FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / Os baixos teores de fÃsforo disponÃveis nos solos tropicais, em geral, requerem permanentes pesquisas com relaÃÃo à eficiÃncia das aplicaÃÃes de diferentes fontes de adubos fosfatados nas culturas cujo objetivo à elevar os teores desse nutriente no solo. Este trabalho teve como objetivo, estudar as respostas do sorgo (Sorghum bicolor) Ãs aplicaÃÃes de diferentes doses e fontes de fÃsforo no que concerne ao crescimento, produÃÃo e remoÃÃo de nutrientes, alÃm de avaliar a eficiÃncia agronÃmica das diferentes fontes. O experimento foi realizado em casa de vegetaÃÃo da Universidade Federal do CearÃ. Foi utilizado o solo da Chapada do Apodi-CE, Cambissolo HÃplico EutÃfico. No presente trabalho foi utilizado o delineamento em blocos inteiramente casualizados, em esquema fatorial 4x4 (doses e fontes de P, respectivamente), sendo os tratamentos composto pela combinaÃÃo de quatro doses de fÃsforo (dose 1 = 0 mg de P kg-1 solo, dose 2 = 100 mg de P kg-1 solo, dose 3 = 200 mg de P kg-1 solo e dose 4 = 300 mg de P kg-1 solo) e quatro fontes de P (Fosfato Industrial Superfosfato Triplo - ST, Fosfato Natural da Bahia - FNB, Fosfato Natural do Tocantins - FNT e Fosfato Natural Reativo â Gafsa â FNR), com 4 repetiÃÃes, totalizando 64 unidades experimentais. Foram avaliadas as seguintes variÃveis: altura da planta, diÃmetro do caule, produÃÃo de matÃria seca da parte aÃrea, e teores foliares de macronutrientes e micronutrientes presentes no sorgo. As variÃveis analisadas foram submetidas à anÃlise de variÃncia (ANOVA), Ãs anÃlises de regressÃo em funÃÃo das fontes e das doses crescentes de fÃsforo e as mÃdias dessas variÃveis foram avaliadas pelo teste de Tukey, a nÃvel de 1% e 5% de probabilidade. O Superfosfato triplo (ST) e o FNB foram as fontes responsÃveis pelas respostas mais altamente significativas das variÃveis biomÃtricas estudadas, enquanto que o FNT apresentou as menores respostas. As fontes que mais contribuÃram para a absorÃÃo de fÃsforo do solo pelo sorgo foram em ordem decrescente: ST > FNB> FNR> FNT. Na dose 300 mg kg-1solo ocorreu a maioria dos valores elevados de absorÃÃo de macronutriente e micronutriente No que concerne Ãs absorÃÃes de macronutrientes e micronutrientes pelo sorgo em funÃÃo das doses e das fontes de fÃsforo usadas, estas ocorreram na seguinte ordem decrescente: N > K > Ca > Mg > P > S; para os micronutrientes, a ordem foi: Mn > Fe > Zn > Cu. A fonte que apresentou o melhor Ãndice de EficiÃncia AgronÃmica foi o Superfosfato triplo (ST), seguido do FNB. / The low available phosphorus in tropical soils generally require constant research regarding the efficiency and the application of different sources of phosphate fertilizers on crops. This work aimed to study the responses of sorghum (Sorghum bicolor) to applications of different levels and sources of phosphorus in terms of growth, yield and nutrient removal, and also to evaluate the agronomic efficiency of these different sources. The experiment was conducted under greenhouse conditions at the Federal University of CearÃ, Brazil. It was used a Cambisol soil from the Chapada do Apodi-CE. The statistical design consisted of a randomized complete block in a 4x4 factorial (rates and sources of P, respectively), with treatments consisting of a combination of four rates of phosphorus (rate 1 = 0 mg P kg-1 soil, rate 2 = 100 mg P kg-1 soil, rate 3 = 200 mg kg-1, rate 4 = 300 mg P kg-1 soil) with 4 replicates, totalizing 64 experimental units; it was used four sources of P (Phosphate Industrial Triple superphosphate - TS, Natural Phosphate of Bahia - NFB, Natural Phosphate of Tocantins - NPT and Natural Reactive phosphate - Gafsa - NRP). The following variables were evaluated: plant height, stem diameter, dry shoot matter production and, macronutrients and micronutrients leaf concentrations. The variables value results were subjected to analysis of variance (ANOVA), regression analysis according to sources and increasing rates of phosphorus; the averages of these variables were evaluated by the Tukey test at 5% probability. The TS and the NFB sources were responsible for the higher significant responses of the biometric variables studied, whereas NPT induced the lowest responses. The sources that contributed most to the plant absorption of soil phosphorus by sorghum were in descending order: TS > NFB > NRP > NPT. In the rate 300 mg kg-1solo occurred the most elevated macronutrient and micronutrient plant P uptake. Considering the amounts of macronutrients and micronutrients absorbed by sorghum, in function of rates and P sources, these occurred in the following order: N > K > Ca > Mg > P > S (macronutrients); Mn > Fe > Zn > Cu (micronutrients). The source that had the highest index of Agronomic Efficiency was the Triple superphosphate, followed by the Natural phosphate of Bahia.