Orientador: Luiz Fernando Rolim de Almeida / Resumo: O desenvolvimento das plantas é controlado por vários fatores ambientais dentre os quais a água, cujo papel vital determina o sucesso no estabelecimento vegetal. Embora as intervenções abióticas as quais estão sujeitas ao longo de seu desenvolvimento possam prejudicá-las, os eventos de estresse anteriores podem induzir seu metabolismo contra posteriores, influenciando respostas. Memória de estresse envolve múltiplas modificações em níveis fisiológicos, proteômicos, transcricionais e mecanismos epigenéticos em plantas em resposta às essas mudanças no ambiente. Neste estudo, sugeriu-se a hipótese de que as plantas de sorgo previamente expostas a ciclos de défice hídrico terão melhor desempenho fisiológico do que as que nunca enfrentaram esta condição, quando ambos grupos estão sujeitos à baixa disponibilidade de água. Este trabalho propôs identificar algumas das possíveis contribuições fisiológicas para com o desempenho fotoquímico de indivíduos da espécie Sorghum bicolor (L.) Moench submetidos a dois eventos de défice hídrico, em comparação com indivíduos expostos a apenas um evento, além do grupo controle mantido sob irrigação. As respostas fisiológicas observadas em plantas submetidas a défice hídrico recorrente indicam ajustes fisiológicos distintos das plantas do grupo submetido a esta condição apenas uma vez. Os resultados de relações hídricas, taxas fotossintéticas e conservação do aparato fotoquímico sugerem que experiência de estresse anterior pode desenvolver memória ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The development of plants is controlled by several environmental factors including water, whose vital role determines success in plant establishment. Notwithstanding the abiotic stresses that are subject throughout their development can harm them, stress events earlier tend to induce metabolism against further tensions in order to improve responses. Stress memory involves multiple changes in physiological, proteomic, transcriptional levels and epigenetic mechanisms in plants in response to these changes in the environment. In this study, the hypothesis was suggested that sorghum plants previously exposed to water deficit cycles will have a better physiological performance than those that never faced this condition, when both groups are subject to low water availability. This work proposed to identify some of the possible physiological contributions to the photochemical performance of individuals of the species Sorghum bicolor (L.) Moench submitted to two water deficit events, in comparison with individuals exposed to only one event, in addition to the control group kept under irrigation. The physiological responses observed in plants submitted to recurrent water deficit indicate physiological adjustments different from plants in the group submitted to this condition only once. The parameters of water relations, photosynthetic rates and conservation of the photochemical apparatus suggest that previous stress experience may develop physiological memory. The data suggest that th... (Complete abstract click electronic access below) / Mestre

Industry demand for local sources of grain for animal feed has increased sorghum production in the mid-Atlantic region of the U.S. Sorghum anthracnose (causal agent Colletotrichum sublineola) and the grain mold complex, which includes mycotoxin-producing Fusarium spp., limit the yield and quality of grain sorghum in humid climates worldwide. A majority of U.S. grain sorghum production is in arid regions, and management strategies have not been developed for the mid-Atlantic U.S. where warm, wet conditions favor disease. The specific objectives of this research were to: (1) determine the effectiveness of fungicides and their application timing for the management of sorghum foliar anthracnose, (2) compare five grain sorghum hybrids for their susceptibility to foliar anthracnose, grain mold and mycotoxin contamination under field conditions, (3) integrate host resistance and fungicide application to manage anthracnose and grain mold, and (4) identify Fusarium spp. associated with grain mold and mycotoxin contamination of sorghum in the mid-Atlantic U.S. For Objective 1, it was determined that a single application of pyraclostrobin-containing fungicide no later than flowering reduced anthrancose, protected yield and maximized farm income. Objective 2 focused on sorghum hybrid selection as a disease management tactic, and it was determined that hybrids with high yield potential and moderate disease resistance should be selected for mid-Atlantic sorghum production in order to maximize grain yield and quality while minimizing the need for fungicide inputs. Objective 3 focused on integrated management and demonstrated that under moderate disease pressure, a high-yielding susceptible hybrid required a single application of pyraclostrobin-based fungicide to minimize fungal diseases and maintain acceptable yields, whereas under high disease pressure it was necessary to integrate hybrid resistance and judicous applications of fungicides. The aim of Objective 4 was to characterize potential causal agents of mycotoxin contamination in mid-Atlantic sorghum, and thirteen phylogenetically distinct Fusarium species (F. lacertarum, F. graminearum. F. armeniacum, F. proliferatum, F. fujikuroi, F. verticillioides, F. thapsinum and several in