The effect of nitrogen and selenium on some phytochemical characteristics and allicin of garlic leaf

Purpose: This research has investigated the effect of different levels of nitrogen and selenium on some growth and physiological characteristics of garlic leaves. Research method: This research was done as a factorial in the form of randomized complete blocks in 3 replications. The first factor included four levels of nitrogen (0, 50, 100, and 150 kg ha^-1) and the second factor included three levels of selenium (0, 5, and 10 mgL^-1). Findings: In all four nitrogen levels, with increasing selenium concentration, plant height (69.66 cm), fresh weight (10.66 g m²), and dry weight (51.33 g m²) of leaf increased. The highest amount of photosynthetic pigments was observed in the treatment of 150 kg ha^-1 of nitrogen along with 10 mg L^-1 of sodium selenate. Nitrogen and selenium increased antioxidant capacity (45.69 μmol g^-1FW), total phenol (295.60 mg 100 g^-1FW) and ascorbic acid (18.30 mg 100 g^-1FW). Contrary to selenium, nitrogen increased the amount of allicin in garlic leaf, and the highest amount of allicin (0.33 mgmL^-1) was in the treatment of 150 kg ha^-1 of nitrogen along with 0 mgL^-1 of sodium selenate. The maximum plant height and wet and dry weight of the leaf were observed in the treatments of selenium and nitrogen, which shows the positive effect of both elements on increasing the amount of chlorophyll synthesis and, as a result increasing the amount of photosynthesis and carbon fixation, which ultimately will have, increasing the growth rate of garlic plant. Research limitations: None were found to report. Originality/Value: As a result, the treatment of 150 kg ha^-1 of nitrogen along with 10 mgL^-1 of sodium selenate is recommended to increase the antioxidant compounds of garlic leaf, which is a good source of these compounds and selenium in early spring, which also plays an essential role in human health.