The morphological and physiological response of Lachenalia to supplemental irradiation

Abstract

The aim of this study was to examine the effects of supplemental irradiation, provided by high-pressure sodium lamps during cultivation, on growth, flowering, and physiological responses of six Lachenalia cultivars: ‘Rainbow Bells’, ‘Aqua Lady’, ‘Josephine’, ‘Riana’, ‘Radient’, and ‘Cherise’. Depending on light conditions and cultivar, lachenalia bulbs flowered from February 20th to March 24th. Additional irradiation accelerated flowering of ‘Rainbow Bells’, ‘Aqua Lady’, ‘Josephine’, and ‘Riana’ plants by 5–19 days depending on the cultivar. Compared with controls, the irradiated bulbs had a higher floral ratio and produced shorter inflorescence stems and inflorescences, a larger number of single florets, and thicker inflorescence stems (except for ‘Rainbow Bells’). The use of lamps resulted in shorter leaves with a higher chlorophyll a content in ‘Aqua Lady’, ‘Riana’, ‘Radient’, and ‘Cherise’ compared to control plants. The shortest leaves were reported in the ‘Josephine’ cultivar, and they were on average two times shorter than in the other cultivars. Bulbs and leaves of all cultivars grown under supplemental irradiation were characterized by higher dry weight than control plants. Dry weight content was highest in the bulbs and in the roots, and it was lowest in lachenalia leaves and shoots. Thus, supplemental irradiation from high-pressure sodium lamps positively affected morphological and physiological plant quality, although differences in the evaluated features largely depended on cultivar.