Introduction to the Characteristics and Traits of the I You 86 Rice Variety

[Basic Information] I You 86 was developed by this institute through test crossing and selection in 1995 between the self-bred new restorer line R8608 (a composite cross progeny of Gui 630/Fei-//Conggui 314/IR8608) and You IA, which was selected and bred by the Hunan Hybrid Rice Research Center. After 4 consecutive years of trials and test plantings from 1996 to 1999, this combination showed high and stable yield, relatively good grain quality, and multiple resistance, with comprehensive traits significantly superior to the control Shanyou 64, and high seed production yield.

This institute used several male sterile lines including Zhenshan 97A, V20A, You IA, and Pei'ai 64S as female parents, and multiple lines of the restorer line R8608 as male parents for test crossing. In 1995, an indica-type medium-maturity hybrid combination with good yielding ability, relatively good grain quality, and strong disease resistance was selected from the test-cross F1 generation. In 1996, it was entered into this institute's comparative trial of new medium-maturity hybrid rice combinations. Because of its significant yield increase and excellent comprehensive traits, it was recommended in 1997 to participate in the medium-maturity group trial of the Shaanxi Province Rice Elite Variety Regional Trial. In the 3-year regional trial from 1997 to 1999, it consistently showed high yield, relatively good grain quality, and multiple resistance, with comprehensive traits clearly superior to the control Shanyou 64, and was named I You 86.

[Characteristics and Traits] I You 86 has a semi-erect plant type, relatively strong tillering ability, and a high effective panicle rate. Plant height is about 105 cm, leaves are long and erect, the main stem has 15.8 leaves, and the panicle type is curved and drooping. The average total grain number per panicle is 122, filled grain number is 110, seed setting rate is 88%, and 1000-grain weight is 27 g. In southern Shaanxi, the whole growth period is 145 d, and from sowing to full heading is 114 d. It is an indica-type medium-maturity hybrid rice, maturing 2 d later than the control variety Shanyou 64. It has strong lodging resistance and good color conversion at maturity. Brown rice rate is 80.8%, milled rice rate is 72.6%, chalky grain rate is 56%, transparency is grade 1, chalkiness degree is 12.8%, grain length is 6.4 mm, alkali spreading value is 4.8, gel consistency is 79 mm, amylose content is 227%, and protein content is 8.3%. The cooked rice is white and its eating quality is better than K You 195. According to disease resistance identification by the Plant Protection Research Laboratory of this institute, I You 86 has R resistance to rice blast at the panicle neck, clearly stronger than the control Shanyou 64; by artificial inoculation identification, its resistance to bacterial leaf blight is comparable to the control Shanyou 64.

In this institute's 1996 comparative trial of medium-maturity hybrid rice, I You 86 had an average yield of 9.24 t/hm2, an increase of 13.3% over the control Shanyou 64. In the 1997 Shaanxi Province Rice Elite Variety Regional Trial, the average yield was 8.19 t/hm2, an increase of 21.49% over the control Shanyou 64, ranking 1st among the test combinations; in the 1998 provincial regional trial, I You 86 had an average yield of 8.08 t/hm2, an increase of 12.11% over the control Shanyou 64, ranking 2nd among the participating combinations; in the 1999 provincial regional trial, the average yield was 8.43 t/hm2, an increase of 11.78% over the control Shanyou 64, ranking 3rd among the participating combinations. The 3-year regional trial average was 15.37% higher than the control. In the production demonstrations arranged for I You 86 in 1998, 1.6 hm2 was planted in Chengguan, Ningqiang County, with an average yield of 8.7 t/hm2, an increase of 28.89% over the control; 13 hm2 was planted in Donggou Township, Liuba County, with an average yield of 8.93 t/hm2, an increase of 24.4% over the control; and 0.3 hm2 was planted in a demonstration by this institute, with an average yield of 7.65 t/hm2, an increase of 21.57% over the control. In the 1999 provincial rice regional trial production test, the trial by Ankang City Seed Company produced a yield of 8.1 t/hm2, an increase of 19.44% over the control Shanyou 64. This combination has begun to be promoted and planted on a large scale in suitable areas.

[Breeder] Hanzhong City Institute of Agricultural Sciences,

[Region and Technology] The growth period of I You 86 is similar to that of Shanyou 64, so it can be raised in open fields, by the two-stage seedling method, or under plastic film mulching within the safe sowing period of suitable ecological zones. For two-stage seedlings, transplant two plants per hill, with a density of 1.5 cm x 2.0 cm. The seeding rate for the field is 15.0-22.5 kg/hm2, and seedling age is 35-40 d. Open-field seedlings should be sown sparsely to cultivate strong seedlings with tillers.