Fusarium incarnatum-equiseti species complex) were found to be associated with grain mold and fumonisin and/or deoxynivalenol contamination of sorghum grain. This work has provided insights into the impacts of fungal diseases on grain sorghum yield and quality in the mid-Atlantic and has aided in development of best management practices for the region. / Doctor of Philosophy / Sorghum is grown in tropics, sub-tropics and semi-arid region worldwide for food, feed, forage and fuel. Sorghum acreage in the mid-Atlantic is increasing due the demand for locally grown grain by poultry and swine industries. During the growing season, warm and humid conditions are common in the southeastern and mid-Atlantic states favoring fungal diseases development that reduce the grain yield and quality. Anthracnose and grain mold, which includes toxic mycotoxin-producing Fusarium species, are the two major constraints in sorghum production in the region. However, management alternatives have not been developed. The main goal of this research was to develop management strategies to protect yield and maximize farm profitability by controlling anthracnose and grain mold of sorghum using chemicals and/or host resistance. The specific objectives were to: (1) determine the effectiveness of fungicides and their application timing for the management of sorghum foliar anthracnose, (2) compare grain sorghum hybrids for their susceptibility to foliar anthracnose, grain mold and mycotoxin contamination under field conditions, (3) assess the value of integrating host resistance and judicious use of fungicides to manage sorghum anthracnose and grain mold, and (4) identify Fusarium spp. associated with grain mold and mycotoxin contamination of sorghum in the mid-Atlantic U.S. Results from this research indicate that a single application of pyraclostrobin-containing fungicides no later than flowering reduces anthrancose, protects yield, and increases farm income. Sorghum hybrids varied in susceptibility to anthrancnose and grain mold, and planting a moderately resistant hybrid and applying a fungicide under high disease risk conditions provided the greatest return on investment. Both fumonisin and deoxynivalenol were frequently detected from sorghum grain, and mycotoxin contamination was associated with 13 different Fusarium species from three distinct species complexes. Based on the results of this work, best management practices for minimizing sorghum disease losses were developed for the mid-Atlantic region.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study aimed to evaluate the effects of three levels of supplementation offered in a quantity equivalent to 0.8%, 1.0% or 1.2 % of live weight on the performance, body development, and ingestive behavior and displacement pattern of 24 steers, with initial average age and weight of 16 months and 334.58 kg kept in continuous grazing in sorghum forage pasture (Sorghum bicolor). The completely randomized design was used with parcels subdivided in time, constituting of three treatments and four repetitions of area (spot) per treatment, and four repetitions (animals) per treatment on the analysis of ingestive behavior and displacement. No difference was observed for daily weight gain (1.188 kg day-1) and stocking rate (894.80 kg LW ha-1) among the studied treatments. The average weight gain per total area was 201.10 kg ha-1 between the treatments, however at the first period it was observed a gain of 113 kg ha-1 (P<0.05), not differing at the second and third periods (48.21 kg ha-1). It was observed greater leaf blades mass of sorghum (670.69 kg DM ha-1) and sorghum accumulation rate (77.83 kg DM ha-1 day) at the first 28 days of utilization of the pasture, being constant at the second and third periods (470.55 kg DM ha-1 and 53,52 kg DM ha-1 day, respectively). No difference was observed on the final body measures, frame and weight: height relation of the animals according to the level of supplementation. The advance of the phenotype cycle of the pasture promotes the decrease on the leaf blades mass, accumulation rate and an increase on the forage mass of others. The steers that received the equivalent to 0.8% of live weight in supplementation presented higher (P<0.05) grazing time during the morning shift (241.25 min. morning-1) compared to the animals of the 1.2% treatment that spent 172.5 min. morning-1 in this activity, while the 1% treatment remained intermediate (205. 42 min. morning-1). The grazing time decreased (P<0.05) with the increase of the utilization of the pasture, with averages of 565.83; 494.09 and 437.5 min. day-1 for the first, second and third periods, respectively. The idle time increased (P<0.05) from the first (423.33 min day-1) to the second and third periods (557.06 min. day-1). The levels of supplementation did not influenced the variables of displacement, however the structural variation of the pasture, influenced on the biting rate min-1 and the number of bitings per feed-1 station. / Objetivou-se avaliar os efeitos de três níveis de suplementação ofertados em quantidade equivalente a 0,8%, 1,0% ou 1,2 % do peso vivo sobre o desempenho, desenvolvimento corporal, comportamento ingestivo e padrões de deslocamento de 24 novilhos com idade e peso médio inicial de 16 meses e 334,58 kg, mantidos sob pastoreio continuo em pastagem de sorgo forrageiro (Sorghum bicolor). O delineamento utilizado foi