عنوان مقاله [English]
Introduction: Limited irrigation leads to a wide spectrum of physiological and biochemical responses in plants, and one of the efficient plant mechanisms against water deficit for maintenance of cell turgidity is osmotic regulation. Nowadays, leaf spraying as complement to soil methods is effective against environmental stress. Since Origanum vulgare and Thymus vulgaris extract contain anti-oxidant compounds, it seems that these compounds may prove useful for reduction of stress intensity. Therefore, this research was carried out to investigate the effect of spraying of Origanum vulgare and Thymus vulgaris extract on some of growth and physiological traits of Sesamum indicum L. (Naz cultivar) under different irrigation levels.
Materials and methods: This experiment was conducted as split plot factorial in two years (at 2015 and 2016) as a randomized complete block design with three replications at Gorgan University of Agriculture. In this study, treatments included two different irrigation regimes include normal condition (every 15 days) and drought stress (every 25 days), three levels of Origanum vulgare extract include 0, 40 and 60 % and three levels of Thymus vulgaris extract include 0, 10 and 20 %. Irrigation regime levels were considered as the main factor and the levels of Origanum vulgare and Thymus vulgaris extract were assigned to sub plots. The first spraying application took place one month after planting and second and third placement at 12 days intervals.
Results and Discussion: Results indicated that limited irrigation significantly reduced the measured indices of leaf area index, length plant, leaf dry weight, stem dry weight, stem dry weight, chlorophyll a, chlorophyll b. The results also showed that limited irrigation increased content of flavonoid, carotenoid, Ca and K. The results of this study showed that using Origanum vulgare and Thymus vulgaris extract significantly improved the measured indices. Results indicated that the highest leaf area index (3.76 and 2.93), leaf dry weight (57.88 gr/m2), length plant (159 cm), chlorophyll a (21.7 mg g-1Fw) and chlorophyll b (20.61 mg g-1Fw) were attending in control conditions were associated with 60% Origanum vulgare and 20% Thymus vulgaris L. extract. The highest carotenoid (18.58 mg g-1Fw), flavonoid (0.003 mg g-1Fw), Ca (0.57 mg g-1Fw) and K (2.97 mg g-1Fw) were attending in limited irrigation conditions were associated with 60% Origanum vulgare and 20% Thymus vulgaris L. extract. It was found that the most measured indices in both control and also limited irrigation conditions were associated with 60 % Origanum vulgare and 20 % Thymus vulgaris essence. Application of plant extract (Origanum vulgare and Thymus vulgaris essence) was effective in both irrigation conditions (normal conditions and limited irrigation), but its effect was more pronounced under stress condition (every 25 days).
Conclusion: Therefore, it can be stated that under dry conditions, the use of Origanum vulgare and Thymus vulgaris extract can induce tolerance in the plant in response to water deficit conditions. Since less cost is needed compared to other methods, therefore, in areas with low water conditions, it is recommended to use the Origanum vulgare and Thymus vulgaris extract.