Agronomic and physiological properties of Nigella sativa as response to humic acid andnano-chelated iron under water deficit

In order to evaluation of humic acid and iron nano-chelated on some physio-chemical properties of Nigella sativa under water stress, an experiment was conducted as split factorial on the basis of randomized complete block design with three replications during two years (۲۰۱۸-۲۰۱۹) in Eghlid Agricultural Research of Fars province. Main plots included three irrigation levels (۵۰ (I۱), ۷۵ (I۲) and ۱۰۰% (I۳) of available water), sub plots include foliar application of humic acid (۰, ۲۵۰ and ۵۰۰ mg.L-۱) and foliar application of nano-chelate iron (۰, ۱ and ۲g.L-۱). Results showed that severe stress (I۱) led to reduction of yield (۲۴%), %essential oil (۳۱%), oil percent (۳%), RWC (۸%), chlorophyll a and b (۲۸%) and increased, catalase (۷۱%), peroxidase (۶۱%), superoxide dismutase (۵۸%), proline (۱۲۹%) and ABA (۷۷%). Application of humic acid at ۲۵۰ and ۵۰۰ (mg.L-۱) led to ۳ and ۱۶% increase and ۱ and ۲ (g.L-۱) iron nano-chelated showed ۹۰ and ۳۲% increase compare to control. In interactions between irrigation, humic acid and iron nano-chelated under ۵۰ and ۷۵% of available water, the highest means observed in ۵۰۰ (mg.L-۱) humic acid + ۲ (g.L-۱) iron nano-chelated. In general, humic acid and nano-chelated was suitable for moderate of drought stress