inteiramente casualizado com parcelas subdividas no tempo, constituindo três tratamentos e quatro repetições de área (piquete) por tratamento, e quatro repetições (animais) por tratamento nas análises de comportamento ingestivo e deslocamento. Não foi verificada diferença no ganho diário (1,188 kg dia-1) e na carga animal (894,80 kg PV ha-1) entre os níveis de suplementação estudados. A média do ganho de peso por área total foi de 201,10 kg ha-1 entre os tratamentos, entretanto no primeiro período observou-se ganho de 113 kg ha-1 (P<0,05), não diferindo no segundo e terceiro períodos (48,21 kg ha-1). Foi observada maior massa de lâminas foliares de sorgo (670,69 kg MS ha-1) e taxa de acúmulo de sorgo (77,83 kg MS ha-1 dia) nos primeiros 28 dias de utilização da pastagem, mantendo-se constantes no segundo terceiro períodos (470,55 kg MS ha-1 e 53,5277,83 kg MS ha-1 dia, respectivamente). Não foi observada diferença nas medidas corporais finais, frame e relação peso: altura dos animais de acordo com o nível de suplementação. O avanço do ciclo fenotípico da pastagem promove a diminuição na massa de lâminas foliares, na taxa de acúmulo e aumento da massa de forragem de outros. Os novilhos que receberam o equivalente a 0,8% do peso vivo em suplementação apresentaram maior (P<0,05) tempo de pastejo durante o turno da manhã (241,25 min. manhã-1) comparado aos animais do tratamento 1,2% que dispenderam 172,5 min. manhã-1 nesta atividade, enquanto o tratamento 1% foi intermediário (205, 42 min. manhã-1). O tempo de pastejo diminuição (P<0,05) com o avanço da utilização da pastagem, com médias de 565,83; 494,09 e 437,5 min. dia-1 para o primeiro, segundo e terceiro períodos, respectivamente. O tempo de ócio aumentou (P<0,05) do primeiro (423,33 min. dia-1) para o segundo e terceiro períodos (557,06 min. dia-1). Os níveis de suplementação não influenciaram as variáveis de deslocamento, entretanto a variação estrutural da pastagem influenciou a taxa de bocados min.-1 e o número de bocados estação-1 alimentar.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / A busca por estratÃgias de cultivo que possam contribuir para a aclimataÃÃo de plantas à salinidade à de fundamental importÃncia, pois, alÃm de possibilitar a identificaÃÃo de genes potenciais para guiar ensaios de modificaÃÃo genÃtica, permite selecionar cultivares com maior capacidade de crescer em solos com excesso de sais. A fim de testar a hipÃtese que a nutriÃÃo nitrogenada com NH4+ aumenta a tolerÃncia de plantas de Sorghum bicolor à salinidade, atravÃs da ativaÃÃo de mecanismos voltados ao controle da homeostase iÃnica, estabeleceram-se trÃs etapas experimentais. Na primeira delas, que objetivou definir a relaÃÃo entre as fontes de nitrogÃnio (N), NO3- e NH4+, que proporcionasse melhor crescimento das plantas sob salinidade, observou-se claramente que a nutriÃÃo somente com NH4+ (proporÃÃo NO3-/NH4+ de 0:100) foi mais vantajosa para o crescimento de S. bicolor sob salinidade que a nutriÃÃo apenas com NO3- ou com o regime misto desses dois Ãons, dado os maiores Ãndices de Ãrea foliar e massa seca da parte aÃrea. Verificou-se tambÃm que, sob estresse, as plantas nutridas somente com NH4+ acumularam menos Na+ nas folhas e nas raÃzes, influenciando positivamente a relaÃÃo K+/Na+, e apresentaram maiores teores de aminoÃcidos solÃveis, principalmente aqueles ricos em N (glutamina e asparagina), que contribuÃram para evitar a toxicidade do NH4+ e provavelmente para o ajustamento osmÃtico. AlÃm disso, enquanto plantas nutridas com proporÃÃes NO3-/NH4+ de 100:0, 75:25, 50:50 e 25:75 apresentaram taxas de assimilaÃÃo lÃquida de CO2 inalteradas ou reduzidas pela salinidade, plantas cultivadas somente com NH4+ (proporÃÃo 0:100) apresentaram incrementos nessa variÃvel, em reposta ao estresse. A segunda etapa teve como objetivo principal investigar se a tolerÃncia à salinidade mediada pelo NH4+ era resultante da regulaÃÃo efetiva dos processos relacionados à fotossÃntese. Nessa ocasiÃo, esse argumento foi refutado, pois a melhor eficiÃncia do fotossistema II sob estresse salino foi observada nas plantas cultivadas com a mesma proporÃÃo de NO3- e NH4+ (proporÃÃo 50:50). Nesse grupo de plantas, a reduÃÃo no quenching nÃo fotoquÃmico (NPQ) confirmou a maior eficiÃncia fotoquÃmica, dado o aumento na eficiÃncia quÃntica potencial (Fv/Fm) e efetiva (&#934;PSII) do fotossistema II e a elevada taxa de transporte de elÃtrons (ETR). Esse fenÃmeno foi diretamente relacionado com os incrementos nos teores de clorofila b e de antocianinas. Por fim, na terceira etapa, objetivou-se elucidar os mecanismos envolvidos no controle do acÃmulo de Na+, sob salinidade, na cÃlula e na planta inteira, bem como identificar o papel da nutriÃÃo com NH4+ nesses processos. Em estudos com vesÃculas de membrana de raÃzes, verificou-se que plantas estressadas cultivadas somente com NH4+ apresentaram maior ativaÃÃo dos transportadores do tipo antiporte Na+/H+ (SOS1) de membrana plasmÃtica e, em menor proporÃÃo, do antiporte Na+/H+ (NHX) de tonoplasto, ao passo que o oposto foi observado nas plantas nutridas com NO3-. Esses dados sugerem que o cultivo somente com NO3- induziu o mecanismo de compartimentaÃÃo de Na+ no vacÃolo, como evidenciado pela anÃlise dos transcritos da famÃlia NHX, em que a expressÃo do gene SbNHX2 (principal isoforma expressa) nas raÃzes das plantas foi aumentada em quase todos os tempos analisados (24, 48, 