Document Type : Research Article
Authors
Ferdowsi University of Mashhad
Abstract
Introduction: Nowadays Nigella Sativa plant is considered as a one of the most important kinds of medicine. Almost all the metabolic activities of plant cells, including the construction of active ingredients in medicinal plants, depend on water. Lack of absorbable water by plants can lead to the morphological, physiological and biochemical changes, including decrease of cell swelling and growth and thus reduction of leaf area and plant height, stomatal closure and photosynthesis restriction, increase in the soluble compounds for regulating the osmotic pressure, reduction of nutrient absorption and ultimately reduction of crop production. The use of anti-transpiration compounds is considered as a promising tool for the regulation of transpiration in respect of water conservation at an optimal level, where the strategies such as the use of anti-transpiration compounds have the potential for transpiration regulation. The aim of the present study is to improve the biochemical characteristics of medicinal plant N. sativa by anti-transpiration compounds under drought stress conditions.
Materials and Methods: The research was done using a split plot experiment based on a randomized complete block design with three replications. The irrigation intervals (8 and 16 days) in main plots and anti-transpiration compounds of chitosan (0.25, 0.5 and 1 %), Plantago psyllium mucilage (0.5, 1 and 1.5 %) and Arabic gum (0.25, 0.5 and 0.75 %) were put in subplots with three replications. The distance between the main plots in each block and distance between the two blocks were also assigned as 100 cm and 200 cm, respectively; so that the moisture content of a plot had no effect on the adjacent plots. Anti-transpiration compounds were sprayed simultaneously with applying drought stress till the flowering stage once a week at sunset. Phenolic compounds, proline, chlorophyll, carotenoids, essential oil were measured.
Results and Discussion: The results showed that there were significant differences between treatments in all studied traits. The best rate of the measured traits was observed at 8-day irrigation interval and chitosan treatment. The results obtained from the study showed that the effect of irrigation intervals and anti-transpiration compounds on the measured traits were significant. The best rate of the measured traits was observed at 8-day irrigation interval and chitosan treatment. The amount of phenolic compounds, proline, chlorophyll and carotenoids increased at 16-day irrigation interval, in which the increase is considered a type of drought tolerance mechanism. Different levels of anti-transpiration compounds decreased the chlorophyll, carotenoids, phenolic compounds, proline, essential oil percentage and yield.
Conclusion: The important processes, including nutrition, photosynthesis, stomatal opening and closure and growth are all influenced by water. Plants are constantly living in tension and develop morphological and physiological changes in the structures and compositions and chemical processes for coping with this tension. In this study, it was observed that the level of phenols, proline, chlorophyll and carotenoids would increase at 16-day irrigation interval, where the increase is considered as a drought tolerance mechanism. The anti-transpiration compounds also led to the significant changes in terms of all the studied traits compared to the control, indicating the effectiveness of theses natural compounds. As the above compounds are natural and biodegradable, as well as safer and less expensive than other chemical anti-transpiration compounds, they can serve as a good alternative to the chemical compounds. Cognition and expertise in water relations of plant and drought stress tolerance is considered as the main program in agriculture and the ability to withstand this stress is of great economic importance.
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