Identification of appropriate planting period for shallot (Allium cepa L. var. ascalonicum baker) seed production at Debre Zeit, Ethiopia

Shallot (Allium cepa L. var. ascalonicum baker) is one of the most widely cultivated vegetable crops in Ethiopia. It is a daily used almost in every house for flavoring local dishes such as 'wot' _ spiced stew. Unlike 'wot' prepared with onion, it is believed that 'Wot' of shallot keeps over night or more without being spoiled (local knowledge). This advantage of keeping quality in tropical climate cannot be overlooked for many Ethiopians do not afford buying refrigerator. Most shallot growers are unable to deep bulbs in their store for use as planting material from season to season and/or year after year. The disadvantages of using bulb as planting material include: requirement of large quantity (1.2 t/ha) of mother bulbs, very expensive especially during planting time and bulky for transportation, low rate of propagation (propagating material constituting about 40% of the total production cost), losses during storage due to decay and sprouting, high costs associated with the large amount of storage space required, perpetuation of soil-borne diseases and pests, associated with the large amount of storage space required, perpetuation of soil-borne diseases and pests, absence of 'cleansing' sexual cycle to eliminate viruses from vegetative tissues and the need for high hand-labour prior to and at planting. The night temperature around Debre Zeit is cold between October and January going down to 5-15 deg C. Exposing young growing plants to cold period could effect induction of bolting and flowering. This trial was therefore carried out to identify appropriate bulb planting periods for successful induction of bolting, flowering and subsequent seed production of shallot without artificial cold or chemical treatment. Two shallot cultivars 'Hurruta' (DZ-SHT-91), bolting tolerant and high bulb yielding, and DZ-SHT-OP-S5, semi bolter were used. Twelve planting dates, at two weeks interval from September 1 up to February 2 were assessed. Planting dates later than the 10th of November resulted in short flower stalks with small umbel and minute florets and failed to develop germinable seeds. The highest seed yield of cultivar DZSHT-OP-S5 was produced from planting dates of 13 October (5.8 qt/ha), 15 September (5.7 qt/ha) and 29 September 4.77 qt/ha).