Photoperiod and gibberellins effect on True shallot seed formation

Photoperiod play an important role on plant flowering while gibberellins were reported to increase vegetative growth and seed production on intact plants. True shallot seed is an alternative way to get shallot seedlings, and has more benefit than used bulb seedling. But, how to produce good true shallot seed in Indonesia it is not clear yet. This research was aimed to determine the effect of photoperiod and gibberellins on shallot (Allium cepa var aggregatum) flowering and true shallot seed production. The experiment was conducted at the Experimental Garden of Indonesian Vegetable Research Institute (IVEGRI) Lembang at altitude of 1,250 m above see level from December 2011 to August 2012. The research was arranged in split plot design with the first factor was photoperiod i.e. 10, 12, 14 and 16 hour, while the second factor was concentration of GA3 i.e. 0, 50, 100 and 200 ppm. The analysis of variance indicated that photoperiod and GA3 independently affected shallot flowering and true shallot seed production. The results also showed that, planting shallot at 12 hour day length increase flowering and this factor could not be substituted by GA3 application. However, sowing in a photoperiod of 16 hours and application of 200 ppm GA3, increase number of flower per umbel and true shallot seed production, do to both factors.