Effect of different zinc fertilizer on green bean nutraceutical values.

Green bean (Phaseolus vulgaris) is a valuable vegetable that has a high amount of functional nutrients and bioactive compounds. The use of zinc (Zn) fertilizer to improve green bean productivity and nutrient value is limited. A study was performed to evaluate plant growth, productivity and harvest quality of different pole and bush green bean (Phaseolus vulgaris) varieties as affected by zinc sulphate and Lys-Zn. Results showed that green bean shoot fresh and dry weights increased by the two sources of Zn fertilizer in pole varieties compared with controls. The bush types, 'Burpees' and 'Black valentine' showed higher yield with Lys-Zn application compared with the control. Antioxidant activity was enhanced by Lys-Zn in 'Blv". The 'Burpees', 'Dragon' and 'Black valentine' indicated highest antioxidant activity. Results indicated that regardless of the source of Zn fertilizer, all the green bean varieties were rich in calcium, magnesium, and potassium. 'Dragon' under ZnSO₄ had the highest Zn content. Also, foliar application with Lys-Zn enhanced protein, starch, calcium, auxin, and folate mostly in 'Burpees', 'Dragon', and 'Black valentine'. Moreover, total essential and non-essential amino acids were improved by Lys-Zn in 'Sunray' and 'Burpees'. A real-time PCR indicated that Lys-Zn increased Bowman–Birk inhibitor (BBI) gene expression in'Sunray', 'Burpees' and 'Cherokee' compared with the others. Moreover, the interaction effect of variety and zinc gave the highest yield, antioxidant capacity, nutrient elements, and folate contents in 'Burpees' under the Lys-Zn treatment. [ABSTRACT FROM AUTHOR]