Physiological response of sesame (Sesamum indicum L.) to application of chitosan and magnesium-nano fertilizers under irrigation cut-off in a sustainable agriculture system

In order to investigate chitosan and magnesium-nano fertilizers’ impact on photosynthetic pigments, protein, proline, and soluble sugar contents of sesame under irrigation cut-off treatment, a split-factorial experiment was conducted based on randomized blocks with three replications. Irrigation cut-off based on BBCH scale as the main factor (normal irrigation and irrigation cut-off in 6 and 75 BBCH stages). Secondary factors as subplot included Oltan and Dashtestan-2 sesame cultivars, and foliar application of Mg-nano fertilizer (application and non-application) and chitosan (control, foliar application of 4.8 g.l-1 in 65 BBCH and 6.4 g.l-1 in 75 BBCH stages). Based on the results, severe drought stress (irrigation up to 65 BBCH) resulted in reducing the mean of chlorophyll a, b, and total compared to the control treatment. Chitosan foliar application yielded more desirable results compared to those of Mg-nano fertilizer and caused an increase in the mean traits of chlorophyll a, b, total, carotenoid, protein, proline, and soluble sugar. In addition, irrigation up to 65 BBCH (severe drought stress) and non-application of nanofertilizer led to a decrease in chlorophyll content and physiological damage. Based on the findings, chitosan biopolymer, as a natural substance, as well as co-application of these two can be an appropriate action in order to decrease the plant damage under drought stress regarding the role of Mg in chlorophyll structure and a large number of the plant vital enzymes.