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MINISTRY OF EDUCATION AND TRAINING MINISTRY OF AGRICUTURE AND RURAL DEVELOPMENT VIETNAM ACADEMY OF AGRICULTURAL SCIENCES DO THI THAO RESEARCH ON SOME TECHNICAL MEASURE TO IMPROVE THE EFFICIENCY OF RICE PRODUCTIN ON ON SALINE SOIL IN COASTAL OF THANH HOA PROVINCE Field of study Code : Crop Science : 9.62.01.10 SUMMARY OF AGRICULTURAL DOCTORAL THESIS HANOI – 2022 The study is published at: VIETNAM ACADEMY OF AGRICULTURAL SCIENCES Scientific supervisors: Assoc Prof Dr Nguyen Huy Hoang Assoc Prof Dr Le Hung Linh Judge : Judge 2: Judge 3: The thesis will be defended at the meeting of the reviewing committee at: Vietnam Academy of Agricultural Sciences Meeting at………………………………………… At… , date…… month……… year 20… The thesis can be found at: National Library of Vietnam Library of Vietnam Academy of Agricultural Sciences INTRODUCTION Urgency of the research topic Saltwater intrusion is one of the main unfavorable conditions hindering agricultural cultivation in the North Central provinces Rice production (Oryza sativa) is heavily affected by saline intrusion, the area of many large farming areas is increasingly shrinking, thereby significantly affecting the output and productivity of the rice growing industry in Vietnam affected provinces In which, Thanh Hoa, with the largest rice growing area in the North (about 145,803 ha), is one of the localities suffering the heaviest losses of saline intrusion Thanh Hoa is a province that is facing many impacts of climate change It is considered as one of the localities most heavily affected by climate change and sea level rise after only the Mekong River Delta and the Red River Delta Currently, Thanh Hoa has about 22,000 hectares of saline soil and is at high risk of increasing in the coming time, arable land is interspersed and scattered along 102km of coastline, this is one of the unfavorable conditions for farming agricultural activities, especially for rice cultivation on saline soils (Thanh Hoa Newspaper 2015) Facing that situation, the local government has proposed many policies and solutions to direct to overcome the fallow situation in the sedge area communes and the model of converting to rice cultivation However, the rice variety structure of the regions is still mainly concentrated on pure varieties such as: BC15, Khang Dan 18, Q5, BT7; hybrid rice varieties Nhi Uu 69, VT404, are susceptible to saline soil conditions, and the economic efficiency is not high compared to sedge cultivation In order to improve efficiency, and at the same time find solutions to cope with climate change in rice production in coastal districts of Thanh Hoa province, the solution is to choose suitable, stable, productive and high-quality rice varieties for the affected land Salinity is essential Stemming from that practical requirement, we conducted the project: "Research on some technical measures to improve the efficiency of rice production on saline soil in coastal of Thanh Hoa province" Objectives and requirements of the project Through the assessment of basic conditions related to rice production of coastal districts of Thanh Hoa province to study and select salt-tolerant rice varieties and identify some suitable cultivation techniques for selected rice varieties on saline soil in coastal areas of Thanh Hoa province Scientific significance of the topic 3.1.Scientific significance: Supplementing the database on the current status of rice production in the coastal area of Thanh Hoa province, serving as a basis for selecting salt-tolerant rice varieties and determining a number of farming techniques (sowing season, transplanting density, amount of fertilizer) in both spring and summer crops and the database on the adaptability of the variety to the environment (genotype and environment interaction) is the basis for the sustainable development of selected rice varieties in the region research It is a valuable reference for research and training in plant science 3.2 Practical significan: Selection of salt tolerant rice variety SHPT15 for higher yield and economic efficiency than the mass rice varieties in coastal districts of Thanh Hoa As the basis for the management and direction of production in coastal districts, contributing to the development of agricultural economy in the direction of efficiency, sustainability and environmental friendliness Scope and limitations of the topic - The study used 20 rice lines/varieties selected to create QTL Saltol in homozygous state, which were selected from the hybrid Bac Thom No and FL478 imported from IRRI The control is Bac Thong variety No for research and selection of varieties and selected varieties for research and development of cultivation techniques - Location: Nga Thai commune of Nga Son district; Hoang Truong commune of Hoang Hoa district; Quang Nham commune, Quang Xuong district The experiments in the thesis were carried out at most consecutive crops (2 spring crops and crops); evaluate and build models in the districts to deploy in the spring crop of 2020 New contributions of the thesis Identification of salt-tolerant rice variety SHPT15 that is adaptable and stable in saline soil conditions, giving high yield in both Spring crop (reaching 55.0 quintals/ha - 57.0 quintal/ha) and Spring crop (reaching 55.0 quintals/ha) reaching 53.0 - 55.0 quintals/ha) on saline soils in coastal districts of Thanh Hoa province; Identify some suitable technical measures to develop the cultivation process for rice variety SHPT15 in saline soils in coastal districts of Thanh Hoa province: Suitable planting time in winter-spring crop sowing on January , transplanted January 27; summer-autumn crop sowing seeds on June 8, transplanting on June 