Effect of Pinching and Thidiazuron on Morphophysiological and Biochemical Properties of Pelargonium graveolens Under Water Deficit Stress.

In order to investigate the effect of pinching and foliar spraying of thidiazuron on improving the tolerance to water-deficit stress in Pelargonium graveolens plants, a factorial experiment was conducted in the form of a completely randomized design with four replications in the research greenhouses of the Faculty of Agriculture of Lorestan University in 2022. The first factor was water deficit stress (80 (control), 50 and 20% available water in the soil (AWC)), the second factor was pinching and non-pinching, and the third one included thidiazoron foliar spraying (zero, 5 and 10 mg/liter). The results showed that water deficit stress had a decrease effect on the indices of plant height, number of lateral branches, total fresh and dry weight, relative water content and essential oil percentage, whereas it had an increase impact on electrolyte leakage, malondialdehyde content and catalase enzyme activity. Pinching of plants and foliar application of thidiazuron in the control level decreased the plant height, number of leaves and the relative water content of the leaves, but increased total fresh and dry weight, root growth, concentration of photosynthetic pigments and electrolyte leakage. However, under the water deficit stress, plant height, number of lateral branches, number of leaves, root growth, total fresh and dry weight, relative leaf water content and essential oil yield increased and electrolyte leakage, malondialdehyde content and catalase enzyme activity decreased. In general, the results showed that the application of pinching and thidiazoron, particularly at a concentration of 5 mg/liter, resulted in a reduction of the adverse effects of water deficit stress by improving the water balance and promoting root growth. [ABSTRACT FROM AUTHOR]