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / This study aimed to evaluate the effects of salinity of irrigation water and organic compound on the development in sorghum [Sorghum bicolor (L.) Moench.] cv. BRS Ponta Negra. Therefore, three experiments were performed: the first, there was the effect of cattle manure and commercial biofertilizer Ative and irrigation with different salinity water in the sorghum plants; in the second there was the cattle manure doses (10, 20, 30 and 40 t ha-1) and the salinity of the irrigation water; and in the third, there was the use of liquid biofertilizer Ative doses (75, 150, 225 and 300 L ha-1 ) and salinity irrigation water. The plants were grown in pots containing 23 kg of sandy soil under greenhouse conditions. Salinity levels were 0.2; 2.0; 4.0; and 6.0 dS m-1, being used for its preparation is pond water with NaCl added in the first experiment; the second and third experiments with NaCl salts, CaCl22H2O and MgCl26H2O , the ratio of 7:2:1. The experimental design was completely randomized with five replicates in a factorial 4 x 3 in the first experiment; four replications, in a factorial 4 x 4, second and third experiments. The following variables were assessed: total dry matter; culms + sheath diameter; plant height; total leaf area; leaf succulence; bulk density leaf; sodium, potassium, chloride, calcium, magnesium and phosphorus in the leaves and culms + sheath of plants; proline and carbohydrates in the leaves of plants. In addition to the soil analysis of the experiments. The results show the three experiments that salinity affected all variables, with beneficial cattle manure and biofertilizer, however, without reducing the deleterious effects of salts when applied through irrigation water. / Este trabalho teve como objetivo avaliar os efeitos da salinidade da Ãgua de irrigaÃÃo e compostos orgÃnicos, sobre o desenvolvimento de plantas de sorgo [Sorghum bicolor (L.) Moench.] cv. BRS Ponta Negra. Para isso foram realizados trÃs experimentos: no primeiro, verificou-se o efeito da aplicaÃÃo de esterco bovino e do biofertilizante comercial Ative e irrigaÃÃo com Ãgua de salinidades diferentes nas plantas de sorgo; no segundo, verificou-se as doses de esterco bovino (10, 20, 30 e 40 t ha-1) e a salinidade da Ãgua de irrigaÃÃo; e, no terceiro, verificou-se o uso de doses de biofertilizante lÃquido Ative (75, 150, 225 e 300 L ha-1) e salinidade da Ãgua de irrigaÃÃo. As plantas foram cultivadas em vasos contendo 23 kg de solo arenoso, em casa de vegetaÃÃo. Os nÃveis de salinidade foram 0,2; 2,0; 4,0; e 6,0 dS m-1, sendo que para a sua confecÃÃo utilizou-se Ãgua de aÃude adicionada com NaCl no primeiro experimento; no segundo e terceiro experimentos com sais de NaCl, CaCl22H2O e MgCl26H2O, na proporÃÃo de 7:2:1. O delineamento experimental foi inteiramente casualizado com cinco repetiÃÃes em esquema fatorial 4 x 3, no primeiro experimento; quatro repetiÃÃes, em esquema fatorial 4 x 4, no segundo e terceiro experimentos. Foram avaliadas as seguintes variÃveis: matÃria seca total; diÃmetro do colmo; altura de plantas; Ãrea foliar total; suculÃncia foliar; massa especÃfica foliar; teores de sÃdio, potÃssio, cloro, cÃlcio, magnÃsio e fÃsforo no colmo + bainhas e limbos foliares das plantas; teores de prolina e carboidratos nas folhas de sorgo. AlÃm das anÃlises de solo dos experimentos. Os resultados evidenciam nos trÃs experimentos que a salinidade influenciou todas as variÃveis analisadas, apresentando efeitos benÃficos do esterco bovino e biofertilizante, no entanto, sem diminuir os efeitos deletÃrios dos sais quando aplicados atravÃs da Ãgua de irrigaÃÃo.

