INFLUENCE OF THE PHENOLOGICAL STAGES ON IONIC ALTERATIONS IN AUBERGINE PLANTS (EGGPLANT)

Aubergine eggplant plants (Solanum melongena L.) were grown under gree nhouse conditions with nitrogen and phosphorus fertilization individua lly, or both, and with a large amount of organic matter and CaSO4 in t he soil superficie. The irrigation water was strongly brackish. In the plants, nitrate and phosphate showed an obvious mobility, whereas chl oride and sulfate were relatively immobile. Cations in the form of pot assium and ammonium were highly mobile, during the growth cycle, where as the other cations tested were immobile. Translocation of anions was weak with little change in concentration throughout the growth cycle, whereas cations showed marked variations in different stages due to t he influence of NH4+ and K+ mobilization. The accumulation of cations was offset by hydrogen extrusion to maintain foliar pH within physiolo gical limits. Sharp changes in pH were buffered by the effect of citri c acid as an organic anion, which absorbed the excess positive charge. Alterations in cations increased the formation of organic acids, a pr ocess clearly dependent on the stage of the growth cycle. The finding of this study is that behavior of ion balances remained constant regar dless of the dose of fertilizer applied, but changed in response to th e stage of the growth cycle.