T/SGSZZ 001-2024 Leafy vegetable (spinach, lettuce, green stem) seedling production techniques operational procedures

Scope

Main Technical Content: 4. Seed Breeding 4.1 Sowing Time In Shandong Province, the suitable sowing period for early- and medium-maturing varieties is May to June, and for late-maturing varieties, it is late June to July. 4.2 Isolation Requirements The breeding and seed production areas must establish isolation zones. For flat land, the minimum spatial isolation distance is 2,000 m; if there are hills or forests as barriers, the minimum spatial isolation distance is 1,000 m. No other cruciferous species, such as Chinese cabbage, white cabbage, rapeseed, mustard greens, or kohlrabi, that can naturally cross-breed with these crops, should be planted around the isolation zone. 4.3 Site Selection Choose soil with good drainage and irrigation, loamy or sandy loam, and ensure that no cruciferous crops have been grown in the area within the past two years. 4.4 Seed Source Elite seeds or parent seeds meeting the quality standards for elite seeds. 4.5 Conventional Seed Breeding 4.5.1 Sowing 4.5.1.1 Land preparation Apply 1,000–2,000 kg of composted organic fertilizer and 5–15 kg of potassium chloride per 667 m2 as base fertilizer. Fine-till the soil and create north-south-oriented ridges with a width (including ditch) of 1.6–1.7 m and a height of 0.2–0.3 m, with a turtle-back shape on the ridge surface. 4.5.1.2 Sowing Use direct sowing (including broadcast sowing, strip sowing, or hole sowing) or seedling transplantation, with direct sowing being the main method. For direct sowing, use 0.2–0.3 kg of seeds per 667 m2 and cover with a cool gauze after sowing. For seedling transplantation, use 0.4–0.5 g of seeds per m2 in the seedbed, with a ratio of 1 seedbed to 6 fields. 4.5.2 Field Management 4.5.2.1 Thinning and transplanting When the seedlings reach 3–4 true leaves, thin and transplant them. For early-maturing varieties, the seedling spacing is 10–13 cm; for medium-maturing varieties, it is 13–16 cm; and for late-maturing varieties, it is

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