Study on breeding medium maturity maize hybrid with high yield for southeast region and central highland of vietnam

MINISTRY OF EDUCATION AND TRAINING MINITRY OF AGRICULTURE AND RURAL DEVOLOPMENT VIETNAM ACADEMY OF AGRICULTURAL SCIENCES VU NGOC QUY STUDY ON BREEDING MEDIUM MATURITY MAIZE HYBRID WITH HIGH YIELD FOR SOUTHEAST REGION AND CENTRAL HIGHLAND OF VIETNAM Ranch of study: Genetic – PlantBreeding Code: 62.62.01.11 SUMMARY OF DOCTORAL THESIS Hanoi– 2014 This theisis is completed at: VIETNAM ACADEMY OF AGRYCULTURAL SCIENCES Science supervisor: 1. Dr. Mai Xuan Trieu 2. As. Prof. Dr. Nguyen The Hung Critic 1: ...................................................................... Critic 2: ...................................................................... Critic 3: ...................................................................... The thesis will be defented before Council for thesis assessment at Institutional level held at Vietnam Academy of Agricultural Sciences At ......hour .......minute, day......month......year 2014 This Thesis can be referred to at: 1. National Library 2. Library of Vietnam Academy of Agricultural Scienses 3. Library of Naional Maize Research Institute 1 INTRODUCTION 1. URGENCY OF THE THESIS Southeast and Central Highlands are two large commodity maize producing regions in Vietnam’s southern provinces. In 2012, the average maize yield in these regions was 5.13 tons/ha, (in which Southeast region and Central Highlands was 5.62 tons/ha and 4.98 tons/ha), by 119,4% and 103,4% compared with country’s maize yield (4.30 tons/ha) and the global maize yield (4.98 tons/ha), respectively. In order to improve the efficiency of maize production in Southeast region and Central Highlands through actively supplying seeds with cheap price, it is essential to implement the thesis “Study on breeding medium maturity maize hybrids with high yield for Southeast region and Central Highlands” 2. PURPOSES OF RESEARCH Breeding and selecting some inbred lines and promissing crosses for maize breeding and production program in Southeast and centre Highlands Breeding new hybrid varieties with medium maturity (90- 96 days), high yield, good quality, suitable to conditions in these regions.. Determining some cultivation technologies such as plant density and row spacing, fertilzer doses for new hybrids with the purpose of introducing and transfering inovative techniques for farmers in these regions 3. THE PRACTICAL AND THEORETICAL SIGNIFICANCES 3.1.Theoretical significances Supply additional data, scientific information and the ability 2 to apply the method to selection inbred lines for maize hybrid breeding. Implementing scientific data on hybrid maize and cultivation techniques in ecological conditions of Southeast region and centre Highlands. 3.2. Practical signficances 8 inbred lines namely IL3, IL4, IL26, IL28, IL50, IL55, IL60 and IL61 are identifed with good charateriesties: well growth and development, good resistance serving as promissing inbred lines for the maize breeding program in the SouthEast region and Central Highlands. Thesis was identified two maize hybrids LVN68 and DP113 with medium- dated growth duration, well growth and development ability, good tolerance to unfavorable conditions; for high and stable yield, adaptation to ecological conditions of Southeast and Central Highlands. Identification of suitable planting density of 66,600 plants/ ha with row spacing of 60 cm x 25cm and the optimal dose of fertilizer of 180N - 80P2O5 - 80 K2O (kg/ha) for maize hybrid LVN68 in Southeast region and Central Highlands. 4. MATERIALS AND SCOPE OF RESEARCH 4.1. Materials Inbred lines are developed from different gemplasm resourses Hybrids are develpoed from the selected inbred lines. The suitable cultivation methods are used for promising hybrid combination. 4.2. The scope of research 3 Conducting field experiments, including experimental evaluation to select test topcross and dialell hybrids, , breeder testing (compared to promissing hybrids), VCU tesing; density and dose of fertilizer experiments.. 5. THE NEW CONTRIBUTIONS OF THE THESIS The thesis was identified 8 inbred lines which have high combining ability, added to the gemplasm resourses of MRI. The research also developed two corn hybrids namely LVN68 and DP113 with suitable plant density and fertilizer doses for contributing to maize production in Southeast region and central Highlands. 