Argentina (Santiago del Estero): Importance of the sowing date in short-cycle onion cultivation

Ariel Rodriguez Torressi, Agricultural Engineer (M.Sc.), Horticulture – Plant Production Group, INTA EEA, Santiago del Estero

Email: rodriguez.ariel@inta.gob.ar

Onion production is determined by the size and weight of the bulb, which is directly related to the number and size of leaves at the time the bulb is stimulated to grow. Planting date is one of the many factors that determine good leaf and bulb development.

Experiments carried out at the Santiago del Estero Agricultural and Agricultural Research Institute (EEA) determined that the ideal planting date is from mid-March to mid-April.

Sowing is often adjusted according to the current year’s market prospects, often without taking into account environmental requirements. Extremely early sowing can affect planting density due to high temperatures and rainfall, while extremely late sowing results in poor vegetative (leaf) development and growth due to low temperatures, lower irradiation, and a shorter biological time for leaf development, from germination to the beginning of seed development.

Onions require temperatures of 15 to 25°C for vegetative growth. They are frost-tolerant, but their growth is halted at low temperatures below 10°C. Short-cycle onions require temperatures between 20 and 25°C to initiate bulb growth, with a photoperiod (day length) of no less than 11 to 12 hours. 

While planting date is important in onion production, other factors determine crop productivity, such as water management, nutrients, weeds, diseases, and insects.