Detailed Introduction to the Rice Variety K You 619

Basic Information K You 619 is a new hybrid early rice combination developed by the Southern Zhejiang Rice Breeding Center of the Wenzhou Academy of Agricultural Sciences, using K17A bred by the Rice and Sorghum Research Institute of the Sichuan Academy of Agricultural Sciences and the restorer line Wen Hui 619 (a hybrid progeny of Ce Zao 2-2/02428) selected by the unit. In 1997, it participated in the early hybrid joint comparison trial of the Zhejiang Province Hybrid Rice Breeding Research Collaboration Group; from 1998 to 2000, it passed the Zhejiang Province regional trial; in 2000, it also participated in the Zhejiang Province production trial. It has already been promoted and applied on a relatively large scale in south-central Zhejiang and northern Fujian.

Characteristics The average whole growth period of K You 619 is 112.7 d, and the active accumulated temperature is about 2580°C, similar to the control Shanyou 48-2. The plant height is 80-85 cm, and the plant type is moderately compact. The number of leaves on the main stem is 12.1-13.3. The leaves are relatively narrow, thick, and erect, with a good light-receiving posture, and the functional leaves have a long lifespan, remaining green with yellow ripening at the late stage. This combination is of the panicle-grain balanced type, with strong tillering ability and a high earbearing tiller percentage. The effective panicles are 3.7 million panicles/hm2, the panicle type is medium, the total number of grains per panicle is 97.3, the number of filled grains is 72.4, the seed setting rate is 74.41%, and the 1000-grain weight is high at 27.33 g.

According to inspection by the Rice and Rice Products Quality Supervision and Testing Center of the Ministry of Agriculture, the brown rice rate is 76.4%, the milled rice rate is 66.3%, the head rice rate is 27.1%, the grain length is 6.8 m, the length-to-width ratio is 2.9, the chalkiness rate is 79%, the chalkiness degree is 10.3%, the transparency is grade 3, the alkali spreading value is grade 15, the gel consistency is 79 m, and the amylose content is 24.8%. Among these, the 3 indicators of grain length, alkali spreading value, and gel consistency reached the first-grade standard for high-quality rice; the 2 indicators of length-to-width ratio and amylose content reached the second-grade standard for high-quality rice. According to 3 a of testing from 1998 to 2000, the average score was 45.7 points, 3.4 points higher than the control Shanyou 48-2. The cooked rice has good palatability, and the eating quality is obviously better than the control.

K You 619 has relatively strong resistance to rice blast, better than the control Shanyou 48-2. According to inoculation by the Institute of Plant Protection over 2 a from 1998 to 1999, the average resistance of K You 619 to leaf blast was grade 4.5, and that of Shanyou 483 was grade 4.8; the average resistance of K You 619 to panicle blast was grade 4.3, while that of Shanyou 483 was grade 6.0 on average. The loss rate from panicle blast was obviously lower than that of the control. Secondly, K You 619 is relatively resistant to sheath blight. Judging from many years of trials and test plantings, although K You 619 is also infected by sheath blight, its occurrence is later and lighter than that of combinations such as Shanyou 483.

The sterile line K17A of K You 619 has a high stigma exsertion rate (exsertion rate 82.7%, double exsertion rate 42.2%, while the exsertion rate of Zhenshan 97A is 47.1%, and the double exsertion rate is only 12.5%), strong stigma vitality, a longer flowering time, and a low glume-closing rate, and its outcrossing seed setting rate is obviously higher than that of Zhenshan 97A; the restorer line Wen Hui 619 has strong tillering ability and sufficient pollen, making it easy to obtain high yield in seed production. In Suichang County, when 4.67 [hm2] were produced in spring in the first year, the average yield was 3.04 t/hm2; among this, 1.6 hm2 of contiguous seed production in Houcun Village, Dazhe Town, had an average yield of 4.32 t/hm2, and high-yield fields exceeded 4.5 t/hm2.

In 1997, this combination participated in the early hybrid joint comparison trial of the Zhejiang Province Hybrid Rice Breeding Research Collaboration Group, with an average yield of 7.45 t/hm2, an increase of 11.13% over the control Zhe 733, ranking 1st among the tested combinations. In the same year, it participated in the Wenzhou City early hybrid regional trial, with an average yield of 7.42 t/hm2, an increase of 5.27% over the control Shanyue 48-2, reaching a significant level. In 1998, it participated in the Zhejiang Province regional trial. Under the abnormal climate conditions of that year, the average yield was 6.30 t/hm2, an increase of 0.11% over Shanyou 48-2 and 8.11% over Zhe 733 (reaching an extremely significant level), ranking 2nd among the 9 tested combinations. In 1999, it continued to participate in the Zhejiang Province regional trial, with an average yield of 6.47 t/hm2, an increase of 7.47% over the control Shanyou 48-2 (reaching an extremely significant level) and 5.50% over Zhe 733 (reaching an extremely significant level), ranking 2nd among the tested combinations. In 2000, it continued to participate in the Zhejiang Province regional trial, with an average yield of 6.45 t/hm2, an increase of 6.73% over the control Shanyou 483 (reaching a significant level), ranking 2nd among the 8 tested combinations; in the same year, it participated in the Zhejiang Province production trial, with an average yield of 6.22 t/hm2, an increase of 0.7% over the control Shanyou 483.

