Effect of planting time and supplemental irradiation on growth and flowering of Lachenalia ‘Romaud’

Abstract

Growth and flowering of lachenalia ‘Romaud’ was studied with reference to its commercial potential as pot plant and the need to obtain flowering plants at a specific time. The experiment was carried out in a heated glasshouse. Lachenalia bulbs were planted in November, December, January and February. The plants were exposed to two lighting regimes, natural lighting and natural lighting with supplemental irradiation (HPS lamps). The later the planting date was, the faster the bulbs flowered, and they produced thicker inflorescence stems with greater number of florets. Depending on the bulb planting date and light conditions, the plants flowered from February to May. The leaves obtained from the bulbs planted in November and December were longer than those produced by the bulbs planted in January and February. Compared with control, supplemental irradiation accelerated flowering by 10–13  days and positively affected plant features by promoting the growth of thicker inflorescence stems with more abundant and longer florets. The leaves of irradiated bulbs were shorter (apart from the bulbs planted in February) and were characterised by a higher content of chlorophyll a, chlorophyll a + b and carotenoids as compared with control. Plants grown under HPS light also had the higher dry weight of bulbs, leaves and stems.