The occasional failure of glyphosate to control all weeds throughout the entire growing season has prompted growers to sometimes use herbicides other than glyphosate on glyphosate-tolerant soybean. Field studies were conducted in 1999 and 2000 to investigate potential crop injury from several herbicides on glyphosate-tolerant soybean, and to determine the relationship between soybean maturity, planting date, and herbicide treatment on soybean injury, leaf area index (LAI), and yield. Three glyphosate-tolerant soybean cultivars representing maturity groups III, IV and V were planted at dates representing the full-season and double-crop soybean production systems used in Virginia. Within each cultivar and planting date, 15 herbicide treatments, in addition to a control receiving only metolachlor preemergence, were applied to cause multiple levels of crop injury. Results of this study indicate that glyphosate-tolerant soybean generally recovered from early-season herbicide injury and LAI reductions; however, reduced yield occurred with some treatments. Yield reductions were more common in double-crop soybean than in full-season soybean. In full-season soybean, most yield reductions occurred only in the early maturing RT-386 cultivar. These yield reductions may be attributed to the reduced developmental periods associated with early maturing cultivars and double-crop soybean that often lead to reduced vegetative growth and limited LAI. Additional reductions of LAI by some herbicide treatments on these soybean may have coincided with yield reductions; however, reduced LAI did not occur with all yield reducing treatments. Therefore, soybean LAI response to herbicide treatments does not always accurately indicate the potential detrimental effects of herbicides on soybean yield. Further, yield reductions associated with herbicide applications occurred, although soybean sometimes produced leaf area exceeding the critical LAI level of 3.5 to 4.0 which is the minimum LAI needed for soybean to achieve maximum yield. / Master of Science

Soybean (Glycine max [L.] Merr.) has become one of the main agricultural grain crops produced in the United States. Soybean production continues to increase in high-yield environments throughout the U.S. New innovations are required to sustain gains in soybean yield potential. Field experiments were conducted at the Delta Research and Extension Center in Stoneville, MS in 2014 and 2015 to evaluate soybean aboveground biomass and grain yield response to supplemental N fertilization in a high-yielding environment on two soil textures commonly cropped to soybean in Mississippi. Greenhouse studies were conducted in 2016 at the Delta Research and Extension Center in Stoneville, MS to evaluate the influence of supplemental N fertilization on nodule formation and belowground biomass of soybean on two soil textures commonly cropped to soybean in Mississippi.

Call number: LD2668 .T4 1978 K55 / Master of Science

In effort to breed for daylength-neutral (DNP) soybean germplasms (Glycine max (L.) Merrill), selected longday cultivars (LDP) from Maturity Group 00 were crossed to local adapted shortday cultivars (DP) from Maturity Group VI. In the segregating populations there were many new hybrid combinations, some of which flowered and set pod as early as the Group 00 parents, however, they were larger in size and matured normally. These lines were considered daylength-neutral plants (DNP), and were evaluated in the field nursery in biweekly date of planting experiments from early May to late July during 1978 and 1979. Selected LDP and local adapted SDP cultivars were utilized as check lines. It was observed that LDP cultivars flowered and set pods normally. However, they did not mature normally; the pods ripened and shattered while the stem and leaves remained green and these plants were short and unproductive. Local SDP were the most sensitive plants in response to the change in planting date and daylength. Number of days to flowering, pod setting, and maturity as well as plant heights had decreased sharply in response to the decrease in daylength of later planting dates. In contrast, DNP lines flowered, set pod and matured normally on large vigorous plants in approximately the same period of time regardless of planting date or the daylength during the growing season. To study the inheritance of the daylength-neutral trait in soybeans, crosses were made between DNP lines and local SDP cultivars. These were extremely wide crosses. Segregating populations from these crosses were tested under three light treatments of 12, 18 and 24 hours. Only DNP plants flowered and set pod normally under the long photoperiod treatments of 18 and 24 hours. The magnitude and continuous nature of the frequency distribution of the segregating populations as well as the low heritability estimates of each trait imply that this response is under polygenic control.