I You 86 has relatively strong tillering ability, larger panicles, and strong lodging resistance. Therefore, on the basis of striving for large panicles, it should be appropriately planted at higher density. The transplanting density is 26.64 cm x 16.65 cm, with 225,000-255,000 hills per hectare and 1.57-1.78 million basic seedlings, which is favorable for high yield.

I You 86 is suitable for planting at medium to upper fertility levels. The application ratio of nitrogen, phosphorus, and potassium fertilizers should preferably be 1.0:1.0:0.5. Generally, 150 kg/hm2 of pure nitrogen is applied. Before transplanting, sufficient organic fertilizer per hectare combined with 65 kg of pure nitrogen, 120 kg each of P2O5 and K2O should be applied as base fertilizer. At 5-7 d after transplanting, 180 kg/hm2 of urea should be applied as topdressing to promote tillering. At the grain-filling stage, foliar spraying with Hekuling combined with 1.5 kg/hm2 of potassium dihydrogen phosphate should be used to enhance leaf function and favor grain filling and seed setting. Water management should be strictly carried out: shallow water in the early stage to promote early development, timely field drying to control tillering, and alternating wet and dry conditions in the later stage, without stopping water too early. Timely pest and disease control should be carried out. The male parent of I You 86 is R8608, an indica-type medium-late maturity variety, and the female parent You IA is an indica-type early-maturity variety. Flowering period arrangement should preferably have the female parent heading 1-2 d earlier than the male parent. Based on the sowing-to-heading period of the parents and 4 years of seed production experience, for summer seed production in Hanzhong, the male parent is placed in a greenhouse for two-stage seedling raising on April 3, and the female parent is raised in the open field on May 29. In normal years, this can ensure good flowering coincidence. The three difference indicators for seed production are: time difference of about 56 d, leaf age difference of 9.51 leaves, and effective accumulated temperature difference of 489.7 degrees C. Starting at the early stage of young panicle development, dissection and inspection should begin, and if flowering non-coincidence is found, timely adjustment should be made.

The female parent You IA has a relatively long flowering period, good glume opening, and relatively strong tillering ability. The transplanting density is 13.3 cm x 13.3 cm, with 8-10 seedlings per hill. The male parent R8608 has strong tillering ability and a large amount of pollen, so the row ratio should preferably be 2:16 or 1:14. The male parent plant-row spacing is 26.6 cm x 16.7 cm, transplanted with two seedlings per hill.

In order to prolong the flowering period of the male parent and increase pollen amount, strong seedlings with tillers should be cultivated. Therefore, the male parent seedling field should receive sufficient base fertilizer, finely prepared seedling beds, heavy application of tillering fertilizer, and proper pre-transplanting fertilizer. After deep plowing and fine harrowing of the field, sufficient base fertilizer should be applied with organic fertilizer combined with nitrogen, phosphorus, and potassium fertilizers. At 7 d after transplanting, appropriate tillering fertilizer should be applied to promote early development. The female parent You IA should be sown sparsely to cultivate strong seedlings, and at the 2-3 leaf stage, heavy tillering fertilizer should be applied. Water management should include shallow transplanting with about one cun of water, deep water to protect seedlings, frequent shallow irrigation, and alternating wet and dry conditions in the later stage.

The female parent You IA is relatively sensitive to "920". When 10% of the female parent has headed, lightly cut the leaves and spray 60 g/hm2; then after 1 d spray 120 g/hm2; after another 1 d spray 15 g/hm2 to relieve panicle enclosure. Every day from 10:30 to 13:30, use bamboo poles to drive pollen once every 30 min to improve the seed setting rate.

Before sowing, seeds of both parents should be soaked and disinfected with strong chlorine. At the tillering stage, Jinggangmycin should be used once to control sheath blight. The key focus is control of rice kernel smut; when the female parent You IA is at full heading, Mieheiling should be used to control rice kernel smut.

Strictly select isolated seed production areas, carry out roguing in the female parent seedling field and at the tillering stage, with emphasis on roguing and removing inferior plants at the heading stage of the female parent. At maturity, harvest the female parent first, then the male parent, and strictly prevent mechanical mixing.