Sesame ability to grow in adverse condition such as dry weather and high temperatures. Pix is a plant growth regulator that can be used by producers to manage crop development, uniformity and maturity. Nitrogen as one of the key structural nutrient elements is needed for plant growth and development. Water scarcity restricted field crop production, especially under rain-fed conditions. A 2-year field experiment was done to determine the effect of irrigation regimes (50% Field capacity, 75% Field capacity and 100% Field capacity) on sesame growth, photosynthetic pigments, enzyme activity and nutritional value. Nitrogen fertilizer from urea source (0, 50 and 100 kg. ha-1) in combination with foliar application of mepiquat chloride (pix) (0ppm, 500ppm and 1000ppm) were applied under different irrigation regimes. Water stress had an adverse effect on plant growth and the application of 50 kg ha-1 urea fertilizer with 500 ppm pix in 100% water requirement had the highest growth parameters including plant height (82.66 cm), plant dry weight (33.33g) and capsule number (53.66). With increasing deficit irrigation level, the greatest MDA was observed with 500 and 1000 ppm of pix treatments.



Materials and Methods

The research was structured as a split-plot factorial based on a randomized complete block design (RCBD) with three replications. Irrigation regimes were allocated to the main plots at three levels: severe drought stress (supplying 50% of the sesame water requirement), moderate drought stress (supplying 75% of the sesame water requirement), and full irrigation (supplying100% of the sesame water requirement). Nitrogen fertilizer from the urea source was applied in three treatments (0 kg.ha⁻¹,50 kg.ha⁻¹, and100 kg.ha⁻¹), in combination with foliar applications of Mepiquat Chloride (Pix) at three levels (0 ppm,500 ppm, and1000 ppm) assigned to the subplots.



Results and discussion

As the water requirement of the plant decreased, the plant height decreased and the lowest value was observed at 50% irrigation level. However, in non-stressed conditions, this trait reached its maximum level. The results showed that the highest level of chlorophyll (0.13 and 0.18 mg.g-1, respectively) was observed at 100% field capacity with 1000 ppm pix. Under conditions of 100% water supply, the highest relative water content (67%) was obtained with the application of 100 kg/ha urea and 1000 ppm Pix. This treatment did not differ significantly from the application of 50 kg. ha urea (Table 5). In the water regimeIn both years, the highest total soluble carbohydrate content (1.58 and 2.06 mg. g-1 DW, respectively) were observed at 50% field capacity sprayed with 100 kg ha-1 nitrogen fertilizer and 1000 ppm of pix. Severe water stress significantly increased proline production in sesame plants and application of pix plant growth regulator and urea fertilizer reduced it in both years. The highest Zn content was recorded at 50% field capacity with 100 kg ha-1 nitrogen fertilizer without application of pix in both years of experiment. Increased deficit irrigation without application of urea fertilizer and pix corresponded with decreased nitrogen, P, K and Fe content. Antioxidant enzymes activity including catalase, and peroxidase increased with water stress and application of urea fertilizer and pix enhanced antioxidant enzyme activity during stress. Overall, application of urea fertilizers and pix improved growth parameters, physiological and biochemical attributes of sesame plants during water stress.