6. THE THESIS STRUCTURE The thesis consists of 155 pages, 67 tables, 16 pictures and photographs: Introduction (3 pages); Chapter 1: Review of literature (38 pages); Chapter 2: Materials, content and research methods (10 pages ); Chapter 3: Results and discussion (101 pages); Conclusion (2 pages), References include 163 documents with 51 Vietnamese documents and 100 English documents and 1 Bulgarian document. 11 wenside documents Three scientific papers related to the thesis contents have been published in domestic and international scientic journals. CHAPTER 1: LITERANTURE REVIEWS 1.1 THE ROLE OF MAIZE IN THE NATIONAL ECONOMY Acoording to Ngo Huu Tinh (1997), maize was used as the main food for 1/3 world population. Maize is the staple food for people in Southeast Africa, West Africa, South Asia, Central and South America, etc. 4 In addition to its role as food crops, corn is the main ingredient in animal feed, is export product, and high nutritional value of food and raw material for the processing industry, especially ethanol industry to replace fossil energy depleted. 1.2. SITUATION OF PRODUCTION AND USE OF HYBRID MAIZE VARIETIES IN THE WORLD AND VIETNAM 1.2.1 Situation of production and use of hybrid maize varieties in the world As compared to wheat and rice, corn yield is ranked the first in yield and the second in productivity [147]. Maize plays an important role in the economy, so that maize production in the world has always been being paid attention and development by Goverments. Although in the current years, maize area in the wold is not increased as compared to the end of the twentieth century, due to the limited cultivation lands but the world corn production has continued to grow. The main reason is due to the application of improved hybrid varieties and the advanced farming techniques in production. In 2001, maize areas worldwide is of 140,2 million hectares with an average yield of 4,3 tonnes / ha; and the total production of 600 million tons. The percentage of maize acreage accounted for 20 % of the total grain crop areas [ 38 ]. The average annual growth rate of maize production worldwide in the period of 2000 - 2010 in area, yield, and productivity is of 1,8 %, 2,1%, and 4,3%, respectively. By 2012 , corn acreage worldwide is 176,9 million ha with average yield of 4,94 tons / ha (decreased 0,4 tons / ha as compared to that in 2011) and production reached 875 million tons [147 ]. 5 1.2.2. Utility of maize hibrid variety and production in Vietnam Hybrid maize playsa major role in increasing productivity and yield of corn Vietnam. Period of 1960 – 1980, corn yield of Vietnam was obtianed by 0,8 to 1,1 tons / ha for local varieties with outdated cultivating techniques. By the year 1990, maize yield was increased up to 1,5 tons / ha, due to starting utiliztion of improved varieties. Hybrid maize has contributed greatly to increasing corn yields in Vietnam. In 1991, hybrid miaze area was extimated by less than 1% of the 447,000 hectares, in 2000, hybrid maize was grown on an area, equal to 65% of total area and average corn yield reached to 2.75 tons/ha and in 2012 , with an area of 1118,2 thousand hectares of maize, of which more than 95 % of the area is the used fo hybrid varieties. The success of hybrid corn program has significantly contributed in bringing corn yields achieved national average of 4.3 tonnes/ha. 1.2.3 Maize production in Southeast region and Central Highlands Southeast region and Central Highlands are the two largest production of maize commodity. These regions have a tropical climate and monsoon divided into two distinct seasons: the dry season from November to April last year after year, The rainy season from May to October, and cool west climate, favorable for crop development, Average annual rainfall is about 1500-2000 mm. In 2012, the average maize yield in these regions was up to 5.13 tons/ha, (in which Southeast region and Central Highlands is 5.62 tons/ha and 4.98 tons/ha), increased by 119,4% and 103,4% compared with national maize yield (4.30 tons/ha) and the global maize yield (4.94 tons/ha). 6 With the aim of developing strong Vietnamese hybrid corns in two corn producing areas of the major commodities in the southern provinces, it is necessary to promote the breeding for these regions. The deployment of inbred line breeding, hybrid testing, and identification of suitable cultivation methods to improve efficiency in maize production are essential requirements for maize production in Southeast and Highlands. 1.3. HETEROSIS AND ITS APPLICATION IN MAIZE BREEDING 1.3.1 The concept of heterosis Heterosis is a phenomenon of offspring heterozygous at the first generation capable of growth, development, resilience, adaptability, productivity, etc, outperformed with their homozygous parents. 