عنوان مقاله [English]
Background and purposes: Pelargonium graveolens is an uncommon Pelargonium species native to the Cape Provinces and the Northern Provinces of South Africa. Pelargonium graveolens is a medicinal plant used in the medical, cosmetic, and food industries. On the other hand, the water shortage and its impact on plants is an eminent environmental factor. In this regard, the disadvantages of water stress can be alleviated by growth and bio stimulators. Hence, study aims to evaluate the effect of Glycine betaine and humi-forthi on morpho-physiological and biochemical properties of Pelargonium graveolens under water stress.
Materials and methods: For this purpose, water stress was applied in three levels (100% Field capacity (FC), 70% FC, and 40% FC) and foliar application used in five levels (control, 2.5 mg/l humi-forthi, 5 mg/l humi-forthi, 50 mM Glycine betaine, and 100 mM Glycine betaine) as factorial based on completely block design in three replications. The traits investigated in the study were Plant height, Root/Shoot ratio, canopy temperature, chlorophyll content, SOD activity, proline, essential oil percent and yield.
Results: Analysis of variance showed the simple effect of water stress and foliar application was significant on all traits including Plant height, Root/Shoot ratio, canopy temperature, chlorophyll content, SOD activity, proline, essential oil percent and yield. However, the interaction of water stress and foliar application was significant on Root/Shoot ratio, canopy temperature, SOD activity, and essential oil yield. 40% FC significantly decreased plant height, chlorophyll content, essential oil percent and yield. In contrast, canopy temperature, SOD activity, and proline increased by applying 40% FC. Foliar application with 100% Glycine betaine increased plant height, essential oil percent and yield, while decreased proline. Amino acids are easily absorbed by the plant after being introduced into the plant cells through solubility, due to their biochemical structural properties. This causes the energy of the plant to be stored to cope with environmental stresses.Biological stimuli increase photosynthesis through increasing water absorption and nutrients, which increases plant properties.
Conclusion: The interaction of 100% FC and Glycine betaine was selected as the most appropriate treatment in improving the morpho-physiological and biochemical properties of Pelargonium graveolens under water stress. Although humi-forthi is a combination of some free amino acids, it could not have a significant impact relative to Glycine betaine. Finally, we can maintain the water need of plant up to 70% FC, and use the Glycine betaine 100 mM to reduce the adverse effects of high water stress.