Tóm tắt Luận án Study on selection and technical measures to improve waterlogging ability of winter soybean in hanoi

Nội dung text: Tóm tắt Luận án Study on selection and technical measures to improve waterlogging ability of winter soybean in hanoi

1. MINISTRY OF EDUCATION MINISTRY OF AGRICULTURE AND AND TRAINING RURAL DEVELOPMENT VIETNAM ACADEMY OF AGRICULTURAL SCIENCES PHAM THI XUAN STUDY ON SELECTION AND TECHNICAL MEASURES TO IMPROVE WATERLOGGING ABILITY OF WINTER SOYBEAN IN HANOI Specialization: Crop Sciences Code: 9620110 SUMMARY OF PhD THESIS Hanoi - 2021
2. The thesis was completed at : VIETNAM ACADEMY OF AGRICULTURAL SCIENCES Supervisors: 1. Assoc. Prof. Dr. Tran Thi Truong 2. Dr. Tran Danh Suu PhD thesis reviewer 1: PhD thesis reviewer 2: PhD thesis reviewer 3: The thesis was reported to the Thesis Committee at the Institutional level in Vietnam Academy of Agricultural Sciences At h, date , month , 2022. The thesis can be found at the libraries: 1. National Library of Vietnam 2. The Library of Vietnam Academy of Agricultural Sciences.
3. 1 INTRODUCTION 1. Necessity of the study Soybean or soya bean [Glycine max (L.) Merrill] belongs to the legume family (Fabaceae), order Fabales. Soybean is one of the important crops of high economic value with multiple uses, providing human feed, being a source of raw materials for livestock, food industry, medicibe, cosmetics. In Vietnam, soybean is a long-standing crop, having an important position in agricultural production and considered as a high economic efficiency crop in the strategy of crop restructure, increasing the value of agricultural products. With short growth duration, soybean can be cultivated in many crop seasons during the year, being ideal in crop rotation, intercropping, increasing of crop seasons and overlapping crop. Soybean production helps to increase land use coefficient, create jobs and increase income for farmers. The soybean planting area in Winter - Spring 2019 of Hanoi reached 2.9 thousand hectares over 3.4 thousand hectares planted for the whole year (accounting for 85.3%); the yield was 1.69 tons/ha, the output reached 4.9 thousand tons out of 5.92 thousand tons/year (accounting for 83.05%). Soybean has become the main crop, occupying an important position in the Winter crop structure of Hanoi as well as the Red River Delta provinces. However, the soybean production in Hanoi is still fragmented, dispersed, low intensive investment, the application of new techniques is limited, and the soybean production area is unstable and gradually shrinking. One of the main reasons for low yield of soybeans is lack of collections of soybean varieties suitable for the ecological conditions of Hanoi, as well as the appropriate and synchronized technical measures. Specifically, it usually rains around the end of September, at the beginning of Winter soybean crop in Hanoi. The rain is prolonged and sometime heavy when sowing soybean, the soil is always wet, the field can be flooded. Previously selected soybean varieties were mostly drought and cold tolerant varieties; research on flood-tolerant varieties has not been focused. Therefore, the selection of soybean varieties that can be tolerant to waterlogging and adapted to the natural conditions of Hanoi as well as identifying technical measures for Winter soybeans soybeans on wet soil after rice harvesting to improve the yield and efficiency of soybean production is necessary. Based on the above mentioned necessity, we conducted the thesis: "Study on selection and technical measures to improve waterlogging ability for Winter soybean in Hanoi". The study on identification of soybean varieties tolerant to waterlogging with farming conditions in Hanoi along with other technical measures will contribute to improving the yield and output of soybeans in Hanoi, and to raising incomes for farmers. 2. Objectives of the study - Identifying soybean lines and varieties tolerant to waterlogging for the
4. 2 development of Winter soybeans on wet soil in Hanoi. - Developing appropriate cultivation technical measures to improve the yield of Winter soybeans on wet soil after Summer rice harvesting in Hanoi. 3. Scientific and practical significance of the study 3.1. Scientific significance - The thesis findings provide valuable scientific basis for selection of soybean lines and varieties capable of growing and developing well in waterlogging conditions and appropriate cultivation techniques for soybean to achieve high yields in wet soil conditions after Summer rice harvesting. - The thesis is a good reference for teaching, learning, scientific research, training and management of soybean production. 