Effect of exogenous amino acids application on the biochemical, antioxidant, and nutritional value of some leafy cabbage cultivars.

Using organic fertilizer as part of plant nutrition for decreasing using chemical fertilizer and increasing plants' nutritional value is scientists' concern. Treatments were three concentrations of a mixture of 16 different AAs (amino acid) (0, 150 and 300 mg/L), sprayed every 7 days for 2 months on 4 leafy cabbages. Results showed 300 mg/L AAs increased anthocyanin, flavonoids, phenol, protein and proline. The SOD, POX and APX rose upon AAs usage. The application of AA significantly increased the total chlorophyll, proline, carotenoid, anthocyanin, phenol, protein and flavonoids compared to control plants. The levels of glucosinolate were increased especially in the treatment of 300 mg/L of AAs and glucobrassicin and gluconapin, both of these together represent more than 50% of the total glucosinolate contents. The highest levels of phenolic and flavonoids mostly belonged to quercetin and catechin. Total AAs and total non-essential AAs showed the highest amounts in all treatments in leaves. AAs with different concentrations by foliar application in "Ka- scotch" variety were effective in growth, physiological parameters such as plant height and shoot dry weight, while AA changes were effective in most of the biochemical and nutritional traits of "Ka-red" variety. Conclusively, the glucosinolate, phenolic and flavonoid contents and AAs varied between four cabbage cultivars. Exogenous AAs application at 300 mg/L could be recommended for cabbage cultivation to improve growth, biochemical traits, productivity and nutritional value.