120 e 240 horas apÃs exposiÃÃo ao NaCl). Mesmo assim, essa resposta nÃo foi suficiente para o controle do Na+, jà que a entrada contÃnua desse Ãon no xilema radicular afetou o influxo de K+ na seiva e limitou o acÃmulo de K+ nas folhas. Por outro lado, a nutriÃÃo somente com NH4+ ativou potencialmente mecanismos de controle do acÃmulo de Na+, uma vez que houve acionamento efetivo do efluxo de Na+ para o apoplasto via SOS1, que restringiu o carregamento desse Ãon no xilema e, consequentemente, limitou a acumulaÃÃo dele nos tecidos aÃreos. A formaÃÃo do gradiente de potencial eletroquÃmico, essencial para a atividade dos transportadores Na+/H+, foi modulada diferencialmente pela fonte de N. A atividade de bombeamento de prÃtons da H+-ATPase de membrana plasmÃtica (P-ATPase) foi estimulada em maior proporÃÃo pela presenÃa de NH4+, sem haver, contudo, aumento na atividade de hidrÃlise de ATP. Jà o aumento da translocaÃÃo de H+ pela P-ATPase em plantas estressadas cultivadas com NO3- foi diretamente relacionado ao incremento na hidrÃlise de ATP. Esses resultados sugerem que a disponibilidade de NH4+ aumentou a afinidade da P-ATPase por H+, pois houve melhor eficiÃncia de acoplamento H+/ATP, e isso tornou a enzima mais efetiva para transportar H+ com menos gasto de energia. AlÃm disso, esse aumento no bombeamento de prÃtons resultou em um maior potencial eletroquÃmico, e favoreceu diretamente a atividade do antiporte SOS1 de membrana plasmÃtica. Os nÃveis de transcritos dos genes SbPHA3 e SbPHA5 (principais isoformas expressas da famÃlia) foram aumentados nas plantas cultivadas somente com NO3-, nos tempos iniciais de exposiÃÃo ao estresse salino (12 e 24 h), enquanto que, nos cultivos somente com NH4+, essa resposta sà foi detectada apÃs 24 h. No vacÃolo, a principal bomba responsÃvel pela formaÃÃo do gradiente de H+ durante a exposiÃÃo ao estresse salino foi a H+-ATPase (V-ATPase), em comparaÃÃo à H+-PPiase. Nas plantas cultivadas somente com NO3-, observou-se uma melhor regulaÃÃo da V-ATPase, em associaÃÃo à atividade aumentada do antiporte NHX, enquanto que no cultivo com NH4+, a ativaÃÃo do transporte de H+ sob salinidade foi diretamente relacionada a incrementos na atividade de hidrÃlise de ATP da V-ATPase, bem como ao aumento da expressÃo dos transcritos do gene SbVHA2, ao longo de todo o perÃodo experimental. Essas observaÃÃes revelam que o NH4+, como fonte Ãnica de N, ativa mecanismos que envolvem uma regulaÃÃo coordenada, nas raÃzes, da atividade e da expressÃo gÃnica de bombas de H+ e transportadores Na+/H+ de membrana plasmÃtica e de tonoplasto, que culminam no controle do acÃmulo de Na+ na planta inteira e aumentam a tolerÃncia de S. bicolor ao estresse salino. / Over the last decades, several researchers have focused the development of cultivation strategies in order to improve the plantâs ability to withstand salinity. Understanding the plant salt tolerance is one of important trait to enhance productivity of crops in saline soils because it provides molecular basis for plant breeding, as well as allows identify plant species with a greater ability to grown in salinized areas. In order to test the hypothesis that nitrogen nutrition with NH4+ improves the salt tolerance in Sorghum bicolor plants, through the restrict control of ionic homeostasis, three experimental steps were established. In the first one, we investigated what would nitrogen regime, as NO3-:NH4+ ratio, contribute to the better growth of plants under salinity. Our data clearly showed that the nutrition with only NH4+ (NO3-/NH4+ at 0:100) was more advantageous for the growth of S. bicolor under salinity than the supply with solely NO3- or the mixed regimes, as evidenced by the higher leaf area and shoot dry mass. Under salinity, Na+ accumulation was severely limited in presence of NH4+ (0:100), which positively influenced on K+/Na+ homeostasis. In parallel, NH4+-fed plants displayed a substantial accumulation of N-rich amino acids (mainly glutamine and asparagine) in both tissues, which seems to be fundamental in alleviating the NH4+ toxicity. Furthermore, whereas plants treated with NO3-:NH4+ ratio of 100:0, 75:25, 50:50 and 25:75 ratios had their photosynthetic rates (A) unaltered or reduced by salinity, plants supplied with only NH4+ showed an increased CO2 assimilation in response to stress. During the second step, we evaluated if the better salt tolerance in NH4+ cultivated plants was due to an effective regulation of photosynthesis-related processes. This idea was rejected because of the most striking effects of nitrogen regime were observed in plants supplied with equal amounts of NO3-: NH4+ (50:50). Under salt stress, plants from 50:50 NO3-:NH4+ treatments displayed a lower non-photochemical quenching (NPQ) and an improved photosystem II maximum efficiency (Fv/Fm). Their superior performance was also indicated by a higher effective quantum yield of PSII (&#934;PSII) and electron transport rate (ETR), as well as increased chlorophyll b and anthocyanins. Finally, at the third step, we supply S. bicolor plants with NO3- or NH4+ to investigate changes in pathways for control of Na+ accumulation, at cell and whole plant level, in response to 75 mM NaCl-stress. By using root membrane-enriched vesicles, it was found that a more pronounced plasma membrane Na+/H+ antiporter (SOS1) activity and low loading of Na+ in the xylem in the NH4+ treated plants, whereas