1.3.2 Method of determining heterosis Heterosis of F1 hybrids is based on comparing the medium of parent heterosis (HMP) or the best of parent heterosis (HBP), with control hetetosis (Hs). 1.4. INBRED LINE AND ITS BREEDING METHODS 1.4.1.Definition of inbred lines Inbred line is a relative concept for selfing lines with the high homozygous and stable for characteristics, with maize, usually after 7-9 times selfing. 1.4.2 Materials for inbred lines primery materials are the foundation of the plant breeding work. Materials for developing inbred lines are diverse, including local varieties, synthetic varieties, gene pool, populations, hybrid... With each different type of material, inbred lines created are different. 7 1.4.3 several methods to develop maize inbred lines Some methods to produce the inbred lines were developed by scientists as Sprague and Eberhart(1955) + The standard method (Selfing): This method was proposed by Shull (1909,1910); sib or fullsib mehtod; Integrated domestication Method; homologous line breeding; Backcross method. Beside the traditional method as metioned above, there are a number of methods to create a new line developed like selective gametes, doubled haploid lines generated by anther culture or unfertilized ovules. 1.4.4. Line evaluation and its method Inbred lines are evaluated at the same time pure line breeding. This is an indispensable work and be relative to the effect of maize breeding, Through line evaluation, breeders can select desirable inbred lines and give approach to use those lines in hybrid maize breeding. 1.4.4.1 The concept of combining ability Combining ability expresses the response of inbred lines via crossing. Sprague and Tatum (1942) devided combining ability into 2 group: General combining ability (GCA) and specific combining ability (SCA), To evaluate combining ability of inbred lines, the breeder uses 2 methods: Topcross and Diallel cross. 1.5. STUDY OF CLASIFICATION OF GROWTH DURATION AND FARMING TECHNIQUE FOR MAIZE CULTIVATION 1.5.1 Classification of growth duration in maize 1.5.2.Research on the plant density and spacing of maize in the world and Vietnam 1.5.3 Research of fertilizer influence to maize production 8 CHAPTER 2: MATERIALS, CONTENT AND RESEARCH METHODS 2.1. MATERIALS Tabe 2.1. List of inbred lines No Name Graphic origin No Name Graphic origin No Name Graphic origin Lines group I 1 IL1 Vietnam 16 IL16 USA 31 IL31 India 2 IL2 Vietnam 17 IL17 USA 32 IL32 India 3 IL3 Vietnam 18 IL18 USA 33 IL33 India 4 IL4 Vietnam 19 IL19 Thailand 34 IL34 India 5 IL5 Vietnam 20 IL20 Thailand 35 IL35 India 6 IL6 Vietnam 21 IL21 Thailand 36 IL36 China 7 IL7 Vietnam 22 IL22 Thailand 37 IL37 China 8 IL8 Vietnam 23 IL23 Thailand 38 IL38 China 9 IL9 Việtnam 24 IL24 Thailand 39 IL39 China 10 IL10 Việnnam 25 IL25 Thailand 40 IL40 China 11 IL11 USA 26 IL26 Thailand 41 IL41 China 12 IL12 USA 27 IL27 Philippin 42 IL42 China 13 IL13 USA 28 IL28 Philippin 43 IL43 China 14 IL14 USA 29 IL29 Philippin 44 IL44 China 15 IL15 USA 30 IL30 Philippin 45 IL45 China Line group 2 46 IL46 Thailand 52 IL52 Thái land 58 IL58 USA 47 IL47 USA 53 IL53 USA 59 IL59 Thailand 48 IL48 USA 54 IL54 USA 60 IL60 Thailand 49 IL49 Vietnam 55 IL55 USA 61 IL61 Vietnam 50 IL50 Vietnam 56 IL56 USA 62 IL62 Vietnam 51 IL51 Thailand 57 IL57 USA 63 IL63 Vietnam Gemplasms consist of 63 inbred lines selected by selfing method-from the dififrent material resources, The inbred lines have 9 selfed 9-12 times, growth duration of the lines from 85-100 days depending on the season and divided into 2 groups: The first line group: the lines were developed in Dan Phuong - Hanoi before 2004, The second line group: selected lines were developed in Trangbom - Dong Nai Province from 2004 to 2008. Checks in experiment + Breeder testing: C919, CP888, CP999 + VCU testing: C919, CP888 2.2. CONTENT - Evaluation on morphological characteristics of inbred lines - Evaluation on combining ability and heterosis of inbredlines - Testing promising maize varieties - The study of farming techniques for hybrid variety LVN68, 2.3 METHODS 2.3.1 Method of field evaluation According to Guideline of evaluation and data collection in maize, comparison experiment of CIMMYT (1985) and National Maize Research Institue. 