ECOPHYSIOLOGICAL ASPECTS OF NITROGEN MANAGEMENT IN DRIP IRRIGATED ONION (ALLIUM CEPA L.).

Environmental factors that promote bolting in long-day onions (cv Valenciana de Grano) were examined. Plants were grown at various densities and light levels and it was found that the upper temperature limit for flower induction was approximately 17°C and that low irradiance impairs flower production. To control of bolting whilst maintaining yield requires high levels of soil N availability during growth and a leaf area index less than 3.5.