Detailed introduction to the cotton variety Ji 668

Ji 668 is a new cotton variety bred by the Cotton Research Institute of the Hebei Academy of Agriculture and Forestry Sciences. In 2000 it passed the approval of the Hebei Provincial Crop Variety Approval Committee and was named Ji 668, and was listed by the Ministry of Science and Technology as a variety under the "Tenth Five-Year" National Key Science and Technology Achievement Promotion Plan. In 2001 it passed national new crop variety approval. In 2002 it passed approval in the ** autonomous region. In recent years, this variety has been promoted and planted in several provinces and cities, producing good economic and social benefits.

1 Genetic basis Ji 668 has a rich genetic background. Its female parent Ji Zi 123 is a high-yielding, Verticillium wilt-resistant variety bred by using upland cotton, Asiatic cotton (Chinese cotton) and wild cotton, employing chromosome doubling technology for interspecific hybridization among three Gossypium species, backcrossing and multiple crossing; its male parent 231 is a line with excellent fiber quality. In 1994 an excellent single plant was selected from the F3 of (Ji Zi 123 x 231), and after several rounds of southern multiplication and generation advancement, it was developed through directional selection. Ji 668 combines the excellent traits of both parents and surpasses both parents.

2 Characteristics This variety emerges quickly and uniformly, with strong seedling vigor, and grows steadily throughout the entire growth period. Plant height is 83.8 cm, plant type is tower-shaped, and the plant is clean and neat. The first fruiting branch node is 6.8, with 11.6 fruiting branches per plant; the stalk is green and hard, the leaves are medium-sized, dark green in color, and rather wrinkled. Bolls are large, with a single boll seed cotton weight of 6.0 g, and the boll is round with a boll tip. Boll-setting ability is strong, with 12.8 bolls per plant, and bolls are distributed evenly on the upper, middle and lower parts. Lint percentage is 40.8%, which is relatively high; seed index is 10.6 g, and the rate of undeveloped seeds is low (6.6%). It has good early maturity and matures early without premature aging; the whole growth period is 130 days, making it a medium-early maturing variety. Boll opening is smooth and concentrated, easy to pick, and the rate of pre-frost cotton is high (90.1%). The fiber color is pure white and the quality is excellent. It has good disease resistance and drought resistance. There are few vegetative branches, and it is easy to manage.

3 Yield performance From 1997 to 1999, in the Hebei Province cotton variety preliminary trial, regional trial and production trial, the average lint cotton and pre-frost lint cotton yields were 1297.5 kg and 1173.4 kg per hectare, respectively increasing yield by 14.0% and 15.1% compared with the control Jimian 20, and ranking first in each trial in each year; from 1999 to 2000, in the national Yellow River Basin regional trial and production trial, the average lint cotton and pre-frost lint cotton yields were 1210.0 kg and 1104.5 kg per hectare, respectively increasing yield by 18.0% and 21.8% compared with the control Zhongmian 12, both ranking first; from 1999 to 2001, in the eighth round of the northwest inland cotton region upland cotton new variety regional trial and production trial, the average lint cotton and pre-frost lint cotton yields were 2182.6 kg and 1954.9 kg per hectare, respectively increasing yield by 25.8% and 25.3% compared with the control Yumian 15, both ranking first. Ji 668 showed outstanding high yield and stable yield in regional trials and production demonstrations at all levels in each year.

4 Fiber quality According to the quality results tested by the Quality Supervision, Inspection and Testing Center of the Ministry of Agriculture, the Hebei provincial regional trial average: 2.5% span length 30.2 mm, specific strength 22.0 cN/tex, Micronaire value 4.4, uniformity 47.7%, elongation 6.9%, quality index 2298; the national Yellow River Basin regional trial average: 2.5% span length 29.1 mm, specific strength 20.0 cN/tex, Micronaire value 4.5, uniformity 46.0%, elongation 6.5%, ring-spun yarn strength 1131bf, quality index 1787. The fiber quality is balanced and stable, the spinning quality is high, and the fiber quality is good.

5 Resistance analysis According to identification by the Plant Protection Laboratory of the Cotton Research Institute of the Chinese Academy of Agricultural Sciences, the Fusarium wilt index is 7.49 and the Verticillium wilt index is 13.88, making it a variety of the Fusarium wilt-resistant and Verticillium wilt-resistant type. Through variety stability and adaptability analysis and multi-index fuzzy comprehensive evaluation, Ji 668 is waterlogging-tolerant, drought-resistant, and tolerant of poor soil, with relatively good yield stability; especially in dry years and under medium-low fertility conditions, its yield-increasing potential is great, and it has very good stress resistance.

6 Suitable planting areas It is suitable for planting in the Yellow River Basin cotton region and the ** South Xinjiang cotton region, and is especially suitable for widespread planting in dry, rain-scarce, poor-soil areas such as Hebei, Shandong, Henan, Shanxi, Shaanxi and ** South Xinjiang. Production demonstration results show that Ji 668 is also suitable for intercropping in various ways such as cotton-potato, cotton-melon and cotton-vegetable, is easy to manage, and gives high yields.

7 Key points of cultivation and management Apply sufficient basal fertilizer and heavily apply flowering and boll fertilizer. Sow at the appropriate time. The planting density is 30,000 to 37,500 plants per hectare for high-water and high-fertility land, 42,000 to 45,000 plants for medium fertility, and about 60,000 plants for dry and poor land. Promptly control various cotton field pests. Conduct chemical regulation at the right time and in the right amount, following the principle of small amounts applied multiple times. According to the cotton growth condition, promptly topdress and water at the initial flowering stage and full flowering stage, pay attention to drainage during the rainy season, and supplement potassium fertilizer in the later stage to prevent premature aging.