Introduction to the Shennong 6 soybean variety and its cultivation key points
[Basic Information] Shennong 6 (original line number Shennong 91-44) was bred by the Department of Agronomy of Shenyang Agricultural University in 1986 through sexual hybridization, using Fengjiao 66-12 as the female parent and Kaiyu 8 as the male parent, selected according to breeding objectives. Since Shennong 6 was introduced to Pulandian City in 1996, it has withstood the test of different years and different climatic conditions (low temperature and scant sunlight, high temperature and drought), consistently showing high and stable yield, disease resistance, and lodging resistance, with an average yield increase of 18.7%-24.7% over the control. In order to fully bring out the excellent varietal characteristics of Shennong 6, through trials and demonstrations we have summarized high-yield cultivation techniques for Shennong 6 with a large-area yield of 3375kg/hm2, and widely promoted them in production, so that the promotion area of Shennong 6 soybean expanded rapidly in a short period. At present, Shennong 6 has become the main soybean variety planted in the Pulandian area, producing obvious social and economic benefits.
[Characteristics and Traits] Shennong 6 is a variety with determinate pod-setting habit, plant height 90-100cm, thick and strong stems, 20 main stem nodes, 2-3 branches, with the characteristics of a long terminal inflorescence and short fruiting branches, and the terminal inflorescence reaching 11cm in length.
Shennong 6 flowers relatively late; in the Dalian area, the first flowering stage is from July 15 to 20, the final flowering stage is August 15, and the flowering period is about 30d, relatively concentrated. It sets many pods, with an average of 50 pods per plant, and the maximum per plant is 157 pods and 320 seeds.
It is relatively resistant to soybean viral disease, drought-tolerant and barren-tolerant, lodging-resistant, with good photosynthetic performance in the later stage, and matures with green stems. The seeds are yellow, with a pale hilum, small seed uniformity difference, no purple spots or brown spots, low insect-feeding rate, and 100-seed weight of 22-24g. Protein content is 45.5%, fat content is 18.9%, and the total of protein and fat is 64.4%. It belongs to the double-high variety category, with excellent quality.
The growth period for spring sowing in the Dalian area is about 130d, and about 90d for summer sowing. In 1998, Shennong 6 soybean was planted respectively in Pulandian City, Wafangdian City, Jinzhou District and other places. Among them, Jiang Chuanhai of Dadian Village, Yuantai Town, Pulandian City planted 3.3hm2 in the gaps of a peach orchard, with an average yield of 3375kg/hm2; Miaopu Village, Fuzhoucheng Town, Wafangdian City planted 0.7hm2, with an average yield of 3900kg/hm2; Dengshahe, Jinzhou District planted 6.7hm2, with an average yield of 3645kg/hm2. Liujia Village, Taiping Township, Pulandian City planted 0.2hm2, with an average yield of 405Okg/hm2.
The Science and Technology Commission of Pulandian City established a project to promote the new soybean variety Shennong 6, carrying out demonstration planting of 66.7hm2 in 27 townships. Among them were flat fertile land, thin land, hillside-foot land, and also paddy-to-dryland converted fields, basically representing various soil types and cultivation levels in the region. According to yield measurement, yields were basically all above 300Okg/hm2, with some plots reaching about 3375kg/hm2.
[Breeder] Department of Agronomy, Shenyang Agricultural University
[Region and Techniques] After several years of trials, demonstrations and production practice, we have summarized high-yield cultivation techniques for Shennong 6 with a yield of 3375kg/hm2, as follows.
After removing diseased-spot seeds, insect-eaten seeds and impurities, treat the seeds with 46% soybean seedling-strengthening agent (agent:seed ratio 1:120) or 25% carbendazim seed-coating agent (agent:seed ratio 1:60) to control underground pests and so on.
Choose plots without continuous or alternating cropping and carry out contiguous planting. For flat fertile land (previous corn yield 900Okg/hm2, apply 7500kg/hm2 of decomposed organic fertilizer, and no seed fertilizer is needed); for medium-fertility plots (previous corn yield 6000-900Okg/hm2, apply 1500Okg/hm2 of decomposed organic fertilizer, 150kg/hm2 of diammonium phosphate, and 150kg/hm2 of potassium sulfate (or 15kg/hm2 of biological potassium) as seed fertilizer); for low-fertility plots (previous corn yield below 600Okg/hm2), apply 22500kg/hm2 of decomposed organic fertilizer, 225kg/hm2 of diammonium phosphate, and 180kg/hm2 of potassium sulfate as seed fertilizer. If growth is insufficient, topdress with 45-75kg/hm2 of urea at the initial flowering stage of soybean.
Shennong 6 should be sown appropriately late to reduce the bottom pod height, and the best sowing period in the Dalian area is from May 10 to May 15. The suitable sowing rate for spring sowing is about 52.5kg/hm2, and for summer sowing about 112.5kg/hm2. Use equidistant hill sowing, with 3 seeds per hill, and cover with soil to a depth of 3-5cm after sowing. For spring sowing, retain 150,000 plants/hm2 in the field, that is, row spacing 57cm, hill spacing 23cm, with 2 plants retained per hill; for plots with higher fertility, retain 120,000 plants/hm2; for summer sowing, retain 375,000-450,000 plants/hm2 in the field.
After the 2 pairs of opposite true leaves have unfolded and before the 1st compound leaf has fully unfolded, carry out manual thinning by hand according to the required hill spacing, removing weak, small and diseased seedlings, and finalize the stand in one operation.
Complete three hoeings and three ridgings before the soybean canopy closes, with an interval of 10-15d.
After soybean sowing and before emergence, use 20% chlorimuron-ethyl 60g/hm2 mixed with acetochlor 2250kg/hm2, diluted in 750kg of water, and spray the soil surface to control weeds. For summer-sown soybean fields where crabgrass is the main weed, use quizalofop-p-ethyl or haloxyfop, at a rate of 750-1500ml/hm2, diluted in 450kg of water, and spray on stems and leaves at the 3-5 leaf stage of the weeds.
(1) Control soybean aphids: from mid-to-late May to early-to-mid July, use 40% dimethoate emulsifiable concentrate 750g, evenly mix into 150kg of moist fine sandy soil, and broadcast along every 6-8 ridges. Or spray with 40% dimethoate emulsion at 1500-2000 times dilution, with a spray volume of 450-600kg/hm2. (2) Control soybean pod borer: in mid-August, make "slow-release cards" by soaking pieces of felt soft paper in 80% dichlorvos emulsifiable concentrate, using 1500g/hm2 of the agent and 750 slow-release cards, hung evenly in the field. Or use 80% dichlorvos emulsifiable concentrate at 2250g/hm2, soak 900-1050 corn cobs, and place them evenly in the field. (3) Control soybean dodder: in areas prone to soybean dodder, use 40% dinitramine emulsifiable concentrate at 100-150 times dilution, with a spray volume of 300-450kg/hm2, after soybean has grown its 4th compound leaf (applying before this is prone to phytotoxicity), and spray on the soybean plants when dodder shifts to harming other plants.
Shennong 6 has a concentrated flowering period, and if drought occurs during the flowering and pod-setting stage, yield losses are large. Therefore, in areas with the conditions, water must be irrigated in time to ensure yield.