23; The appropriate amount of fertilizer in the winter-spring crop: 10 tons of manure 100 kg N + 90 kg P2O5 + 80 kg K2O /ha+ 450 kg lime powder/ha, the amount of inorganic fertilizer in the summer-autumn crop is reduced by 10% compared to the winter-spring crop ; Planting density 35-40 clusters/m2, transplanting 02- 03 stalks/cluster Layout: The thesis consists of 1116 pages (excluding appendices): Introduction (4 pages), Chapter 1: Overview of documents and scientific basis of the topic (25 pages); (Chapter 2: Research materials, content and methods (14 pages), Chapter 3: Research results and discussion 71 pages), Conclusion and recommendations (3 pages), References (105) , using 49 Vietnamese documents, 53 English documents, 03 internet documents The thesis has 68 tables, pictures and 11 appendices, 02 published works CHAPTER OVERVIEW OF THE DOCUMENTATION AND SCIENTIFIC BASIS OF THE TOPIC 1.1 Theoretical basis of the research problem 1.1.1 Climate change, saline intrusion in the world and Vietnam In the world Climate change is currently having a serious impact on agricultural production, life and the environment not only of a country or a region but also of the whole world Rising temperatures, rising sea levels cause flooding and salinization of water sources, affecting agriculture, posing great risks to industrial production and future socio-economic systems Survey data show that over the past 100 years (1906-2005) global temperature has increased by 0.740C, sea level has increased at an average rate of 1.8mm/year in the period from 1961-2003 and increased faster at a rate of 1.8mm/year rate of 3.1mm/year in the period from 1993-2003 Saltwater intrusion reduces the world's irrigated area by 1-2% per year, there are about 43 countries (mainly from arid and semi-arid regions), which are using salt water to different degrees for irrigation through irrigation systems Saline intrusion is considered to be the second largest cause of lost productive land and can threaten up to 10% of global cereal production This is a big challenge for rice production In Vietnam Vietnam has a coastline of more than 3,260 km with 28/64 coastal provinces and cities, and is one of the most vulnerable countries to climate change Due to the long and low coastline, vulnerable to tropical storms, high and variable rainfall, Vietnam's coastal areas will be most affected by climate change Droughts, storms, floods, coastal erosion and saltwater intrusion will occur more frequently The coastal strip of the Red River Delta - Thai Binh River and the Mekong River Delta are two key economic regions of Vietnam, with high and concentrated population density, flat and low terrain In recent years in the Mekong Delta, salt water has penetrated earlier and longer, encroaching further into the inland along the system of rivers and canals with complicated changes 1.1.2 Saline soils and saline areas 1.1.3 Formation, classification and characterization of saline soils 1.1.4 Effect of salinity on growth and development of rice 1.1.5 Effects of salinity on the growth and development stages of rice 1.1.6 Effect of salinity on morphological characteristics of rice 1.1.7 Effect of salinity on physiological and biochemical properties of rice 1.1.8 Adaptation of rice plants to saline conditions 1.1.9 Salt tolerance threshold of rice 1.1.10 Selective adsorption between ions 1.1.11 Planting season and scientific basis of rice growing season 1.1.12 The role and scientific basis of nutrition for rice 1.1.2.1 Nutritional requirements of rice plants 1.1.2.2 Phosphorus nutrient requirements for rice plants 1.1.12.3 Potassium nutritional requirements of rice plants 1.1.13 Water demand for rice 1.2 The practical basis of the research problem 1.2.1 Situation of saline intrusion in coastal districts of Thanh Hoa province Thanh Hoa is a coastal province, located in the key economic region of the North Central region In the past ten years, Thanh Hoa has had an average temperature increase of 1.62oC, a sea level increase of 15cm, from 2008 to now, the rainfall has tended to decrease sharply and the drought has increased from an alarming level (Department of the Department of Agriculture and Rural Development) Agriculture and Rural Development, 2018) Therefore, the area and extent of salinization are also increasing The area of rice land affected by salinity in Thanh Hoa is mainly concentrated in the coastal districts Therefore, in order to have a database for building a model of adaptation to salinity, we investigated the salinity-affected rice area in coastal districts and the data is shown in 1.7 The data in the above table shows that the number of salt-affected areas of Hau Loc district for the whole year is 4,827, accounting for 33.1% Nga Son district 1,419 accounting for 9.1% of the whole year, followed by Hoang Hoa 2,258 ha, accounting for 29.1%, Tinh Gia 1,369 accounting for 6.7%, the lowest is Quang Xuong 143 accounting for 1.8% 1.2.2 Effects of saline intrusion on rice production in coastal districts of Thanh Hoa province The data show that the average rice yield tends to increase, but on saline soils, rice yield has decreased over the years, from 2.9 tons/ha (2014) to 2.8 tons/ha (2015); 2.5 tons/ha (2016); 2.6 tons/ha (2017) and 2.7 tons/ha (2018) Thus, rice yield reduced due to salinity fluctuates from 1.1-2.2 tons/ha, corresponding to 27.046.2% In which, rice yield was most severely affected in 2017 and 2018, in areas with high salinity, rice yield was sharply reduced from 2.0 to 2.2 tons/ha 1.2.3 The situation of using salt-tolerant rice varieties in Vietnam and the coastal saline area of Thanh Hoa province In recent years, in the North Central provinces, especially Thanh Hoa province, there have