Document Type : Original Article
Authors
Assistant Professor of Biotechnology, Department of Production Engineering and Plant Genetics, Faculty of Engineering Sciences, Razi University, Agriculture and Natural Resources Campus, Kermanshah, Iran
Abstract
Introduction
One of the most significant global challenges is drought stress, which leads to a reduction in agricultural and horticultural crop yields and an increase in secondary metabolites. Zinc, as a mitigating factor against drought stress, plays a crucial role in this context. Chlorophyll fluorescence parameters are essential for assessing the photosynthetic capacity throughout the plant's lifecycle. This study aimed to compare resistance to varying moisture levels, evaluate physiological indicators, and assess the functionality of photosystem II using chlorophyll fluorescence parameters and biochemical characteristics. Plant adaptation to drought is examined through various physiological, morphological, biochemical, and molecular responses and adjustments. Soluble sugars help prevent protein and cell membrane dehydration by maintaining osmotic pressure in plant leaves under drought stress conditions.
Materials and methods
In a factorial experiment with a completely randomized design, the first factor comprised three levels of drought stress (75%, 50%, and 25% of field capacity), while the second factor included three concentrations of zinc nitrate (0, 5, and 10 mg.l-1) applied to the Balangue (Lallemantia iberica) plant. The uppermost leaves of the plant were selected to determine the desired indices and were covered with special clamps for fifteen minutes. Subsequently, light was shone on the leaf for two seconds using a device, and the desired indicators were recorded. The aerial parts of the plants were harvested, dried, powdered, and soaked in ethanol and methanol at room temperature for 48 hours to assess biochemical characteristics. The concentration of methanolic and ethanolic extracts was performed using a rotary evaporator, and the samples were stored in a refrigerator.
Results and discussion
In the results comparing the mean with increasing levels of drought stress and application of foliar spraying with nitrate, there was no decrease in Pi and Fv/Fm at different stress levels. The greatest effect of foliar spraying was related to the amount of ten milligrams per liter of zinc nitrate in the investigated levels. Also, at different levels of drought stress, foliar spraying using zinc nitrate caused a significant change in the amount of phenol (13.50 mg.l-1), soluble sugar (94.15 mg.l-1), and flavonoid (8.49 micrograms). per liter and anthocyanin content (0.138 μg.l-1).
Conclusion
The results have shown that the application of moisture stress at the investigated levels significantly increased the content of biochemical traits (soluble sugar, total phenol, flavonoid content, and anthocyanin content) and chlorophyll fluorescence indices. Increasing the level of carbohydrates, especially sugars, plays an important role in protecting and regulating osmosis. Additionally, the accumulation of soluble sugar molecules stabilizes the structure of macromolecules and ultimately prevents the deformation and destruction of biological molecules. Therefore, the use of foliar spraying at two levels of five and ten milligrams of zinc nitrate during the stress period has shown a decrease in the level of these compounds. The highest difference was related to 50% moisture stress and the use of 10 mg.l-1 of zinc nitrate. The use of zinc oxide and green zinc nanoparticles in the soil and foliar application by spray significantly increases the absorption of nitrogen, phosphorus, potassium, and zinc and reduces the adverse effects of drought stress. Therefore, under the influence of different moisture regimes at various growth stages of the plant, it is possible to improve the growth of the plant and enhance the biochemical characteristics of the balangue plant under drought stress conditions by using foliar spraying.
Keywords
Main Subjects
)