Phang Tsui-Hung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 146-162). / Abstracts in English and Chinese. / Thesis committee --- p.i / Statement --- p.ii / Abstract --- p.iii / Acknowledgement --- p.vi / Abbreviations --- p.viii / Table of contents --- p.xii / List of figures --- p.xviii / List of tables --- p.xx / Chapter 1. --- Literature Review --- p.1 / Chapter 1.1 --- Salinity as a global problem --- p.1 / Chapter 1.2 --- Formation of saline soil --- p.1 / Chapter 1.3 --- Urgent need to reclaim saline lands --- p.2 / Chapter 1.4 --- Cellular routes for Na+ uptake --- p.2 / Chapter 1.4.1 --- Carriers involved in K+ and Na+ uptake --- p.2 / Chapter 1.4.2 --- Channels involved in K+ and Na+ uptake --- p.4 / Chapter 1.5 --- Adverse effects of high salinity --- p.5 / Chapter 1.5.1 --- Hyperosmotic stress --- p.5 / Chapter 1.5.2 --- Ionic stress --- p.6 / Chapter 1.5.2.1 --- Deficiency of K+ --- p.6 / Chapter 1.5.2.2 --- Perturbation of calcium balance --- p.7 / Chapter 1.5.3 --- Toxicity of specific ions --- p.7 / Chapter 1.5.4 --- Oxidative stress --- p.10 / Chapter 1.6 --- Mechanisms of salt stress adaptation in plants --- p.11 / Chapter 1.6.1. --- Maintenance of ion homeostasis --- p.12 / Chapter 1.6.1.1 --- Regulation of cytosolic Na+ concentration --- p.12 / Chapter 1.6.1.2 --- SOS signal transduction pathway --- p.15 / Chapter 1.6.2 --- Dehydration stress adaptation --- p.17 / Chapter 1.6.2.1 --- Aquaporins ´ؤ water channel proteins --- p.17 / Chapter 1.6.2.2 --- Osmotic adjustment --- p.20 / Chapter 1.6.2.2.1 --- Genetic engineering of glycinebetaine biosynthesis --- p.23 / Chapter 1.6.2.2.2 --- Genetic engineering of mannitol biosynthesis --- p.27 / Chapter 1.6.3 --- Morphological and structural adaptation --- p.28 / Chapter 1.6.4 --- Restoration of oxidative balance --- p.29 / Chapter 1.6.5 --- Other metabolic adaptation --- p.31 / Chapter 1.6.5.1 --- Induction of Crassulacean acid (CAM) metabolism --- p.34 / Chapter 1.6.5.2 --- Coenzyme A biosynthesis --- p.34 / Chapter 1.7 --- Soybean as a target for studying salt tolerance --- p.36 / Chapter 1.7.1 --- Economical importance of soybean --- p.36 / Chapter 1.7.2 --- Reasons for studying salt stress physiology in soybeans --- p.38 / Chapter 1.7.3 --- Salt tolerant soybean in China --- p.39 / Chapter 1.7.4 --- Exploring salt tolerant crops by genetic engineering --- p.41 / Chapter 1.8 --- Significance of this project --- p.47 / Chapter 2. --- Materials and methods --- p.48 / Chapter 2.1 --- Materials --- p.48 / Chapter 2.1.1 --- Plant materials used --- p.48 / Chapter 2.1.2 --- Bacteria strains and plasmid vectors --- p.48 / Chapter 2.1.3 --- Growth media for soybean --- p.48 / Chapter 2.1.4 --- Equipment and facilities used --- p.48 / Chapter 2.1.5 --- Primers used --- p.48 / Chapter 2.1.6 --- Chemicals and reagents used --- p.49 / Chapter 2.1.7 --- Solutions used --- p.49 / Chapter 2.1.8 --- Commercial kits used --- p.49 / Chapter 2.1.9 --- Growth and treatment condition --- p.49 / Chapter 2.1.9.1 --- Characterization of salt tolerance of Wenfeng7 --- p.49 / Chapter 2.1.9.2 --- Samples for subtractive library preparations --- p.50 / Chapter 2.1.9.3 --- Samples for slot blot and northern blot analyses --- p.50 / Chapter 2.1.9.4 --- Samples for gene expression pattern analysis --- p.50 / Chapter 2.2. --- Methods --- p.52 / Chapter 2.2.1 --- Total RNA extraction --- p.52 / Chapter 2.2.2 --- Construction of subtractive libraries --- p.53 / Chapter 2.2.3 --- Cloning of salt-stress inducible genes --- p.53 / Chapter 2.2.3.1 --- Preparation of pBluescript II KS(+) T-vector for cloning --- p.53 / Chapter 2.2.3.2 --- Ligation of candidate DNA fragments with T-vector --- p.53 / Chapter 2.2.3.3 --- Transformation --- p.54 / Chapter 2.2.3.4 --- PCR screening --- p.54 / Chapter 2.2.4 --- Preparation of recombinant plasmid for sequencing --- p.55 / Chapter 2.2.5 --- Sequencing of differentially expressed genes --- p.55 / Chapter 2.2.6 --- Homology search of differentially expressed genes --- p.56 / Chapter 2.2.7 --- Expression pattern analysis --- p.56 / Chapter 2.2.7.1 --- Preparation of single-stranded DIG-labeled PCR probes --- p.56 / Chapter 2.2.7.2 --- Preparation of cRNA DIG-labeled probes --- p.57 / Chapter 2.2.7.3 --- Testing the concentration of DIG-labeled probes --- p.58 / Chapter 2.2.7.4 --- Slot blot --- p.58 / Chapter 2.2.7.5 --- Northern blot --- p.59 / Chapter 2.2.7.6 --- Hybridization --- p.60 / Chapter 2.2.7.7 --- Stringency washed --- p.60 / Chapter 2.2.7.8 --- Chemiluminescent detection --- p.60 / Chapter 3. --- Results --- p.61 / Chapter 3.1 --- Characterization of salt tolerance of Wenfeng7 --- p.61 / Chapter 3.2 --- Identification of salt-stress induced genes from Wenfeng7 --- p.70 / Chapter 3.2.1 --- Screening subtractive libraries of Wenfeng 7 for salt inducible genes --- p.70 / Chapter 3.2.1.1 --- Results of homology search for salt inducible genes --- p.71 / Chapter 3.2.1.2 --- Northern blot showing the salt inducibility of selected clones --- p.72 / Chapter 3.3 --- Genes expression pattern of selected salt inducible genes --- p.104 / Chapter 3.3.1 --- Expression of genes related to dehydration adjustment --- p.104 / Chapter 3.3.1.1 --- Dehydration responsive protein RD22 (Clone no.: HML806) --- p.104 / Chapter 3.3.1.2 --- Beta-amylase (Clone no.: HML767) --- p.104 / Chapter 3.3.2 --- Expression of genes related to structural modification --- p.105 / Chapter 3.3.3 --- Expression of genes related to metabolic adaptation --- p.105 / Chapter 3.3.3.1 --- Subgroup 1: Gene related to protein synthesis --- p.105 / Chapter 3.3.3.1.1 --- Translational initiation factor nsp45 (Clone no.: HML1042) --- p.105 / Chapter 3.3.3.1.2 --- Seed maturation protein PM37 (Clone no.: HML931) --- p.106 / Chapter 3.3.3.2 --- Subgroup 2: Genes related to phosphate metabolism (Clone no.: HML1000) --- p.107 / Chapter 3.3.3.3 --- Subgroup 3: Genes related to storage and mobilization of nutrient resources --- p.107 / Chapter 3.3.3.3.1 --- Vegetative storage protein A (Clone no.: HML762) --- p.107 / Chapter 3.3.3.3.2 --- Cysteine proteinase (Clone no.: HML928) --- p.107 / Chapter 3.3.3.4 --- Subgroup 4: Genes related to senescence --- p.109 / Chapter 3.3.4 --- Expression of genes encoding novel protein (Clone no.: HML782) --- p.109 / Chapter 4. --- Discussion --- p.125 / Chapter 4.1 --- Evaluation of salt tolerance of Wenfeng7 --- p.125 / Chapter 4.2 --- Isolation of salt inducible genes in Wenfeng7 --- p.127 / Chapter 4.2.1 --- Genes associated with dehydration adaptation --- p.129 / Chapter 4.2.1.1 --- Dehydration responsive protein RD22 --- p.129 / Chapter 4.2.1.2 --- Beta-amylase --- p.130 / Chapter 4.2.2 --- Genes associated with structural adaptation --- p.132 / Chapter 4.2.3 --- Genes associated with metabolic adaptation --- p.133 / Chapter 4.2.3.1 --- Subgroup 1: Genes related to protein synthesis --- p.133 / Chapter 4.2.3.2 --- Subgroup 2: Genes related to phosphate metabolism --- p.137 / Chapter 4.2.3.3 --- Subgroup 3: Genes related to storage and mobilization of nutrient resources --- p.138 / Chapter 4.2.3.4 --- Subgroup 4: Genes related to senescence --- p.140 / Chapter 4.2.4 --- Novel genes --- p.142 / Chapter 4.3 --- Brief summary --- p.142 / Chapter 5. --- Conclusion and perspectives --- p.144 / References --- p.146 / Appendix I: Screening for salt tolerant soybeans --- p.163 / Appendix II: Major equipment and facilities used --- p.165 / Appendix III: Major chemicals and reagents used in this research --- p.166 / Appendix IV: Major common solutions used in this research --- p.168 / Appendix V: Commercial kits used in this research --- p.170