3.2. Practical significance - Selection of soybean varieties with good growth, high productivity suitable to the conditions of Winter crop season on wet soil after Summer rice has high practical significance in expanding Winter soybean production, increasing income for farmers in Hanoi. - The study results of soybean cultivation technical measures contribute to completing the intensive cultivation process of Winter soybean for wet land areas after Summer rice in Hanoi. 4. Subject and scope of the study 4.1. Subject of the study - 30 lines, soybean varieties selected and introduced by domestic research institutions and imported from aboard are used for studying the waterlogging ability in the net house. - 06 varieties of soybeans evaluated as capable of waterlogging through experiments in net house were used for study in artificial waterlogging condition in fields. - Studying appropriate technical measures for ĐT32 soybean variety on wet soil after Summer rice. 4.2. Scope of the study The thesis focused on studying the effects of waterlogging conditions on the growth and development of 30 soybean lines and varieties in the Winter of 2016 and Winter of 2017 in Hanoi. In the Winter of 2018 and Winter of 2019, its was continued to study the growth and development of 06 soybean varieties in artificial waterlogging conditions in the field and appropriate technical measures for ĐT32 soybean variety. Technical measures (sowing times, density, fertilizer) were only applied to varieties selected by the thesis for their waterlogging tolerance. 4.3. Limited scope of the topic - The thesis has inherited some published research results of domestic and foreign authors - The thesis had not studied some indicators due to limited time. Those are the
5. 3 indicators related to the damage of cotyledons and radicles in the germination period under flooding condition; degree of root rot; rate of wilting plants; rate of dead plants; the remaining density after flooding in the period of artificial flooding V2, R1 and R4. 5. New contribution of the thesis - 3 varieties of soybeans (ĐT32, ĐT35 and ĐT26) were selected with good growth, high real yield (2.07, 1.98 and 2.11 tons/ha in My Duc; 2.24; 2.35 and 2.29 tons/ha in Phuc Tho, respectively) in waterlogging conditions. - Appropriate technical measures for ĐT32 soybean varieties were identified in the Winter on wet soil after the Summer rice in Hanoi: Appropriate sowing times from 15 - 29th September; sowing density of 40 - 45 plants/m2; fertilizer dose for 1 hectare was 30 - 40 kg N : 60 - 80 kg K2O : 60 - 80 kg P2O5. - Treatment of seeds before sowing with G3 preparations and foliar nano- fertilizers significantly increased the yield and economic efficiency of ĐT32 soybean variety (yield increased 26.7 - 28.25%; net profit increased 49.81 - 55.33% compared to the control). - Treatment of seeds before sowing with G3 preparations and foliar nano- fertilizers combined with reducing the amount of macronutrient fertilizers by 10% and 30%, the yield of ĐT32 soybean variety was still high (yield reached 2.63 - 2.73 tons/ha, net profit increased by 44.16 - 51.42% compared to the control). 6. Structure of the thesis The thesis has 151 A4 pages with 54 tables and 6 figures, including: Introduction (7 pages); Chapter 1: Overview and scientific basis of the thesis (36 pages); Chapter 2: Materials, content and study methods (13 pages); Chapter 3: Results and discussion (76 pages); Conclusions and recommendations (2 page); References (16 pages). Chapter 1. OVERVIEW AND SCIENTIFIC BASIS OF THE THESIS 142 literature sources, including 56 Vietnamese, 79 English and 7 from the internet related to the study topic have been referenced, overviewed and quoted, including: 1. Introduction to soybeans; 2. Soybean production; 3. Overview of soybean research; 4. Study on technical measures for soybeans. 1.1. Introduction to soybean Cultivated soybeans are scientifically named Glycine max (L.) Merrill, belonging to order Fabales, family Fabaceae, sub-family Papiomoideae, genus Glycine, sub-genus soja. Soybeans are legumes native to China, known to humans about 5000 years ago. Around 200 BC, soybeans were introduced to Korea, then to Japan. By the mid-17th century, soybeans were grown in Europe, and then thrived in the United States, Brazil and Canada. 1.2. Soybean production situation Soybean is one of eight important oil plants, first grown in China, and then
