Introduction to the Salt-and-Alkali-Tolerant Cotton Variety F502-2

I. Characteristics and Traits

The plant is tower-shaped, with Type II fruiting branches, and a relatively loose plant architecture. The leaves are dark green, of ordinary leaf shape, medium-sized, with a smooth surface; the leaves are relatively thin and hard, and the fruiting branches tend to grow slightly upward. Emergence is fast and uniform, and growth is robust. The seedling growth vigor is moderate and steady, and the plants grow rapidly around the bud stage. The first fruiting branch node is at the 6th to 7th node, and the plant height is about 70 cm. It has strong boll-setting ability, with 10 to 12 bolls per plant. The boll shape is oval and relatively large, with a single boll weight of 6.6 g. The boll shell is thin, boll opening is concentrated and smooth, and the boll-holding capacity is good, making picking easy. The lint is snow-white with a silky luster, the lint percentage is 42%, and the fiber quality is excellent: 2.5% span length 32.52 mm, specific strength 30.87 g/tex, micronaire value 3.94, yellowness 6.82, and spinning coefficient 174. The quality is excellent, and the growth period is 130 days. This line has tough stalks and is lodging-resistant; it is resistant to cotton bollworm, tolerant to aphids, and highly disease-resistant, especially to cotton Fusarium wilt and Verticillium wilt; it has strong salt-and-alkali tolerance. According to trials by Shihezi University, when the sodium chloride salt concentration reaches 2.5% to 3.5%, the germination rate is 2.5 times higher than that of ordinary cotton varieties. As measured by the electrical conductivity method, when the total field salt content is 0.5%, the germination rate is 10% higher than that of ordinary cotton varieties, and the mature plant rate is 8% higher.

II. Yield Performance

In 2003, when planted on heavily saline-alkali land in East China, it reached a seed cotton yield of 113.8 kg of lint cotton per 667 sq m, achieving a new breakthrough in salt-and-alkali-tolerant cotton breeding. In 2005, when planted in **Shihezi Township, Shihezi City, the boll-setting rate per plant was especially high, with 430 kg of seed cotton per 667 sq m and 172 kg of lint cotton per 667 sq m.

III. Cultivation Characteristics

1. Sow early at the appropriate time. In northern Xinjiang, sow on April 10; in southern Xinjiang, sowing can be done in early April.

2. Planting density. Because the plant architecture is relatively loose, it should not be too dense; a stand of 12,000 to 13,000 plants per 667 sq m is appropriate.

3. Strengthen early-stage management to promote early emergence, so as to achieve early budding, flowering, and boll opening.

4. Because growth is vigorous, chemical regulation must be done well to control internode length. At the 2-leaf 1-heart, 4-leaf 1-heart, 6-to-8-leaf, and 12-leaf stages, use mepiquat chloride to strictly control internode length; top the plants and use mepiquat chloride to seal the top. Control water and fertilizer well to ensure there is no excessive vegetative growth and no delayed maturity.

5. Strengthen field management during the flowering and boll stage, ensure the supply of fertilizer and water, and do not let the plants go without fertilizer. At the same time, strictly ensure there is no delayed maturity, promote boll development, and encourage early boll opening.

6. To promote early maturity, it is necessary to promptly remove the lower leaves ("take off the pants") and remove superfluous buds during the bud stage, top the plants in time, remove the group tips, and on August 10, use the flower as the boundary to remove the excess upper portion.

7. On saline-alkali land, fine land preparation should be carried out even more, sowing quality should be strictly controlled, and soil crusting should be broken in time and seedlings released. Water-saving techniques should be applied to suppress evaporation. After sowing, cultivate in time to cut off the capillaries in the surface soil layer, reduce evaporation, raise soil temperature, and promote seedling growth. In cotton fields on saline-alkali land, cultivate 2 to 3 times during the seedling stage, to a depth of 16 to 18 cm.