The Role of Melatonin in Improving The Vegetative Growth Characteristics of Four Genotypes of Faba Bean (Vicia faba L.)

Abstract

A field study was conducted at a research station in Al-Hamidiyah, which is affiliated to the College of Agriculture - University of Anbar, during winter 2020-2021. It aims to study the effect of four concentrations of the growth regulator melatonin on the vegetative growth traits of four genotypes of faba bean. A split –plot arrangement in randomaized complete block design RCBD, in three replications, was used. The concentrations of the growth regulator occupied the main plots (0, 5, 10 and 15) mg.l-1. While the American (Sakis), Dutch (Aquadulce), Italian (Ackerbhone) and Turkish (Aquadlge) genotypes occupied the sub plots. The most important results were the following: The American genotype superiority in most growth traits gave the height of plant is 96.94 cm, branches number in plant is 10.08, leaf area is 4770 cm2. plant-1, dry weight of plant is 184.71 g, chlorophyll content in the leaves is 48.21 spad, and the length of the pod is 19.63 cm. As for the Italian variety, it gave the lowest period from planting to the beginning of flowering, which was 59.42 day. As for the Turkish genotype record, the longest period from planting to beginning of flowering 64.57day. Spraying with the growth regulator melatonin led to the emergence of significant differences between all the traits. The concentration 15 mg.l-1 of melatonin gave a highest mean for each: plant height is 78.23 cm, branches number is 8.50, leaf area is 3840 cm2. Plant-1, dry weight is 177.63 g, chlorophyll content in the leaves is 44.02 spad, and the length of the pod is 18.15 cm. There was a significant overlap between American genotype with concentration 15 mg.l-1 in each of the leaf area, dry weight of the plant, and chlorophyll content of leaves. The overlap was significant between American genotype with concentration 10 mg. l-1 in plant height.