Typescript (photocopy). / Digitized by Kansas Correctional Industries

by Wong Fuk Ling. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 100-115). / Abstracts in English and Chinese. / Thesis committee --- p.i / Statement --- p.ii / Abstract --- p.iii / Chinese abstract --- p.v / Acknowledgements --- p.vii / Abbreviations --- p.ix / Table of contents --- p.xii / List of figures --- p.xvi / List of tables --- p.xvii / Chapter 1. --- Literature review / Chapter 1.1 --- Soybeans / Chapter 1.1.1 --- Economical importance of soybean --- p.1 / Chapter 1.1.2 --- History and origin of soybean --- p.4 / Chapter 1.1.3 --- Qualitative traits of cultivated and wild soybeans --- p.5 / Chapter 1.1.4 --- Soybean resource in China --- p.6 / Chapter 1.1.5 --- Salt tolerant soybeans in China --- p.6 / Chapter 1.2 --- Salinization as a global problem --- p.7 / Chapter 1.3 --- Toxicity of salt in plants --- p.8 / Chapter 1.4 --- Salt stress signal transduction in plants --- p.10 / Chapter 1.4.1 --- Ionic and osmotic stress signaling / Chapter 1.4.1.1 --- Ca2+ signaling --- p.11 / Chapter 1.4.1.2 --- The SOS pathway --- p.12 / Chapter 1.4.1.3 --- Protein kinase pathways --- p.13 / Chapter 1.4.1.4 --- Phospholipid signaling --- p.14 / Chapter 1.4.1.5 --- ABA signaling --- p.17 / Chapter 1.4.2 --- Detoxification signaling --- p.17 / Chapter 1.4.3 --- signaling to coordinate cell division ana expansion --- p.18 / Chapter 1.5 --- Plant adaptations in plants --- p.18 / Chapter 1.5.1 --- Ion homeostasis --- p.18 / Chapter 1.5.1.1 --- Reduction of Na+ influx into the cells --- p.19 / Chapter 1.5.1.2 --- Extrusion of Na+ out of the cell --- p.19 / Chapter 1.5.1.3 --- Vacuolar compartmentation of Na+ --- p.20 / Chapter 1.5.2 --- Osmotic adjustment --- p.20 / Chapter 1.5.3 --- Antioxidant protection --- p.21 / Chapter 1.5.4 --- Morphological and structural modification --- p.21 / Chapter 1.6 --- The relationship of salt stress and phosphorus deficiency --- p.22 / Chapter 1.7 --- The importance of phosphorus in plants --- p.25 / Chapter 1.8 --- The role of purple acid phosphatase (PAP) in plants --- p.25 / Chapter 1.9 --- PAPs in soybean --- p.27 / Chapter 1.10 --- Hypothesis and significance of this project --- p.27 / Chapter 2. --- Materials and methods / Chapter 2.1 --- Materials / Chapter 2.1.1 --- Plant materials --- p.29 / Chapter 2.1.2 --- The clones used in this work --- p.30 / Chapter 2.1.3 --- Growth media for soybeans --- p.31 / Chapter 2.1.4 --- Equipment and facilities --- p.31 / Chapter 2.1.5 --- Primers --- p.31 / Chapter 2.1.6 --- Chemicals and reagents --- p.31 / Chapter 2.1.7 --- Solutions --- p.32 / Chapter 2.1.8 --- Commercial kits --- p.32 / Chapter 2.1.9 --- Software --- p.32 / Chapter 2.2. --- Methods / Chapter 2.2.1 --- Growth and salt treatment condition / Chapter 2.2.1.1 --- Establishment a collection of typical salt tolerant and sensitive soybean varieties --- p.33 / Chapter 2.2.1.2 --- Samples for northern analysis of salt inducible genes --- p.33 / Chapter 2.2.1.3 --- Samples for characteristics of GmPAP3 gene --- p.35 / Chapter 2.2.1.4 --- Samples for oxidative stress test --- p.36 / Chapter 2.2.2 --- Total RNA extraction --- p.36 / Chapter 2.2.3 --- Denaturing gel electrophoresis of RNA --- p.38 / Chapter 