6. 4 developed to other continents. Due to its wide adaptability, soybean is grown on all continents but most concentrated in the Americas, followed by Asia. The countries with the highest soybean planting area, production and productivity in the world are the United States, Brazil and Argentina, 80% of soybean production is from these three countries. Soybean is also an agricultural product exported of many countries around the world. Due to the high increase in demand in recent years, soybean production has increased compared to other main crops in terms of both area and yield. Soybean has been grown in Vietnam for long time. However, up to now, the area of soybean cultivation is still very limited, the yield is still low, and soybean production is not high compared to many countries in the world. Domestic soybean production currently only meets a very small part of the consumption demand; the rest must be imported from outside. Currently, according to statistics, in 2017, soybean is grown in 26 provinces and cities across the country, of which about 87.8% is in the North and 12.2% in the South. Particularly in Hanoi, the area and soybean production of Hanoi from 2015 to 2018 are fluctuated erratically, especially the area tends to decrease gradually. In 2015, Hanoi had 20.2 thousand hectares of soybean cultivation, but by 2019 only 3,4 thousand hectares remained. In contrast to the area, soybean yields tend to increase gradually, especially from 2015 to 2018, soybean yield increased from 1.495 - 1.818 tons/ha. 1.3. Overview of soybean research The USA is the leading country in soybean yield and production, and has many achievements in soybean research and development. China has been improved soybean varieties since 1913, and about 1,100 varieties have been selected. India is also a country with many achievements in the study of soybean breeding. India conducts testing of local and introduced varieties at Pathaga University. The latest study around the world in soybean selection shows that not only using traditional methods (sexual crossing) with aim to increase productivity, but also focusing on modern studies such as biotechnology, gene technology to create high-quality varieties, resistant to pest and diseases, varieties tollereant to against unforable conditions (waterlogging, drought tolerance). The selection of soybean varieties in Vietnam is carried out by many research agencies. Regarding the achievement of selecting soybean varieties, it can be temporarily divided into 3 periods: (1) Selecting specialized soybean varieties for seasoning: including the group specialized in cold season (Spring, Winter) and the group specialized in hot season (Spring - Summer, Summer - Autumn); (2) Selecting soybean varieties used for 3 crops seasons; (3) Selecting highly resistant, widely adapted soybean varieties. Around the world, there have been many studies on the effects of watwerlogging on soybean crops. Watwerlogging ranks second after drought
7. 5 among the abiotic factors causing the greatest economic losses in soybean (Valliyodan et al., 2014). Flooding reduces soybean production worldwide by about 16% and causes billions of dollars in losses for producers (Ahmed et al., 2013). Flooded soil often causes hypoxia in the root system, causing damage of the soybean plant and severely inhibiting plant growth (Takahashi et al., 2018). 1.4. Research on technical measures Technical measures such as sowing time, sowing density, fertilizer doses, etc. have great effects on the growth and development as well as the yield of soybean. Changing of the sowing time means that the soybean will grow under different lighting conditions of the photoperiod. Appropriate planting density has a very important significance to ensure crop yields. In fact, in our country, there have also been many researches by many authors on the density of crops in general and the planting density of soybean in particular. According to Dave Franzen and collaborators (2019), for good growth and development, soybeans need 14 nutrient elements, of which macronutrient elements such as nitrogen (N), phosphorus (P), potassium (K) are essential. Soybean has a high demand for nitrogen due to high protein content in the seeds. Research reports show that nano-fertilizers can improve crop yield by enhancing seed germination rate, seedling development, photosynthetic activity, nitrogen metabolism, and carbohydrate and protein synthesis (P. Solanki et al., 2015). In conclussion: Most of the researches in the world and in Vietnam have focused on breeding, assessing the adaptability and tolerance of soybean lines and varieties, thereby screening and selecting high-quality lines and varieties for production. However, in Vietnam, research on waterlogging tolerance of soybean has not been focused. Therefore, the selection of soybean varieties tollerant to waterlogging, adapted to the natural and climatic conditions of Hanoi as well as developement of appropriate cultivation techniques for Winter soybeans (sowing time, sowing density, fertilization, ) are necessary. Chapter 2. MATERIALS, CONTENT AND STUDY METHODS 2.1. Materials Thirty soybean lines and varieties, some of which have been recognized varieties or promising lines were used for the study. 