Today, the high cost and environmental hazards of chemical fertilizers have led to the use of plant growth-promoting rhizo- bacteria (PGPR) as biofertilizers in crop production. This study was performed aiming to evaluate the effect of co-inoculation of free-living nitrogen-fixing, phosphate solubilizing, and potassium solubilizing bacteria (namely biofertilizer) and foliar application of potassium, calcium, and silicon (namely spraying) on growth and physiology of single (SC) and poly capsule (PC) sesame. The study was conducted at Ferdowsi University of Mashhad, Iran during 2017 and 2018 growing season. The results indicated biofertilizer and spraying imposed a positive effect on photosynthetic pigment content, net photosynthetic rate, maximum efficiency of PSII, PSII operating efficiency, and nutrient content (N, P, K, Ca). The biofertilizer + spraying increased net photosynthetic rate of the single (21% in 2017 and 2% in 2018) and ploy (25% in 2017 and 14% in 2018) capsule sesame. The grain yield of SC sesame was increased by 21% (both fertilizer treatments) in 2017, while, it was increased by 87 and 89% due to the application of biofertilizer and biofertilizer + spraying, respectively, in 2018. Generally, PC sesame showed a greater response to the application of PGPR compared with SC. A positive correlation was observed among the photosynthetic pigment content, photosynthesis rate, leaf nutrient content, capsule number per plant and grain yield of sesame. The advantages of PGPR to improve physiological and agronomical performance along with the environmental benefits to reduce the utilization of chemical fertilizers leads to recommend using PGPR in sesame production.

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