\nT/QHNX 057-2026 Technical Specifications for Seedling Raising of Lettuce Vegetables in Cell Trays

Scope

This document specifies the environmental requirements for lettuce seedling production sites, facilities and equipment, greenhouse disinfection, tray selection, seedling substrate, variety selection, sowing, seedling management, and seedling standardization, etc. This document is applicable to lettuce seedling production in Qinghai Province. 6. Greenhouse disinfection Use the potassium permanganate + formaldehyde method for disinfection. Add 15 g~20 g of potassium permanganate and 30 mL~40 mL of formaldehyde (in a ratio of 1:2) per cubic meter of greenhouse and fumigate for 48 h~72 h. In July-August, use the high-temperature fumigation method to disinfect the greenhouse by sealing it for 7 d~15 d at high temperatures. Alternatively, combine the fumigation method with high-temperature fumigation, sealing the greenhouse for 48 h~72 h. 7. Tray selection Use standard 98 or 105-hole seedling trays. The selection of trays shall comply with the provisions of NY/T 2312. 8. Seedling substrate 8.1 Substrate selection It is recommended to use commercial seedling substrates supplemented with arbuscular mycorrhizal fungi. Alternatively, prepare the substrate with a volume ratio of 1:1 of peat and perlite. The selection of substrates shall comply with the provisions of NY/T 2118 and NY/T 2119. 8.2 Substrate disinfection Before use, chemically disinfect the substrate by adding 25.00 kg of a 50-fold solution of 40% formaldehyde per cubic meter and sealing it with plastic film for one week for storage. 9. Variety selection Select varieties with strong growth potential, high germination rate, and strong resistance to adverse conditions. The seed specifications shall comply with the provisions of GB 16715.5. 10. Sowing method Use manual or mechanical sowing, with 2~3 seeds per hole and a sowing depth of 0.5 cm. After sowing, cover the seeds with a layer of 0.3 cm~0.5 cm thick perlite. After the seeds sprout, move them to the seedling bed, water them thoroughly,

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