Influence of nano-silicon in antioxidants enzymes, ions absorption, and biochemical indicators of King Mandarin saplings leaves (<i>Citrus nobilis</i>) under salt stress

High salinity levels are particularly problematic in Iraq's southern and central regions, limiting the growth and productivity of many fruit plants. One effective approach to enhance mandarins' salt tolerance is the exogenous application of Nano-Silicon. The objective of the present research was to evaluate the performance of foliar applications by potassium silicate nanoparticles (K2SiO3NPs) in antioxidants’ enzymes, ions absorption, bio-chemical indicators of one-year-old for King Mandarin saplings grown in salt stress conditions. The experiment was conducted under controlled saline conditions and it included two factors. The first factor was three irrigation water salinity levels (0, 40 and 80 mM) using sodium chloride ( NaCl2 ) salt. The second factor was spraying with K2SiO3 NPs at three levels (0, 2 and 4ml L-1). A randomized complete block design (RCBD) was used to execute the factorial experiment. High level of NaCl (80 mM) had a negative effect on chlorophyll, carbohydrates, N, P, K , K/Na, Fe, Ca % and Mg in leaves and increased the accumulation of Si, proline, Cl, Na, Catalase (CAT), Peroxidase (POD) and Superoxide Dismutase (SOD) in leaves, compared to the control. K2SiO3NPs at 4 ml L-1 caused significant positive findings in ions absorption and biochemical indicators (chlorophyll, carbohydrates, N, P, K, K/Na, Fe, Ca, Mg and Si) compared to control. K2SiO3NPs at 4 ml L-1 caused a positively decreased of proline , Cl, Na, CAT, POD and SOD, compared to control. The utility of the present experiment is to enhance the tolerance of King Mandarin seedlings to saline irrigation water by applying foliar K2SiO3 NPs.