been a number of research programs on climate change adaptation solutions in rice production However, the results of research on selection of rice varieties for saline soils are limited and also a new research problem, so there are no suitable salt-tolerant rice varieties for saline soils in coastal districts of Thanh Hoa The varieties commonly used today in the coastal districts of Thanh Hoa province are BT7(Đ/C); Thien uu 8, F1, Bio 404, HT1, NX30, BC15, have low salt tolerance and long growth time Therefore, in breeding work, we will aim to use key varieties with high yield, good tolerance, good rice quality and especially varieties with short and mid-day growth period, avoiding good conditions agreement (Thanh Hoa Department of Agriculture and Rural Development 2018) 1.2.4 Season of growing salt-tolerant rice in Vietnam and coastal districts of Thanh Hoa province 1.2.5 The situation of fertilizer use for rice in Vietnam and coastal districts of Thanh Hoa province 1.3 Comments drawn from the literature review Rice is a short-term food crop with an important and irreplaceable position in agricultural production of Vietnam in general and Thanh Hoa province in particular A review of domestic and foreign documents has shown the results and research works on: Climate change, saline intrusion in the world and in Vietnam; Effect of saline intrusion on agro-biological characteristics and quality parameters of rice; Studies on selection and development of technical measures such as season, density and fertilizer suitable for saline conditions in coastal districts In addition, the review of the thesis has synthesized and evaluated the research results on the selection and selection of salt-tolerant rice varieties and the influence of technical measures on the growth and development of rice plants rice adapting to saline soils in coastal districts to improve rice production efficiency Research results on the situation of salt-tolerant rice production in the world and Vietnam show that research achievements on salt-tolerant rice have made great strides Scientists have focused on research, breeding and selection of many promising new rice varieties with high yield and good quality, resistant to pests and diseases, and adapted to saline conditions in other saline soils together However, at present, there is no set of salt-tolerant rice varieties used on saline soils in coastal areas of Thanh Hoa province Therefore, the selection and application of technical measures to produce salt-tolerant rice varieties that contribute to improving the efficiency of rice production on saline soils in coastal districts of Thanh Hoa province is very necessary The overview of the research thesis has gathered a lot of scientific and practical data showing the role of farming techniques in the growth, development, yield and quality of rice plants In which many studies have also demonstrated the influence of seasonality; Fertilizer dosage and sowing density are very important technical measures in improving rice production efficiency However, the requirements on the season, the amount of fertilizer and the density of transplanting are not the same in rice varieties, regions and ecological sub-regions Therefore, it is necessary to have studies to determine the planting season, fertilizer dosage, and reasonable transplanting density for each variety and each specific region In order to cope with climate change in general and to cope with saltwater intrusion in particular in Thanh Hoa province, the selection of suitable rice varieties and the development of appropriate farming techniques on the contaminated land is essential salt is extremely urgent and necessary; contribute to increase the efficiency of rice production on the saline soil of Thanh Hoa province, increase income for farmers and ensure food security for the province, and at the same time contribute to the development of a sustainable agro-ecology Starting from the above purpose, the study focuses on solving the following problems: - Evaluation of basic conditions in relation to rice production on saline soil in coastal areas of Thanh Hoa province in order to identify limiting factors along with solutions to improve rice production efficiency; - Researching and selecting salt-tolerant, high-yielding and stable rice varieties in saline soil conditions in both Winter-Spring and Summer -Autumn crops in some coastal districts of Thanh Hoa province; - Research to identify a number of suitable farming techniques for selected rice varieties, contributing to building rice production process on saline soils in coastal districts of Thanh Hoa province; - Develop a model of synchronous application of cultivation techniques for selected rice varieties; recommended expansion of production CHAPTER RESEARCH MATERIALS, CONTENTS AND METHODS 2.1 Materials and contents of research 2.1.1 Rice varieties - Research materials include 20 promising salt-tolerant rice lines/varieties carrying QTL Saltol in homozygous state, which were selected from the hybrid Bac Thom No and FL478 imported from IRRI Bac Thom rice variety No as a control 2.1.2 Fertilizers and supplies The study used fertilizers such as: - Manure produced by the people by traditional methods (C=32%, Ntotal=0.98%; Total P2O5 = 0.31%; Total K2O=0.47%) - Inorganic fertilizers: + Protein: Urea has a content of 46%, Lan Van Dien has a P2O5 content of 15%, Potassium chloride has a K2O content of 60% - Pesticides: used according to the locality where the experiment is conducted 2.2 Location and time of research 2.2.1 Location of research The experiments were arranged on saline-affected rice fields of coastal districts: Nga Son, Hoang Hoa and Quang Xuong The chemical composition of the