2.2.4 --- Expression pattern analysis / Chapter 2.2.4.1 --- Preparation of single-stranded DIG-labeled PCR probes --- p.39 / Chapter 2.2.4.2 --- Testing the concentration of DIG-labeled probes --- p.40 / Chapter 2.2.4.3 --- Northern blot --- p.41 / Chapter 2.2.5 --- Soluble ions analysis --- p.42 / Chapter 2.2.6 --- Acid phosphatase activity assays --- p.42 / Chapter 2.2.7 --- Phylogenetic analysis and subcellular localization prediction of GmPAP3 --- p.43 / Chapter 3. --- Results / Chapter 3.1 --- Establishing a collection of typical salt tolerant and sensitive soybean varieties --- p.44 / Chapter 3.2 --- Characterization of salt inducible genes --- p.48 / Chapter 3.3 --- Characterization of GMPAP3 gene --- p.63 / Chapter 3.3.1 --- Phylogenetic studies of the GmPAP3 --- p.64 / Chapter 3.3.2 --- The salt-inducible GmPAP3 gene in soybean encodes a putative mitochondria-located PAP --- p.64 / Chapter 3.3.3 --- Expression of GmPAP3 was induced by NaCl stress but not P deficiency --- p.71 / Chapter 3.3.4 --- Expression of GmPAP3 was induced by oxidative stress --- p.80 / Chapter 4. --- Discussion --- p.82 / Chapter 4.1 --- A collection of typical salt tolerant and sensitive soybean varieties --- p.83 / Chapter 4.2 --- Inducibility of identified salt-inducible gene in different varieties --- p.85 / Chapter 4.2.1 --- The possible roles of identified salt-inducible genes --- p.85 / Chapter 4.2.2 --- Expression profiles of identified salt-inducible genes --- p.89 / Chapter 4.3 --- The novel gene GmPAP3 --- p.92 / Chapter 5. --- Conclusion and perspectives --- p.98 / References --- p.100 / Appendix I: Expression profiles of the salt inducible genes in root tissue of selected varieties --- p.116 / Appendix II: Major equipment and facilities used in this research --- p.124 / Appendix III: Major chemicals and reagents used in this research --- p.125 / Appendix IV: Major common solutions used in this research --- p.127

我們在大豆的耐鹽候選基因中進行了篩選和調查，確定了一個穀胱甘肽-S -轉移酶（Glutathion-S-transferase ）基因（ GmGSTL1 ）具抗鹽特性，其表達量也跟隨鹽處理上調。系統發育分析表明，GmGSTL1 屬於LAMBDA 類，文獻對這類蛋白功能的記載甚少。我們在異源系統，包括煙草BY- 2 細胞和擬南芥，測試其保護細胞/植物對鹽脅迫的功能。結果表示GmGSTL1 轉基因細胞的活性氧積累比對照顯著降低，存活率也有所改善。同樣，轉基因擬南芥在鹽處理壓力下的症狀也得以緩解。為了進一步剖析GmGSTL1 的保護機制，我們在大豆葉片中提取多元酚，並發現兩個候選黃酮（槲皮素，山奈酚）與GmGSTL1 起相互作用。槲皮素的外源性應用同樣可以緩解細胞/植物在鹽脅迫下的症狀，表示槲皮素在功能上與GmGSTL1 相約。 / In a survey of candidate genes located in the salinity tolerance locus of soybean, we identified a putative glutathione-S-transferase (GST) gene (GmGSTL1) which was up-regulated in response to salt treatment. Phylogenetic analyses revealed that this putative GST belongs to the Lambda class, a plant-specific group with unknown functions. We expressed GmGSTL1 in heterologous systems, including tobacco BY-2 cells and Arabidopsis thaliana, to test its ability to protect cell/plant against salinity stress. Compare to the wild type control, we observed a marked reduction of ROS accumulation in transgenic cells under salt treatment, and their survival rate was also improved. Similarly, expression of GmGST1 in transgenic A. thaliana also alleviated stress symptoms under salt treatment. To further address the possible protective mechanisms of GmGSTL1, we identified two candidate flavonoid interactants (quercetin and kaemferol) of the GmGSTL1 protein from soybean leaf extract. Exogenous application of quercetin could reduce salinity-induced ROS accumulation in BY-2 cells and leaf chlorosis in A. thaliana. / Detailed summary in vernacular field only. / Chan, Ching. / Thesis (Ph.D.) Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 80-104). / Abstracts also in Chinese.

