Yield, Antioxidant Components, Oil Content, and Composition of Onion Seeds Are Influenced by Planting Time and Density.

Carmine Amalfitano,Silvano Somma,Gianluca Caruso,Laura Del Vacchio,Antonio Cuciniello,Giuseppe Morano,Mario Cannoniero,Giuseppe Russo,Nadezhda A Golubkina

doi:10.3390/plants8080293

Abstract

Research was carried out on onion landrace (Ramata di Montoro) for seed production in southern Italy, with the aim to evaluate the effects on yield and quality of four bulb planting times in factorial combination with four densities, using a split plot design with three replicates. The number of flower stalks per plant, their height and diameter, and the inflorescence diameter decreased with the bulb planting delay and density increase. The highest plant leaf area and LAI (leaf area index), seed yield, number, and mean weight were recorded with the earliest planting time, with the lowest bulb density eliciting the highest plant leaf area but the lowest LAI and seed yield per hectare. The ratio between seeds and inflorescence weight, and seed germinability, decreased with the planting delay and density increase. Seed oil, protein, and antioxidant content (polyphenols and selenium) were highest with the last crop cycle. The polyunsaturated fatty acids, predominant in oil, increased with planting time delay, whereas the monounsaturated fatty acids decreased. Linoleic, oleic, and palmitic acid prevailed among polyunsaturated, monounsaturated, and saturated fatty acids, respectively. Planting from 20 December to 10 January with 3.3 cold-stored bulbs per m2 was the most effective combination in terms of seed yield per hectare, whereas seed oil content and quality were the best, with the last crop cycle starting on 21 February, independent of bulb density.

Highlights

Onion (Allium cepa L.) belongs to Liliaceae, and, as reported in the FAO (Food and AgricultureOrganization) database, it is the second most cultivated vegetable in the world after the potato, with a total surface area of about 5.4 million hectares and 103 Mt production, mostly produced in Europe and Asia, with China and India being the major producing countries [1]
As regards the biometrical parameters (Table 1), both bulb planting time and density showed a significant effect on the number of stalks per plant, as well as their height and diameter, inflorescence diameter, and leaf area index (LAI)
From research carried out in southern Italy on onion landrace Ramata di Montoro in the Montoro plain, which is its area of origin and cultivation since the 19th century, significant effects of bulb planting time and density on seed yield and quality arose

Summary

Introduction

Onion (Allium cepa L.) belongs to Liliaceae, and, as reported in the FAO (Food and AgricultureOrganization) database, it is the second most cultivated vegetable in the world after the potato, with a total surface area of about 5.4 million hectares (ha) and 103 Mt production, mostly produced in Europe and Asia, with China and India being the major producing countries [1]. There are several high quality landraces, among which ‘Ramata di Montoro’ took origin in the Irno valley plain, including the town of Montoro (Avellino province, Campania region, southern Italy) in the late 19th century [3]. Ramata di Montoro is a storage onion whose bulbs are consumed for their qualitative and aromatic characteristics [4,5]. Bulb planting occurs from autumn to spring in Mediterranean areas or from late winter to early spring in northern regions, and, along with bulb density, it is among the major factors greatly affecting the growth and yield of onions [4], as well as seed yield and quality [7,8]. Ashagrie et al [9] recorded in northern

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Conclusion