experimental soil is presented in Appendix 2.2.2 Time of research From 2017 - 2020 2.3 Research contents 2.3.1 Assessment of basic conditions related to rice production in saline soils of coastal districts of Thanh Hoa province; 2.3.2 Research and select suitable rice varieties for saline soils in coastal districts of Thanh Hoa province; 2.3.3 Research to identify some suitable technical measures for selected salttolerant rice varieties; 2.3.4 Building a model for synchronous application of technical measures for selected rice varieties on saline soils in coastal districts of Thanh Hoa province 2.4 Research methods 2.4.1 Evaluation of the current status of rice production on saline soils in the coastal area of Thanh Hoa province 2.4.1.1 Secondary data collection method Collect all sources of documents, statistics, maps, technical procedures, scientific reports, production reports related to the current status of rice production on saline soils in the districts The coastal area of Thanh Hoa province needs to be investigated Implementation time 2017 2.4.1.2 Primary data collection method 2.4.2 Research on selection of salt-tolerant rice varieties for saline soils in coastal areas of Thanh Hoa province Experiment 1: Study on selection of salt-tolerant rice lines/varieties on saline soils in coastal areas of Thanh Hoa province - Experimental formula included 20 lines/varieties of rice; in which the control variety Bac Thong No 7, is the variety that is commonly grown locally - The experiment consisted of 20 formulas, designed according to Randomized Complete Block (RCB), repetitions (Courtesy of Nguyen Huy Hoang et al., 2014) Experimental Diagram: Rep Rep Rep G14 G20 G3 G1 G8 G9 G2 G10 G16 G1 G11 G18 G12 G19 G15 G8 G17 G7 G5 G14 G6 G2 G20 G17 G15 G13 G3 G1 G15 G13 G10 G20 G12 G8 G16 G4 G11 G2 G9 G11 G16 G7 G5 G9 G5 G13 G4 G6 G4 G10 G19 G12 G18 G6 G17 G18 G14 G7 G19 G3 - The experimental plot area is 10.0 m2 (2.5 m x 4.0 m) Total experimental area 20 treatments (lines/varieties) x 10.0 m2 / CT x replicates = 600 m2 (excluding protection area) - Experimental location: in Nga Thai commune, Nga Son district, Hoang Truong commune, Hoang Hoa district and Quang Nham commune, Quang Xuong district - Implementation period: Winter-spring crop 2017 and summer-autumn crop 2017 - Cultivation techniques: + In the winter-spring crop, sow seeds on January 7th, transplant when the age of seedling reaches 3.5-4.0 leaves; + Summer-autumn crop sown on June 8, transplanted when seedling age reaches 3.5 -4.0 leaves + Planting density: to branches/clump, density 35 clusters/m2; + The amount of fertilizer used for hectare is 8.0 tons of manure + 450 kg of lime powder + 100 kg of N + 90 kg of P2O5 + 90 kg of K2O in the winter-spring crop; In the summer-autumn crop, the fertilizer formula only changed the amount of nitrogen fertilizer to 90 kg N/ha; - Research targets and monitoring methods: + Time of growth; Some agro-biological characteristics of rice lines/varieties such as: plant height, maximum number of branches, cotton/clump, effective number of branches; indicators for monitoring the situation of pests and diseases; components of yield and actual yield The monitoring criteria, methods of assessment and data collection are applied according to the National Regulation on testing the value of cultivation and use of rice varieties QCVN 01-55: 2011/BNNPTNT) of the Ministry of Agriculture and Rural Development and Rural Development Experiment 2: Evaluation of salt tolerance in artificial conditions of some elite rice lines 2.4.3 Research to identify some suitable technical measures for selected rice varieties Experiment 3: Study on the effect of planting season on selected rice varieties (SHPT15) on saline soil in coastal areas of Thanh Hoa province + One-factor experiment, including seasonal formulas: SS1, SS2 and SS3 One-factor experiment was designed in a randomized complete block design, replicates including cells, and designed in a randomized complete block design Experimental design diagram: Rep SS1 SS3 SS2 Rep SS3 SS2 SS1 Rep SS2 SS1 SS3 Experimental plot area 30 m2/1 plot; Total experimental area: 30 m2 x formula x replicates = 270 m2, excluding guard band area - Experimental location: in Nga Thai commune, Nga Son district, Hoang Truong commune, Hoang Hoa district and Quang Nham commune, Quang Xuong district - Time of implementation: Winter-spring crop 2019 and summer-autumn crop 2019 - Cultivation techniques: Planting density: 35 clusters/m2, transplanting 1-2 stalks Amount of fertilizer/ha: Winter-spring crop: 100 kgN + 90kg P2 O5 + 80 kg K2O + 10 tons of manure + 450 kg of lime powder Summer-autumn crop: 90 kgN + 80 P2 O5 + 70 kg K2O + 10 tons of manure + 450 kg of lime powder - Research targets and monitoring methods include: Growth time; Some agro-biological characteristics of rice lines/varieties such as: plant height, maximum number of branches, cotton/clump, effective number of branches; indicators for monitoring the situation of pests and diseases; components of yield and actual yield The monitoring criteria, methods of assessment and data collection are applied according to the National Regulation on testing the cultivation and use value of rice varieties (QCVN 01-55: 2011/BNNPTNT) of the Ministry of Agriculture and Rural Development Agriculture and Rural Development Experiment 4: Studying the effect of transplanting density and amount of fertilizer on growth, development and yield of selected rice varieties (SHPT15) The experiment consisted of factors: factor 1: density (M), including levels: M1, M2, M3; factor 2: fertilizer (P), including levels: P1, P2, P3 The experiment was designed in the style of large and small plots; repetitions; a total of 27 