Discovery of novel traits in seed-propagated Lilium: Non-vernalization- requiring, day-neutral, reflowering, frost-tolerant, inter-hardy L. xformolongi.II. Photoperiodism in parents and hybrids

The discovery of seed-propagated lily hybrids which flower in <1 year from sowing in any photoperiod presents unique opportunities for transforming lilies. Recent research documented such hybrids to possess additional traits such as reflowering capabilities, frost tolerance, and winter hardiness. Objectives of this research were to examine Lilium xformolongi hybrids, backcrosses, and parental species (L. formosanum, L. longiflorum) in photoperiods (SD/LD) to clarify flowering in more stringent environments (growth chambers, greenhouses) than previously. Case cooled (CC) and non-CC bulbs (L. formosanum, L. longiflorum 'Nellie White'); non-vernalized L. xformolongi seed-propagated cultivars (5 cultivars, 9 seed lots), L. longiflorum 'Snow Trumpet', and L. xformolongi backcrosses (5 BC₁F₁ were tested. Seed germination ranged from 4% to 83.3%; yield potential was similar. Flowering L. xformolongi (growth chamber) did not differ from L. longiflorum 'Nellie White' for VBD. Cultivar x photoperiod interactions were not significant except flowering date (P = 0.04). 'Nellie White' (CC) flowered in 213 d, while L. xformolongi cultivars flowered in 247 d ('Sakigake Raizan') to 306 d ('Raizan No. 3') from sowing. Non-vemalized L. formosanum, L. longiflorum bulbs never flowered in either photoperiod or environment. Both VBD and flowering date were highly heritable and correlated. Regardless of photoperiod and environment, seed-propagated L. xformolongi flowered in <1 year. One backcross was day-neutral for flowering. Two L. xformolongi BC₁F₁ and L. longiflorum 'Snow Trumpet' produced significantly less leaves than 'Nellie White'. Leaf number (h²= 0.83) was not as tightly linked in L. xformolongi as 'Nellie White'. Plant height in L. formosanum (CC bulbs, several backcross L. xformolongi hybrids) did not differ from 'Nellie White'. In contrast, only 'Sakigake Raizan' was taller than 'Nellie White' in growth chambers.