Histone modifications and histone variants are of importance in many biological processes. Whether they play some roles in regulating soybean salinity stress response is unknown. Previously, no study of histone modifications and histone variants in soybean were reported. In this study, I elucidated that in soybean leaves, mono-, di- and tri-methylation at Lysine (K) 4, 27 and 36, and acetylation at Lysine 14, 18 and 23 were present in histone H3. Moreover, H3K27 methylation and H3K36 methylation usually excluded each other. Although H3K79 methylation was not reported in Arabidopsis, they were detected in soybean. In soybean histone H4, Lysine 8 and 12 were acetylated. In addition, the variants of histone H3 and H4 and their modifications were also determined. The variants of histone H3 were different at positions of A31F41S87S90 (histone variant H3.1) and T31Y41H87 L90 (histone variant H3.2), respectively. Lysine 4 and 36 methylation were only detected in histone H3.2, suggesting that histone variant H3.2 might associate with actively transcribing genes. The two variants of histone H4 (H4.1 and H4.2) were different at amino acid 60. Moreover, I also found that the abundance of most of the histone modifications and histone variants did not change under the salinity stress except that H3K79 methylation would be up-regulated by the salinity stress. / In a parallel study, a PHD (plant homeodomain) finger domain containing protein, GmPHD1, was able to decipher the 'code' underlying H3K4 methylation. GmPHD1 was ubiquitously expressed in soybean and its expression increased upon salinity stress. GmPHD1 could bind to histone H3K4 methylation, with the preference to H3K4 dimethylation. It could then recruit several proteins, which were GmGNAT1, GmElongin A, and GmISWI. The interaction between GmPHD1 and GmGNAT1 was regulated by the self-acetylation of GmGNAT1. GmGNAT1 could also acetylate histone H3; GmElongin A was a transcription elongation factor; and GmISWI was a chromatin remodeling protein. Our data also indicated that the GmPHD1 located at the promoter of several soybean salt stress inducible genes. Therefore, the GmPHD1 recruited proteins to remodel the chromatin structure and facilitate the transcription of those salt stress inducible genes. Moreover, GmGNAT1 exhibited the preference to acetylate histone H3K14, therefore representing a kind of histone crosstalk between H3K4 methylation and H3K14 acetylation. / Proteomics studies with 2-DE revealed that salt treatment may affect soybean photosynthesis and chloroplast formation. Comparison between the proteomic profiles of salt tolerant soybean variety (wild type) and salt sensitive soybean variety (cultivated, Union) indicated that protein levels in the detoxification and defense pathway as well as energy metabolism were higher in the wild type soybean, while the process of protein metabolism was less active. In addition, proteomic profiles of the cultivated soybean roots at different developmental stages were also compared to identify proteins related to soybean development. The expression of proteins which play critical roles in detoxification and defense pathways were higher at the seedling stage, especially the proteins which regulated the formation of ROS. / Soybean is an important economic crop and its production can be severely affected by salinity stress. At present, the soybean response to salinity stress is not clear. In my studies, I tried to understand this process from the perspective of proteomics and epigenetics, especially histone modifications. / Wu, Tao. / Advisers: Njai Sai Ming; Lam Hon Ming. / Source: Dissertation Abstracts International, Volume: 73-02, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 126-151). