THE EFFECT OF DIFFERENT PHOTOPERIODS AND TEMPERATURES FOLLOWING BULB INITIATION ON BULB DEVELOPMENT IN TROPICAL ONION CULTIVARS

G.C. Wiles
Onion plants of five short-day cultivars were induced to bulb by exposing them to long photoperiods and subsequently transferring them to a number of photoperiod and temperature treatments once bulbing had commenced. In an 8-h photoperiod, all cultivars resumed bladed leaf production. In cultivar Bon Accord, bladed leaf production was also resumed in an 11-h photoperiod. It is concluded that in photoperiods insufficient for bulb initiation, reversion to bladed leaf production will eventually occur. However, even in the 8-h photoperiod, bulb-scale formation continued for a while, particularly in the cultivar with the shortest photoperiod requirement for bulbing, before reversion to bladed leaf production.

Considerable bulb swelling took place after plants had been returned to short (8 h) photoperiods. Once bulb-scale formation had occurred, the swelling of these scales and the leaf bases of the bladed leaves surrounding them continued even in an 8-h photoperiod. Thus, photoperiod serves primarily to determine the fate of developing leaf initials. High temperature increased the rate of leaf senescence and hastened neck fall and maturity.

Wiles, G.C. (1994). THE EFFECT OF DIFFERENT PHOTOPERIODS AND TEMPERATURES FOLLOWING BULB INITIATION ON BULB DEVELOPMENT IN TROPICAL ONION CULTIVARS. Acta Hortic. 358, 419-428
DOI: 10.17660/ActaHortic.1994.358.69
https://doi.org/10.17660/ActaHortic.1994.358.69

Acta Horticulturae