a largest vacuolar Na+/H+ exchanger (NHX) activity was noticed by NO3- grown plants. These data suggest that the NO3- availability induced the compartmentalization of Na+ into the vacuole, as supported by the upregulation of SbNHX2 gene expression over time of NaCl exposure (12, 24, 48, 120 and 240 h). Nonetheless, it composed an inefficient pathway of Na+ control, since the incessant entrance of Na+ in the xylem sap impaired the K+ loading and limited the K+ accumulation in the shoot. On the other hand, the NH4+ supply potentially activated the mechanisms for control of Na+ accumulation, driving an effective efflux of Na+ out of the cell, via SOS1, restricting its loading in the xylem and thus limiting Na+ reach and accumulation in the aerial tissues. Surprisingly, we found that the generation of electrochemical potential gradient for Na+/H+ exchange activity is differentially modulated by the nitrogen source. The H+-pumping activity driven by plasma membrane H+-ATPase (P-ATPase) was greatly stimulated by the presence of NH4+ in growth medium, however, without an increase in ATP hydrolysis activity. Conversely, the improvement of P-ATPase-generated H+-pumping of NO3- fed stressed plants was directly related to the increase of ATP hydrolysis. These data show that the NH4+ availability enhances the H+/ATP coupling efficiency of P-ATPase, i. e. the enzyme displayed a high capacity of transport H+ across plasma membrane with low ATP consumption. Moreover, the bigger H+ translocation resulted in a greater electrochemical potential which in turn favored the SOS1 activity. The expression of SbPHA3 and SbPHA5 genes was upregulated in NO3- grown stressed plants at the beginning of salt exposure (12 and 24 h), whereas it was enhanced in NH4+ supplied stressed plants only after 24 h. At vacuole level, the H+-ATPase (V-ATPase) was the main proton pump responsive to salinity, as compared do H+-Pyrophosphatase (PPase). A better regulation between V-ATPase and NHX antiporter activities was noticed by plants from NO3- treatments. Under NH4+ supply, the increase of H+ pumping was directly associated to the improvement of ATP hydrolysis by V-ATPase, coupled to upregulation of SbVHA2 gene expression over time of salinity exposure. Taken together, our data reveal that the NH4+, as the only nitrogen source, activates an intricate regulation of Na+ control pathways, involving the existence of a robust regulation and systematic mechanism firstly on root cell and subsequently on whole plant in sorghum upon salinity. In conclusion, the NH4+ stimulated salt tolerance is resulted from a more active SOS1 protein and high efficiency of P- and V-ATPase in the roots, which help to efficient Na+ exclusion and counteract net Na+ accumulation in the cytosol, thus preventing the loading of Na+ in the xylem sap and its reach in the photosynthetic tissues.

Doctor of Philosophy / Department of Agronomy / Tesfaye T. Tesso / The lack of effective post-emergence weed control options is often highlighted as one of the major factors behind dwindling acreage under sorghum (Sorghum bicolor (L.) Moench) in the United States. The discovery of herbicide resistance sources in wild sorghum population and subsequent efforts to incorporate them into cultivated sorghum was received with much optimism to change weed management practices in sorghum. As the development of the technology advances, especially of the Acetolactate synthase (ALS) resistance, concerns over the temporary interveinal chlorosis and reduced seedling vigor in some of the resistant families became heightened. This thesis research is designed to shed light on the genetic basis of seedling chlorosis and assess its impacts on yield potential. The study has three parts; the first part is focused on identifying the genetic causes and plant mechanisms associated with the chlorotic phenotype. ALS herbicide resistant sister-lines expressing normal and chlorotic phenotypes were analyzed via RNA sequencing at four time points during seedling growth. The study identified several variants of genes coding chloroplast precursors and those that cause epigenetic modifications. Once confirmed, genetic markers can be developed to track these gene variants in the breeding population and eliminate segregates genetically prone to chlorosis/yellowing. The second part of the study focuses on assessing the effect of ALS resistance associated chlorosis on agronomic and nutritional parameters of sorghum inbred lines. A set of ALS resistant lines expressing different levels of the chlorotic phenotype were evaluated in replicated field trials and laboratory methods. Results showed that interveinal chlorosis delays flowering but does not have negative effect on yield and nutritional parameters with and without herbicide treatment. The last part addresses whether there is any yield drag that may be associated with herbicide resistance traits and foliar interveinal chlorosis. For this, we synthesized a large set (182) of hybrids from ALS resistant, ACCase resistant and regular (susceptible) seed and pollinator parents. The hybrids were then evaluated in three sets at multiple locations during the 2014 and 2015 crop seasons along with commercial checks. The results revealed that resistance to both herbicides do not cause any drag to grain yield. The traits also do not have any negative impact on grain and nutritional quality of resistant hybrids.

