Response of onion (Allium cepa L.) to sowing date and plant population
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Date
2012-06
Authors
Bosekeng, Gagopale
Journal Title
Journal ISSN
Volume Title
Publisher
University of the Free State
Abstract
Field trials were conducted on the West Campus facility of the Department of Soil, Crop
and Climate Sciences of the University of the Free State in Bloemfontein during 2009 and
2010. The first trial during 2009 investigated the response of onion (Allium cepa L.)
cultivars to sowing date. Cultivars namely; Charlize, Jaquar, Python and South Wester
were used in 2009. Onions were sown on 31 April, 7 May and 21 May during 2009. The
second trial was conducted during 2010, where cultivar Ceres Gold was used to replace
South Wester as the latter was no-longer available in the market and sowing was done on
11 May, 25 May and 8 June. In both seasons, experiments were laid out as a randomized
complete block design with each treatment combination replicated three times. During
2009, plant population of 41 plants m·2 was used, while in 2010 plant population of 61
plants m·2 was used. Plots of 1.8 m2 were used with each plot having five rows. Each row
had fifteen plants during 2009 and twenty two plants during 2010. Before planting, soil
sampling and analysis were made, thereafter, fertilizers were applied as per soil analysis
results.
A third field trial was conducted in 2010 to evaluate the three sowing dates (11 May, 25
May and 8 June) with a combination of five plant populations (95, 83, 74, 67 and 61 plants
rn") using one onion cultivar ('Jaquar'). The experiment was laid out as a randomized
complete bock design, with three replications having 1.8 m2 plots. In each plot there were
five rows. A bulb storage trial was also conducted under room (±25°C) and cold room
temperatures (±5°C). This was done for all field trial in both seasons.
In a trial investigating response of cultivars to sowing date, better plant height, number of
leaves, bulb fresh mass, and yield were observed when sowing was done from the end of
April to the end of May. Sowing date significantly influenced bulb and neck diameters only
during 2009. Bulbs were becoming more firm as sowing date was delayed, and the
opposite was observed for bolting. Cultivar South Wester bolted more, followed by cultivar
Jaquar while other cultivars did not bolt. The shape of bulbs was not significantly
influenced by sowing date but it showed to be cultivar authentic. No split bulbs were
observed. In a trial of sowing date and plant population, significantly taller plants were obtained with
early sowing date than the two later sowing dates. Leaf production was not significantly
influenced by sowing date. Sowing date and plant population affected bulb fresh mass,
yield, bulb and neck diameters as well as firmness. Sowing date did not influence bulb
shape while plant population did. None of the bulbs bolted from this trial.
Mid-intermediate day cultivars ('South Wester' and 'Ceres Gold') recorded the shortest
duration (105 days and 63 days respectively), while on average other cultivars were
stored for 126 days in 2009 and 105 days in 2010. Storage disease (black mould),
sprouting and loss of moisture from the bulbs were the contributing factors for reduction in
storage duration. These factors were promoted by both field and storage conditions.
Onion producers should have adequate information on the cultivars and the production
In a trial of sowing date and plant population, significantly taller plants were obtained with
early sowing date than the two later sowing dates. Leaf production was not significantly
influenced by sowing date. Sowing date and plant population affected bulb fresh mass,
yield, bulb and neck diameters as well as firmness. Sowing date did not influence bulb
shape while plant population did. None of the bulbs bolted from this trial.
Mid-intermediate day cultivars ('South Wester' and 'Ceres Gold') recorded the shortest
duration (105 days and 63 days respectively), while on average other cultivars were
stored for 126 days in 2009 and 105 days in 2010. Storage disease (black mould),
sprouting and loss of moisture from the bulbs were the contributing factors for reduction in
storage duration. These factors were promoted by both field and storage conditions.
Description
Keywords
Onions -- Breeding, Dissertation (M.Sc.Agric. (Soil, Crop and Climate Sciences))--University of the Free State, 2012