2.2. Content of the study Content 1. Study on waterlogging tolerance in germination, vegetative and reproductive growth stages of soybean lines and varieties in net house. Content 2. Selection of waterlogging tolenrant soybean varieties in the Winter on wet soil after Summer rice in Hanoi (field experiment). Content 3. Study on appropriate technical measures (sowing time, sowing density, fertilisers) for soybeans on wet soil after Summer rice in Hanoi. 2.3. Methods of the study 2.3.1. Experimental design
8. 6 Experiment 1: Evaluation of growth, development, yield of 30 soybean lines, varieties in artificial waterlogging conditions in covered net house * Artificial waterlogging area: Soybeans lines and varieties grown in pots with a diameter of 30 cm, height of 45 cm, with drainage holes. The pots placed in the waterlogged plot with 60 cm height of the shore. Each line/variety was grown in 9 pots containing 6.5 kg of soil. 15 seeds were sown in each pot and were covered by soil. After having 2 true leaves, the soybean plants were trimmed to 5 plants/pot; when having 3 true leaves trimmed to 4 plants/pot. Time of artificial waterlogging: 3 days after sowing, water level was maintained at 3 cm above soil surface in 6 hours. Further waterlogging: At the seedling stage (V2); beginning bloom (R1); fully developed pod (R4), water level was maintained for 7 days (For J.W. and T. Yamakawa, 2006). * Non-waterlogging area (control): Each soybean line, variety was planted in pot with the same size, amount of soil, distance as in artificial waterlogging area, but did not cause waterlogging; soil moisture was kept regularly at 70 - 75% humidity. * Amount of fertilizer and applying: Amount of fertilizer for 1 pot: 0.21 g N; 0.42 g P2O5; 0.42 g K2O and 5.65 g of microbial-organic fertilizer Song Gianh (equivalent to the amount of fertilizer for 1 ha: 30 kg N + 60 kg P2O5 + 60 kg K2O + 800 kg of microbial-organic fertilizer Song Gianh). Applying: Basal application of all phosphate fertilizers, microbial-organic fertilizer Song Gianh before sowing. Dressing application, fertilizing 2 times combined weeding; the first time apply 1/2 of nitrogen and potassium fertilizer when the plant has 2 - 3 true leaves; the second time apply 1/2 of nitrogen and potassium fertilizer when the plant has 4 - 5 true leaves. Implementation time: In Winter 2016 (sowing on 25th September and Winter 2017 (sowing on 26th September). Experiment 2: Evaluation of the growth, development and productivity of 06 soybean lines and varieties in the Winter season in My Duc and Phuc Tho districts, Hanoi in artificial waterlogging field - The experiment was carried out for 06 soybean lines, varieties that have been screened from the net house experiment (experiment 1) and control variety DT84. - The study was conducted on alluvial soil of My Duc and Phuc Tho districts. The soil was sampled at the beginning of the experiment and processed, analyzed at the laboratory of the Division of Soil Genesis and Classification - Soils and Fertilizers Research Institute * Artificial waterlogging area: The experiments were arranged in a completely randomized block (CRB) with 3 replications; area of each plot was 8.5 m2 (5 m x 1.7 m). Total experiment area was 178.5 m2 (8,5 m2/plot x 7 plots x 3 repl). Time of artificial waterlogging: 3 days after sowing, water level was maintained at 3 cm above field surface in 6 hours. Further waterlogging: At the seedling stage (V2); beginning bloom (R1); fully developed pod (R4), water level was
9. 7 maintained for 7 days (For J.W. and T. Yamakawa, 2006). * Non-waterlogging area (control): The experiments were arranged in a completely randomized block (CRB) with 3 replications; area of each plot was 8.5 m2 (5 m x 1.7 m). Total experiment area was 178.5 m2 (8,5 m2/plot x 7 plots x 3 repl). Soil moisture was kept regularly at 70 - 75% humidity. * Amount of fertilizer for 1 ha: 30 kg N + 60 kg P2O5 + 60 kg K2O + 800 kg of microbial-organic fertilizer Song Gianh. Basal application of all phosphate fertilizers, microbial-organic fertilizer Song Gianh before sowing. Dressing application, fertilizing 2 times combined weeding; the first time apply 1/2 of nitrogen and potassium fertilizer when the plant has 2 - 3 true leaves; the second time apply 1/2 of nitrogen and potassium fertilizer when the plant has 4 - 5 