Fundação de Amparo a Pesquisa no Estado do Rio Grande do Sul / The Brazilian ethanol production is mainly based on the sugarcane crop, however in the off-season mills plants cease processing, decreasing revenues as a result of the shortage of raw materials. It is in this scenario that fits the sweet sorghum, being able to provide quality material during the off-season sugarcane, in the summer months. The objective of this study was to evaluate the qualitative parameters and maturation curves of eleven genotypes of sweet sorghum, aiming ethanol production. Field experiment was conducted in Santa Maria-RS, in two growing seasons (2012/13 and 2013/14). The experimental design was randomized blocks with three replications and the treatments consisted of eleven genotypes, seven varieties (BRS506, BRS511, Fepagro 17, Fepagro 19, Past 81-04, Past 29-51 and Past 29-49) and four hybrids (CV007, CV147, CV568 and CV198). The quality of sweet sorghum juice was evaluated based on parameters: sucrose content (%), reducing sugars (%), purity (%), total soluble solids (°Brix), total recoverable sugar (kg t-1), fiber (%) and ethanol production (l ha-1). It was determined the maturity curve to characterize the industrial use period (IUP). The genotypes BRS506, BRS511 and CV198 showed IUP over 30 days. The BRS506 and BRS511 genotypes showed better characteristics for ethanol production. / A produção brasileira de etanol é baseada principalmente na cultura da cana-de-açúcar, porém, no período de entressafra as usinas cessam o processamento, diminuindo as receitas em decorrência da escassez de matéria-prima. É neste cenário que se encaixa o sorgo sacarino, capaz de fornecer material de qualidade durante o período de entressafra da cana, nos meses de verão. Desta forma, o objetivo do presente estudo foi avaliar os parâmetros qualitativos e as curvas de maturação de onze genótipos de sorgo sacarino durante dois anos de cultivo, visando a produção de etanol. O experimento foi conduzido em Santa Maria-RS, nos anos agrícolas de 2012/13 e 2013/14. Foi utilizado o delineamento experimental de blocos ao acaso com três repetições e os tratamentos foram compostos por onze materiais genéticos, sendo sete variedades (BRS506, BRS511, Fepagro 17, Fepagro 19, Past 81-04, Past 29-51 e Past 29-49) e quatro híbridos (CV007, CV147, CV568 e CV198). Foram avaliados os parâmetros qualitativos sacarose do caldo (%), açúcares redutores do caldo (%), pureza do caldo (%), sólidos solúveis totais (°Brix), açúcar total recuperável (kg t-1), fibra (%), rendimento de etanol (l ha-1) e também as curvas de maturação para a obtenção do período de utilização industrial (PUI). Os genótipos BRS506, BRS511 e CV198 apresentaram PUI superior a 30 dias. Os genótipos BRS506 e BRS511 apresentaram melhores características para produção de etanol.