2.3.2.Method of inbred line selection: Using of traditional method (self pollinated, Sib, backcross,,,) 2.3.3. Method of heterosis and combining ability Identify heterosis, combining ability of seed yield of inbred lines by topcross and diallel cross according to Omarov, NgoHuu Tinh and Nguyen Dinh Hien (1996), 2.3.4 Official tesing of the promising hybrids 10 According to rule: “Maize Varieties-Procedure to conduct tests for Value of Cultivation and Use” - 10 TCN 341 – 2006 2.3.5 Data analysis Data were computed and analyzed in microsoft excel, IRRISTAST software version 4.0 and qualitities genetic software program (Ver 2,0 Nguyen Dinh Hien, 1996), 2.4. TIME AND LOCATION, 2.4.1 location Variety selection experiment, lines assessment, crosses evaluating, genetic diversity analysis were conducted at National Maize Research Institure Official testing: implemented by network of National Centre for Plant and Fertilizer Testing (NCPFT) southern region. 2.4.2. Times - Materials collection and its evaluation 2002-2010 -Selection, inbred line evaluation of lines, hybrid testing combined from 2004 to 2008 -The experiments on plant spacing, ferrtilizer dose from 2010 to 2012 CHAPTER 3: RESULTS AND DISCUSION 3.1. Result of inbred lines selection from different gemplasm resources. The selection and assessment of inbred lines have been conducted since 2002. From 45 origin collected materials, by adaptative assessment, 18 lines with good characteristic were selected, they were : IL1, IL2, IL3, IL4, IL8, IL11, IL13, IL14, IL19, IL20, IL22, IL24, IL26, IL27, IL28, IL31, IL33 and IL35, 11 From 18 new lines developed in trang bom district-Dongnai province after two seasion (summer-autum and autum-winter 2008) for testing, adaptive evaluation, some characteristics of agricultural biological, 12 lines selected, they were : IL46; IL47; IL49; IL50; IL54, IL55; IL56; IL57; IL60; IL61; IL62 and IL63, The lines have many good characteristics and can be used for maize breeding programs in Southeast and Central Highlands, 3.3 THE RESULTS ON COMBINING ABILITY VALUATION OF INBRED LINES 3.3.1 The results on general combiming ability on the yield of lines 3.3.1.1 Result of first topcross Through two seasons for topcross between 18 lines and 2 testers (DF2 and D6), The line which showed highest GCA value was IL28 and followed by IL26, IL3, IL1 IL19, IL2 và IL4... The lines IL4, IL1, IL26, IL3, IL19, IL13 and IL28 have high combining ability variances. Table 3.8. General combiming ability values on yield trial of the 18 lines and two testers in summer-autum and Autum-winter 2005 in district-dongnai provice No lines Tester Line Name ĝi Tester name ĝj Summer - Autum Autum - winter Summer - Autum Autum - winter Summer - Autum Autum - winter 1 IL1 6.774 6.899 T1(DF2) -0.669 - 0.802 2 IL2 4.211 4.620 T2 (D6) 0.669 0.802 3 IL3 6.941 6.785 Ʃ 0.000 0.000 4 IL4 4.448 5.304 Summer autum season 2005 Edi = 1.144 Ed (di – dj) = 1.617 5 IL8 -2.911 -0.311 6 IL11 -2.571 -5.758 12 7 IL13 -8.629 -9.096 LSD0,05 line = Edi *t(0,05;70) = 1.144*1.994 = 2.281 Ecj = 0.381 Ed (ck – cl) = 0.539 LSD0,05 tester plant = Ecj * t(0,05;70 = 0.381* 1.994 = 0.759 8 IL14 -7.226 -7.665 9 IL19 5.918 5.864 10 IL20 -3.116 -3.020 11 IL22 -4.271 -4.230 12 IL24 -7.106 -6.941 Autum –winter season 2005 Edi = 1.084 Ed (di – dj) = 1.534 LSD0,05 lines = 2.161 Ecj = 0.361 Ed (ck – cl) = 0.511 LSD0,05 tester plant = 0.719 13 IL26 6.519 7.712 14 IL27 -3.504 -3.893 15 IL28 9.951 9.477 16 IL31 0.144 -0.481 17 IL33 -2.819 -2.855 18 IL35 -2.467 -2.413 Ʃ 0.000 3.3.1.2 Result of second topcross expresiment 12 lines namely IL46, IL47, IL49, IL50, IL54, IL55, IL56, IL57, IL60, which have good growth and development ability, resistant to pests, high yielding were taken for topcross with 2 testers DF2 and D6 in the Summer- spring and Autum- witer 2009. The table 3.11 showed that: The lines which had high GCA value were IL60, IL49, IL61, IL50 and IL55; the lines which had high variance of SCA value were IL60, IL61 and IL49; the lines which had both high GCA and SCA value were IL60, IL61 and IL49 Table 3.11. General combiming ability values on yield trait of the 12 lines and tester in summer-autum and Autum-winter 2009 in district-dongnai provice No line Tester Line name ĝi Tester name ĝj Summer autum Autum winter Summer autum Autum winter Summer autum Autum winter 1 IL46 -4.695 -4.666 T1(DF2) -3.079 -0.906 2 IL47 -1.453 -1.513 T2 (D6) 3.079 0.906 3 IL49 6.585 6.609 Ʃ 0.000 0.000 13 4 IL50 5.095 5.629 Summer –Autumn season 2009 Edi = 1.849 Ed (di – dj) = 2.616 LSD0,05 line = Edi x t(0,05;46) = 3.723 Ecj = 0.755 Ed (ck – cl) = 1,=.068 LSD0,05 tester = Ecj x t(0,05;46) = 1.520 5 IL54 -3.483 -3.554 6 IL55 4.718 4.561 7 IL56 -6.818 -6.893 Autumn-Winter season 2009 Edi = 1.046 Edi = Ed (di – dj) = 1.480 LSD0,05 line = Edi x t(0,05;46) = 2.106 Ecj = 0.427 Ed (ck – cl) = 0.604 LSD0,05 tester = Ecj x t(0,05;46) = 0.859 8 IL57 -6.623 -6.739 9 IL60 7.743 7.599 10 IL61 5.805 5.769 11 IL62 -5.333 -5.349 12 IL63 -1.540 -1.451 Ʃ 0,000 3.3.2 The results on evaluation of agro-morphological characteristics and SCA of inbred lines and hybrids 3.3.2.1 The results of first Diallel experiment Based on results of evaluation on agro-morphological characters of 45 lines (developed before 2004) and the GCA on yield traits of 18 lines through topcross in the Summer –Autumn and Autumn –winter 2005 (First topcross experiment), 7 lines: IL1, IL2, IL3, IL4, IL19, IL26, IL28, with good agro-morphological characteristics and high GCA were selected for diallel cross in 2 seasons: Autumn-winter 2005 and Summer- Autumn 2006. Hybrids C919 and CP888 were used as checks. 