Environmental and cultural effects on vegetative growth and flowering of selected 'bedding' ornamentals. II. Night-break lighting and gibberellic acid applications

Weekly foliar applications of GA47 (GA; 25 p.p.m.) during seedling growth promoted reproductive development of both Tagetes patula and Matthiola incana whether grown in short days (8 h), or long days effected by night-breaks (NB). The NB treatment was unfavourable for flowering in Tagetes but promoted leaf growth whereas both GA and NB, favourable for early flowering and associated stem elongation in Matthiola, inhibited leaf growth. The GA applications substituted for the long-day requirement for flowering in Matthiola. These findings are coupled with those reported earlier for the effects of night temperature on vegetative growth and flowering and are discussed in relation to a possible “blue-print” for commercial horticultural practice.