Introduction to the Characteristics of the Late Japonica Rice Variety Zhejing 30

I. Variety Introduction

"Zhejing 30" was developed by the Institute of Crops and Nuclear Technology Utilization, Zhejiang Academy of Agricultural Sciences, in the spring of 1995 by crossing Xiushui 63 as the female parent with R9475. Through years of south propagation and north breeding, it was developed using a breeding method that combines low-generation selection for appearance quality (grain shape, transparency, chalkiness degree, chalkiness rate) and resistance identification in disease nurseries, with high-generation determination of physicochemical quality such as amylose content, taste testing, and resistance identification. It has been entered in trials at various levels since 1999, and passed the approval of the Zhejiang Provincial Variety Approval Committee in March 2003.

Zhejing 30 is a dense-panicle type variety with a compact plant type and strong tillering ability. Its whole growth period is 134.5 days, with 233,000 effective panicles per mu, 82 filled grains per panicle, a seed-setting rate of 91.6%, and a 1000-grain weight of 25.7 grams. According to identification results from the Institute of Plant Protection, Zhejiang Academy of Agricultural Sciences, the average grades for leaf blast and panicle blast were 2.7 and 2.0 respectively (the control variety Xiushui 63 had leaf blast and panicle blast grades of 7.0 and 3.0 respectively), showing resistance to rice blast, moderate resistance to bacterial leaf blight, and susceptibility to narrow brown leaf spot, brown planthopper, and white-backed planthopper. In the Zhejiang 2000-2001 late rice regional trials, the average yield per mu was 467.47 kg, an increase of 5.46% over the control variety Xiushui 63 (reaching an extremely significant level). In 2002, 20.6 mu was trial-planted in Xiaonan District, Xiaogan City, Hubei Province, where the average yield per mu set a high-yield record of 805.3 kg, and it was regarded as a new super-high-yield high-quality japonica rice variety. Trial plantings in Zhejiang, Jiangsu and other provinces all showed good adaptability, with cumulative planting reaching 1,446,600 mu (1,384,600 mu in Zhejiang Province and 62,000 mu in Jiangsu Province).

According to analysis by the Rice and Rice Products Quality Supervision and Testing Center of the Ministry of Agriculture in 2000, Zhejing 30 (regional trial variety name: ZH992) had a brown rice rate (84.3%), milled rice rate (76.1%), head rice rate (73.0%), grain length (5.2 mm), length-to-width ratio (1.8), alkali spreading value (grade 7), gel consistency (78 mm), chalkiness rate (4.3%), chalkiness degree (3.3%), amylose content (15.7%), and transparency (grade 1). All the above indicators reached the first-class standard of the Ministry-issued "High-Quality Edible Rice" (NY20-1986). Compared with the control Xiushui 63, Zhejing 30 had a brown rice rate 1.2% higher, a milled rice rate 4.0% higher, and a head rice rate 3.0% higher. In other words, compared with the control Xiushui 63, Zhejing 30, on the basis of increasing rice grain yield by 5.46%, also increased the rice milling yield by 4.0%.

Because Zhejing 30 has excellent rice quality, high yield, strong resistance and good adaptability, it is suitable for planting throughout Zhejiang Province and the middle and lower reaches of the Yangtze River rice region. According to novelty search by the Zhejiang Provincial Institute of Scientific and Technical Information, the comprehensive traits of "Zhejing 30" such as rice quality, yield and resistance are the best among varieties of the same type. Since trial planting in Zhejiang in 2000, the planting area has expanded year by year, and has now grown to an annual planting area of more than 600,000 mu, and is gradually expanding to neighboring provinces (municipalities), with excellent prospects for promotion and application. After passing the approval of the Zhejiang Provincial Variety Approval Committee in 2003, the pace of promotion and application of this variety in the above areas has been further accelerated. It is predicted that the suitable sowing area for Zhejing 30 is about 20 million mu. If this variety accounts for a 10% share, the annual promotion area is expected to reach 2 million mu. Based on a two-year cumulative promotion of 4 million mu, an increase of 20 kg per mu, and a price of 1.0 yuan per kg of rice grain, an additional income of 80 million yuan can be achieved; because the rice milling yield can increase by 4.0% compared with the control variety, based on a yield of 450 kg per mu and a promotion of 4 million mu, an additional 72 million kg of milled rice can be obtained, increasing income by 129 million yuan (rice: 1.8 yuan/kg). The two items combined can generate social and economic benefits of 209 million yuan.

II. Cultivation Regulations

1. Seed disinfection: Soak seeds with seed disinfectants such as "402" or "Jinzhongling" to ensure that seeds enter the soil disease-free.

2. Adapt to local conditions and sow at the appropriate time: In areas north of the Qiantang River in our province, June 20-25 is suitable; in areas south of the Qiantang River, sowing can be appropriately delayed according to local conditions.

3. Pay attention to controlling the seed rate: Zhejing 30 has relatively strong tillering ability, so the sowing rate per mu in the seedling field should not exceed 30 kg; sparse sowing for strong seedlings is required, cultivating seedlings with tillers, and the seedling age should not exceed 30 days. The seed rate for the main field is generally 3-3.5 kg for double-cropping rice, and generally 2.5-3.0 kg per mu for single-cropping rice. Excessive seed rate easily causes lodging, affecting both yield and rice quality. Reasonable dense planting: for continuous late rice cultivation, generally 30,000 hills per mu, with 3-4 seedlings per hill; for single-cropping rice cultivation, 25,000 hills per mu, with 2-3 seedlings per hill.

4. Scientific fertilization: Experiments show that excessive application of chemical fertilizers reduces rice quality. Fertilizer use should be based mainly on organic fertilizers and biological fertilizers, with less inorganic chemical fertilizer, and appropriately increased application of P and K fertilizers, to help reduce rice chalkiness and improve processing quality. The total fertilizer amount per mu is 50 dan of standard fertilizer for continuous late rice, and 55 dan of standard fertilizer for single-cropping rice, and it needs to be applied early. The later fertilizer must not be applied too late or too heavily, otherwise it easily causes lodging and reduces rice quality.

5. Pay attention to water management and pest and disease control: Panicles formed from high-position tillers easily produce half-filled grains or green grains, affecting rice quality. For this reason, water management in the early growth stage should mainly be alternating dry and wet, promoting low-node tillering and reducing the number of high-position tillers. Zhejing 30 is a dense-panicle type, and in some years is easily infected by rice false smut, affecting yield and quality. Use 100 grams of Wenqukexing powder per mu added to 40-50 kg of water, and spray 5-7 days before heading.

6. Grasp the appropriate harvest timing: Zhejing 30 is a dense-panicle type, and the grains at the base of its panicle fill more slowly. The maturity of these grains largely determines the rice chalkiness rate and chalkiness degree indicators. The harvest timing after maturity does not have a great impact on economic yield, but it has a relatively large impact on rice quality. Appropriately delaying harvest can reduce the proportion of green rice, improve rice quality, and improve the palatability of cooked rice.