small cells Small plot area 10 m2 The area of the whole experiment excluding the protection area: 10 m2 x x x = 270 m2 There is a boundary between the cells 2.4.4 Developing a farming model with synchronous application of appropriate technical measures for selected rice varieties (SHPT15) on saline soils in coastal districts of Thanh Hoa province Using the model building method to evaluate the effectiveness of technical measures determined from the experimental results of the topic - Implementation location: The model is deployed on the land of winterspring rice crops in the communes: + Quang Nham commune, Quang Xuong district + Hoang Truong commune, Hoang Hoa district + Nga Thai commune, Nga Son district 11 seed with and over 40% of households plant thickly at a density of 50 clusters/m2 in both Spring and Summer crops, making investment costs more expensive high, but the yield is low and infected with many pests and diseases 3.1.2.3 Fertilizer use situation 3.1.2.4 Use of pesticides by farmers 3.1.2.4 Harvest and preserve 3.1.2.5 Rice yield on saline soils in coastal districts of Thanh Hoa province Summary: Rice production plays a strategic role in the long-term agricultural economic development of the coastal area of Thanh Hoa province This is still considered a key economic sector and accounts for a high proportion However, due to economic integration and agricultural restructuring to industrialization and modernization, the area of agricultural production land is gradually shrinking and climate change is complicated, causing sea level rise The encroachment has become more and more complicated, greatly affecting agricultural production today In addition, the infrastructure for production, production costs such as seeds, agricultural materials, pesticides, etc., are high, but product prices are low, which greatly affects agricultural production in the coastal area of Thanh Hoa province Regarding the structure of the breed set, it has not shown the advantages of the production area, the management and propaganda on the application of science and technology and the selection of the breed set structure of the state management agencies are not close to the local reality, leading to Farmers in coastal saline areas still use the same set of seeds from the whole province Currently, on the basis of the general rice variety structure of the province, each district selects and arranges the seed structure accordingly Spring crop has 4-5 hybrid rice varieties and pure rice varieties; In the Season crop, 2-3 hybrid rice varieties and pure rice varieties are planted at the rate recommended by each locality In particular, there is no recommendation on the structure of specific rice varieties for the coastal saline areas of Thanh Hoa province Most of the farmers still keep the old farming habits and have not yet accepted the new sets of suitable varieties along with the application of technical measures With advanced farming techniques and processes in production, the efficiency of rice production in the region is not high Therefore, the development of solutions to promote rice production is very necessary and plays an important role in the agricultural restructuring strategy of the coastal area of Thanh Hoa province In order to achieve this, it is necessary to regularly promote research, hybridization, and selection of rice varieties with high yield, quality, tolerance to adverse weather conditions, pests and diseases, and adaptation to conditions salinization, to put into production in saline soil in coastal areas of Thanh Hoa province Using pesticides and fertilizers effectively and economically in order to reduce production costs, limit pollution to the environment and groundwater Building an intensive farming model for selected rice varieties on saline soils from which to replicate the model to neighboring districts of Thanh Hoa province 12 3.2 Research results on selection of salt-tolerant rice lines/varieties suitable for saline soils in coastal areas of Thanh Hoa province 3.2.1 Agro-biological characteristics, yield and yield components of some promising salt-tolerant rice lines Experiments on selecting promising salt-tolerant lines/varieties were conducted in the winter-spring and summer-autumn crops of 2017 in Quang Xuong, Hoang Hoa and Nga Son districts Summary of the results of evaluation of agro-biological characteristics, pest resistance and yield components in the two winter-spring and summer-autumn crops of 2017 at all three experimental sites showed that the BC2F5 lines had Plant height and growing time were at the same level and less than that of the original variety BT7 The HL15 series has been identified with potential for production development The line has good agro-biological characteristics, low plants, shorter growth time than BT7, reaching 114 - 120 (day) and 115 - 117 days (winter-spring crop) and 102 - 103 days (summer-autumn crop) Table 3.15 Actual yield of experimental lines/varieties in winter-spring and summer-autumn crops in 2017 Actual yield of winter-spring Actual yield of winter-spring crop crop (quintal/ha) (quintal/ha) Name Quang Hoang Nga Average Quang Hoang Nga Average Xuong Hoa Son Xuong Hoa Son HL1 52,0 52,0 51,0 52,0 50.0 48,0 49,0 49,0 HL2 51,0 54,0 52,0 52,0 50,0 49,0 50,0 49,0 HL3 39,0 42,0 40,0 40,0 37,0 36,0 38,0 37,0 HL4 52,0 55,0 53,0 53,0 51,0 50,0 51,0 51,0 HL5 41,0 44,0 40,0 41,0 41,0 40,0 38,0 40,0 HL6 43,0 43,0 39,0 42,0 42,0 41,0 39,0 40,0 HL7 37,0 37,0 33,0 36,0 37,0 37,0 35,0 36,0 HL8 37,0 37,0 33,0 35,0 41,0 37,0 35,0 38,0 HL9 41,0 41,0 40,0 41,0 47,0 43,0 37,0 42,0 HL10 45,0 45,0 44,0 45,0 44,0 42,0 41,0 42,0 HL11 45,0 51,0 51,0 49,0 48,0 49,0 48,0 48,0 HL12 43,0 47,0 47,0 46,0 41,0 44,0 45,0 43,0 