ABSTRACT
Portulaca oleracea L. is a C4 succulent belonging to the family Portulacaceae. It is a nitrogen-loving plant with high oxalic acid content. The main objective of the present study was to determine the relationship between nitrogen and organic acid metabolism and the drought-tolerant nature of this plant. In this context, one-month-old seedlings of P. oleracea raised in acid-free silica sand with ½ strength Hoagland’s culture medium were water stressed by watering them at an interval of 4, 8, and 15 days separately in separate pots, while control plants were watered every alternate day. Results indicated that there is an increase in total nitrogen, nitrate, and nitrite nitrogen in the roots, stem, and leaves of P. oleracea imposed by water stress as compared to well-watered control. The investigation into organic acid metabolism revealed that under water stress conditions, the accumulation of oxalic acid content in the root, stem, and leaves of P. oleracea was followed by increased activity of the enzyme glycolate oxidase. The role of nitrogen and oxalic 278acid metabolism in P. oleracea in the water stress tolerance mechanism is discussed.