Orientador: Renato de Mello Prado / Resumo: A pulverização foliar de silício (Si) pode diminuir os efeitos da deficiência de zinco (Zn) nas plantas, pois a adição de Si e de Zn na calda pode aumentar a eficiência da adubação foliar, porém os efeitos em plantas de sorgo ainda não são conhecidos. Assim, objetivou-se avaliar a aplicação foliar de Si na ausência de Zn e com a adição na calda em plantas de sorgo e seus efeitos na nutrição e no desenvolvimento das plantas. O delineamento foi em esquema fatorial 4 x 2, com cinco repetições, tendo quatro concentrações de Zn, na forma de Zn-EDTA: 0; 0,60; 1,20 e 1,80 g L-1 e na ausência e na presença de Si (0,50 g L-1) na calda. Avaliou-se o acúmulo de Zn e Si, eficiência de uso de Zn, extravasamento de eletrólitos celular, teores de clorofila, carotenoides, proteína e a massa seca de parte aérea e de raiz. Nas plantas deficientes em Zn, a pulverização foliar de Si ao aumentar o acúmulo deste elemento na planta diminuiu o extravasamento de eletrólitos celular, aumentou o conteúdo dos pigmentos fotossintéticos e incrementou a produção de massa seca da parte aérea e de raiz. A pulverização foliar de Zn na forma de quelato com adição de Si na calda, em relação a sua ausência, aumentou o acúmulo de Zn na planta, o teor dos pigmentos fotossintetizantes, o teor de proteína e a produção de massa seca de raiz. Conclui-se que a pulverização foliar de Si alivia a deficiência de Zn, e a adição de Si na calda com o Zn é viável agronomicamente para plantas de sorgo. / Abstract: Foliar spraying of silicon (Si) can decrease the effects of zinco (Zn) deficiency on plants. While the addition of Si and Zn in the solution may increase the efficiency of foliar fertilization with this micronutrient, however the effects on sorghum plants are not yet known. The objective of this study was to evaluate the foliar application of Si in the absence of Zn and with the addition of different concentrations of Zn in sorghum plants and their effects on plant nutrition and development. The experiment was carried out in a 4x2 factorial scheme with five replicates having four concentrations of Zn as Zn-EDTA: 0.60, 1.20 and 1.80 g L-1 and in the absence and presence of Si (0.50 g L-1) in solution. Zn and Si accumulation, Zn use efficiency, cellular electrolyte leakage, chlorophyll content, carotenoids, protein content and shoot and root dry mass were evaluated. In the plants deficient in Zn, a foliar spraying of Si increasing the accumulation of this element in the plant, decreased the cellular extravasation and increased the photosynthetic pigments and the dry mass production of shoot and root. Foliar spraying of Zn in the chelate form with addition of Si in relation to its absence increased the accumulation of Zn in the plant, the content of photosynthetic pigments, protein content and root dry mass production. It is concluded that foliar spraying of Si alleviates Zn deficiency and the addition of Si in the solution with Zn is agronomically viable for sorghum plants. / Mestre

Orientador: José Roberto Môro / Banca: Cícero Beserra de Menezes / Banca: Robert Eugene Schaffert / Banca: Dilermando Perecin / Banca: Rinaldo César de Paula / Resumo: O trabalho objetivou identificar e classificar linhagens de sorgo, eficientes e ineficientes ao P avaliadas em ambientes com estresse e sem estresse de P, identificar a importância relativa da eficiência de aquisição e a eficiência de utilização em relação à eficiência de uso de P, obter as estimativas dos coeficientes de correlação genética e fenotípica, realizar análise de trilha e identificar os componentes principais. Avaliou-se 243 linhagens de sorgo e duas testemunhas adicionais divididas em três látices 9x9 com três repetições. Avaliaram-se as seguintes características nos ambientes com e sem estresse de P: florescimento, altura de plantas e produtividade de grãos. As características teor de fósforo nos grãos, eficiência de aquisição, eficiência de utilização interna de P, eficiência de uso de P, índice de colheita de P e quociente de utilização, foram avaliadas somente no ambiente com estresse de P. Foram identificadas e classificadas 107 linhagens eficientes ao P e 138 linhagens ineficientes avaliadas em ambientes com e sem estresse de P. Na importância relativa das eficiências o índice eficiência de aquisição foi o que melhor se relacionou com a eficiência uso de fósforo. De acordo com os resultados das correlações fenotípicas e genotípicas o índice de eficiência de uso de fósforo pode ser avaliado indiretamente, pela avaliação da produtividade de grãos em ambiente com estresse de P. Dentre as variáveis explicativas na análise de trilha, o teor de P total na planta foi a que melhor explicou os efeitos diretos nas variáveis básicas de eficiência de aquisição e uso de P. Foram identificados três componentes principais (PCA 1, 2 e 3), que juntos explicaram 81% da variação original dos dados / Abstract: This study aimed to identify and classify sorghum lines for P efficiency in environments with high and low P, to identify