HL13 35,0 41,0 39,0 38,0 38,0 40,0 37,0 38,0 HL14 41,0 46,0 44,0 44,0 41,0 41,0 42,0 41,0 HL15 57,0 58,0 55,0 56,0 55,0 54,0 53,0 54,0 HL16 44,0 44,0 40,0 43,0 43,0 41,0 38,0 41,0 HL17 43,0 43,0 41,0 42,0 39,0 37,0 39,0 39,0 HL18 34,0 35,0 33,0 34,0 39,0 35,0 37,0 37,0 HL19 47,0 46,0 44,0 46,0 43,0 41,0 42,0 42,0 BT7 47,0 47,0 46,0 47,0 46,0 45,0 44,0 45,0 CV(%) 5,8 5,2 LSD0,05 2,7 1,2 2,2 2,5 13 The studied lines/varieties showed yield components at the same level as that of BT7 under the cultivation conditions of districts affected by saline intrusion in Thanh Hoa The HL15 line has the highest net yield, reaching about 55 - 58 quintals/ha (Spring crop) and 53 - 55 quintals/ha (Summer crop) Field monitoring showed that the rice lines had the same resistance/infection level as the BT7 background variety under production conditions using pesticides Three lines, HL1, HL13 and HL15 were mildly infected with leaf blight, while HL15 showed good resistance to pests and diseases 3.2.2 Evaluation of the stability of yield of experimental rice lines/varieties in saline soils in some coastal districts of Thanh Hoa province độ ổn định qua đường hồi quy theo số môi trường độ lệch so với đường hồi quy Research the stability of each trait of the line/variety fully to make reasonable recommendations for producers and production areas In order to select rice lines/varieties with high stability and wide adaptability on saline soil in coastal areas of Thanh Hoa province, in this study, in addition to evaluating growth and development characteristics, resistance to Tolerance to major pests and diseases and yield and yield components of the experimental rice lines/varieties, the study also focused on analyzing the stability of the lines/varieties in terms of yield through the stability model of Eberhart and Russell (1966), using the software ondinh.com of Nguyen Dinh Hien (1999) to analyze the data (quoted by Nguyen Huy Hoang et al., 2014) Evaluation of the stability of yield of 20 experimental rice lines/varieties in winter-spring and summer-autumn crops in 2017 at locations: Hoang Hoa, Nga Son and Quang Xuong using ondinh.com software of Nguyen Dinh Hien based on Nguyen Dinh Hien's software according to the model of Eberhard Russel (1966) to analyze the stability through the regression line according to the environmental index and the deviation from the regression line According to this model, a variety is considered stable when the regression coefficient bi = and the deviation from the regression line s2di is small (gradually approaching zero), that is, the ability of the variety to perform relatively stable average values of yield under different ecological conditions Breeding varieties with higher yields than the general average is the goal of breeders Therefore, for a variety to be considered stable as an ideal variety, it must have an index of deviation of the regression line S2di close to 0, the regression coefficient (bi) is close to When processing yield results equal to The stable software will give us a summary table for selecting stable varieties based on testing the values of bi and S2di According to this table, the values of bi and S2di with asterisks are significant differences from and from zero, respectively Based on the yield test results, it is possible to separate the yield data of each crop to assess the yield stability of the tested varieties, then it can be generalized for the winter-spring and summerautumn crops Results of evaluation of yield stability of tested lines/varieties in spring and summer-autumn crops in 2017 at sites: Nga Son; Hoang Hoa; Quang Xuong is presented in Table 3.16 14 Environmental index analysis data (I) at locations Quang Xuong, Hoang Hoa, Nga Son in the winter-spring and summer-autumn crops in 2017 and yield estimation by regression with environmental indexes of lines/ The experimental rice varieties presented in Table 3.16 show that: Hoang Hoa has index I of -0.841 and 1,990; Nga Son has an I equal to -1.298 and -0.260 and Quang Xuong has an I equal to 0.155 and 0.254 respectively Thus, in the conditions of saline soil in the coastal districts of Thanh Hoa province at experimental sites, Nga Son has more difficult conditions than the other sites Quang Xuong has the most favorable conditions for rice to grow in both winter-spring and summer-autumn crops In 2017, the conditions were favorable for winter-spring rice to grow and develop well in all three experimental districts compared to the summer-autumn crop In which, HL15 has the highest yield, estimated at 55,050 quintals/ha Table 3.17 presents the value of regression coefficient (bi) and deviation from the regression line S2di as summary parameters for selecting stable lines/varieties in Spring and Summer crops at experimental locations Table 3.17 Summary of parameters for selection of rice lines/varieties with stable yield for Winter-Spring and Summer-Autumn crops in 2017 at experimental sites Average Varieties HQ (bi) Ttn P S2di Ftn P Tons/ha HL1 50,072 1,203 0,504 0,679 0,136 1,148 0,668 HL2 50,506 1,205 0,475 0,670 0,885 1,966 0,904 HL3 38,561 1,335 0,497 0,677 2,034 3,220 0,988* HL4 51,739 1,238 0,454 0,664 0,863 1,942 0,901 HL5 40,328 1,561 2,860 0,977 -0,665 0,274 0,105 HL6 40,883 1,357 0,730 0,745 0,646 1,705 0,856 HL7 35,644 0,676 0,495 0,676 1,882 3,055 0,984* HL8 36,289 0,567 0,383 0,641 7,418 9,099 1,000* HL9 41,222 0,708 0,233 0,590 9,349 11,208 1,000* HL10 43,461 1,123 0,380 0,640 -0,235 0,744 0,435 HL11 48,744 0,472 0,567 0,698 4,724 6,158 1,000* HL12 44,511 0,248 0,771 0,756 5,274 6,758 1,000* HL13 38,189 0,554 0,520 0,684 3,872 5,228 1,000* HL14 42,422 0,981 0,030 0,512 1,746 2.907 0,980* HL15 55,050 1,347 0,820 0,769 0,248 1,271 0,722 HL16 