Introduction to the Rice Variety II You 725

II You 725 is a new high-quality medium-maturing late-season hybrid rice combination bred by the Mianyang Agricultural Science Research Institute of Sichuan Province. In production, this combination shows characteristics such as large panicles with many grains, high yield potential, good grain quality, strong resistance and good adaptability.

1. High yield level In 1997, it participated in the Sichuan Province production trial, planted in different ecological zones of Chengdu, Weiyuan, Bazhong, Wusheng and Zhongjiang, with an average yield of 8.85 t/hm2, an increase of 8.57% over Shanyou 63; in 1997, it was planted as a demonstration on 40 hm2 in Jiepai Town, An County, and through multi-point yield measurement and acceptance, the yield reached 9.345 t/hm2, an increase of 13.78% over Shanyou 63. From 1998 to 1999, it participated in the Hubei Province regional trial, with an average yield of 9.15 t/hm2, an increase of 4.28% over the control Shanyou 63. In 2001, as a national new variety display, it was planted as a demonstration on 200 hm2 in An County, Mianyang City, Sichuan Province, and after yield measurement and acceptance by an expert group, the yield reached 10.456 t/hm2, an increase of 14.26% over Shanyou 63. The results of trials and demonstrations show that II You 725 generally yields 8.25-9.375 t/hm2, an increase of 5%-15% over Shanyou 63, showing a relatively high yield level and yield potential.

2. Good agronomic traits The whole growth period of II You 725 is 151-154 days, about 4 days longer than Shanyou 63 and about 2 days shorter than II You 63. The plant type is compact, the stems are thick and strong, the leaves are stiff and upright, the flag leaf is relatively long, and the leaf color is dark green. Early growth is vigorous, and color conversion in the later stage is good. The plant height is 115 cm, the effective panicles are 2.10-2.55 million/hm2, the panicle length is 26 cm, the number of grains per panicle is 170-195, the seed setting rate is above 85%, and the 1000-grain weight is about 27 g.

3. Strong stress resistance II You 725 has a well-developed root system and thick, strong stems, and its lodging resistance is obviously stronger than that of Shanyou 63. According to inoculation identification of rice blast on II You 725 by the Institute of Plant Protection, Sichuan Academy of Agricultural Sciences, leaf blast was grade 5 and neck blast was grade 5, while Shanyou 63 had leaf blast grade 8 and neck blast grade 9. The conclusion from two years of Sichuan Province regional trials was: lightly susceptible to sheath blight, no bacterial leaf blight was found, and resistance was obviously stronger than that of Shanyou 63.

4. Good grain quality and good palatability The appearance and eating quality are obviously superior to those of Shanyou 63. According to tests by the Rice and Rice Products Quality Supervision and Inspection Testing Center of the Ministry of Agriculture, three indicators reached the ministry-issued first-grade high-quality rice standard: milled rice rate (72.3%), alkali spreading value (grade 6.6) and protein content (10.0%); seven indicators reached the ministry-issued second-grade high-quality rice standard: brown rice rate (80.6%), grain length (6.3 m), length-width ratio (2.5), chalkiness (4.8), transparency (grade 2), gel consistency (46 mm) and amylose content (23.5%). In the Hubei Province regional trial grain quality determination, the brown rice rate was 80.64%, the head milled rice rate was 53.93%, the amylose content was 18.11%, and the gel consistency was 49 mm, with a comprehensive score reaching the ministry-issued second-grade high-quality rice standard.

Breeder: Mianyang Agricultural Science Research Institute of Sichuan Province

1. Sow at the right time and cultivate strong seedlings with many tillers II You 725 is sown in Mianyang from late March to early April, with a seedling bed sowing rate of 150 kg/hm2 and a field seed rate of 22.5 kg/hm2, cultivating strong seedlings with many tillers, with a seedling age of about 45 days.

2. Reasonable close planting and sufficient basic seedlings II You 725 has medium tillering ability and requires reasonable close planting, adopting sufficient seedlings to strive for more tillers to obtain high yield. Transplant 225,000 hills/hm2, with two seedlings per hill, ensuring about 1.5 million basic seedlings/hm2.

3. Reasonable fertilization to ensure the variety's demand for fertilizer nutrients II You 725 is a large-panicle combination, so the variety's demand for fertilizer nutrients should be fully ensured. In the paddy field, good base fertilizer should be applied, organic fertilizer and phosphorus and potassium fertilizer should be increased, and tillering fertilizer should be applied early to promote early growth and rapid development and ensure sufficient effective panicles. Generally, 675 kg of calcium superphosphate, 150 kg of potassium chloride and 150-180 kg of pure nitrogen per hm2 should be applied, and 18-30 kg of zinc sulfate should be applied as base fertilizer. The fertilization method should be "promote, stabilize and apply skillfully": in the early stage, promotion should be dominant, so base fertilizer accounts for 60%-70%; in the middle stage, stabilization should be dominant, with 20%-30% tillering fertilizer; in the later stage (7-10 days before heading), panicle fertilizer should be applied skillfully according to seedling growth.

4. Scientific water management and timely field drying In the early stage, shallow water irrigation should be used to promote tillering. When the stem and tiller seedlings reach 3 million/hm2, field drying should begin so that the maximum number of seedlings is controlled within 3 million/hm2. From booting to heading, a shallow water layer should be maintained in the field; in the later stage, alternate dry and wet conditions should be used, mainly keeping moisture, so as to nourish roots and protect leaves until yellow ripening. Water should be cut off about 5 days before maturity, and it should not be cut off too early, so as not to affect grain filling.

5. Integrated control of pests and diseases The key work is to control rice blast, sheath blight, stem borers and rice planthoppers. At the same time, attention should be paid to the occurrence of rice false smut to ensure a bumper harvest.