Growing Habits, Floral Development, and Temperature Requirements for Flowering in Lachenalia unicolor (Liliaceae)

Abstract

Inflorescence initiation of Lachenalia unicolor occurred in early September before planting. Flower primordia at the lowest position of the inflorescence formed perianth and stamen primordia in early October and pistil primordia in early November. They maintained the same stage until early January in a greenhouse without heating. Mature pollen was formed in mid-February, with subsequent flowering in mid-April. Additional inflorescences were formed at the axil of storage leaves in some bulbs. Bulbs grown in a growth chamber kept at 20°C showed deformed inflorescence, although bulbs grown at 15°C flowered normally. Bulbs grown at 25°C produced no scapes. Bulbs stored at 5, 10, 15, 20, 25, or 30°C for 8 weeks from 6 August showed inflorescence initiation at any temperature, except at 5°C. The optimum temperature for floral development was 20–25°C. After floral initiation at 20, 25 + 20, or 25°C, bulbs were cultured in a growth chamber in a temperature combination of 20°C and 15°C. Bulbs grown at 20°C failed in normal flowering with a high frequency of seriously deformed inflorescences. Once bulbs had been exposed to 15°C for at least 2 months, flowering was accelerated by transferring to 20°C. Growing temperature at a constant 15°C delayed anthesis because of the long period from budding to anthesis.