41,344 1,654 1,468 0,892 0,376 1,410 0,773 HL17 40,167 1,452 0,564 0,697 3,271 4,571 0,999* HL18 35,294 0,210 1,189 0,850 5,822 7,357 1,000* HL19 43,522 1,427 0,547 0,692 3,0363, 4,315 0,998* BT7 (đ/c) 45,544 1,059 0,399 0,646 -0,772 0,157 0,043 Note The difference of and is significant with P≥ 95%, bi and S2di respectively Số liệu bảng 3.17 cho thấy: Trong số 20 dịng/giống lúa thí nghiệm có 12 dịng The data in Table 3.17 shows that: Among the 20 tested rice lines/varieties, 12 lines/varieties HL3, HL5, HL7, HL8, HL9, HL11, HL12, HL13, 15 HL14, HL17, HL18 and HL19 are unstable The asterisks in column P test for regression coefficients other than are significant and column P test for other S2di is not significant) across experimental sites: Nga Son, Hoang Hoa, Quang Xuong in winter-spring and summer crops collect The remaining lines were stable in both winter-spring and summer-autumn crops In which, the HL15 line gave the highest yield (average of 56,367 quintals/ha) Table 3.16 Evaluation results of artificial salt tolerance of promising rice lines Survival rate No Name Saltol SES Evaluation (%) HL1 + 85 3-5 Resistant HL2 + 95 Resistant HL4 + 91 3-5 Resistant HL5 + 97 3-5 Resistant HL6 + 86 3-5 Resistant HL10 + 90 3-5 Resistant HL11 + 89 3-5 Resistant HL12 + 85 3-5 Resistant HL15 + 97 Resistant HL17 + 88 3-5 Resistant 10 HL19 + 93 Resistant 11 IR29 (MC) Severe hypersensitivity 12 FL478 + 98 Resistant 13 Pokkali + 100 Resistant 14 BT7 10 Poor salt tolerance Note: (+): With Saltol gene; (-): without Saltol gene; MC: Salt sensitive standard sample The promising pure line HL15 has many good agro-biological characteristics, resistance to major pests and diseases, high yield potential and 6‰ salinity tolerance (Figure 3.1) The line changed its name to SHPT15 and continued to conduct author testing, basic testing, and production testing in the national and local testing system in order to have enough grounds for variety recognition Figure HL15 Prospect Line (SHPT15) After 15 days of salinity test at a concentration of 6‰ 16 3.3 Research to determine some suitable technical measures for selected salttolerant rice varieties (SHPT15 rice variety) 3.3.1 Study on the effect of sowing season on growth and development, yield components of rice variety SHPT15 3.3.1.1 Effect of transplanting time on growth time of rice variety SHPT15 The growth time of the experimental rice variety SHPT15 in the Spring crop in the provinces from sowing to harvest ranged from 119-125 days, of which the shortest growing time was in formula CT3 (119-120 days) In the Seasonal crop, the growing time of the variety ranged from 100 to 105 days (Table 3.19) Table 3.19 Some agro-biological characteristics of the experimental variety SHPT15 in 2019 Winter-Spring Summer-Autumn District Formula Growing time Height Growing time Height (ngày) (cm) (ngày) (cm) CT1 122 104,1 103 103,2 Nga CT2 120 103,7 100 102,6 Son CT3 119 102,5 100 102,3 CT1 125 102,3 105 101,8 Hoang CT2 123 101,6 103 101,5 Hoa CT3 120 101,3 100 101,1 CT1 121 105,2 104 105,0 Quang CT2 120 104,3 102 103,7 Xuong CT3 119 102,8 100 102,5 Thus, through the results of experimental monitoring of two winter-spring crops and summer-autumn crops, the rice variety SHPT15, when transplanted at different seasons, has different growth times but the difference is not large Through monitoring, the SHPT15 variety in the experimental treatments for both crops had plant height ranging from 101.1–105.2 cm In both crops, formula CT1 had the highest tree height, in winter-spring crop, the corresponding tree height in Nga Son, Hoang Hoa and Quang Xuong provinces was 104.1, 102.3 and 105.2 The corresponding summer-autumn crop is 103, 2; 101.8 and 105 The lowest plant height in treatment with CT3 (101.3- 102.8 cm) 3.3.1.2 Effect of planting season on the level of pest and disease infection of the experimental variety SHPT15 From the results of Table 3.20 showing the effect of transplanting time on the resistance to pests and diseases of the rice variety SHPT15 in the winter-spring crop in 2019 and Table 3.21 shows the influence of the transplanting time on the resistance to pests and diseases Damage of rice variety SHPT15 in the summerautumn crop in 2019 The results of seasonal experiments in both crops showed that SHPT15 was suitable for transplanting at different seasons, however, in late spring and late season, the rate of pests and diseases was more severe, requiring frequent monitoring and spraying medication periodically to reduce damage 3.3.1.3 Effect of transplanting season on yield and yield components of the experimental variety SHPT15 17 Table 3.22a, Table 3.22b, table 3.23 Effect of season on the actual yield of the experimental variety SHPT15 in the winter-spring and summer-autumn crops of 2019 of the rice variety SHPT15 at the experimental sites showed that: Winterspring 2019 number of panicles/clump: In all districts, CT2 has the highest number of panicles/clump The average rice variety SHPT15 has the same number of panicles/clump, ranging from 254.3-261.7 panicles/m2 Number of firm seeds/flower: The average number of firm seeds/flower of SHPT15 rice in the experimental treatments ranged from 102.3 to 104 seeds/flower The summer-autumn crop in 2019 showed that: When transplanted at different times, the variety SHPT15 had the same number of flowers/clump that did not differ much, ranging from 251 to 255.7 flowers/m2 The average number of seeds/flower of rice variety SHPT15 in the formula ranged from 103.1 to 104.7 seeds/head (table 3.22a) The monitoring results in Table 3.22b showed that at different times of transplanting, the percentage of SHPT15 in the winter-spring crop was not significantly different, ranging from 8.1 to 10.5% The