Changes in carbohydrate and phytochemical content in the bulbs and leaves of ten onion accessions between two developmental stages

Zahra Kiani [Department of Horticulture Science, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran]
Kambiz Mashayekhi [Department of Horticulture Science, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran]
Seyyed Javad Mousavizadeh [Department of Horticulture Science, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran]
Khalil Zeinali Nezhad [Department of Plant Biotechnology and Breeding, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran]

Onion (Allium cepa L.) is a rich source of anthocyanins, flavonoids, and polyphenols. Sugars affect the quality and taste of bulbs. The aim of the study is to investigate the changes in phytochemicals and carbohydrates of onion accessions at the juvenile and bulbing stages. All accessions had higher leaf chlorophyll and carotenoid content, phytochemical, and soluble sugars at the bulbing stage compared to the juvenile stage. The highest leaf and bulb phenols were measured in 'Azarshahr' and 'Malbacea' plants (39.79 and 25.63 mg·g-1, respectively), whereas the highest bulb flavonoid content was found in 'Azarshahr' and 'Kordestan' plants (21.40 and 16.79 mg·g-1, respectively). DPPH assay indicated that 'Azarshahr' and 'Sarze'had the highest antioxidant capacity (92.66 and 90 mg g-1, respectively). Furthermore, the highest bulb anthocyanin content was measured in 'Azarshahr' and 'Malbacea' (0.163 and 0.133 mg·g-1, respectively). Positive correlations were found between bulb anthocyanins and antioxidant capacity (rs = 0.82), and between bulb flavonoids and antioxidant capacity (rs = 0.60). Bulb fructose content showed positive correlations with anthocyanin content (rs = 0.88), phenols (rs = 0.93), and flavonoids (rs = 0.64). Leaf total soluble sugars was positively correlated to bulb anthocyanin content (rs = 0.61). Varieties, plant organ and development stage affected phytochemical content. Varieties with dark color had higher bulb phytochemical contents. Leaf sugars content was also positively correlated to phytonutrient content and bulb quality of onion. Therefore, it is hypothesized that nutrition management prior to bulbing phase can increase bulb quality and valuable phytochemical content of onion bulb at bulbing stage.

DOI: 10.26353/j.itahort/2022.2.4755

Keywords: Allium cepa L., antioxidant capacity, phytochemical traits, carbohydrates

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Kiani, Z., Mashayekhi, K., Mousavizadeh, S.J. and Nezhad, K.Z. (2022) 'Changes in carbohydrate and phytochemical content in the bulbs and leaves of ten onion accessions between two developmental stages', Italus Hortus, 29(2), pp. 47-55. doi: 10.26353/j.itahort/2022.2.4755