Document Type : Research Paper - Medicinal Aromatic Plants
Authors
1 Faculty Member, Department of Agriculture science, National university of skill (NUS), Tehran, Iran
2 Agricultural school of shahrekord
Abstract
Introduction
Humic acid is a principal component of humic substances, which increasing cell membrane permeability, increasing photosynthesis and respiration rates, enhancing mineral uptake and enhancing protein synthesis. The effects of Humic acid on the physiological and photosynthetic characteristics of plants under drought stress have been, including the growth parameters, osmotic regulation, antioxidase activity (such as the superoxide dismutase, peroxidase, and catalase) and photosynthesis parameters. Also, drought stress is one of the most important abiotic stresses that adversely influences the growth and production of crops and disturbs plant water relationships, reducing leaf size, root growth and root multiplication. Plants exhibit various physiological and biochemical responses to drought stress at cellular and whole organism levels. The results of some study indicated that the appropriate concentration of humic acid could effectively alleviate the damage of drought stress on plants.
Materials and Methods
In order to investigate the effect of drought stress on germination characteristics, as well as the effect of different levels of humic acid and water deficit on some characteristics of the medicinal plant of lallemantia, two experiments were conducted. In the first experiment, the characteristics of germination of lallemantia under the influence of five levels of drought stress including 0 potential, -0.4, -0.8, -1.2 and -1.6 MPa in the form of a completely randomized design with 4 replications in the laboratory of the Faculty of Agriculture Shahrekord University was evaluated. In the second experiment, in order to investigate the different levels of humic acid and water deficit stress on some characteristics of the lallemantia, a field experiment was conducted in the form of a split plot in the form of a completely randomized block design in three replications. The treatments included four irrigation levels of 50, 70, 90 and 110 mm evaporation, from the evaporation pan surface as the main factor and four humic acid levels of 0, 5, 10 and 15 liters per hectare as secondary factors.
Results and Discussion
The results showed that the percentage and speed of germination and fresh weight of lallemantia seedlings decreased due to drought stress levels and the root length increased. Also, in the results of the field experiment, it was observed that the number of flowers, inflorescences, seeds per plant, seed yield, and the amount of biomass were affected by the simple effects of drought stress and humic acid treatments, and drought stress decreased them, while the use of humic acid increased them. As a result of drought stress, the percentage of mucilage increased and the yield of essential oil decreased. Also, the use of humic acid increased the yield of essential oil compared to the control. In general, the use of humic acid, especially at a concentration of 15 liters per hectare, increased the seed yield and the medicinal properties of the lallemantia plant. In general, the use of humic acid, especially at a concentration of 15 liters per hectare, increased the seed yield and the medicinal properties of the lallemantia plant.
Conclusion
humic acid is an alicyclic ring, and a hydrophilic group, such as a carboxyl group, a hydroxyl group, or a carbonyl group is bonded to enhance the water retention of the plant. Humic acid can be used directly on plants at low concentrations to enhance plant growth, yield and nutrient uptake, thus constituting a popular category of plant biostimulants. Our findings further illustrated that humic acid can relieve the damage of drought stress because humic acid also has the effect of stabilizing the plasma membrane system by increasing the activity of antioxidant enzymes and participating in cell osmotic regulation. Our findings may help to elucidate of the effects of humic acid on lallemantia plant under drought stress and provide substantial guidance for the use of humic acid in agricultural production.
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