Evaluate the physiological role of tetrapyrroles precursor on growth, yield and some biochemical composition of two cultivars of Vicia faba L.

It is well known that 5-aminolevulinic acid (5ALA) is a non-protein amino acid and essential for the formation of biosynthesis of tetrahydropyrroles. So, two field experiments were carried out in a private farm at Sharkia Governorate to study effect of foliar spraying with 5ALA (1, 3, and 6 mgL(-1)) on both quality and economic characters of two cultivars of Vicia faba L. (Giza 843 and Nubaria 1). Results indicated that plants belong to Nubaria 1 cv. are characterized by significant increases in all components of photosynthetic pigments, indole acetic acid, free amino acids, seed yield /fed and straw yield/fed over those of Giza 843 cv. under control treatments. Notably, yielded seeds of Giza 843 cv. are characterized by significant increases in total carbohydrate and protein content than those of Nubaria 1 cv. Whereas, yielded seeds of Nubaria 1 cv. are characterized by significant increases in total phenolic content and vicine. Moreover, 5ALA treatments significantly increased most of all values of vegetative growth parameters, photosynthetic pigments, indole acetic acid, proline and free amino acids as well as seed and straw yield/fed, total carbohydrate and protein, and phenolic contents accompanied by significant decreases in vicine content of two faba bean cultivars relative to corresponding controls. On the other hand, the increments in most of investigated parameters were in opposite direction with concentration of 5ALA.The least concentration of 5ALA (1mg/L) was the most significant treatment in both cultivars. Since it increased seed yield by 17.86% and 72.27% in Giza 843 cv. and Nubaria 1 cv. respectively relative to corresponding controls. Regarding anti-nutritional substance called vicine, 5ALA at 3mg/L caused significant decrease in vicine content of Giza 843 cv. relative to control. It could be concluded that faba bean plants belong to Nubaria 1 cv. effectively responded to 5ALA at 1mg/L more than faba bean plants belong to Giza 843 cv.