true leaves. Implementation time: In Winter 2018. Experiment 3: Determination of appropriate sowing time for the selected waterlogging tolerant soybean variety on wet soil after Summer rice The experiments were arranged in a completely randomized block (CRB) with 3 replications; area of each plot was 8.5 m2 (5 m x 1.7 m). Total experiment area was 178.5 m2 (8,5 m2/plot x 7 plots x 3 repl). ĐT32 soybean variety was sown in 5 different time formulas (CT): TV1 on 15th September 15; TV2 on 22th September; TV3 on 29th September; TV4 on 6th October TV5 on 13th October. Amount of fertilizer for 1 ha: 30 kg N + 60 kg P2O5 + 60 kg K2O + 800 kg of microbial-organic fertilizer Song Gianh. Basal application of all phosphate fertilizers, microbial-organic fertilizer Song Gianh before sowing. Dressing application, fertilizing 2 times combined weeding; the first time apply 1/2 of nitrogen and potassium fertilizer when the plant has 2 - 3 true leaves; the second time apply 1/2 of nitrogen and potassium fertilizer when the plant has 4 - 5 true leaves. Implementation time: In Winter 2018 and Winter 2019. Experiment 4: Determination of the planting density and fertilizer dose suitable for the selected waterlogging tolerant soybean variety on wet soil after Summer rice The 2 factorial experiment was arranged in a Split - plot with 3 replications; in which the planting density was assigned as subplot and fertilizer dose as mainplot. Area of subplot was 8.5 m2 (5 m x 1.7 m); area of mainplot was 34 m2 (8.5 m2 x 4). Total experiment area was 306 m2 (8.5 m2/plot x 4 x 3 x 3 repl.). + Experimental formula: Planting density formulas: M1: 35 plants/m2, M2: 40 plants/m2, M3: 45 plants/m2 and M4: 50 plants/m2. Fertilizer formulas: P1: 20 kg N : 40 kg K2O : 40 kg P2O5; P2: 30 kg N : 60 kg K2O : 60 kg P2O5; P3: 40 kg N : th 80 kg K2O : 80 kg P2O5. Sowing times: in Winter 2018, sown on 25 September; in Winter 2019, sown on 26th September. Implementation time: Winter 2018 and Winter 2019.
10. 8 Experiment 5: Study on the growth, development and yield of the selected waterlogging soybean variety under the influence of seed treatment with G3 preparations and foliar nano fertilizers in Winter crop on wet soil after Summer rice Experiment composed of 4 formulas (CT), all of them fertilizing 30 kg N : 60 kg K2O : 60 kg P2O5. The difference between the formulas was that the seeds were treated or not treated with G3 preparation before sowing and the number of times of foliar application. (1) CT1: PBL0 (control): No seed treating, no foliar fertilizer; (2) CT2: PBL1: Seed treatment, foliar fertilization once when the plant has 3 - 4 true leaves; (3) CT3: PBL2: Seed treatment, foliar fertilization twice: the first time when the tree has 8 - 9 true leaves, the second time when the tree has baby pod; (4) CT4: PBL3: Seed treatment, foliar fertilization 3 times: the first time when the tree has 3 - 4 true leaves, the second time when the tree has 8 - 9 true leaves, the third time when the tree has baby pod. Growing time: Sown on 25th September. Implementation time: Winter 2018. Experiment 6: Study on the growth, development and yield of the selected waterlogging soybean variety under the influence of seed treatment with G3 preparations and foliar nano fertilizers combined with decreasing dose of macroelement fertilizer in Winter crop on wet soil after Summer rice Experiment consisted of 4 formulas (CT), of which CT1 was a control (ĐL0) - non-treating seeds, with the fertilizer dose of: 30 kg N : 60 kg K2O : 60 kg P2O5. The other 3 formulas were with G3 seed treatment and foliar fertilization twice: the first time when the plant had 8 - 9 true leaves, the second time at the baby pod stage. The difference between the formulations is the different amount of macronutrient reduction: ĐL1: decrease by 10%; ĐL2: decrease by 30% and ĐL3: decrease by 50%. Sowing density and time: Sown on 26th September; planting density: 40 plants/m2. Implementation time: Winter 2019. 2.3.2. Monitoring and evaluating indicators Monitoring and evaluating indicators were followed by the National technical regulation on testing for value of cultivation and use of soybean varieties QCVN 01-58: 2011/BNNPTNT. 2.3.2.1. Development indicators The time from sowing to emerging (days) was determined when 50% of the plants in the plot having cotyledons pulled through the soil surface. Emerging rate (%): Number of emerging plants/number of sown seeds x 100. The time from sowing to flowering (days) was determined when about 50% of plants having at least one flower on node. Growth duration (days): The time from sowing to ripening (when 90% of the pods have reached their full mature color).