Master of Science / Department of Agronomy / Tesfaye Tesso / Sorghum [Sorghum bicolor (L.) Moench] is listed as one of the potential feedstock sources for biofuel production. While sorghum grain can be fermented into ethanol in a similar way as maize, the greatest potential of the crop is based on its massive biomass and sugar rich juices. Thus development of the crop as alternative energy source requires improvement of these traits. The objectives of this study were (1) to determine the mode of inheritance of traits related to ethanol production and identify suitable genetic sources for use in breeding programs, and (2) to evaluate the potential of low lignin mutations for biomass feedstock production and assess biotic stress risks associated with deployment of the mutations. The study consisted of three related experiments: (i) estimating the combining ability of selected sweet and high biomass sorghum genotypes for biofuel traits and resistance to stalk lodging, (ii) determine the impact of brown mid-rib mutations on biofuel production and their reaction to infection by Macrophomina phaseolina and Fusarium thapsinum, and (iii) assess the reaction of low lignin mutants to green bug feeding. In the first experiment six sorghum genotypes of variable characteristics (PI193073, PI257602, PI185672, PI195754, SC382 and SC373) were crossed to three standard seed parent lines ATx3042, ATx623 and ATx399. The resulting hybrids and the parents were evaluated at four locations, three replications during 2009 and 2010 seasons. Data were collected on phenology, plant height, juice yield, °brix score and biomass production. In the second experiment, two brown mid-rib mutations (bmr6 and bmr12) and their normal versions were studied in four forage sorghum backgrounds (Atlas, Early Hegari, Kansas Collier and Rox Orange). The experiment was planted in four replications and at 14 d after flowering five plants in a plot were artificially infected with F. thapsinum and another five with M. phaseolina. The plants were harvested and rated for disease severity (lesion length and nodes crossed). Another five normal plants in each plot were harvested and used to determine biofuel traits (juice yield, ºbrix score and biomass). In the third experiment, a subset of entries evaluated in experiment II and three tolerant and susceptible checks were tested for greenbug feeding damage. Biotype K greenbug colony was inoculated to each genotype using double sticky foam cages. Feeding damage was assessed as percent chlorophyll loss using SPAD meter. There was significant general combining ability (GCA) effect among the male entries for juice yield, stem obrix and biomass production indicating that these traits are controlled by additive genes. Lines PI257602 and PI185672 in particular, had the highest GCA for all the traits and should serve as excellent breeding materials. There was no significant difference among the bmr mutants and between the bmr and normal genotypes for both stalk rot and greenbug damage. In conclusion, juice yield, °brix and biomass are largely controlled by additive genes and hence are amenable to genetic manipulation. The bmr mutations despite their impact on lignin content do not increase risk of attack by stalk rot pathogens and greenbugs and thus can be deployed for biofuel production without incurring losses to these factors.

Submitted by Isabo Melina Pascoaloto null (isabomelina@gmail.com) on 2017-03-08T11:29:00Z No. of bitstreams: 1 Dissertação versão FINAL.pdf: 3911089 bytes, checksum: 8ce0f61c10f4a03f01925084f2630564 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2017-03-13T19:10:49Z (GMT) No. of bitstreams: 1 pascoaloto_im_me_ilha.pdf: 3911089 bytes, checksum: 8ce0f61c10f4a03f01925084f2630564 (MD5) / Made available in DSpace on 2017-03-13T19:10:49Z (GMT). No. of bitstreams: 1 pascoaloto_im_me_ilha.pdf: 3911089 bytes, checksum: 8ce0f61c10f4a03f01925084f2630564 (MD5) Previous issue date: 2017-02-20 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O aumento da população mundial e a necessidade crescente de alimentos têm levado à procura de sistemas de cultivo de alta produtividade e sustentabilidade. A integração lavoura-pecuária preenche esses requisitos pois permite a produção de grãos, carnes e outros produtos de origem animal em uma mesma área, garantindo também, quando bem manejada, o equilíbrio e conservação do solo. Entretanto, diferentes espécies concomitantemente em uma mesma área podem prejudicar a produtividade. Por isso, o objetivo foi analisar qual a melhor opção técnica e econômica num sistema de integração lavoura-pecuária sob plantio