Detailed introduction to the cotton variety Jiumian No. 2

Jiumian No. 2 is a new cotton variety developed by the Cotton Experiment Station of the Jiuquan Prefecture Agricultural Science Institute of Gansu Province through sexual hybridization of the early-maturing, high-yielding, high-lint-percentage line 77-118 with the disease-resistant, late-maturing variety Zhongmiansuo 16, followed by pedigree selection and directed breeding. It was approved and named by the Gansu Provincial Crop Variety Approval Committee in 2001. This variety is suitable for planting in the Hexi Corridor cotton region of Gansu Province, as well as in **, Inner Mongolia's Ejin Banner, and Ningxia.

1 Main characteristics and traits: this variety is a ultra-early-maturing upland cotton, with a whole growth period of 138 days, and a pre-frost boll ratio of 83.8%. Emergence is fast and uniform, early-stage growth and development are rapid, and mid-stage vigor is strong. The plant is columnar in shape, columnar in shape, and compact, with a plant height of 58.0-64.9 cm, fruit branches of type I-II, the first fruit branch node at 3.5, and 8 layers of fruit branches per plant. The leaves are medium to small, with hairs on the leaf underside, light green in color, and a normal palmate shape with 3-5 lobes, shallow sinuses, and obvious wrinkles. The number of bolls per plant is 5.1-8.2, with many inner bolls concentrated together; the bolls are large, round, and pointed, with 4-5 locules; the average pre-frost single boll weight is 6.0 g; the boll shell is thin, boll opening is smooth, lint retention is strong, and the lint is snow-white with silk luster, easy to pick. The seeds are white and pear-shaped, with a seed index of 12.3 g. The lint samples from each trial location were tested by the Cotton Fiber Testing Center of the Ministry of Agriculture, with the following results: 2.5% span length 28.9 mm, length uniformity 50.4%, breaking strength 19.6 cN/tex, and Micronaire value 3.8. According to stalk-splitting grading inspection at harvest in a natural Fusarium wilt nursery by the Plant Protection Research Institute of the Gansu Academy of Agricultural Sciences, the average incidence of Fusarium wilt was 5.4%, and the stalk-splitting disease index was 2.1, which was 74.1 and 63.4 percentage points lower than the susceptible control Xinluzao No. 7, respectively, and 0.9 and 0.3 percentage points higher than the resistant control Jiumian No. 1, with no significant difference from Jiumian No. 1; both belong to the highly resistant to Fusarium wilt category.

2 Yield performance: from 1999-2000, it participated in the Gansu Provincial new cotton variety (line) regional trial. The two-year average yield per hectare was 4983 kg of seed cotton and 1911 kg of lint cotton, an increase of 21.1% and 24.4% respectively over the control variety Xinluzao No. 7, and the average yields of seed cotton and lint cotton both ranked first among the 9 tested varieties. The yield was also stable; among the 6 trial sites over two years, 5 sites increased yield compared with the control Xinluzao No. 7, and only one site decreased. From 2000-2001, it participated in production trials and demonstrations. The average yield per hectare was 5436 kg of seed cotton and 2136 kg of lint cotton, increases of 4.6% and 11.3% respectively over the control Xinluzao No. 7.

3 Cultivation points: sow early at the proper time and keep seedlings uniform. In the Hexi Corridor cotton region of Gansu, sowing in early to mid-April is appropriate. To strive for full emergence in one sowing, early seedlings, and strong seedlings, keep 165,000-180,000 plants per hectare.

Balanced fertilization and scientific irrigation: on the basis of conventional basal application of high-quality fertilizer, apply flower and boll fertilizer early and heavily, and supplement with top-covering fertilizer to prevent late-stage nutrient deficiency in the cotton plants, which can cause yield reduction. According to the cotton's growth vigor and appearance, spray foliar fertilizer in a timely manner. For the whole growth period, N:P:K is preferably 1:0.67:0.3. Irrigate the first water around the flowering stage, then irrigate once every 15-25 days, with 3-4 irrigations during the whole growth period.

Timely pruning and scientific regulation: prune in time when the first fruit branch is obvious, top the plants in early to mid-July, and retain 8-10 layers of fruit branches. Scientific chemical regulation should be carried out, combining regulation with control, adhering to the principle of "early control, light control, frequent control," and using plant growth regulators (mepiquat chloride, chlormequat, etc.) 3-4 times during the bud stage and flower and boll stage.

Prevention first, combined with control: for the more serious pests such as cotton aphids, red spiders, and cotton bollworms, do a good job of forecasting according to their occurrence patterns, and achieve early detection and early control. Implement the principle of prevention first, combined with control, and integrated control; try as much as possible to avoid or delay whole-field chemical pesticide spraying, adopt methods such as hidden application of pesticides, protect and utilize natural enemies, reduce control costs, and improve production efficiency.