Influence of Temperature, Light, and Ethylene on Seedlings of Geranium (Pelargonium × hortorum Bailey) during Simulated Shipping Conditions1

Geranium seedlings were exposed to various levels of ethylene (0–10 µl/liter air) at 23°C for 2 and 5 days in light. Seedlings held in ethylene for 2 days developed more chlorotic leaves and did not grow as well as seedlings held in air. Seedlings exposed to ethylene for 5 days abscised leaves, whereas those exposed for 2 days did not. Seedlings exposed to ethylene (1 µl/liter air) at 23° for 3 days in dark had more chlorotic leaves and did not grow as well as seedlings exposed to ethylene in light. Seedlings held in air in darkness had more chlorotic leaves than seedlings held in air in light. Seedlings held in air in the laboratory grew as well as seedlings held in the greenhouse. Seedlings exposed to ethylene (1 µl/liter air) for 3 days in dark retained more chlorophyll and had better growth at low temperatures (4.5°, 10°) than those exposed at higher temperatures (15.5°, 23°). Seedlings held in air at all temperatures for 3 days had similar chlorophyll levels and growth patterns. Temperature was negatively correlated with loss of chlorophyll and plant dry weight and positively correlated with number of chlorotic leaves of seedling held in darkness for 7 days.