21 crosses were evaluated on the agro-morphological characteristics, productivity, pet resistance There were 21 crosses for evaluating on the agro- morphological characteristics, productivity, and disease/pet resistance, fresh quality... As a result, the cross of IL26 x IL28 was the most promising, which has medium duration and plant height, high yield, especially nice formed cob, high resistance to pests. This 14 cross have been continued to be breeder testing with the name was TB68 and official testing with the name was LVN68. Table 3.18. Weigth of 1000 grains , rate of grain/ear and yield of crosses in Autumn-winter 2005 and Summer-Autumn 2006 No. Crosses P1000 grains(g) Grains/ear ( %) Yield (Tones/ha) Aut., Win. Sum - Aut Aut., Win. Sum - Aut Aut., Win. Sum - Aut 1 IL1 x IL2 289.6 298.7 77.95 78.02 6.950 7.047 2 IL1 x IL3 304.2 305.2 79.40 79.46 6.082 6.777 3 IL1 x IL4 304.1 311.4 74.60 74.68 7.395 7.491 4 IL1 x IL19 311.3 312.5 74.35 74.44 6.796 6.891 5 IL1 x IL26 306.2 308.2 74.80 74.87 7.461 7.556 6 IL1 x IL28 312.4 314.4 75.63 75.71 7.487 7.674 7 IL2 x IL3 295.9 300.8 77.39 77.46 6.445 7.052 8 IL2 x IL4 279.8 281.8 75.95 76.03 7.332 7.428 9 IL2 x IL19 295.8 297.9 75.45 75.54 7.295 7.389 10 IL2 x IL26 284.7 288.7 73.07 73.14 7.959 8.045 11 IL2 x IL28 306.7 312.7 78.08 78.16 7.191 7.473 12 IL3 x IL4 290.2 291.2 77.81 77.88 7.894 7.991 13 IL3 x IL19 300.2 304.2 76.30 76.38 7.007 6.723 14 IL3 x IL26 298.9 299.9 75.74 75.81 7.319 7.411 15 IL3 x IL28 267.2 279.9 78.59 78.65 7.726 7.922 16 IL4 x IL19 305.8 305.9 72.83 72.91 7.320 7.412 17 IL4 x IL26 320.2 320.9 72.35 72.43 7.518 7.610 18 IL4 x IL28 288.5 288.8 75.08 75.16 7.935 8.028 19 IL19 x IL26 323.2 332.7 70.66 70.75 7.402 7.493 20 IL19 x IL28 301.9 302.9 72.96 73.06 7.663 7.390 21 IL26 x IL28 326.7 335.2 74.63 75.82 8.537* 9.000* 22 C919 (Check1) 310.5 312.2 79.71 75.96 7.602 8.056 23 CP888 (Check 2) 317.9 318.8 77.08 75.07 6.950 7.047 CV (%) 4.8 5.3 LSD0.05 0.585 0.655 Note: (*) Yields exceeding probability control at P ≥ 0.95 15 The result in evalution of heterosis of cross from 7 lines group I The results showed that the heterosis of crosses was more dominant than parental lines which were obtained in most of the traits: growth duration, plant height, yield components and especially productivity. In these trials, HBP was from 128.82 % to 202.32 %. The highest was estimated by 202.32% for IL3 x IL28 cross and the lowest was 128.82% for IL3 x IL26 cross. 3.3.2.2. The results of second Diallel cross: Table 3.29. Weigth of 1000 grains , rate of grain/ear and yield of crosse in Summer and Autumn Winter 2010 in Trangbom - Dong Nai No Cross P1000 grains (gam) Grain/ear (%) Grain yield (Tons/ha) Sum- Au. Au- Win. Sum- Au. Au- Win. Sum- Au. Au- Win. 1 IL49 x IL50 304.1 299.6 78.84 77.63 7.402 7.303 2 IL49 x IL55 300.3 295.7 79.40 77.24 7.158 7.068 3 IL49 x IL60 301.2 299.5 77.97 78.08 7.989 7.757 4 IL49 x IL61 292.0 288.4 77.50 78.46 7.424 7.393 5 IL50 x IL55 324.2 320.7 77.49 77.87 8.093 7.955 6 IL50 x IL60 338.5 335.7 76.28 76.40 9.104 8.749 7 IL50 x IL61 310.3 308.7 78.95 79.73 6.844 6.755 8 IL55 x IL60 310.3 305.7 76.72 76.87 7.837 7.739 9 IL55 x IL61 310.3 305.7 76.21 76.77 7.724 7.605 1 10 IL60 x IL61 320.3 318.7 77.34 77.29 7.965 7.849 C919 (đ/c1) 325.0 318.6 79.48 78.49 8.047 7.876 CP888 đ/c2) 310.3 308.7 78.14 77.42 7.545 7.409 CV (%) 4.8 5.6 LSD0.05 0.635 0.585 Note: (*) Yields exceeding probability control at P ≥ 0.95 16 The data in table 3.29 showed that: cross IL50 x IL60 had high yield and stability in both seasons (9.103 tons dry grain/ha in Autumn-winter and 8.749 tons dry grain/ha in Summer-Autumn season by check 1(C919) was 113.15% in Summer –Autumn season, 111.01% in Autumn-winter season and by checked 2 (CP888) in two trials respectively were 120,55 and 118,00 %. Through evaluating 10 croses from 5 lines in the second diallel cross on the agro-biological characteristics, productivity, resistance cross IL50 x IL60 was the most promising, especially productivity and resilience. This cross have been continued to be breeder testing with the name was TB80 and official testing with the name was DP113. The resul of heterosis evalution of crosses from 5 lines group II The results showed that the heterosis of crosses was more dominant than parental lines which presented in most of the traits: growth duration, plant height, yield components and especially productivity. In this trial, HBP reach from 129,49 % to 182,73 %, which the highest was IL55 x IL61 cross (182,73 %) and the lowest was cross IL50 x IL61 (129.49 %),. 