Calcium Chloride and Drought Stress Changed Grain Yield and Physiological Traits in Sesame (Sesamum indicum L.)

Water deficit or drought stress is one of the most significant abiotic stresses that induce reduction in plant growth and crops yield. Calcium chloride has been shown to ameliorate the adverse effects of drought stress on many plants. Therefore, this study aimed to investigate the role of calcium chloride in drought resistance and its effect on some physiological characteristics in sesame. Calcium is essential for good growth and structure of plants. In sesame (Sesamum indicum L.), the foliar application of calcium chloride (C1=0 (control), C2=5, C3=10 and C4=15 mM concentration) significantly affected on grain yield under drought stress (W1= 7 (control, no drought stress-plants irrigation at a 7-day interval), W2= 12 (severe drought and plants irrigation at a 12- day interval) and W3= 17 (the most severe drought and plants irrigation at a 17-day interval). Drought stress reduced grain yield and 1000 seed weight, but these were enhanced by foliar application of calcium chloride when drought levels increased from W1 to W3. Although the increasing calcium chloride concentration reduced the content of photosynthesis pigments in leaves, the drought treatment until W2 increased the content of photosynthetic pigments (chlorophyll “a” and carotenoids) in leaves. The foliar application of calcium chloride increased the seed weight in plant, the number of capsules per plant, plant height, and the concentration of potassium and phosphorus in leaves and seeds. The greatest amount of potassium in leaves and seeds were measured under the W1C3 treatment. Sesame plants under W3C3 and W2C3 had the highest amount of phosphorus in leaves and seeds, respectively. Overall, although drought stress reduced the growth and grain yield in sesame, the foliar application of calcium chloride at the concentration of 10 mM, prevented the drought-stressed sesame plants from damage by improving their physiological parameters