Xin Zhang

In recent years, the soybean acreage in Sichuan province expanded rapidly year after year, and it increased to 270,000 hectares in 2008, which exhibit great growth potential. The acreage will be more than 1 million hectares through developing soybean intercropping. According to farming systems, climate, ecological characteristics and so on in Sichuan province, authors think that it is a main way to breed new varieties suitable with maize intercropping and planted in late summer. In this word, some suggestions are as follows: Super-high-yield breeding, the soybean high-yield potential should be more than 4500kg/hm2, the high-yield potential in intercropping should be more than 3000kg/hm2. Better-quality breeding, the crude protein content of soybean should be more than 50%. Anti-multiplicity breeding, soybean should be anti-Soybean mottle virus, anti-Etiella zinckenella Treitschke, have better resilience and so on. Soybean varieties suitable for intercropping with maize must have good anti-shady, strong lodging resistance, growth retardation, resilience, strong pod, high production with one strain, good anti-insects and other excellent properties. Nandou 12 is a special variety with maize intercropping. It was breed by Nanchong Institute of Agriculture Science in 2008. The yield of Nandou 12 in intercropping planting is 2100-3000kg/hm2, crude protein content is 51.79%, crude protein + crude fat is 69.42%. Nandou 12 was identified as dominant species by Ministry of Sichuan province and Agriculture Department in 2009.

Key words: Sichuan, soybean, production potential, focus on breeding

本文譯自2008年《作物遗传育种研究》经济作物特刊“四川大豆生产发展潜力与育种重点商榷”一文

1. The demand statas of soybean in Sichuan province

It is very contradictory between soybean demand and supplying in china. And many soybeans are mainly relying on imports. In recent years, Chinas soybean imports were increasing year by year. The imports of soybean in China have reached 34.13 million tons at the year of 2008. According to the predicte of U.S. Department of Agriculture in February 2006, Chinas soybean imports will arrive at the level of 57.2 million tons. Which are the main factors to affect food security and national stability in China. All the statas were caused by some reasons just as low level of soybean yield, low compare efficiency and the good quality of soybean production in the United States, Brazil and Argentina. So, soybean acreage is decrease, the Soybean production capacity is 16 million tons, far from enough to meet the needs of our country.

The total demand of soybean in Sichuan is around 2 million tons, in 2006, the provinces soybean production was 460,000 tons, and the gap is beyond 1.5 million tons, which main be satisfied through importing. But Soybean production is contrast between Sichuan and the whole country. It is rapid development and the situation is promising in Sichuan. The development potential and space is very large, foe example: the soybean acreage in increasing to 27.3 million hectares in 2008 from 11.7 million hectares in 1996.

2. The soybean production development potential in Sichuan

For food security and national stability in China, the realization of the industrial structure adjustment of agriculture, agricultural efficiency and increaseing farmers income in Sichuan, we should try to develop the soybean industry and production.

As long as we correct the feasible species, technical supporting, a sets of parallel development of soybean replant in addition to the attention of the Government，Sobean acreage is possible to achieve at 667,000 hectares in Sichuan Province.

2.1 “wheat/Zea mays/soybean” model

“wheat/Zea mays / soybean” model is the largest potential for soybean production in Sichuan. The cultivation area of sweet potato is about 73.3-80 million hectares year-round in Sichuan province. And if 50% of the acreage was taken up by soybean, it is expected to arrive at 333,000 hectares every years.

2.2 “Soybean in ridge” model

Soybean in ridge has strong marginal advantages, ventilation light, the yield potential is up to 4500kg/ha, the economic efficiency and ecological benefits are very significant. With the exception of sporadic cultivation of broad beans, corn, trees outside the economy, the vast majority is free, Ridge area of Sichuan is more than 13.4 million acreages, which play an important role in increasing agricultural efficiency for farmers. And if 50% of the acreage was taken up by soybean, soybean acreage will increase at 6.7 million hectares every year.

2.3 “soybean cultivation in absurd ground” model

As the result of many effective labors going out to earn money, some farmers at home are the sick and elderly, the absurd ground areas are larger which arrived at 334,000 hectares. If 50% of the acreage was taken up by soybean cultivation, soybean acreage will increase at 167,000 hectares every year.

2.4 mitigation drought disservice through soybeans

Sichuan hilly area is the main soybean-producing areas in Sichuan, but also be the worst drought areas. According to statistics of 2000 to 2005 in Sichuan province, the drought disaster area is up to 106.7 million hectares. Soybean has the variety of species(spring soybean, summer soybean and autumn soybean), has flexibility sowing date, resistance, stable yield，higher economic and ecological advantages and so on. Soybean is one of the main crops against disaster. And if 1/3 of the acreage was cultivated by soybean, new soybean acreage will increase at 334,000 hectares every year.