11. 9 - Leaf area index (LAI): (m2 leaf area/ground cover-m2). LAI = Number of plants/m2 x leaf area of 1 plant/ 1 m2 ground cover. - Plant height (cm): Measured from the bottom of the shoot to the top of the main stem; taken from 5 sites of the plot, 2 representative plants for each site. - Pod insertion height (cm): Measured from the bottom of the shoot to the first pod insertion node. - Number of primary branches/plant: Counting the number of branches of 10 plants when harvesting. - Number of nodules: Counting the total number of nodules and the number of effective nodules of 10 plants in different stages. For experiment 1 and 2: the period of full bloom and the beginning seed; For experiments 3, 4, 5 and 6: begenning bloom and beginning seed. Ratio of effective nodules/plant (%) = (Number of effective nodules/Total number of nodules per plant) x 100. 2.3.2.2. Pest and disease susceptibility - Severity of pest infection: 10 random plants on the diagonal of the investigation area were investigated. + Leaf Folder (Lamprosema indicata): Ratio of damaged leaves = Number of folded leaves x 100 (%) / Total number of investigated leaves. + Pod borer (Eitiella zinekenella): Ratio of damaged pods (%) = Number of damaged pods x 100 (%) / Total number of investigated pods + Stem minor (Melanesgromyza sojae): Ratio of damaged plants (%) = Number of damaged plants x 100 (%) / Total number of investigated plants + Collar rot (caused by Rhizoctonia solani Kunh): Investigating all plants in a plot after 7 days of emergence. Ratio of infected plants (%) = Number of infected plants x 100 (%) / Total number of infected plants. - Powdery mildew (caused by Microsphaera diffusa): Assessing by a scoring scale from 1 - 5 as follows: 1: non-infected ( 76% highly susceptibility). - Lodging resistance: Counting the number of lodged plants before harvesting and assessing by a scoring scale from 1 - 5 as follows 1: None (most plants are upright). 2: Slight (less than 25% of plants lodging). 3: Moderate (25% - 50% of plants lodging, other leaning ≥ 45%). 4: Severe (51 - 75% of plants lodging). 5: Very severe (> 75% of plants lodging). - Flooding tolerance index (FTI) was determined according to each monitoring trait and was calculated as follows: FTI = Value of individual trait under waterlogging condition/value of the same individual trait under control conditions. Calculating FTI indicators: Number of effective nodules; height of
12. 10 the plants; number of primary branches/plant; number of filled pods/plant; weight of 1,000 seeds, individual yield and real yield. 2.3.2.3. Yield components and real yield Before harvesting, 10 plants from each experimental plot were used for following yield data: Number of filled pods/plant and ratio of filled pods/plant: Counting the total number of pods and the number of filled pods of 10 plants and calculating the average. The ratio of filled pods/plant (%) = (Number of filled pods/ Total number of pods/plant) x 100. The ratio of pods with 1 seed, 2 seeds, 3 seeds to the number of firm pods/plant. Weight of 1,000 seeds (g): Collecting dry seeds after harvesting and adjusting to 12% moisture; weighing 3 samples, 1,000 seeds each. Individual yield (g/plant): Weighing total grains of 10 plants and calculating the average. Theoretical yield (tons/ha) = Individual yield (g/plant) x 10-6 x density (plant/m2) x 10,000 m2. Real yield (tons/ha) = (yield of a plot (kg)/8.5 m2 x 10-3) x 10,000 m2. 