direto, cultivado por dois anos com sorgo consorciado com forrageiras tropicais e/ou guandu-anão e sucedido por soja ou milho. O delineamento experimental foi de blocos ao acaso, com quatro repetições. Os tratamentos foram constituídos por modalidades de sorgo forrageiro consorciado com: 1) Urochloa brizantha cv. Marandu; 2) U. brizantha cv. Marandu e guandu-anão; 3) Megathyrsus maximus cv. Mombaça; 4) M. maximus cv. Mombaça e guandu-anão; 5) guandu-anão e 6) sorgo solteiro, colhidos para silagem no primeiro corte e na rebrota e sucedidos por soja ou milho. Para tanto foram determinados: os atributos físico-químicos do solo antes de cada ano agrícola e após a colheita dos grãos de soja ou milho; os componentes de produção do primeiro corte e rebrota dos consórcios de sorgo com gramíneas forrageiras e/ou guandu-anão; o acúmulo de macronutrientes nas plantas em consórcio; o crescimento das forrageiras para formação de pasto; a taxa de decomposição da palhada das forrageiras; os componentes de produção da soja e do milho; o acúmulo de macronutrientes nos grãos; os custos de produção dos três anos agrícolas e os respectivos índices de lucratividade. A forrageira M. maximus prejudicou a rebrota do sorgo e a produtividade do milho semeado em sucessão, resultando em prejuízos econômicos. Os consórcios com o sorgo aumentaram o teor de matéria orgânica do solo na camada de 10 a 20 cm em relação ao sorgo solteiro. O uso de uma leguminosa acelerou a decomposição da palhada da forrageira consorciada. O cultivo de várias espécies em uma mesma área resultou em maior microporosidade do solo e acidez potencial se comparado ao cultivo do sorgo solteiro. Houve menor interferência dos consórcios cultivados anteriormente na soja em relação ao milho na região do Cerrado. / FAPESP: 2015/06685-0

Five breeding populations were created by crossing elite U.S. sorghum parental lines (RTx430, RTx436, BTx631, BTx635, and Tx2903) with 'Sureño', a dual purpose grain mold resistant sorghum cultivar. Molecular markers associated with five previously-reported quantitative trait loci (QTL) for grain mold resistance originating in 'Sureño' were used to determine if their presence enhanced selection for grain mold resistance in these populations. The allelic status of 87 F4 lines, with respect to these QTL, was determined using both simple sequence repeats (SSR) and amplified fragment length polymorphism (AFLP) markers. All 87 F4:5 lines and their parental lines, were evaluated for grain mold resistance in replicated trials in eight diverse environments in South and Central Texas during the summer of 2002. The effects of each allele from the grain mold resistant parent 'Sureño' were determined across and within all five populations, within individual environments, and in each population x environment combination. With a few exceptions, the QTL were effective in reducing grain mold susceptibility only within the RTx430/Sureño progeny, the identical cross that was used in the original mapping study. The results indicate that while that these alleles do confer additional grain mold resistance, they are only selectable in the original mapping population. This fact limits their potential usefulness in an applied breeding program.

Crops adapted to dry conditions are essential to meet future food, feed and energy needs. Knowledge of interaction between drought tolerance traits and their response to varying water supply conditions would improve selection for yield stability traits. This study focused on determining the association between the QTL regulating the staygreen trait in sorghum with improved canopy temperature depression (CTD) as regulated by total and compositional epicuticular wax content in a recombinant inbred line population derived from BTx642 and RTx7000. Phenotypic data were collected in 3 replicated field trials and 1 greenhouse trial. Plants with higher leaf EWL had cooler canopies. Our results also confirmed that staygreen genotypes are able to maintain cooler canopy than the non-stay-green genotypes under drought and hot conditions. We have suggested that wax might offer a more stable indicator for selection of drought tolerance under a variety of weather conditions. Composite interval mapping identified a total of 28 QTL, fifteen of which had significant overlaps. The overlap between QTL for cuticular leaf wax and QTL for staygreen exhibits a departure from the QTL overlaps for other traits with that of cuticular leaf wax. We have also suggested that under drought stress, the QTL for staygreen may be expressed earlier in time (at anthesis) than had been previously believed.

