Breeding of colored tuberose (Polianthes) and cultural experiments in Taiwan

Hybrid tuberoses with pink, reddish-purple, purple, orange and yellow flowers were bred by crossing and backcrossing using Polianthes tuberosa 'Single' and 'Double' and Polianthes howardii. In addition, their pigment constituents were analyzed. Among the selected nine bred lines, one hybrid contained only carotenoids, four hybrids had only anthocyanins and the other four had both carotenoids and anthocyanins in their petals. The main anthocyanidin in the anthocyanin containing petals was cyanidin with some hybrids also containing delphinidin. Variation of pigment contents contributed the diversity of flower colors in hybrid tuberoses. One of the lines, '77A05', of which the main pigment was anthocyanin showed reddish-purple flowers when cultivated at 20°C under natural light, whereas the color was white at 30°C. It was almost white at 25°C with 45% shading of natural light, but pale with 25% shading. Cultivation of '77A05' in open fields was carried out at four different altitudes, 25, 75, 500 and 1,200 m in Taiwan. Days to flowering from planting at 25 and 1,200 m were 80.3 and 89.5, respectively. The higher the altitude, the longer the flower stalk, but there was no significant difference in inflorescence length. The anthocyanin content at 500 and 1,200 m was approximately two and three times higher than that at 25 m, respectively. The site selection for cultivation of colored tuberose when the primary pigment is anthocyanin must be carefully considered.