2.5 The development of fresh soybean cultivation

Due to the rapid development of Chinas cities and towns, the population is large year by year, addition to the improving of peoples living, the demand for fresh soybean are growing, as a result, fresh vegetable soybean has larger development space in Sichuan province.

Moreover, “wheat/Zea mays/soybean”model, soybean intercropped with young forest, soybean cultivated in e rice paddy after early maturings harvest and seed production fields, the soybbean cultivated area is at least more than 300 million acreages.

3. The focus and breeding direction of soybean in Sichuan province

Sichuan has a long history of soybean cultivation, and summer soybean(commonly known as winter soybean) is the main plant all the year, the cultivated area of soybean cultivation in the province accounted for more than 90%. Summer soybean production paly a most important role in Sichuan, so, the new varieties of summer soybean breeding should be the focus of soybean research in Sichuan Province. However, since the liberation, soybeans bred or introduced in Sichaun province has been more than 50. Which are early spring varieties, mid-maturing varieties and varieties not suitable for the production in Sichuan province. The main cultivated soybean in Sichaun province is Rongxian winter beans (Gong election No.1) and some local varieties such as harvest in October.

As a result of the differences among breeding objectives, ecological characteristics, farming systems and farmers cultivation practices, some new varieties of soybeans in the production can not play a leading role. Therefore, exploring the direction of soybean breeding has become the focus of scientific research workers in the future.

3.1 Summer soybean breed

Soybean is divided into the spring, summer and autumn according the planting season in Sichuan province. And summer soybean is the main species just because the special reality in our province, special climate systems and ecological conditions.

In Sichuan province, “ rutabaga-rice”, “wheat-rice” and ‘only rice” are the main cultivate model in paddy field，and "wheat/Zea mays/sweet potato” is main cultivate model in arid land.

Under these cropping systems, wheat, oilseed rape and bean are harvested during late April and late May universally. So, there is no place for soybean cultivate except for some sporadic wasteland, fallow land and the young forest rapid development in recent years.

At the same time due to climate reasons of high temperatures, high humidity, heavy late summer and pod borer hazard period in Sichuan province, spring soybean vulnerable during the month of 7-8. The soybean yields are lower, poor performance and poor quality. In the contrast, there is great space for summer soybean production cultivated just as “wheat/Zea mays/soybean” and “wheat/Zea mays/sweet potato” models. The summer soybean breeding especially species suitable for intercropping will be the most important in Sichuan province.

3.2 Soybean high yields breed

Since the beginning of soybean breed in China liberation decades years ago, a lot of gratifying achievements of soybean varieties has been achieved. The new soybean species were more than 1000. And soybean yield, quality, resistance and so on have been improved gradually.

However, there still some problems in soybean yield improving. In 10 years, the yield of new soybean varieties is about 2700-3000kg/ha in small areas in Sichuan and China. And only be of 2250-2550kg/ha in large areas production. Some new species have good yield as 4500kg/ha, but has non-repeatability and operability in production. Therefore, the soybean area is decrease in China.

The author believes that ultra-high-yielding soybean should be 4500kg/ha in small areas and 3000kg/ha in the production levels according to the practice of Sichuan. Which will improve soybean production and increase the farmer income.

3.3 New soybean species breeding on ultra-high-protein

The market has been internationalized since Chinas accession to the WTO. In order to enhance development of new soybean varieties in the international competitiveness, we should give much more emphasis on quality breeding just as high-yield breeding. Sichuan is located in subtropical, there is significant differences during spring, summer, autumn and winter.

In summer and autumn when the soybean reproductive growth, it is rain, humidity, and the temperature difference is small between day and night, it is good for soybean protein formation and accumulation. Therefore, soybean quality breeding in Sichuan Province, the first should be focus on breeding new varieties of ultra-high-protein, the protein content should be above 50%. Secondly, soybean appearance of commercial should be attention while improving the soybean internal quality. Soybean with yellow, light navel, shiny, good grain shape will be changed as a key direction. In order to adapt to the increasingly fierce international competition challenges, the inherent quality and appearance of the organic integration of commercial should be combination with each other.

3.4 Soybean resistance breeding

In recent years, disease, pests, especially the legume pod borer and leaf against the virus disease are particularly serious in Sichuan province and South of China. Due to illness, insects against, the soybean production is reduced year-round. Therefore, to enhance new varieties breeding with anti-pod borer, viruses, worms and other disease-centric multi-resistant is imperative.

