Breeding and Promotion of Dunyu 107, a High-yielding and Stable-yielding Maize Variety

Jikun GUO, Zhibin YAN, Yang XI, Yanbiao YAN, Xiang LI

Gansu Dunhuang Seed Group Co., Ltd., Jiuquan 735000, China

Abstract Dunyu 107 is a new maize variety bred by the Gansu Dunhuang Seed Group Co., Ltd. with the self-bred excellent inbred line HA189 as the female parent and HB38 as the male parent. The variety has early maturity, tolerance to dense planting, lodging resistance, good yielding stability, good comprehensive resistance and suitability for mechanized harvesting. It passed the national approval in 2019 and has great market potential and application value.

Key words Maize, Variety breeding, Combination identification, Quality analysis

1 Introduction

Huang-Huai-Hai Plain is one of the main regions for maize cultivation in China. It is the second largest maize production region and the largest summer maize production region in China, and the annual planting area accounts for more than 30% of the total of China. The maize yield differs greatly among different areas of the region, and the potential for yield increase is large[1]. Maize production has played an important role in food security. Since 2013, various types of disasters occur continuously in the summer maize-producing areas of the region, including high temperature, drought, overcast and rainy weather, heavy rain, strong wind, and southern corn rust, so that higher requirements have been put forward on the resistance of maize[2].According to the statistics of the National Agricultural Technology Center in 2017,Zhengdan 958[3], Weike 702[4], Jundan 20[5], Dedan No.5[6]and Longping 206[7]are still the mainstream varieties with a relatively large promotion area in the summer sowing areas. The female parents of the varieties are dominated by 478 and its derivative lines, and the male parents are dominated by Chang 7-2 and its derivative lines. This kind of varieties have stable yield, wide adaptability and high seed production in Huang-Huai-Hai Plain, but slow dehydration has always been a difficult problem to solve. Therefore, the main characteristics of the urgently needed varieties in maize production at this stage are: mid-early maturity, dense planting resistance, high yield, high quality, lodging resistance, high temperature resistance and suitability for mechanized operation.

In the Production Capacity Plan (2009-2020) for An Increase of 50 Billion Kilograms of Grain issued by the State Council in 2009, it is proposed to promote excellent varieties and high-yield cultivation techniques to realize the matching of good varieties and good methods, combine modern biotechnology with conventional technology, and focus on cultivating maize varieties that are resistant to dense planting, lodging and diseases and insect pests, and are adapted to mechanized operations[8], so exploring a modern maize production and marketing road that leads to the production of maize with cost saving, efficiency, quality improvement and product conversion and efficient use is urgent.

Dunyu 107 is a new maize variety bred by Gansu Dunhuang Seed Group Co., Ltd. with HA189 as the female parent and HB38 as the male parent. After multi-year and multi-point tests, it has been found that the comprehensive performance of this variety is excellent, with outstanding characteristics of high and stable yield, mid-early maturity, high temperature resistance, dense planting resistance, beautiful plant type, lodging resistance, loose bracts, hard cob, quick dehydration of seeds and high bulk density. It is adapted to dense planting and full mechanized harvesting. Dunyu 107 is suitable for promotion in the summer maize producing areas in Henan Province, Shandong Province, Baoding City of Hebei Province, southern areas of Cangzhou City, irrigation areas of Shaanxi Province, Yuncheng City and Linfen City of Shanxi Province, some flat areas of Jincheng City and north of Huaihe River in Anhui Province, with great market potential and application value. In 2019, it passed the approval by the National Crop Variety Approval Committee, with approval number of Guo Shen Yu 20190278.

2 Parental sources and breeding process

2.1 HA189In 2011, the hybrid Zhongzhong No.8 was subjected to self-crossing, and excellent individuals were selected from the F2and F3generations at a planting density of 150 000 plants/ha. In the F3generation, using Chang 7-2 as a test variety, excellent single panicles with good general combining ability were selected for ear-to-row testexsitu. After continuous selfing in Henan, Jiuquan and Sanya, the special combining ability was determined in the F5generation, and ears with stable row number were selected in the F7generation. According to the test number, the variety was named as HA189. The inbred line has early maturity, good comprehensive resistance, 95% kernel percentage, 98 d of growing period under summer sowing in Henan, purple seedling coleoptile, compact plant type, plant height of 180 cm, ear height of 55 cm, few tassel branches , purple filaments, yellow anthers, white cob, 14-14 rows per ear, ear length of 17 cm and dent-shaped yellow kernels.

