Effect of Foliar Application of Humic Acid and Origanum Majorana Extract on Some Quantitative, Qualitative, and Biochemical Traits Changes of Two Greenhouse-Grown Bell Pepper Cultivars (Paramo and Taranto)

Capsicum annuum L. is an annual fruit vegetable of the family Solanaceae, native to Mexico and South America, and has always had a special place in the diets of various communities. Excessive accumulation of nitrate and nitrite is one of the criteria for reducing the quality of vegetables. In this study, the effect of foliar application of different concentrations of humic acid and Origanum majorana extract on nitrate, nitrite, and some quantitative, qualitative, and biochemical traits of two greenhouse-grown bell pepper cultivars (Paramo and Taranto) was investigated. The treatments were the control, humic acid (0.2, 0.6, and 1 gl-l), and marjoram extract (3 and 6%). All treatments were sprayed on plants for 12 consecutive weeks. In this study, traits such as fruit nitrate and nitrite content, fruit length, fruit diameter, number of fruits per plant, TSS, fruit potassium and calcium content, total yield, anthocyanin content, and weight loss percentage after harvest were measured. The results showed that the Taranto cultivar treated with the humic acid (0.6 gl-l) had better and more desirable nitrate and nitrite levels (52.2 and 3.2 mg/kg, respectively) compared to the control and other treatments. Moreover, the Taranto cultivar treated with the humic acid (0.6 gl-l) showed better results in terms of the fruit length and the number of fruits per plant. The Paramo cultivar treated with the humic acid (0.6 gl-l) had better TSS. Comparing the individual effect of cultivar on the traits showed that the Taranto cultivar had better potential than Paramo in most traits. Results indicated that humic acid 0.6 gl-1 had lower and more desirable nitrate and nitrite compared control and other treatments.