Five breeding populations were created by crossing elite U.S. sorghum parental lines (RTx430, RTx436, BTx631, BTx635, and Tx2903) with 'Sureño', a dual purpose grain mold resistant sorghum cultivar. Molecular markers associated with five previously-reported quantitative trait loci (QTL) for grain mold resistance originating in 'Sureño' were used to determine if their presence enhanced selection for grain mold resistance in these populations. The allelic status of 87 F4 lines, with respect to these QTL, was determined using both simple sequence repeats (SSR) and amplified fragment length polymorphism (AFLP) markers. All 87 F4:5 lines and their parental lines, were evaluated for grain mold resistance in replicated trials in eight diverse environments in South and Central Texas during the summer of 2002. The effects of each allele from the grain mold resistant parent 'Sureño' were determined across and within all five populations, within individual environments, and in each population x environment combination. With a few exceptions, the QTL were effective in reducing grain mold susceptibility only within the RTx430/Sureño progeny, the identical cross that was used in the original mapping study. The results indicate that while that these alleles do confer additional grain mold resistance, they are only selectable in the original mapping population. This fact limits their potential usefulness in an applied breeding program.

The introduction of dwarfing genes in wheat and rice enabled significant yield improvements and was later termed the “Green-Revolution”. Dwarfing genes in sorghum have not been accompanied by such increases in grain production. On the contrary, some of the commercially employed dwarfing genes in sorghum have been associated with negative effects on grain yield. A positive correlation between plant height and grain yield was also observed in trial data for a diverse range of hybrids tested within the Queensland Department of Primary Industries and Fisheries Sorghum Breeding Program in north-eastern Australia. No attempts have previously been made to examine the physiological basis of the relationship between plant height and grain yield in sorghum. The dwarfing genes that are commercially used in wheat, Rht-B1 and Rht-D1 (formerly known as Rht1 and Rht2, respectively), on the other hand, have been studied extensively. They have been shown to have substantial and positive effects on grain number and harvest index, while not considerably reducing plant biomass, increasing grain yield. Our objective in this study was to examine the effect of height on the physiological and genetic determinants of growth and yield in sorghum to determine whether there was scope to improve yield by increasing the height of sorghum. A positive correlation between plant height and yield was observed in a population that was fixed for the major dwarfing genes, but showed variation in peduncle and panicle length, which are under control of minor dwarfing genes. To study the effects of a single major dwarfing gene (dw3) on biomass production and grain yield, 2- and 3-dwarf isogenic contrasts were developed in three different genetic backgrounds (R931945-2-2, R955343-1, R955637). In some cases, dw3 led to a significant reduction in plant biomass, which was not sufficiently offset by increase in harvest index to avoid yield reduction. This is contrary to the situation in wheat. The observed reductions in plant biomass in sorghum were associated with reduced tiller number and a reduction in radiation use efficiency (RUE) in the short types. Subsequent experiments suggested that an increase in allocation of biomass to the roots, rather than differences in photosynthetic capacity or respiration, was the main cause for the apparent reduction in RUE. However, due to plant-to-plant variability and the difficulty in accurately measuring root-total biomass ratio, studies with greater replication are required to confirm this hypothesis. It was also found that interactions with genetic background (and environment) moderated the effects of dw3, resulting in smaller height, biomass and grain yield reductions in some isogenic pairs. The effects of dwarfing genes on grain yield therefore need to be assessed separately for different genetic backgrounds. As lodging may be controlled by means other than height reduction (e.g. stay-green), we suggest that yield of standard sorghum types used in industrialised countries may benefit from moderate increases in plant height.