2.2 HB38Yongchang 7-2 was crossed with JL795 (male parent of Dunyu No.8) and then backcrossed in Hainan in 2011. Excellent single plants were selected from the F2and F3generations at a planting density of 150 000 plants/ha. For F3generation, Zheng 58 was used as a test variety, and then excellent single ears with good general combining ability were selected. After continuous selfing in Henan, Jiuquan and Sanya, the special combining ability of the F5generation was determined, and ears with stable row number were selected. According to the test number, the variety was named as HB38. The inbred line has a large amount of pollen, high general combining ability, low ear position, and good erection capability. Under the condition of summer sowing in Henan, it takes 96 d from seedling emergence to maturity. It has purple leaf sheaths in young seedlings, yellow anthers, compact plant type, plant height of 175 cm, ear height of 65 cm, light purple filaments, tubular ear, ear length of 18 cm, 14-16 rows per ear, white cob, orange-yellow kernels, and strong comprehensive resistance.

2.3 Hybrid breeding and combination identificationAccording to the theory of heterosis, 300 test-cross combinations were prepared by incomplete diallel-cross combination using the Zhongzhong No.8 population and the "C7-2/JL795" population in Sanya in winter of 2014.In 2015, after identification in Xinxiang, Xingyang, Shangqiu and Yucheng, 30 test-cross combinations with yield increased by greater than 10% were screened for comparative test. In particular, the hybrid combination with the inbred line HA189 as the female parent and HB38 as the male parent has outstanding comprehensive performance and is named Dunyu 107, which participated in the comparative test of Gansu Dunhuang Seed Group Co., Ltd. and Hebei-Shandong-Henan consortium preliminary test in 2016. The results of the comparative test of Gansu Dunhuang Seed Group Co., Ltd. show that the average yield of Dunyu 107 was 10 521.9 kg/ha, with an increase of 17.16%. In the 36 test sites (Cangzhou, Dezhou, Gucheng, Handan, Hebi,etc.), the yield increased in 29 test sites and decreased in 7 test sites. The percentage of test sites with yield increased reached 81%. The results of the Hebei-Shandong-Henan consortium preliminary test show that the average yield of Dunyu 107 was 10 770 kg/ha, increased by 15.8%. Among the 25 test sites, the yield increased in 21 test sites and decreased in 4 test sites, and the percentage of test sites with yield increased was 84%. After two consecutive years of appraisal of suitability in 2015 and 2016, it was found that Dunyu 107 has high yield potential, strong disease resistance, strong lodging resistance, and good grain quality.

3 Characteristics

3.1 Botanical characteristicsDunyu 107 has a growth period of 102 d (0.8 d shorter than the control), light purple leaf sheaths in seedling stage, compact plant type after entering adulthood, moderate size, low ear position (ear height of about 93 cm), plant height of about 238 cm, about 20 leaves in the entire plant, tough stem, moderate-quantity and short branches in tassels, light purple filaments and anthers, short tubular ears of uniform size, small angle between ears and stalk, ear length of 16.6 cm (slightly longer than that of Zhengdan 958), moderate-length ear stalk, moderate-quantity bracts, 16 rows per ear, bald tip of 0.6 cm, white cobs, yellow hard kernels, 100-kernel weight of 35.0 g, small marginal superiority, good lodging resistance (average lodging rate of 0.1% and average breaking rate of 0.8%), uniform and robust emerged seedlings, beautiful plant type, tolerant to dense planting, dwarf stalks, and quick dehydration in the later stage.

