Correlation study of physicochemical properties of some Sudanese onion genotypes (Allium cepa L.)

Abstract

Onion is a traditional vegetable of Sudan and is by far the most popular and widely grown crop. This study was conducted to characterise the variability of selected genotypes in terms of their growth, yield and chemical characteristics. The study also examined the associations between growth, yield and chemical characteristics. Four local cultivars (Saggai, Kamleen, Baftaim and Abu Fraiwa) were used along with one introduced American cultivar (Texas Early Grano) as a check variety. The study revealed that genotypes under the study vary considerably for almost all the traits studied. Variability exists greatly for a trait such as fresh weight and pyruvic acid content recording a significantly higher standard error. The variability is also considerable for traits such as dry weight, leaf length at harvest, percentage dry weight and vitamin C. Physical parameters such as bulb polar, dry weight, leaf length, bulb diameter and percentage dry weight recorded higher heritability estimates, indicating that these characteristics can be improved by simple selection. Bulb polar, dry weight, vitamin C, protein content, leaf length at harvest and total soluble solids recorded the highest estimates for the genotypic coefficient of variability (GCV) coupled with equivalent higher values for broad sense heritability.Abu Fraiwa and Texas Early Grano showed excellent performance in almost all the characters under the study. The number of leaves and leaf length at harvest has a strong association with bulb diameter, bulb polar, fresh weight, vitamin C and pyruvic acid. Total soluble solid recorded a negative association with bulb diameter, bulb fresh weight, pyruvic acid and fiber content, suggesting that genotypes with smaller bulbs tend to have high soluble solids and a more pungent taste.