Variety Characteristics and High-Yield Cultivation Techniques of Wandao 175

Wandao 175, also known as Luyou 136, is a three-line hybrid indica combination developed by the Hefei Fenghai Marker Rice Research Institute of Hefei City, Anhui Province, by crossing Luzhou 86A with Hui 136. This combination has high yield, relatively good grain quality, wide adaptability, and high seed production purity. From 2002 to 2004, it participated in the Anhui Province medium indica rice regional trial and production trial, and in March 2005 passed the Anhui Province variety approval (Wan Pin Shen 05010474).

1 Parental sources and application of the albino marker

The novelty of Wandao 175 lies in the successful application of albino marker breeding technology. The sterile line Luzhou 86A and the maintainer line Luzhou 86B of this combination carry a recessive albino gene. They were developed by using a single plant with the albino marker trait obtained from II-32B through Co radiation mutagenesis as the male parent, and through continuous backcrossing with II-32A. The seedlings of the sterile line and maintainer line carrying the albino marker have completely white leaves at the 1-3 leaf stage, making them easy to identify. Therefore, in field planting and propagation of the sterile line, the green seedlings mixed among the sterile line at the 1-3 leaf stage are off-types and can be directly removed in the seedling bed, saving labor and effort. The male parent Hui 136 was developed by the pedigree method from an early-maturing mutant plant of Zhenhui 084, and matures 3-5 d earlier than Zhenhui 084.

2 Yield performance

From 2002 to 2003, it participated in the Anhui Province medium indica regional trial, with average yields of 8917.5 kg/hm2 and 7762.5 kg/hm2 respectively, increasing yield by 1.28% and 7.54% respectively compared with the control variety Shanyou 63. In the 2004 Anhui Province medium indica production trial, the average yield was 9013.1 kg/hm2, an increase of 11.07% over Shanyou 63.

3 Characteristics

3.1 Main agronomic traits Wandao 175 is of the medium indica type, with a whole growth period of 141-145 d, plant height 120 cm, compact plant shape, good luxuriance, strong tillering ability, uniform and reasonable panicle layer distribution, and good yield potential. Under the condition of 2.7 million/hm2 effective panicles, the average total grain number per panicle is about 160 grains, the seed setting rate is about 85%, and the 1000-grain weight is 28 g.

3.2 Disease resistance Wandao 175 has strong resistance to rice blast and moderate resistance to bacterial leaf blight. According to identification by the Institute of Plant Protection, Anhui Academy of Agricultural Sciences, its resistance to rice blast is grade 1 (R), and its resistance to bacterial leaf blight is grade 4 (MS).

3.3 Rice quality According to determination by the Rice and Rice Products Quality Supervision and Inspection Testing Center of the Ministry of Agriculture, Wandao 175 has a brown rice rate of 81.8%, a milled rice rate of 74.2%, a head rice rate of 58.6%, grain length 6.2 mm, length-width ratio 1:4, chalky grain rate 26%, chalkiness degree 10.8%, transparency grade 3, alkali spreading value 5.5, gel consistency 84 mm, amylose content 19.9%, and protein content 10.9%.

4 Key points of cultivation techniques

4.1 Selecting the best heading and flowering period Wandao 175 has wide adaptability. When cultivated as medium rice in the Yangtze River basin, it is generally sown from late April to early May, with a seedling age of about 35 d. Sowing can also be arranged at the proper time to schedule the flowering period. Its heading and flowering period requires no continuous rain for more than 3 d, a maximum temperature not exceeding 35°C, a minimum temperature not lower than 21°C, an average daily temperature of about 27°C, and relative humidity of about 80%. In this way, light conditions are good, the seed setting rate is high, and high yield is easy to obtain.

4.2 Cultivating strong seedlings

4.2.1 Sprouting. Soak seeds in 400-fold strong chloroisocyanurate solution for 24 h to eliminate pathogens carried on the seeds.

4.2.2 Paclobutrazol treatment of sprouted grain. Place the well-sprouted seeds into 500-fold paclobutrazol solution, stir thoroughly, soak for 20 min, remove, drain, and then sow.

4.2.3 Sparse and uniform sowing. When the seedlings reach the 1-leaf-1-heart stage, promptly fill in gaps to ensure uniform individual development of seedlings, strong seedlings, and more tillers.

4.2.4 Applying sufficient fertilizer. Apply 18.75 t of decomposed human and livestock manure, 375 kg of ammonium bicarbonate, 750 kg of superphosphate, and 225 kg of potassium chloride per hectare of seedling field as base fertilizer. When the seedlings reach the 1-2 leaf stage, apply 75 kg of urea per hectare of seedling field as weaning fertilizer. Five d before transplanting, apply 60 kg/hm2 of urea as send-off fertilizer.

4.2.5 Scientific management. Before the 1-leaf-1-heart stage of seedlings, mainly manage with moist aeration to promote rooting and seedling establishment. After the 1-leaf-1-heart stage, alternate shallow water irrigation with moist management to ensure well-developed roots, steady growth, and more tillers.

4.3 Reasonable close planting Reasonable close planting, uniform seedlings and shallow transplanting. For fields of medium fertility, transplant 240,000-270,000 hills per hectare, with 1-2 seed seedlings per hill, and about 1.35 million/hm2 basic seedlings.

4.4 Skillful fertilization, increasing tiller-promoting fertilizer For fields of medium fertility, apply 150-180 kg of pure nitrogen, 450 kg of phosphate fertilizer, and 300 kg of potassium fertilizer per hectare. Apply sufficient base fertilizer and combine it with organic fertilizer. For topdressing, adopt the method of "promoting at the early stage, controlling at the middle stage, and supplementing at the late stage." Apply tillering fertilizer early, applying tiller-promoting fertilizer 5-7 d after transplanting, generally 105 kg of pure nitrogen per hectare, and supplement later according to seedling condition. Pay attention to increasing phosphate and potassium fertilizer, appropriately control nitrogen fertilizer application, and avoid an excessively large population.

4.5 Scientific water management Shallow water transplanting, 1-cun water for seedling establishment, thin water for tillering, and sunning the field when enough seedlings are present. In the early stage, irrigate frequently with shallow water; in the middle stage, expose and lightly sun frequently; in the late stage, alternate wetting and drying, and ripen fully until maturity.

4.6 Integrated control of diseases and insect pests The main diseases and insect pests of Wandao 175 include the striped stem borer, rice leaf roller, rice skipper, bacterial leaf blight, and rice blast. The policy of "prevention first, integrated control" should be adopted, agricultural control measures should be widely used, supplemented by chemical control, and the following two points should be emphasized: 1) Increase phosphate and potassium fertilizer. Increasing phosphate and potassium fertilizer can make stems hard and strong, improve resistance to diseases and insect pests, also prevent lodging, improve the field microclimate, and reduce the incidence of disease; 2) Persist in selecting appropriate pesticides and applying them according to control thresholds, so as to avoid applying pesticide without eliminating diseases and insect pests.