rate of leprosy was highest in CT3 The weight of 1000 seeds inoculated at different times did not affect the weight of 1000 seeds of the variety SHPT 15, the weight ranged from 22.9 to 23.4g Similarly, the summer-autumn crop in 2019 was also the highest in CT3, ranging from 8.5-10.1% The rate of leprosy was highest in CT3 The weight of 1000 seeds of SHPT15 variety is from 22.7-23.1g - The percentage of flat seeds: at different times of transplanting, the percentage of SHPT15 variety was not significantly different, ranging from 9.9 to 11.3% The rate of splintering was highest in formula CT2 (winter-spring crop) - Weight of 1000 seeds: transplanting at different times did not affect the weight of 1000 seeds of SHPT15, the weight ranged from 22.8 to 23.0g The summer-autumn crop is shown in Tables 3.22a and 3.22b When transplanted at different times, the rice variety SHPT15 had the same number of panicles/m2, ranging from 244 to 260 panicles/m2 The average number of seeds/inflorescence of SHPT15 rice plants in the experimental treatments ranged from 101 to 106 seeds/head The percentage of flat seeds at times of inoculation was not significant, ranging from 8.8-9.9% The rate of splintering was highest in formula CT3 (late summer-autumn crop) The weight of 1000 seeds of SHPT15 variety is from 22.8 to 23.1g Table 3.23 Effect of season on actual yield of experimental variety SHPT15 in winter-spring crop and summer-autumn crop in 2019 Season CT1 CT2 CT3 LSD 0,05 CV% Actual yield of the winter-spring Actual yield of the summer-autumn crop crop (quintal/ha) (quintal/ha) Quang Hoang Nga Quang Hoang Nga Average Average Xuong Hoa Son Xuong Hoa Son 57,9 57,9 59,7 57,6 56,1 60,1 58,5 57,9 57,9 60,3 60,3 59,1 59,2 57,7 61,7, 59,5 57,2 59,0 59,0 58,4 57,3 55,8 59,8 57,6 1,26 1,12 1,08 1,20 7,2 6,7 - Through the obtained results shown in Table 3.23, transplanting at different times in the winter-spring crop did not significantly affect the actual yield of the 18 rice variety SHPT15 The highest net yield was achieved when transplanting the main winter-spring crop (57.9 - 60.3 quintals/ha), the lowest was in CT3 at 57.2 quintals/ha (late winter-spring) followed by 59 in CT1 ,7 quintals/ha (early spring winter), but the yield difference is not statistically significant at the 95% confidence level The results obtained in Table 3.23 show that the different planting times in the summer-autumn crop did not significantly affect the actual yield of the rice variety SHPT15 The highest net yield was achieved when transplanting CT2 at all sites (57.3-57.8 quintals/ha), the lowest when transplanting CT3 was 57.8 quintals/ha, however the yield difference was not significant statistics at the 95% confidence level Summary: Seasonality does not significantly affect the resistance to pests and diseases of the variety SHPT15 in saline areas of Thanh Hoa province The results of the study on the planting season of the variety SHPT15 in 2019 showed that the variety SHPT15 is a variety with a short growth period (119-125 days in Spring, 100-105 days in Winter crop) suitable for transplanting in both Spring and Summer crops in coastal districts of Thanh Hoa province The resistance to pests and diseases of the variety in transplanting seasons in 2019 was good, however, when transplanting in TV3 (January 17, 2019) and TV3 (June 18, 2019) the resistance to pests and diseases of the variety was good Lesser diseases cause yield loss, but not significantly Thereby showing that the time of transplanting does not affect the yield of the variety SHPT15 3.3.2 Study on the effect of density, fertilizer on growth and development, yield components of rice variety SHPT15 3.3.2.1 Effect of fertilizer dosage and transplanting density on the growth time of rice variety SHPT15 Through the data table of districts, it shows that the growth time of the winterspring crop formulas ranged from 118-125 days, the summer-autumn crop ranged from 103-110 days, the growth time difference in the formulas was not significantly 3.3.2.2 Effect of fertilizer dosage and transplanting density on the level of pest and disease infection of the experimental variety SHPT15 The results of monitoring the effects of fertilizer dosage and transplanting density on the level of pest and disease infection of the SHPT15 variety tested in the winter-spring crop of 2019 in Nga Son are shown in Table 3.26a The results showed that, in the experimental formulas, the level of pest and disease infection was mild (score 0-3) In which, mainly infected with stem borers and leaf rollers, most of them were in dense transplanting and high fertilizer application (points 13) The reason is that when applying a lot of fertilizer and transplanting at high density, the environment in the rice field will not be well-ventilated, the leaves obscure each other, creating conditions for pests to arise, develop and cause harm Field monitoring results showed that SHPT15 rice cultivars were not infected with BPH Rice blast and blight are infected but very mild in the tillering stage In Hoang Hoa and Quang Xuong, the results were similar to Nga Son, the level ... intrusion in coastal districts of Thanh Hoa province Thanh Hoa is a coastal province, located in the key economic region of the North Central region In the past ten years, Thanh Hoa has had an average... conditions of coastal districts of Thanh Hoa province in relation to rice production 3.1.1 Natural conditions in saline-affected areas in Thanh Hoa province The coastal area, Thanh Hoa province is influenced... About the structure of agricultural land use in Thanh Hoa province Thanh Hoa has a total natural area of 11,134.73 km2 (Statistical Yearbook of Thanh Hoa Province, 2019) In which, the total area