the relative importance of acquisition efficiency and utilization efficiency in relation to P use efficiency, to obtain the estimates of correlation coefficients and evaluate genetic and phenotypic path analyzes through the development of the direct and indirect effects of independent variables on the dependent variables, and identify the major components. Two hundred forty-three sorghum lines and two additional controls divided into three 9x9 lattices with three replications. Flowering, plant height and grain yield were evaluated in low and high P environments. Phosphorus content in the grain, P acquisition efficiency, P utilization efficiency of internal P, P use efficiency, harvest index and P utilization quotient were evaluated in the low P environment. One hundred and seven lines were identified and classified as P efficient and 138 lines as P inefficient. The relative efficiency of the P acquisition index was the most highly correlated with the efficiency of phosphorus use. These results suggest that the phenotypic correlation index of phosphorus use efficiency can be evaluated indirectly by the assessment of grain yield in P environments total P content in plant was the variable that best explained the direct effects, in the path analysis, of variables in the basic efficiency of acquisition and use. Three main components; 1, 2 and 3, together explained 81% of the variation of the original data / Doutor

Submitted by Aline Batista (alinehb.ufpel@gmail.com) on 2017-06-22T21:51:45Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao - DAVID BANDEIRA.pdf: 1130012 bytes, checksum: f633afdd8b2deff51d0d86126e78a258 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-06-22T21:52:08Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao - DAVID BANDEIRA.pdf: 1130012 bytes, checksum: f633afdd8b2deff51d0d86126e78a258 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-06-22T21:52:16Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao - DAVID BANDEIRA.pdf: 1130012 bytes, checksum: f633afdd8b2deff51d0d86126e78a258 (MD5) / Made available in DSpace on 2017-06-22T21:52:24Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao - DAVID BANDEIRA.pdf: 1130012 bytes, checksum: f633afdd8b2deff51d0d86126e78a258 (MD5) Previous issue date: 2015-02-26 / Sem bolsa / O Brasil tem uma produção de aproximadamente 2,2 milhões de toneladas de grãos de sorgo, ocupando a oitava posição em produção mundial. A produção brasileira está distribuída em diferentes regiões do país, o que mostra a adaptação da cultura às condições edafoclimáticas existentes no país. A qualidade final do produto após o armazenamento está diretamente relacionada com a qualidade dos grãos no momento da colheita, porém durante a secagem e o armazenamento esta qualidade pode sofrer alterações resultantes da temperatura de secagem e do tempo de armazenamento. O objetivo do presente estudo, foi avaliar efeitos da temperatura de secagem e do tempo de armazenamento sobre parâmetros de qualidade tecnológica dos grãos e parâmetros de propriedades do amido isolado de grãos de sorgo. Os grãos foram produzidos no município de Aceguá, Rio Grande do Sul, e colhidos com umidade próxima a 22%. A secagem foi realizada em secos estacionário as temperaturas de 25 (testemunha), 45, 65 e 85°C, até que os grãos atingissem a umidade desejada para o armazenamento, próximo a 12,5 %. Os grãos secos foram armazenados a 16°C, por seis meses. As avaliações foram realizadas no início, aos três meses e aos seis meses de armazenamento. A secagem dos grãos de sorgo com temperatura de 85 °C apresenta um comportamento inverso aos grãos secados à 25 °C, causando alterações nos grânulos de amido. Nos resultados obtidos, a melhor temperatura de secagem mantendo ao máximo as características físico-químicas dos grãos e sobre propriedades físico-químicas, térmicas e de pasta do amido isolado de grão de sorgo é a 45 °C visto a redução do tempo de secagem, que é importante na conservação dos grãos. / The Brazilian sorghum production is approximately 2.2 million tons, occupying the eighth position in world production. Brazilian production is distributed in different regions of the country which shows the adaptation of culture to soil and climatic conditions existing in the country. The final product quality after storage is directly related to the grains quality at the harvest, however during drying and storing that quality can vary as a result of drying temperature and storage time. This study evaluated the effects of drying temperature and time of storage on parameters grain quality and properties of starch in sorghum grains. The grains were produced in Aceguá municipality, Rio Grande do Sul, and harvested with moisture content around 22%. The drying was performed in stationary dryer utilizing temperatures of 25, 45, 65 and 85 ° C until the grains reach the moisture close to 12.5%. The grains were stored at a temperature of 16 ° C for a period of six months. The evaluations were performed at the beginning of grain storage, in three and in six months. The drying of grain sorghum at 85 ° C showed an inverse pattern to the control dried at 25 ° C, causing changes in the starch granules. The results showed that the best physico-chemical characteristics occurred at the temperature of 45 ° C.