Sorghum is a valuable grain crop and a principle source of food of particular importance in human and animal nutrition in the semi-arid regions of Africa and Asia. Despite its value, sorghum grain quality is a major limitation to its productivity and profitability. Sorghum grain is usually discounted as feed grain when compared to wheat and barley, predominantly because of its poor digestibility. The sorghum endosperm is composed of a complex starch protein matrix, whereby the starch is physically bound within the storage proteins, the kafirins. The kafirins are synthesised on the membrane bound polysomes and have a signal peptide which targets them to the lumen of the endoplasmic reticulum. Growth of protein bodies occur as - kafirins fill in the interior with  and γ kafirins occupy the periphery. Despite the -kafirins being more digestible and composing of 60- 80% of the kafirins, they are not easily accessible due to  and γ kafirins which have a high content of intermolecular disulphide bonds (S-S), rendering them highly resistant to proteases. Alteration of the structure of the protein bodies and change of the location of the-kafirins could result in a higher digestibility of sorghum proteins. This could be achieved by upregulating or downregulating the -kafirins. The improvement of grain quality, both in increased protein and starch digestibility would substantially enhance the digestibility of sorghum as animal feed as well as for human consumption. Various techniques have been utilised to classify the kafirins according to their mobility on SDS PAGE electrophoresis, Reverse Phase High Performance Liquid Chromatography (RP-HPLC), Free Zone Capillary Electrophoresis (FZCE) and Lab on Chip. Until recently the characterisation and classification of the kafirins generally have relied on the characterisation of zeins from maize. Zeins have about 70% homology to the kafirins both at the nucleotide and amino acid level. Based on the high similarity of the -kafirins to the -zeins, the - kafirins have been classified as 19 and 22 kDa. Despite their 70% homology the migration of the - kafirins on SDS PAGE is quite different to that of the zeins. Hence, I propose a new classification of the -kafirins as 23 kDa and 25 kDa based on their mobility on SDS PAGE Characterisation and cloning of the 23 and 25 kDa genes was performed using QL41 the Queensland inbred line of sorghum. Ten positive clones were isolated from a cDNA library for the 25 kDa and two clones for the 23 kDa -kafirins. The isolated clones of the 25 kDa -kafirins showed 98-99% homology with each other and also with the GenBank sequences. The major finding was the characterisation of the 23 kDa -kafirins. The two clones obtained showed 100% homology to each other as well as to the published sequences on the GenBank, and were full-length sequences. Also a partial sequence was obtained that lacked the signal peptide and was different to the other two clones. Whilst characterising the 23 kDa a second group of the 25 kDa -kafirins was identified from the genomic DNA, of all the three genotypes (QL41, 296B and QL12), which was unique from the previously isolated clones. This group of -kafirins was not among the cluster but was 5’ upstream of the cluster. This group had a higher content of the glutamine compared with the other 25 kDa group. The expression level was studied to show how each gene family contributed to the level of - kafirins. QL41 and 296B were used for this study. From the studies it was shown that the 23 kDa - kafirins genes were 20% more expressed than the 25 kDa. An attempt to identify suitable markers for the -kafirins was investigated using RFLP and SSR analysis. Thirty-two different genotypes were utilised for this study. The observed variation indicated by cluster analysis (4-38%) clearly showed variation of the -kafirins in genotype and within the kafirin genes as elucidated by the sequences in Chapter 4. Markers able to identify this variation could help in the selection of highly digestible mutants. Hence, there is potential for sorghum grain improvement using marker-assisted breeding. The need to identify a tissue specific promoter was essential, especially for a strong promoter that could drive expression in the endosperm of the monocots. A vector construct consisting of the - kafirin promoter driving the GUS reporter genes was used for transient expression from QL41. This was assessed in the sorghum and barley calli, sorghum endosperm and leaves and corn endosperm. Tissue specific expression as well as higher levels of transient expression were seen using the - kafirin promoter, compared with the ubiquitin promoter. Preliminary experiments have illustrated the potential use of a gene silencing mechanism that could enhance the digestibility of sorghum grain. The 25 kDa -kafirin gene was used as the target for gene silencing using the mechanism of iRNA. Transformation constructs were developed using the throughput vector pSTARGATE in an effort to silence the 25 kDa -kafirins. The characterisation of the -kafirins has provided valuable information for future sorghum improvement research.