Tolerance of dry-sale lily bulbs to elevated carbon dioxide in both ambient and low oxygen atmospheres

Previous research has demonstrated that storage of dry-sale Asiatic hybrid lily bulbs in a 1% O2 atmosphere can improve quality and shelf-life (22–24 °C) of certain cultivars compared with storage in air, indicating a possible application for modified atmosphere packaging (MAP) [Legnani, G., Watkins, C.B., Miller, W.B., 2004a. Low oxygen affects the quality of Asiatic hybrid lily bulbs during dry sale storage and subsequent forcing. Postharv. Biol. Technol. 32, 223–233]. The success of a MAP system would be dependent on the tolerance of lily bulbs to the elevated CO2 levels that would occur within the MAP; therefore, the effects of warm (22 °C) bulb storage with elevated CO2 atmospheres (4%, 8%, or 16%) in combination with 1% O2 or air on growth and development of three cultivars of Asiatic hybrid lily bulbs have been investigated. Elevated CO2 in combination with 1% O2 had no effect on shoot elongation prior to transplanting, flower development, and height at flowering of ‘Colosseo’ and ‘Vermeer’ bulbs. Leaf area of ‘Vermeer’ bulbs stored in 1% O2 was reduced by increasing CO2 concentrations, but was still greater compared with plants stored in air or 21% O2 + 16% CO2. Elevated CO2 in combination with 1% O2 had a beneficial effect on growth and development of ‘Vivaldi’, inhibiting shoot elongation prior to transplanting, increasing flower bud number, height at flowering, and leaf area, while lessening the severity and occurrence of flower abnormalities. Compared with air, storage of bulbs in 21% O2 + 16% CO2 showed benefits for all cultivars, inhibiting shoot elongation prior to transplanting and flower bud abortion, while increasing height at flowering and leaf area. Flower bud number was decreased slightly and flowering was delayed by 10–14 days depending on cultivar. Elevated CO2 did not affect bulb respiration rate but it did increase ethylene production. Possible developmental effects of increased ethylene production under elevated CO2 are discussed. The data demonstrate that Asiatic hybrid lily bulbs can tolerate the high CO2 concentration that would occur in a modified atmosphere package (MAP) designed to extend shelf-life by lowering the ambient O2 concentration.