3.3. THE TESTING RESULTS OF PROMISING CROSSES 3.3.1. BREEDER TESTING 3.3.1.1 The result of breeder testing cross IL26 x IL28 (TB68)) Since Summer –Autumn seasons 2006, IL26 x IL28 (TB68) cross has been tested at Trangbom-Dongnai and Eaka-DakLak. In compared experiment, TB68 cross had average yield at two location were 9.394 tones/ha (from 8.77 to – 9.770 tones/ha) higher than 2 checked variety C919 and CP999 from 14,66 to 19,76 % (table 3.37). 17 Table 3.37. Grain yield of TB68 at breeder testing (tons/ha) No Variety Trangbom- dongnai Eaka-daklak Average Sum- Aut 2006 Aut- Win 2006 Sum- Aut 2007 Sum- Aut 2006 Aut- Win 2006 Sum- Aut 2007 1 TB68 9.47b 9.69b 8.95b 9.71b 8.77b 9.77a 9.39 2 C919 (Ch 1) 8.39 7.42 7.08 8.09 7.05 9.05 7.84 3 CP999(Ch 2) 8.69 7.93 7.61 8.69 7.40 8.84 8.19 CV (%) 6.0 7.4 6.8 6.6 7.1 8.4 LSD0.05 0.73 0.84 0.70 0.84 0.77 0.99 Notes (a ) Yields exceeding 1 in 2 probability control at P ≥ 0.95 ( b ) Yields exceeding both probability control at P ≥ 0.95 3.3.1.2 The result of breeder testing cross IL50 x IL60 (TB80) Table 3.40: Grain yield of TB80 at breeder testing (tons/ha) No Variety Trangbom- dongnai Eaka-daklak Average Aut- Win 2010 Sum- Aut 2011 Aut- Win 2011 Aut- Win 2010 Sum- Aut 2011 Aut- Win 2011 1 TB80 8.99b 9.31b 9.02b 9.10 b 9.24 8.96 b 9.10 2 C919 (Ch 1) 8.08 7.79 8.17 818 8.76 8.06 8.17 3 CP999(Ch 2) 7.58 7.63 7.32 760 8.36 7.77 7.71 CV% 6.1 7.8 8.2 6.3 7.9 8.0 LSD0.05 0.68 0.91 0.83 0.71 0.94 0.82 Notes (a ) Yields exceeding 1 in 2 probability control at P ≥ 0.95 ( b ) Yields exceeding both probability control at P ≥ 0.95 Since Autumn-Winter season 2010 to Autumn-Winter seasons 2011, IL50 x IL60 cross has been tested at Trangbom- Dongnai and Eaka-DakLak. TB80 had avegare yield in three seasons experiment at two point was 9.10 tons/ha, hight than check variety 18 1(C919) and check variety 2 (CP888) from 11,35 to 18,06 % (table 3.40). 3.5.2 Basic test results on value of cultivation and use 3.5.2.1. The testing results on VCU of LVN68 Table 3.41. Grain yield of LVN68 on value of cultivation and use testing (tons/ha) Sea. Location LVN68 (tons/ha) Check ( tons/ha) %/ chech 1 (C919) %/ chech 2 (CP888) LSD 0.05 C919 CP888 Aut- Win. 2007 Chau Đoc - Barịa Vung Tau 8.37 b 6.83 5.88 122.55 142.55 0.85 Trangbom - Đongnai 6.99.b 5.88 5.71 118.88 122.42 0.69 Cammy - Đongnai 7.53 a 6.65 6.19 113.23 121.50 0.97 Ductrong -Lamdong 7.51 b 5.82 5.03 129.04 140.00 0.97 Buondon-Daklak 6.05 a 5.28 5.04 114.58 120.04 1.01 Avegare 7.29 6.09 5.57 119.67 130.92 Win. -Spri 2007 - 2008 Thongnhat-Dongnai 10.19 b 9.17 8.35 111.12 127.38 0.89 Cammy - Dongnai 10.10 a 9.24 8.18 109.31 123.47 0.90 Longphu - Soctrang 7.24 6.86 6.38 105.54 113.48 - Tanchau- Angiang 9.61 10.20 10.45 94.95 91.96 0.74 Avegare 9.28 8.86 8.34 104.74 111.27 Sum. - Aut. 2008 Chau Đoc - Barịa Vung Tau 8.19 a 7.52 7.02 108.91 116.67 1.12 Trangbom - Đongnai 7.38 b 6.35 5.78 116.22 127.68 1.08 Cammy - Đongnai 6.34 6.00 5.67 105.67 111.82 0.90 Ductrong -Lamdong 8.54 a 7.89 6.43 108.24 132.81 0.96 Buondon-Daklak 9.65 b 8.40 6.38 114.88 151.25 1.06 Avegare 8.02 7.23 6.26 110.90 128.20 Aut- Win. 2008 Chau Đoc - Barịa Vung Tau 7.02 b 6.36 5.22 110.38 134.48 0.58 Trangbom - Đongnai 6.58 a 5.73 5.22 113.83 126.05 0.97 Cammy - Đongnai 6.75 a 6.25 5.33 108.00 126.64 0.96 Ductrong -Lamdong 6.95 b 5.65 4.89 123.01 142.13 0.54 Buondon-Daklak 7.95 b 6.28 6.64 126.59 119.73 0.91 Avegare 7.05 6.05 5.46 116.45 128.60 Notes (a ) Yields exceeding 1 in 2 probability control at P ≥ 0.95 ( b ) Yields exceeding both probability control at P ≥ 0.95 Source: National Centre for Plant and Fertilizer Testing Southern Region 19 Basical asays to test the value of cultivar were implemented by National Centre for Plant and Fertilizer Testing Southern Region for the same breeder tessting. LVN68 short growth duration, equivalent with check 1(C919), high uniformity, resistance to pest and lodging, husk cover is relatively good, Avegare yield of LVN68 from 7.05 to 10.19 tones/ha higher than check 1 (C919) from 4.74 to 19.67 % and higher than check 2 (CP888) from 11.27 to 30.92 %. LVN68 was provisionally released in 2010. 