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Thesis (M.Sc. (Agronomy)) --University of Limpopo, 2015 / Soybean (Glycine max (L.) Merrill) is considered to be an important grain legume and an oil crop. It is also important in livestock feeding and improvement of soil fertility through biological nitrogen fixation (BNF). Until recently, soybean was not widely grown by smallholder (SH) farmers in Africa. This has led to breeding of promiscuous varieties to ensure wide adoption of the crop by SH farmers, without the use of inoculants or expensive nitrogen fertilizers. Field and glasshouse experiments were conducted during 2012/2013 growing season. One commercial (specific) variety Dundee and three naturally-nodulating (promiscuous) soybean varieties (TGx-1937-1F, TGx-1740-2F, TGx-1835-10E) were evaluated in a field trial for their growth, nodulation and yield response to B. japonicum strain WB74 inoculation. Seed inoculation in the field enhanced chlorophyll content, number of nodules, nodule dry weight, and the percentage of active nodules, number of pods, hundred seed weight, shelling percentage and grain yield. Varietal differences exerted significant (P≤0.05) effect on all field parameters evaluated except on nodule number and percentage of active nodules. TGx-1937-1F achieved the highest number of nodules (28 per plant) while the highest percentage of active nodules (69%) was achieved by TGx-1740-2F. Huge effect of inoculation was observed on Dundee variety, and resulted in significant grain yield increases (237.8%) while smaller gain increases were observed in TGx-1740-2F (43.9%) and TGx-1835-10E (38.7%). The yield of TGx-1937-1F did not respond to inoculation. Two promiscuous (TGx-1937-1F and TGx-1740-2F) varieties and one commercial (Dundee) variety were evaluated in a glasshouse trial for their growth and nodulation response to inoculation in different soil types (sandy clay loam, sandy loam, loamy sand) of Limpopo Province. In the glasshouse inoculation showed effect on chlorophyll content only, and effect of soybean variety was found to be significant on days to flowering, chlorophyll content, plant height, number of nodules and root dry weight. Soil type showed significant effect on all parameters evaluated in the glasshouse study except on nodule dry weight. Loamy sand soil from Ga-Molepo gave tallest plants and highest nodule number at 61 cm and 29 nodules/plant compared to other soils. All soils evaluated in the study resulted in percent active nodules ranging from 74.5% to 77.4% showing possibility of presence of cowpea-type rhizobia in Limpopo soils capable of fixing atmospheric nitrogen. Inoculation x variety interaction was significant on days to flowering, plant height and chlorophyll content. Inoculant application in TGx-1740-2F variety reduced the number of days it took to flowering from 61 to 54 days and increased its plant height by 57% from 44.8 to 67.9 cm. Eighty three percent (83%) increase on chlorophyll content of variety Dundee was observed due to effect of inoculation. Inoculation x soil type interaction had significant effect on plant height and dried plant biomass. Varity x soil type interaction influenced chlorophyll content, while the interactive effects of inoculation x variety x soil type were significant on chlorophyll content only. The study showed that it is beneficial to inoculate the soybean varieties studied, especially the commercial variety Dundee, in order to enhance their growth, nodulation and yield. / Department of Agriculture Forestry and Fisheries