Flowering and Seed Development in Onion—A Review

Khokhar, K. M.

doi:10.4236/oalib.1101049

Cited by 25 publications

(26 citation statements)

References 49 publications

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“…Early attempts at vernalizing seedlings were met with mixed results until the discovery that seedlings must pass a juvenile phase before they are receptive to chilling (Holdsworth and Heath, 1950). The juvenile phase is cultivar dependent and can range from the 4-to 14-leaf stage, after which the plants are vernalized for %60 d (Khokhar, 2014;Rabinowitch, 1985;Shishido and Saito, 1976). Although seedling vernalization is a useful tactic for producing seed rapidly, and it has applications in marker-assisted selection and backcrossing, there are limitations for its use in phenotypic selection of bulb traits because this procedure does not allow for evaluation of the mature bulb.…”

mentioning

confidence: 99%

Temporal Aspects of Vernalization and Flowering in Long-day Storage Onion

D’Angelo¹,

Goldman²

2018

J. Amer. Soc. Hort. Sci.

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Vernalization is an important step for floral initiation in onion (Allium cepa), but our understanding of the minimum vernalization time for long-day storage onions to gain floral competence is limited. A series of time course experiments were conducted over 4 years to determine the effects of vernalization time on sprouting, scape emergence, and flowering in ‘Cortland’, ‘Sherman’, and CUDH2107. We found an endodormancy period is present in the bulbs of these cultivars that lasts for 8 to 10 weeks. In addition, these three accessions achieve optimum uniform scape emergence after chilling for 14 weeks at 10 °C. On average, when bulbs were chilled for 14 weeks, it took 96.8 ± 15.6 days from planting to flowering in all accessions evaluated. As storage duration under vernalizing temperatures increases, the time to sprouting, scape emergence, and flowering decrease. Furthermore, the variance in time from sprouting to scape emergence was greatly reduced between 10 and 12 weeks of storage for ‘Cortland’ and CUDH2107, and between 12 and 14 weeks for ‘Sherman’. After 10 weeks of chilling, each additional week of storage resulted in an average decrease in time to flowering of 4.1%. We also observed large percentages of bulbs flowering without receiving any vernalization. This observation supports our finding that the relationship between vernalization and flowering in long-day storage onion is facultative rather than obligate. These findings help define the relationship between dormancy, vernalization, and flowering in long-day storage onion.

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confidence: 99%

Temporal Aspects of Vernalization and Flowering in Long-day Storage Onion

D’Angelo¹,

Goldman²

2018

J. Amer. Soc. Hort. Sci.

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“…Seed production plays a key role in onion cultivation and is a highly specialized activity requiring special knowledge (Khokhar, 2014). According to the results of our surveys, only a few producers specialized in the production of onion seeds.…”

Section: Agricultural Inputs Seed Productionmentioning

confidence: 91%

“…Thus, it has been shown that storage temperatures ranging from 7˚C to 12˚C induce flowering earlier than the lowest or highest temperatures (Jones andEmsweller, 1939 andJones, 1927). In a literature review, it was concluded that onion cultivars appear to differ somewhat in their optimal temperature requirements depending on the locality to which they are adapted (Khokhar, 2014). The best yield of onion seeds is obtained with large bulbs (Morozowska and Holubowicz, 2009; Aminpour and Mortazavibak, 2004).…”

Section: Agricultural Inputs Seed Productionmentioning

confidence: 99%

Panorama of Onion Production in Tillabéri, A Region of the Far West of Niger

Rabiou

Moussa

Mella

et al. 2018

ESJ

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The objective of this study was to evaluate onion production systems in four municipalities along the Niger River. A cross-sectional survey was carried out among seventy-five onion producers distributed over ten perimeters. The results obtained reveal that onion is mainly grown by women (95%). 70% of the farmers own the farmed land, 20% rent and 10% borrow. The cultivation takes place between September and March. The cultivated varieties are ‘Galmi violet’ and ‘Gothèye white’, Onions are essentially transformed into Gabou, a traditional condiment. The areas exploited are generally less than half a hectare. Irrigation relies mainly on the gravity system. NPK fertilizer and urea in combination with manure are the most commonly used. For phytosanitary treatments, producers use pesticides and/or natural products based on aqueous extract. At harvest time, the price per 100 kg bag varies from 8 000 to 15 000 FCFA (12 to 23 €) and from 40 000 to 50 000 FCFA (61 to 76 €) after four months of storage. The average production cost per hectare is 1 208 564 FCFA (1844 €) and that of the net margins 551 857 FCFA (840 €). There is a low correlation between strong investments and net margins. The major constraints faced by producers are the high cost of agricultural inputs, the rapid drying up of water points, limited access to credit, the straying of animals, the collapse of prices during the harvest period and the difficulties of farming storage and conservation.

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“…1) and this variation in terminal heat condition greatly influenced the seed development and production. Olani Nikus and Fikre Mulugeta (2010) and Khokhar (2014) had reported that temperature ranges between 4.5-14 o C with low humidity is favorable for seed stalk formation. If this type of temperature prevails for longer periods then each plant will produce more number of flowers in each umbel.…”

Section: Productivitymentioning

confidence: 99%