3.5.2.1. The testing results on VCU of DP113 Table 3.42. Grain yield of DP113 on value of cultivation and use testing (tons/ha) Sea. Location LVN68 (tons/ha) Check ( tons/ha) %/ chech 1 (C919) %/ chech 2 (CP888) LSD 0.05 C919 CP888 Sum. Aut . 2012 Tanthanh-Bảiavungtau 5.83 5.62 6.51 103.74 89.55 0.68 Cammy-Dongnai 7.18a 6.99 6.26 102.72 114.70 0.69 Trangbom-Dongnai 6.88b 6.08 5.80 113.16 11.62 0.49 Ductrong- Lamdong 9.80b 9.78 8.97 100.20 109.25 0.71 Buondon - Daklak 8.82b 7.75 6.80 113.81 129.71 0.62 Average 7.97 7.50 7.04 106.27 113.21 Aut. Win. 2012 Tanthanh-Bảiavungtau 2.85 3.79 3.22 75.20 88.51 0.49 Cammy-Dongnai 4.52a 4.01 3.59 112.72 125.91 0.53 Trangbom-Dongnai 6.07b 4.99 4.58 121.64 132.53 0.84 Ductrong- Lamdong 8.02 7.63 7.75 105.11 103.48 0.53 Buondon - Daklak 8.62b 7.27 6.15 118.57 140.16 1.03 Average 6.40 5.86 5.37 109.22 119.18 Win. Spri. 2012- 2013 Tanthanh-Bảiavungtau 4.42 3.86 6.36 114.51 69.50 0.90 Cammy-Dongnai 9.14 8.35 8.25 109.46 110.79 1.09 Trangbom-Dongnai 8.48b 7.21 7.45 117.61 113.83 0.82 Tanchau- Angiang 9.27a 9.15 7.45 101.31 124.43 0.99 Average 7.68 7.14 6.77 107.59 113.52 Notes (a ) Yields exceeding 1 in 2 probability control at P ≥ 0.95 ( b ) Yields exceeding both probability control at P ≥ 0.95 Source: National Centre for Plant and Fertilizer Testing Southern Region 20 DP113 was VCU testing at 6 locations (Tanthanh-Baria- vungtau, Trangbom-dongnai, Cammy-dongnai, Ductrong-Lamdong and Tanchau- Angiang from Summer-Autumn 2012 and the end in Winter Spring season 2012-2013 by National Centre for Plant and Fertilizer Testing Southern Region. Basical asays to test the value of cultivar were implemented by National Centre for Plant and Fertilizer Testing Southern Region for the same breeder tessting. DP113 had a good resistant to pets and diseases, long ear and beutufull grain colour. Grain yield of DP113 averaged from 6.40 to 7.97 tons/ha, higher than check 1 (C919) from 6.27 to 9.22 % and higher than check 2 (CP888) from 13.37 to 19.18 7 %. National Centre for Plant and Fertilizer Testing Southern Region concluded that: “DP113 is promising cross” which has been accepted for testing production. 3.4. THE RESEARCH RESULTS TO FARMING TECHNIQUES FOR MAIZE HYBRYD LVN68 IN SOUTHEAST AND CENTRAL HIGLADS 3.4.1. The result of density research for maize hybrid LVN68 The data in tables 3.45 and 3.48 showed that: Grain yield of LVN68 varied with the plant density and changed from 8.008 to 10.486 tons/ha. In which, LVN68 gave the higtest yield at density of 66.6 thousand plants/ha with spacing of 60 x 25 cm, from 10.003 to 10.486 tons, higher than check variety (57.0 thousand plants/ha) from 17,43 to 19,78 % in trangbom-dongnai and from 15,80 to 24,71 % in Ductrong-Lamdong area Statistical analysis data showed that the yield from 3 levels of plant spacing: 60 x 28cm; 60 x 22cm and 60 x 25cm exceeded to the 21 control at significant probability P ≥ 0. 95. With the density of 66.600 plants/ha and planting distance of 60 x 25cm, productivity showed the highest and exceeding the other treatments in the probability P ≥ 0, 95 Table 3.45. Grain yield of different planting densities with maize hybrid LVN68 in summer Autum and Autum –Winter 2010 in Trangbom-dongnai province. No. Spacing (cm) Plant density (Plants/ha) Sum - Aut 2010 Aut. - win 2010 Yield (tons/ha) % /check Yield (tons/ha) % /check 1 60 x 30 55,500 8.758 100.05 8.732 99.59 2 60 x 28 59,500 9.693* 110.72 9.711* 110.75 3 60 x 25 66,600 10.486* 119. 78 10.297* 117.43 4 60 x 22 75,750 9.099* 103.93 9.228* 105.25 5 70 x 25 (check) 57,000 8.754 100,00 8.768 100,00 CV (%) LSD0.05 7.9 0.303 7.2 0.334 Note: (*)Yields exceeding probability control at P ≥ 0.95 Table 3.48. Grain yield of different planting densities with maize hybrid LVN68 in Ductrong-lamdong province in Winter –Spring 2011-2012 and Summer Autumn 2012. No. Spacing (cm) Plant density (Plants/ha) Win –Spri 2011-2012 Sum- Autn 2012 Yield (tons/ha) % /check Yield (tons/ha) % /check 1 60 x 30 55,500 8.685 99.50 8.008 99.83 2 60 x 28 59,500 9.752* 111.72 9.306* 116.02 3 60 x 25 66,600 10.108* 115.80 10.003* 124.71 4 60 x 22 75,750 9.234* 105.78 9.073* 113.12 5 70 x 25 (Check) 57,000 8.729 100.00 8.021 100.00 CV (%) LSD0.05 6.6 0.409 9.9 0.570 Note: (*) Yields exceeding probability control at P ≥ 0.95 22 3.4.2 The research result of fertilizer dose for maize hybrid LVN68. Table 3.51. Grain yield of maize hybrid LVN68 of different fertilizer doses in Trangbom-dongnai in Autumn-Winter season 2010 and Winter –spring season 2010-2011. Fom. Fertilizer dose (kg/ha) Aut.