How is the Changnongjing No. 2 rice variety?

The new rice variety "Changnongjing No. 2" (formerly named 89-94) was developed by the Changshu City Institute of Agricultural Sciences in Jiangsu Province in 1989 through a double cross of 84G091/Xiushui 04//Wuyujing No. 2, followed by continuous non-greenhouse generation advancement of F1 and F2, and was bred in 1993 as a new medium-maturing late japonica variety. This line has the characteristics of excellent grain quality, high yield, early maturity and good adaptability.

Characteristics: This variety has large panicles and large grains, a low sterility rate and a high 1000-grain weight. It is a large-panicle type variety, similar to hybrid japonica rice. The usual yield is more than 650 kg per mu, with 198,500 panicles per mu, 133.4 total grains per panicle, a sterility rate of 10%, and a 1000-grain weight of 29 g. To further raise the yield level, there is a trend of decreasing panicle number and increasing panicle size. In 1998, as determined by the Rice and Rice Products Quality Supervision, Inspection and Testing Center of the Ministry of Agriculture: brown rice rate 85.7%, milled rice rate 79.0%, head rice rate 77.5%, grain length (mm) 4.8, length/width 1.5, chalkiness rate 50%, chalkiness degree 4.2%, transparency 2, alkali spreading value 7.0, gel consistency (mm) 82, amylose 17.8%, protein content 8.8%. Among the above indicators, except for transparency and chalkiness degree, which meet the second-grade standard for high-quality rice, all other indicators reach the first-grade standard for high-quality rice issued by the Ministry, and the palatability is good. Under the same conditions, the heading stage of "Changnongjing No. 2" is basically similar to that of "Wuyunjing No. 7", but the maturity stage is about 2 d later. It is generally sown in mid-May, transplanted in mid-June, heads from September 2 to 6, and matures in late October. The whole growth period is 164 d, belonging to the medium-maturing late japonica type. It is moderately resistant to rice blast.

Yield performance: In 1995, this variety participated in the collaborative joint evaluation of new rice lines in Suzhou City. The summary of 5 pilot sites showed an average yield of 611.6 kg per mu, ranking first among 14 tested varieties (lines), increasing yield by 4.12% over Xiushui 122 CK1 and by 0.87% over "Taihujing No. 2" CK2. In 1996, it was promoted to participate in the comparative trial of new rice varieties in Suzhou City. The average yield of 7 pilot sites was 641.8 kg per mu, ranking first among 6 tested varieties (lines), increasing yield by 1.21% over the control Taihujing No. 2, and it was also the only variety that exceeded Taihujing No. 2. In 1998, it was promoted to participate in the single late rice regional trial of Jiangsu Province. The average yield of 10 pilot sites was 667.6 kg per mu, ranking first among 11 tested varieties (lines), increasing yield by 1.8% over Wuyunjing No. 7 CK2 and by 6.83% over CK1 Wuyujing No. 2. In view of the outstanding performance of this line, in 1999, while participating in the provincial regional trial, it skipped a level to participate in the provincial production trial. Under the unfavorable climatic conditions of that year, it withstood the test and showed very strong adaptability, and its yield still ranked first, with 579.61 kg per mu, increasing yield by 2.1% over control I Wuyunjing No. 7 and by 12.7% over control I Wuyujing No. 2. In the same year, it participated in the provincial production trial, with an average yield of 561.5 kg per mu, also ranking first, increasing yield by 11.7% over the control Wuqingjing No. 2, showing high and stable yield.

Breeder: Changshu City Institute of Agricultural Sciences, Jiangsu Province

Region and techniques: The Changnongjing No. 2 variety has weak tillering ability and a high ear-bearing tiller rate. In cultivation measures, the following should be done well: 1. Cultivate strong seedlings: Changnongjing No. 2 has weak tillering ability, so cultivating age-appropriate strong seedlings is even more important. For water-raised large-seedling cultivation, the seedling-raising techniques should be as follows: first, strictly disinfect seeds before sowing to prevent bakanae disease; second, sow at the right time, preferably from May 18 to 20; third, sow appropriately sparsely, with the sowing rate per mu of seedling field controlled at about 30 kg; fourth, apply sufficient fertilizer, with total pure N for the seedling field at 16-18 kg/mu, of which base and surface fertilizer accounts for 50%, weaning fertilizer 30%, and standing-up fertilizer 20%; fifth, apply pesticides at the right time to control weeds and prevent and control diseases and insects. 2. Transplant at the right time: Early transplanting at the right time is beneficial for low-node tillering and can make up for the weakness of poor tillering. The suitable transplanting period is from June 15 to 20, with a seedling age of 28-30 d. For transplanting density, through 2 years of production practice, a row spacing of 8 cun and a plant spacing of 3.5 cun is reasonable, ensuring no fewer than 20,000 hills per mu, with 4 seedlings per hill (including large tiller seedlings), and about 80,000 basic seedlings, so as to ensure a certain number of panicles per mu. 3. Scientific fertilization: Changnongjing No. 2 is a large-panicle variety with relatively strong fertilizer tolerance and lodging resistance. In fertilizer management, the total pure N in the field should be controlled at 17-18 kg/667 sq m, and the maximum pure N application per mu should not exceed 20 kg. In fertilizer use, earlier is better than later, and it is important to avoid applying panicle fertilizer too heavily and too late, so as to avoid increased empty grains, aggravated disease, and adverse effects such as poor ripening color. Fertilizer management is as follows: early stage (base and surface fertilizer and tillering fertilizer applied before the end of June) accounts for 60%, middle stage (stem-thickening fertilizer) accounts for 20%, and late stage (panicle fertilizer) 20%. 4. Reasonable irrigation: For high-yield cultivation, field water management should be as follows: shallow water at transplanting to ensure transplanting quality; maintain a water layer during the greening stage to facilitate establishment and improve the weed-control effect of herbicides; shallow water layer during the tillering stage to improve fertilizer efficiency and promote tillering; around July 18, according to seedling conditions, begin field drying in combination with the application of stem-thickening fertilizer; from August 15 to the heading stage, maintain a shallow water layer in the field; after full heading, alternate dry and wet conditions; in the late stage, do not cut off water too early, so as to avoid reducing grain weight; cut off water one week before harvest to ensure green stalks and living maturity, full grains, and a bumper harvest. In addition, disease and insect control should be done well, with emphasis on controlling the yellow stem borer and panicle rice blast. For the control of other diseases and insect pests, refer to varieties of the same type.