Improving some physiological and yield parameters of safflower by foliar sprays of Fe and Zn under drought stress

Water deficiency limits nutrient availability and causes physiological disruptions resulting in decreased crop productivity in the field. The spray of Fe and Zn on drought-stressed plants may reduce some of the detrimental impacts of this stress on crop performance. Thus, this research was laid out as a split-plot design based on a randomized complete block design with three replications to assess the effects of exogenous iron (Fe: 1 g/l) and Zinc (Zn: 1g/l) on safflower (Carthamus tinctorius L.) under different irrigation intervals (irrigation after 70, 100, 130, and 160 mm evaporation as normal irrigation, and mild, moderate, and severe water deficits, respectively). Water deficiency decreased green ground cover by reducing plant growth. Leaf water content, chlorophyll content index, capitols per plant, grains per plant, and 1000-grain weight also decreased but leaf temperature increased due to water limitation, leading to a significant loss in the grain yield per unit area under moderate and severe stresses. Foliar sprays of Zn and especially Fe considerably improved the grain yield of safflower under different irrigation intervals, via increasing leaf chlorophyll content, grains per capitol, and grains per plant. However, this superiority in the grain yield decreased with increasing water deficit, which shows that foliar sprays of Fe to a larger extent and Zn to a lesser extent can alleviate some detrimental impacts of mild and moderate water limitations on safflower plants.