was very effective to mitigate the adverse effects of increased NaCl salinity (0.0, 50, 75, 100 mM). Growth (shoot height, and dry mass) was significantly reduced with increased salinity, whereas increasing P improved growth with elevated salt concentrations. Leaf osmolarity was decreased (more negative) with salinity effect and it was increased (less negative) by P treatments. Percent ash was increased with salinity and it was not highly affected by P. Root number and root length were significantly reduced with increased salinity and improved with increased P. The percentage of shoot content of nitrogen (N), P, calcium (Ca), potassium (K), and magnesium (Mg) were reduced with elevated salinity level and this reduction was less as P concentration increased in the medium. Sodium (Na) was significantly increased with imposed salinity and its uptake was reduced with increased P level. Zinc (Zn), manganese (Mn), and copper (Cu) uptake were increased with elevated salinity level and reduced with elevated P level in the media. Increased NaCl level strongly reduced Fe uptake and P was very effective in increasing iron (Fe) uptake. An overall increased P was very effective in regulating macro and micronutrients uptake, counteracting the increased salinity adverse effects. We can conclude that P is a key element for studying the physiological responses of different plant species to salinity. Also in vitro cultures (a rigorously controlled system) could work as an efficient alternative for the study of salinity.