Growth, flowering and partitioning of 14C-assimilate in oriental lily ‘Star Gazer’ as affected by light level and flower removal

Abstract

SummaryOriental hybrid lily ‘Star Gazer’ plants were forced in a greenhouse during winter months under natural conditions or with artificial lighting. Supplemental lighting improved plant quality expressed as greater plant fresh weight, longer flower buds and earlier flowering. Lilies grown with supplemental lighting were shorter than control plants. To determine how light conditions and the presence of buds affect growth, whole lily shoots were exposed to 14CO2 at flowering time. Removing lily buds two weeks before flowering in conjunction with higher light level significantly increased the specific 14C radioactivity in mother and daughter scales in lily bulbs when harvested 24 h after exposure. The specific radioactivity in the upper leaves and stems was always higher than in the bottom parts. Bottom leaves showed lower specific 14C radioactivity in the presence of buds but it was not influenced by light level. The highest 14C radioactivity in the bottom and upper parts of the stem was observed in non-irradiated plants without buds. Sink activity of the anthers of irradiated plants was 14 times lower than that of non-irradiated plants. These results demonstrate that the maturation of pollen grains was not completed due to insufficient light level in greenhouse during forcing. Regardless of the light treatment, the specific 14C radioactivity in perianth segments was not affected but the relative sink strength (RSS) was four times higher on plants grown with supplementary lighting than in the control.