2.3.3. Method of calculating economic efficiency Economic efficiency of experiments on density and fertilizer; foliar nano fertilizers are calculated according to the financial accounting method of CIMMYT (1988). - Gross Return (GR) = Yield x selling price. - Total Variable Cost (TVC) = Cost of materials (seeds, fertilizers, pesticides, preparations) + labor + interest on investment capital. - Net profit [(Return Above Variable Cost (RVAC)] = GR – TVC. - Value Cost Ratio (VCR) = RVAC/TVC. 2.3.4. Data analysis and processing Data were collected by Excel 2013, processed by Statistix 8.2 program, analyzed by ANOVA (Nguyen Huy Hoang et al., 2014). Identifying waterlogging tolerant varieties through experimental results to evaluate growth, development and yield of 30 soybean lines and varieties in greenhouse by Selection Index according to Nguyen Dinh Hien (1995). 2.4. Time and place of the study - Experiments to assess the growth, development and yield of 30 soybean lines and varieties in artificial waterlogging conditions in covered net house were carried out in 2 crop seasons (Winter 2016 and Winter 2017) at the Legume Research Center - Field Crops Research Institute. - The experiment to assess the growth, development and productivity of 6 soybean varieties in artificial waterlogging conditions in the field was carried out in the Winter 2018 in My Thanh commune, My Duc district and Tam Thuan commune, Phuc Tho district - Hanoi city. - The experiment to determine the sowing time, density and fertilizer dose
13. 11 suitable for waterlogging tolerant soybean variety on wet soil after Summer rice was carried out in the Winter 2018 and Winter 2019 in My Thanh commune, My Duc district and Tam Thuan commune, Phuc Tho district - Hanoi city. - The experiment to study the growth, development and yield of waterlogging tolerant soybean variety under the influence of seed treatment with G3 preparations and foliar nano fertilizers on wet soil after Summer rice were carried out in the Winter 2018 in My Thanh commune, My Duc district and Tam Thuan commune, Phuc Tho district - Hanoi city. - The experimental to study on the growth, development and yield of waterlogging tolerant soybean variety under the influence of seed treatment with G3 preparations and nano-foliar fertilizers combined with reducing the level of macronutrients on wet soil after Summer rice was carried out in the winter crop of 2019 in My Thanh commune, My Duc district and Tam Thuan commune, Phuc Tho district - Hanoi. Chapter 3. RESULTS AND DISCUSSION 3.1. Study on the waterlogging tolerance of soybean lines and varieties in the net house in Winter 2016 and Winter 2017 in Hanoi 3.1.1. Effects of artificial waterlogging conditions on the growth duration and emerging rate of soybean lines and varieties in the Winter 2016 and 2017 - Time from sowing - emerging: The majority of lines, varieties have growth duration of 6 days (17 lines, varieties). This period is 0.5 - 1 day longer than the soybean varieties under control conditions. 4 lines, varieties have growth duration of 5.5 days and 9 lines have growth duration of 6.5 - 7 days. - Emerging rate: The emerging rate of soybean lines and varieties was not high, varied from 31.11 - 77.04%. The emerging rate of soybean lines and varieties under waterlogging conditions was significantly reduced compared to the same line and varieties in non-waterlogging (control) conditions. Out of 30 studied lines and varieties, only 7 lines and varieties had emerging rate over 65% (accounting for 23.3%), namely: ĐT22, NAS-S1, ĐT35, GMS18, PT01, ĐT26 and ĐT32. - Growth duration: The growth duration of the lines and varieties ranges from 74 - 96.5 days under control condition and 76 - 100 days under waterlogging condition. Varieties with short duration are ĐT12, DT2010 and ĐT32 with growth duration in waterlogging conditions: 76, 85, 86 days and in non- waterlogging condition: 74, 83 and 84 days, respectively. 3.1.2. Effects of artificial waterlogging condition on nodule formation of soybean lines and varieties in Winter 2016 and 2017 * Full bloom (R2): This period the number of effective nodules of lines and soybean varieties in waterlogging condition changed from 11.58 - 23.88 nodules/plant; in particular, the lowest was the line GMS12, the highest was the