Distribution, Storage, and Remobilization of 14C-labeled Assimilate in Easter Lily

Abstract

Abstract Whole shoots of Easter lily (Lilium longiflorum Thunb. cv. Nellie White) were exposed to 14CO2 at 25, 37, and 51 days after full bloom of the commercial crop. Seven days after each exposure, 20% of the total recovered 14C remained in the shoot, which included stem roots, 10-25% in stem bulblets, 11-20% in mother scales, and 34-44% in daughter scales. Sink activity increased sharply from the outer mother scales to the inner daughter scales. The fraction of total 14C in the main bulb decreased, while that in the stem bulblets increased at successive exposures. Another group of plants was labeled repeatedly by dosing with 14CO2 on the three previous occasions and, also, at 65 days after full bloom. Bulbs were harvested 7 days after the final exposure, stored at 18°C for 14 weeks, and then replanted, At bulb digging, 50%, 30%, and 20% of the total 14C recovered were in the main bulb, stem bulblets, and shoot, respectively. Mother scales lost dry weight and 14C during storage and were nearly depleted when flower buds were visible the next season. Specific 14C activity in the emerging flowering shoot was high but decreased dramatically as the leaf number rapidly increased. The shoot and new daughter scales were the principal recipients of mobilized scale reserves, although only 28% of the 14C lost from mother scales were recovered in other plant parts. A majority of the carbon originally in mother scales was likely lost in respiration between fall harvest and 3 weeks after anthesis the following year. The daughter bulb contained 64% of the 14C in the bulb at fall harvest, and lost very little 14C during regrowth the following year.