ONION SEED PRODUCTION TRIALS IN THE HIGHVELD OF ZIMBABWE

Bulbs of several onion cvs were exposed to artificial vernalization treatment in a cold room at 8–9°C for 12, 9 and 6 weeks in 1990 and 9 and 6 weeks in 1991. A control was kept at ambient temperature for corresponding periods for each variety and the bulbs were planted at monthly intervals from February to April in 1990 and three-weekly intervals from March to May 1991.

Controls flowered in late August or in September irrespective of planting date, following exposure to low winter temperatures.
Artificial vernalization gave earlier flowering, the effect being greater the longer the period of vernalization.

Yields from the unvernalized controls, although coming later in the season, were similar to those from vernalized bulbs, which indicates that winters in Marondera are naturally cold enough for onion seed production.
Problems with disease, especially purple blotch due to Alternaria porri, greatly reduced yield in 1990 but were controlled in the less humid 1991 season and yields or more than 100 g/m² were obtained from four of the five cvs (Texas Grano, White Creole, Sivan and Niv) while the fifth, Yodalef, averaged only 45 g/m². Despite these good results the problems of disease control were such that it is likely that drier areas of Zimbabwe will be more suited to onion seed production, with or without artificial vernalization.

I International Symposium on Edible Alliaceae

R.L. Msika, J.E. Jackson, L. Currah

vernalization, flowering, cultivars

https://doi.org/10.17660/ActaHortic.1997.433.36