Foliar Application of Iron and Zinc on Quinoa under Drought Stress Affects Its Seeds Germination and Biochemical Properties

Recently the use of plant products instead of chemical materials is one of the most important needs of the modern civilization in terms of human health. Drought stress during growth and seed maturation is one of the major environmental constraints, which influences seed grain filling and consequential germination and early growth stages of plants. In this study, the impact of foliar application of micronutrients (control, Zn, Fe, Zn + Fe, nano-Zn, nano-Fe, and nano-Zn + nano-Fe) were evaluated on quinoa at 2 reproductive stages (50% and 100% of flowering stage) under 2 levels of drought stress (50% and 85% of depletion of soil moisture content). Results revealed that germination traits including germination percentage, and seed technological parameters such as germination value and germination energy, antioxidant enzymes activities, and chlorophyll (Chl) content were significantly affected by foliar application of micronutrients, time of micronutrient spraying, and drought stress level. The correlation results showed that 1000- grain weight had a positive and significant relationship with grain filling period, physiological maturity, germination percentage (GP), and germination speed (GS). Drought stress also increased the antioxidant enzymes activities of catalase (CAT) and peroxidase (POD) in all nutrient treatments. Drought stress at seed formation stage had a significant effect on seed filling and its weight and could decrease seed germination rate. It was concluded that application of nano-Zn + nano-Fe in 50% flowering stage could promote the germination performance, seedling growth, and the antioxidant capacity under drought stress conditions.