-win. 2010 Winter-spring 2010- 2011 yield (tons/ha) % /check yield (tons/ha) % /check CT1 120 N-80 P2O5-80 K2O 7.744 95.02 7.578 91.92 CT2 120 N-80 P2O5-100 K2O 7.965 97.73 7.924 96.12 CT3 150 N-80 P2O5-80 K2O 8.933* 109.61 8.958 * 108.65 CT4 150 N-80 P2O5-100 K2O 9.207 * 112.97 9.215 * 111.77 CT5 180 N-80 P2O5-80 K2O 10.057 * 123.40 10.076 * 122.22 CT6 180 N-80 P2O5-100 K2O 10.025 * 123.01 10.034 * 121.70 CT7 150N-80P2O5-60K2O (check) 8.150 100.00 8.245 100.00 CV (%) LSD0,05 3.8 0.598 2.7 0.419 Table 3.54: Grain yield of maize hybrid LVN68 of different fertilizer doses in Ductrong-lamdong in Winter –spring season 2011-2012 and Summer-Autumn 2012. Fom. Fertilizer dose (kg/ha) Win-spri 2011- 2012 Sum –aut 2012 yield (tons/ha) % /check yield (tons/ha) % /check CT1 120 N-80 P2O5-80 K2O 7.744 92.58 7.995 96.00 CT2 120 N-80 P2O5-100 K2O 8.203 98.06 8.233 98.86 CT3 150 N-80 P2O5-80 K2O 9.099 * 108.77 9.096* 109.22 CT4 150 N-80 P2O5-100 K2O 9.399 * 112.36 9.327* 112.00 CT5 180 N-80 P2O5-80 K2O 10.139 * 121.21 10.116 * 121.47 CT6 180 N-80 P2O5-100 K2O 10.078 * 120.48 10.069 * 120.91 CT7 150N-80P2O5-60K2O (check) 8.365 100.00 8.328 100.00 CV (%) LSD0.05 3.7 0.594 2.7 0.426 Note: (*)Yield exceeding probability control at P ≥ 0.95 23 The data in table 3.51 and 3.54 showed that: Grain yield hybrid LVN68 at different fertilizer doses expressed big difference ranging from 7.744 to 10.139 tons/ha. 4 fomualas gave yield exceeding probability check at P ≥ 0.95 were CT3, CT4, CT5, CT6 in which the highest ones is CT5 fomuala and ranged from 10.076 to 10.139 tons/ha, higher than check (CT7) from 21.22 to 24.40 % in Trangbom-dongnai and from 21.21 to 21.27 % in Ductrong-lamdong and CT5 formula give the highest economic efficiency. CONCLUSION AND RECOMMENDATION 1.CONCLUSION 1.1. 8 inbred lines namely IL3, IL4, IL26, IL28, IL50, IL55, IL60 and IL61 were identified with high general combining ability (GCA) and specific combining ability (SCA), adaptable to ecological conditions of Southeast and Highland. These inbred lines were the first materials developed by NMRI for maize breeding program of Southeast region and were the foundation of the maize breeding projects of Southern provinces. 1.2. The heterosis of crosses was more dominant than parental lines which presented in most of the traits: growth duration, plant height, yield components and especially productivity. HBP reached from 128.82 to 202.32 %, in which IL3 x IL28 cross expressed the highest heterotic value (202.32). 1.3. Results from the research were identified two maize hybrids LVN68 and DP113 with medium- dated growth duration, growth and development ability, good tolerance to unfavorable conditions; high and stable yield, adaptation to ecological conditions of Southeast and Highlands. LVN68 was provisionally released in November, 2010 and National Centre for Plant and Fertilizer Testing Southern Region 24 concluded that: “DP113 is promising cross” which has been recognized for provisional release. 1.4. The result was also identified: In adaptation to ecological conditions in Trangbom-dongnai and Ductrong-Lamdong, plant density and fertilizer doses did not affect to growth duration and development of Maize hybrid LVN68. LVN68 expressed the highest yielding and economic efficiency in planting density of 66,600 plants /ha and fertilizer dose 180 kg N - 80 kg P2O5 - 80 kg K2O. 2.RECOMMENDATION 2.1. Continuing to research, exploid and use of inbred lines namely IL3, IL4, IL26, IL28, IL50, IL55, IL60 and IL61 with good agronomic characteristics in hybrid breeding programs of Vietnam generally and Southeast and Central Highlands particularly. 2.2. Continuing to expand the research and improvement of the cultivation techniques, seed production procedure for LVN68 and DP113, the recognition of new varieties LVN68 and production testing of DP113 to implement two new hybrids into maize production program of Southeast and Central Highlands. 25 PUBLISHED DOCCUMENTS RELATED TO THE THESIS 1. Vu Ngoc Quy, Dao Ngoc Anh, Nguyen Duy Duyen (2013), “Study of density research for maize hybrid LVN68”, Journal of Vietnam Agricultural Science and Technology, No 1(40), page 57-61. 2. Vu Ngoc Quy, Dao Ngoc Anh, Nguyen Duy Duyen (2013), “The effectiveness of fertilizer dosages to yield of hybrid maize, LVN68 variety”, Journal of Vietnam Agricultural Science and Technology, No 1(40), page: 57-61. 3. Vu Ngoc Quy, Nguyen Tien Truong, Nguyen Duy Duyen (2013), “The estimate results of heterotic and combinnation ability of 5 inbred lines by dialell method”, Journal of Vietnam Agricultural Science and Technology, No 7/(46), page: 118-123