In 1998, expanded test planting and demonstration of nearly 40 hm2 were carried out in various places in Wenzhou City, with an average of 6.1 t/hm2, an increase of 2.3% over Shanyou 48-2, 6.9% over Weiyou 402, and 9.5% over Shanyou Zhe 3. In 1999, test plantings were carried out in Wenzhou, Lishui, and the Ningde area of Fujian, with an area reaching 1060 hm2, and the general feedback was relatively good; about 800 hm2 were planted in Yuanhai District of this city, with an average of 6.08 t/hm2, an increase of 5.9% and 8.26% over the main planted combinations Shanyou 48-2 and Shanyou Zhe 3, respectively. In 2000, about 1300 hm2 of expanded test planting were carried out in Wenzhou City. According to the statistical results reported by each county (city, district), the yield range was 6.35-8.27 t/hm2, all higher than the local main planted varieties (combinations), and 5.58%-7.07% higher than Shanyou 48-2.

Breeder: Southern Zhejiang Rice Breeding Center, Wenzhou Academy of Agricultural Sciences

Region and key cultivation techniques: a) Cultivate strong seedlings and lay a good foundation. The sowing period may be in late March, the sowing rate may be 150-225 kg/hm2, the field seed rate is 22.5 g/hm2, and the seedling age should be kept at about 30 d. b) Rational close planting and sufficient seedlings in the field. For hand-transplanted fields, 300,000 hills/hm2, with 2 seedlings per hill, and about 1.2 million seedlings/hm2 in the field is appropriate.

For seedling-throwing fields, the number of seedlings in the field should be ensured at about 1.35 million/hm2 to ensure the number of effective panicles and make it easy to obtain high yield. c) Scientific fertilizer and water management to build a high-yield seedling framework. The total nitrogen application rate is 150-180 kg/hm2, with combined application of P and K fertilizers. The fertilization method should follow the principle of "apply sufficient base fertilizer, apply tillering fertilizer early, and apply panicle-grain fertilizer as appropriate." The base fertilizer is required to be mainly organic fertilizer, quick-acting tillering fertilizer should be applied early, K fertilizer should be applied after field drying and rewatering, and potassium dihydrogen phosphate should be sprayed before meiosis. For water management, it is advocated to mainly use shallow water irrigation, drain the field when there are enough seedlings, and implement alternate drying and wetting in the middle and late grain-filling stages to prevent stopping water too early at the late stage. d) Grasp pest and disease conditions and control them in time. K You 619 has relatively green leaf color and luxuriant growth, and is prone to pests and diseases. It is necessary to strengthen the control of pests such as stem borers, rice leaf rollers, and rice planthoppers, and at the same time pay attention to integrated control of sheath blight and rice blast.

Key points of seed production technology: a) Grasp the characteristics of the parents and formulate a reasonable sowing interval. In south-central Zhejiang, for early summer seed production, the sowing-to-heading duration of the male parent is about 75 d, and that of the female parent is about 68 d. The reasonable sowing interval between the parents is 8 d, with a leaf difference of 2 leaves. The male parent is sown in 2 stages, with an interval of 6-7 d. The female parent is allowed to head 1-2 d earlier than the male parent. b) Determine the row ratio and plant sufficient seedlings in the field. The row ratio of male and female parents is 2:(10-12). The male parent is planted in large double rows, with the two stages planted alternately, with a row spacing of 30 cm x 17 cm, a field seed rate of 4.5 kg/hm2, 45,000 hills/hm2, 2 seedlings per hill, and 450,000 seedlings/hm2 in the field. The female parent has a plant-row spacing of 13 cm x 17 cm, a field seed rate of 30 kg/hm2, 300,000 hills/hm2, 2-3 seedlings per hill, and 2.1 million seedlings/hm2 in the field. The spacing between male and female parents is 15 cm. c) Strengthen fertilizer and water management and build a high-yield seedling framework. In fertilization, follow the principle of "heavy base fertilizer, sufficient organic fertilizer, and mainly one-time topdressing." Before plowing, use 15.0-22.5 t/hm2 of decomposed barnyard manure as the base, and before transplanting the parents, use 300-450 kg of ammonium bicarbonate and 225-300 kg of superphosphate per hectare as surface fertilizer. After regreening, apply 225-300 kg of urea and 150 kg of potassium chloride per hectare as a one-time topdressing. Drain the field in time after enough seedlings are reached to control ineffective tillering. At the late stage, maintain moist shallow irrigation, alternate drying and wetting, nourish roots and protect leaves, and promote grain filling and seed setting. d) Take measures to ensure high yield and high quality in seed production. K17A and Wen Hui 619 are sensitive to "920." Generally, 105-120 g/hm2 of "920" is used, plus 1500 ml/hm2 of "920" synergist. Spraying should follow the principle of "light at the front, heavy in the middle, and supplementary at the end," and artificial pollen dusting should be carried out in a timely manner to improve the outcrossing seed setting rate. Strictly isolate, prevent mixing, and remove impurities to ensure seed purity. After seed harvest, prevent exposure to the sun to ensure the seed germination rate.