Effects Of Higher Temperature Storage On Physiological And Biochemical Characteristic And Quality In Petunia (Petunia Hybrida) Plug Seedlings

Industrial seedling nursery is an important part of modern agriculture, which promotes developement of seedling storage and transportation technique. The special air and humidity conditioning equipments which guarantees feasible environment for seedling storage are used abroad. However, domestic seedling enterprises lack these equipments, so plug seedlings are stored and transported under normal temperature in summer.This paper investigated the effects of different storage temperature and water content in substrate on seedling quality, antioxidant enzyme, chlorophyll fluorescence, substance metabolism, recovery after transplanting and flower quality of petunia seedlings. Double factors design was carried out. 2 temperature levels were 25℃(average temperature between July and August in Shanghai) and 35℃(average highest temperature between July and August in Shanghai), and 2 water content in substrate levels were 50% and 80%. Main result is:1. Height of Petunia seedling increased, weight and chlorophyll content decreased under 4 treatments. Compared with 0 days, Low water content in substrate benefited seedling storage quality at 2, 4 days storage, but after 6 days, survival percentage of petunia seedlings dropped distinctly. Average flower number and florescence decreased, first bud time delayed with storage days, and each treatment has distinct difference with 0 days after 4 days storage.2. Starch, soluble sugar and soluble protein content decreased with storage days, but free amino acid content increased quickly. After 6 days storage, starch content decreased by 84.3%, 85.1%, 91.6%, 85.1%, soluble sugar content decreased 69.2%, 73.5%, 76.2%, 79.5%, soluble protein content decrease 27.4%, 39.8%, 40.4%, 42.9% and free amino acid content increased 96.5%, 405.6%, 547.9%, 615.9% under treatment of 50% 25℃, 50% 35℃, 80% 25℃, 80% 35℃. The results indicated that substances in seedlings were consumed fewer under lower temperature and lower water content in substrate.3. SOD, POD and CAT specific activity increased with storage time. SOD activity decreased, but POD and CAT activity increased at the beginning and decreased at the end. H₂O₂ and MDA content increased. After 4 days storage, each treatment has distinct difference. Seedlings under treatments of higher temperature and lower water content in substrate were damaged by active oxygen more badly, which was consistent with the result of the chlorophyll fluorescence.4. Chlorophyll fluorescence parameter Fv/Fm, Fv/Fo decreased with storage days. Treatment of 35℃decreased more quickly than 25℃. Chlorophyll fluorescence parameter distinctly decreased after 2 days storage under 35℃, but 4 days storage under 25℃. Water content in substrate has no distinct effect on chlorophyll fluorescence parameter under same storage temperature. After transplanting, shorter storage days, petunia seedlings recovered more quickly.