4. The advantages and prospects of inter-cropping, center-cropping model

“wheat/Zea mays/soybean”and “wheat/Zea mays/sweet potato” models are researched by Professor Wenyu Yang from Sichuan Agricultural University and Mingrong Zhang from Nanchong Institute of Agricultural Sciences in recent years. It is about soybean cultivate in dry land. The technology of two models is mature, matching, simple and feasible, which has good applied potential, good socio-economic, good ecological benefits, and strong vitality. The inter-cropped soybean planting patterns show five prominent features as follow:

4.1 Combination of land use and construction

Soybean belongs to leguminous crop which has a strong capability of N-fixing. In general, 11kg urea applied is equal to the mature leaves falling into the soil, the root and the root nodule left in 1 acreage soil with soybean cultivation. At the same time, as a result of natural organic matter into the soil also helps to improve soil fertility, ecological and economic benefits, which can promote the sustainable development of agriculture.

4.2 The realization of the simple, saving, high-yielding and high-efficiency agriculture. Soybean cultivation do not need much more labor and cost, labor-saving, easy, which is a typical “lazy crop” ,and is very suitable for the low quality of workforce, labor shortage and the agriculture needs reality in Sichuan province.

4.3 As a result of the coverage of no-tillage technology, water-saving moisture and drought relief has become a reality.

4.4 “wheat/Zea mays/sweet potato” is to meet the requirements for pig corn and sweet potato in Sichuan province and the devilment of soybean cultivation in Sichuan province. It is a good cultural model for soybean.

4.5 It is possible to alleviate the contradiction between soybean supply and demand tension in Sichuan province when taking good use of existing arable land and sown area.

Now-days, “wheat/Zea mays/soybean” and “wheat/Zea mays/sweet potato” models have been attracting the great attention from leaders of Sichuan province. Since 2004, the government of Sichuan province has focused the model to be increasing food production as “300”project.

The cultivation area of sweet potato in Sichuan Province is about 73.4-80 million hectares year-round, if we development of “wheat/Zea mays/soybean” model, the addition soybean cultivation area will be 667,000 hectares every year, in addition to the traditional “wheat/Zea mays/sweet potato” model, soybean intercropping with young forest, ridge soybean and so on, the increasing potential for inter-area inter-planting of soybean will be at least 867,000 hectares which has great prospects for soybean development in Sichuan province.

5. New soybean species suitable for intercropping breeding

At present, the main cultivation models are “wheat/Zea mays/soybean” and “wheat/Zea mays/sweet potato”. Under these two models, the soybean is intercropped with corn, due to the growth of tall corn plants, the lower the growth of soybean plants, thus forming a high temperature, humidity, shading the special micro-climate environment ecology.

Accordingly, soybean varieties suitable for intercropping with maize should have the characteristics of good tolerant with shadowing，growth retardation (dwarf varieties), good resistance against lodging, high plant productivity, disease resistance, insect resistance, summer growing period 130-140 days and so on in Sichuan province. According to the special climates of Sichuan, we should pay more attention in new soybean species suitable for intercropping breeding in future.

In recent years, Nanchong Comprehensive Experiment Station has been successfully cultivated new soybean varieties of Nandou 12, Nandou 14, Nandou 16 and NanF04-255, which are fit for intercropping with maize. Nandou was approved the adoption of Sichuan 12 in March 2008, and it was approved as the leading varieties by the National Ministry of Agriculture and the Agriculture Department of Sichuan Province in 2009.

During 2007-2008, in the “wheat/Zea mays/soybean” high-yield model, the yield was up to 2250kg/ha, in the “wheat/Zea mays+soybean/soybean “mode the yield was 3000kg/ha. The species of Nandou 12 showed great prospect in the inter-cropped cultivation. Nandou 12 has many good quality as follow: First, suitable for inter-cropped with maize; Second, strong resistance with lodging; Third, excellent quality; fourth, high protein content of 51.79%, the sum of protein and fat is 69.42%; fifth, high resistance to virus diseases.

After identification of Nanjing Agricultural College: Nandou 12 has strong anti-virus of SC3 and SC7; sixth, it is good to avoid insects. During mid- july and early-september, the bean pods insect is reappearance, but Nandou 12 of this period coincided with the early vegetative growth and flowering, pod borer from the leaves and flowers do not harm, it is not formed on soybean yield. In mid-September to late October, with the delay of the season, the temperature gradually decreased, the fall of cotton increased rain, growth and reproduction of the pod borer is extremely unfavorable, this period coincided with the reproductive growth of Nandou 12, that the yield formation of a critical period, basically do not the formation of hazards, to avoid insects; seventh, barren-resistant, drought, stability, and is highly adaptable species ecology. Nandou 12 is a typical high degree of adaptability of the ecological species, high and stable yield.

References

1. Xuelan Lu, The status and measures of soybean industry development in Sichuan, 2007, national soybean oil and fat industry development forum collection.

2. Weiguang Du, Lijun Liu, Thinking of Super-species of cultivated soybean, Soybean report, 2006, 5: 7

3. Mingrong Zhang, Haiying Wu, The Problems of studying on soybean breeding and development strategies in Sichuan, Soybean report, 2006. 5:1