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. 2019 Aug 20;8(8):293.
doi: 10.3390/plants8080293.

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

Carmine Amalfitano  1 , Nadezhda A Golubkina  2 , Laura Del Vacchio  1 , Giuseppe Russo  3 , Mario Cannoniero  1 , Silvano Somma  1 , Giuseppe Morano  1 , Antonio Cuciniello  4 , Gianluca Caruso  5
Affiliations

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

Carmine Amalfitano et al. Plants (Basel). .

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.

Keywords: Allium cepa L. ‘Ramata di Montoro’; coldstored bulbs; fatty acids; plant biometrical and growth indicators; polyphenols; proteins; seed production; selenium.

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Conflict of interest statement

The authors declare no conflict of interest. Green Company was involved in the present research because they own the farm we partly rent for this investigation, which is located in Montoro district, i.e., the origin area of the onion landrace ‘Ramata di Montoro’ we used for the trial in object; Giuseppe Russo (G.R.) is the agronomist managing the field work on behalf of Green Company and, therefore, he cooperated in the research design and supervising.

Figures

Figure 1
Figure 1
Interaction between bulb planting time and density on onion seed yield per plant (n = 3). Different letters mean significant difference in the comparison between planting times (lowercase letters) or between bulb densities (capital letters), according to the Duncan test at p ≤ 0.05. Standard deviation bars are shown per each value.
Figure 2
Figure 2
Interaction between bulb planting time and density on onion seed yield per ha (n = 3). Different letters mean significant difference in the comparison between planting times (lowercase letters) or between bulb densities (capital letters), according to the Duncan test at p ≤ 0.05. Standard deviation bars are shown per each value.
Figure 3
Figure 3
Interaction between bulb planting time and density on onion seed number per plant (n = 3). Different letters mean significant difference in the comparison between planting times (lowercase letters) or between bulb densities (capital letters), according to the Duncan test at p ≤ 0.05. Standard deviation bars are shown per each value.
Figure 4
Figure 4
Interaction between bulb planting time and density on onion seed number per m2 (n = 3). Different letters mean significant difference in the comparison between planting times (lowercase letters) or between bulb densities (capital letters), according to the Duncan test at p ≤ 0.05. Standard deviation bars are shown per each value.
Figure 5
Figure 5
Interaction between bulb planting time and density on onion mean seed weight (n = 3). Different letters mean significant difference in the comparison between planting times (lowercase letters) or between bulb densities (capital letters), according to the Duncan test at p ≤ 0.05. Standard deviation bars are shown per each value.
Figure 6
Figure 6
Trend of temperature and rainfall in Montoro (Avellino, southern Italy) in 2014 and 2015.
See this image and copyright information in PMC

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