The Effect of Ascorbic Acid Foliar Application on the Ecophysiological Characteristics of Catharanthus roseus L. Under Water Deficit Stress

A factorial pot experiment in the form of a completely random basic design with three replications was conducted to investigate the effect of water deficit on the morphological and physiological characteristics of Catharanthus roseus (L.) under ascorbic acid foliar spraying in 2019. The test factors include: Drought stress (I) at 4 levels based on field capacity (FC): 1) no stress (I1) irrigation at 100% FC, 2) mild stress (I2) irrigation at 75% FC; 3) medium stress (I3) of irrigation at 50% FC; and 4) severe stress (I4) of irrigation at 25% FC; Foliar application of ascorbic acid was at 4 levels: 0, 25, 50, 100 mM. The obtained results showed that the concentration of chlorophyll a and carotenoids, leaf soluble sugar, proline amount and catalase enzyme activity increased with increasing severity of water deficit, but the morphological characteristics of root and shoot dry weight decreased. The application of ascorbic acid led to the improvement of the measured traits, and the results of the application of ascorbic acid were significantly superior to its non-use, and the level of 50 mM had a greater effect on most of the traits than other levels. According to the obtained results, it is recommended to use ascorbic acid to improve the growth of plants such as Catharanthus roseus under drought stress.Key words: Ascorbic acid, Catalase, Drought stress. Dry weight, Ornamental and medicinal plants.