3.2 Resistance identificationThe disease resistance in the field is good, with high resistance to gall smut, stem rot and smut disease and resistant to southern leaf blight andCurvularialeaf spot. The disease resistance identification results of the College of Plant Protection of Henan Agricultural University in 2017 show that Dunyu 107 was highly resistant (HR) to stem rot, resistant (R) to southern leaf spot and ear rot, moderately resistant (MR) toCurvularialeaf spot and gall smut, and highly sensitive (HS) to southern rust. The disease resistance identification results of Institute of Plant Protection of Henan Academy of Agricultural Sciences show that Dunyu 107 was sensitive (S) to stem rot, southern leaf spot and ear rot and highly sensitive (HS) toCurvularialeaf spot, southern rust and gall smut. The disease resistance identification results of the College of Plant Protection of Henan Agricultural University in 2018 show that Dunyu 107 was resistant toFusariumear rot, moderately resistant toFusariumstem rot,Curvularialeaf spot and gall smut, sensitive to southern leaf blight, and highly sensitive to southern rust. According to the disease resistance identification of the Institute of Plant Protection of Henan Academy of Agricultural Sciences in 2018, Dunyu 107 was resistant to stem rot,Curvularialeaf spot and ear rot, sensitive to southern leaf blight and gall smut, and highly sensitive to rust. After multi-point field identifications in 2015, 2016, 2017 and 2018, there was no pollen abortion, fruiting failure or obvious pollen grains, indicating that Dunyu 107 is a high temperature-resistant variety.

3.3 Quality analysisThe bulk density, crude protein content, crude fiber content, crude starch content and lysine content of grains of the variety are 774 g/L, 10.68%, 4.8%, 69% and 0.32%, respectively. The grain quality reaches the national first-class standard of ordinary corn and the national first-class standard of corn for feed.

4 Yield performance

In the regional trials in 2017 and 2018, the average yield of Dunyu 107 was 9 801 kg/ha, increased by 4.8% compared with that of Zhengdan 958 (control). The sites/times with yield increased accounted for 78.15%. The lodging rate was 0.7%, and the breaking rate was 0.55%. The moisture content of the kernels was 26.5%, 2.5% lower than that of the control. In the production test in 2018, the average yield was 9 313.5 kg/ha, 6.1% higher than that of the control. The percentage of sites/times with yield increased reached 90.2%. The lodging rate was 0.3%, and the breaking rate was 0.7%. The moisture content of the kernels was 26.8%, 2.2% lower than that of the control.

5 Key points of cultivation

This variety is suitable for cultivation in Henan Province, Shandong Province, southern Baoding and Cangzhou and the area to the south in Hebei Province, irrigation areas in central Shaanxi Province, Yuncheng City and Linfen City in Shanxi Province, some flat areas in Jincheng City, north of Huaihe River in Anhui Province, and so on. The key points of the cultivation are as follows. (i) Early sowing. For summer sowing in Huang-Huai-Hai region, the variety should be sown from June 1-25. (ii) Reasonable dense planting. The general planting density is 63 000-75 000 plants/ha. (iii) Reasonable fertilization. Nitrogen fertilizer is the dominant, supplemented by appropriate amounts of phosphorus and potassium fertilizers. (iv) Pest control. Attention should be paid to the control of borers and aphids in the middle and late stages.

6 Conclusions and discussion

The purpose of the development of maize industry in China in the future is to improve the overall benefit and farmers’ income, focusing on reducing production costs and improving corn quality. It is urgent to explore a production and marketing road, characterized by cost saving, high efficiency, quality improvement and product efficient transformation and efficient use, for maize production led by varieties. (i) Dunyu 107 is a new maize variety bred with HA189 as the female parent and HB38 as the male parent. The parents belong to different germplasm groups, with great genetic differences and strong heterosis, in accordance with the cross combination principle and heterosis model theory. This heterosis model will play a guiding role in the breeding of Huang-Huai-Hai region in the future. (ii) Dunyu 107 has better overall performance, and excellent lodging resistance. Its root system is developed, with large rooting depth and strong absorption capacity. The stalk has good toughness. The ear position is neat and 20 cm lower than the control. The ears are uniform, and the ear length and grain length are superior to the control, with high kernel percentage and bulk density. Dunyu 107 has good resistance to diseases, insect pests and stresses, good erection capability, quick dehydration in the later period, and is suitable for mechanized harvesting. This variety is suitable for popularization and planting in the summer sowing areas of Huang-Huai-Hai region (prudently promoted in rust-prone areas). It is in line with the current demands for the promotion of dwarf stalk, lodging resistance, dense planting tolerance, high temperature resistance, wide adaptability and med-early maturity.