Σκοπός της παρούσας εργασίας ήταν να μελετηθεί η επίδραση των εντομοπαθογόνων μυκήτων Beauveria bassiana Balsamo (Vuillemin) (Hypocreales: Cordycipitaceae), Metarhizium robertsii (Metchnikoff) Sorokin (Hypocreales: Clavicipitaceae) και Isaria fumosorosea (Wize) Brown & Smith (Hypocreales: Clavicipitaceae), πουαπομονώθηκαν από ελληνικά εδάφη, επί του κυριότερου και πιο επιβλαβούς εχθρού της καλλιέργειας του γλυκού σόργου, του λεπιδόπτερου Sesamia nonagrioides (Lefebvre) (Lepidoptera: Noctuidae). Μελετήθηκε στο εργαστήριο η επίδραση έξι στελεχών των παραπάνω μυκήτων στην επιβίωση των προνυμφών του εντόμου. Τα στελέχη των μυκήτων προκάλεσαν υψηλή θνησιμότητα στις προνύμφες του εντόμου, που κυμάνθηκε σε ποσοστά από 78%-98%. Αποτελεσματικότερα στελέχη ήταν τα B. bassiana (ΙΓΕ3), M. robertsii (Elateridae) και I. fumosorosea (Άγιος Στέφανος). Αυτές οι τρείς απομονώσεις επιλέχθηκαν προκειμένου να εξεταστεί η επίδραση της πυκνότητας των κονιδιακών εναιωρημάτων στη θνησιμότητα των προνυμφών. Καταγράφηκαν ποσοστά θνησιμότητας 7%-93% σε σχέση με την πυκνότητα των κονιδιακών εναιωρημάτων επί των προνυμφών. Διαπιστώθηκε ότι η ικανότητα που παρουσιάζουν οι εντομοπαθογόνοι μύκητες στον έλεγχο της επιβίωσης προνυμφών του εντόμου ήταν ανάλογη της χρησιμοποιημένης πυκνότητας των κονιδιακών εναιωρημάτων. Επίσης, μελετήθηκε η αλληλεπίδραση των εντομοπαθογόνων μυκήτων B. bassiana (ΙΓΕ3) και M. robertsii (Elateridae) με εμπορικό σκεύασμα Bacillus thuringiensis subsp. kurstaki όσον αφορά τη θανάτωση προνυμφών του εντόμου S. nonagrioides. Η θνησιμότητα των προνυμφών καταγράφηκε καθημερινά για δεκαέξι ημέρες και κυμάνθηκε από 56-100% για τον M robertsii μαζί με το B thuringiensis subsp. kurstaki και 54-100% για τον B. bassiana μαζί με το βάκιλο. Επίσης, η συνδυασμένη δράση των μικροοργανισμών υπολογίστηκε για την όγδοη, δέκατη τρίτη και τη δέκατη έκτη μέρα και βρέθηκε προσθετική στους περισσότερους συνδιασμούς για την δέκατη τρίτη και δέκατη έκτη μέρα ενώ την όγδοη μέρα η συνδυαστική δράση των παθογόνων βρέθηκε αρνητική στους περισσότερους συνδιασμούς και χαρακτηρίζεται ως ανταγωνιστική. Η ανάπτυξη των εντομοπαθογόνων μυκήτων όταν καλλιεργήθηκαν σε θρεπτικό υπόστρωμα που περιείχε υδατικό διάλυμα B. thuringiensis subsp. kurstaki, δεν επηρεάστηκε από την παρουσία του βακτηρίου. Ο συνδυασμός του B. thuringiensis subsp. kurstaki με τους εντομοπαθογόνους μύκητες που εξετάσαμε είχε ως αποτέλεσμα να αυξηθεί η θνησιμότητα των προνυμφών του S. nonagrioides. Τα στελέχη ΙΓΕ3, Elateridae και Άγιος Στέφανος των εντομοπαθογόνων μυκήτων B. bassiana, M. robertsii και I. fumosorosea αντίστοιχα, δοκιμάστηκαν επί των προνυμφών του S. nonagrioides σε τρεις κονιδιακές συγκεντρώσεις και μελετήθηκε η επίδρασή τους στην πρόσληψη τροφής, στην κατανάλωση τροφής και στην ανάπτυξη των προνυμφών. Παρατηρήθηκε μείωση της πρόσληψης τροφής από προνύμφες 3ης προνυμφικής ηλικίας σε ποσοστά 41-81%, μείωση του βάρους τους κατά 29-45% και μείωση των απορριμάτων κατά 46-81%. Παρατηρήθηκε επίσης ελάττωση της σχετικής ταχύτητας ανάπτυξης των προνυμφών κατά 31-72% και της σχετικής ταχύτητας κατανάλωσης τροφής κατά 12-35%. Τέλος, ο δείκτης πεπτικότητας, ο δείκτης μετατροπής της προσληφθείσας τροφής και ο δείκτης μετατροπής της αφομοιωμένης τροφής ήταν υψηλότεροι σε σχέση με τους αντίστοιχους του μάρτυρα. Τα παραπάνω αποτελέσματα υποδεικνύουν ενδεχομένως ότι η μόλυνση από τους εντομοπαθογόνους μύκητες προκαλεί επιδείνωση σε ορισμένες τροφικές διεργασίες της προνύμφης που θα μπορούσαν να οδηγήσουν στην υπονόμευσή της από ασιτία. Επίσης πραγματοποιήθηκαν πειράματα στο πεδίο προκείμενου να μελετηθεί η επίδραση της ενδοφυτικής παρουσίας των εντομοπαθογόνων μυκήτων B. bassiana, M. robertsii και I. fumosorosea στις προνύμφες του εντόμου S. nonagrioides in planta. Kαι οι τρείς μύκητες έδρασαν αποτρεπτικά απέναντι στην προσπάθεια των προνυμφών να εισέλθουν στο στέλεχος του φυτού. Οι προνύμφες της 4ης προνυμφικής ηλικίας που πέτυχαν να εγκατασταθούν στο στέλεχος των φυτών δημιούργησαν στοές μικρότερου μήκους παρουσία των μυκήτων, και η θνησιμότητά τους ήταν μεγαλύτερη, επιβεβαιώνοντας τα αποτελέσματα των in vitro πειραμάτων. Ως προς τις επιπτώσεις της παρουσίας των ενδοφύτων στο φυτό ξενιστή, η επίδραση της παρουσίας των μυκήτων στην ανάπτυξη, την τελική βιομάζα και την κατανομή της βιομάζας σε υπέργειους ή υπόγειους ιστούς των φυτών καταγράφηκε ως ουδέτερη. Η συγκέντρωση της χλωροφύλλης και η περιεκτικότητα σε νερό δεν παρουσίασαν μεταβολές που μπορούν να αποδοθούν στην παρουσία των ενδοφύτων. Ωστόσο, ορισμένες παράμετροι της φωτοσυνθετικής διαδικασίας (καθαρή φωτοσύνθεση, ταχύτητα ροής ηλεκτρονίων, η πιθανότητα μετατροπής της συλληφθείσας ενέργειας σε ροή ηλεκτρονίων, η πιθανότητα μεταφοράς ηλεκτρονίων από τους ενδιάμεσους φορείς μέχρι την αναγωγή των τελικών υποδοχέων στο PSI και ο δείκτης ζωτικότητας της φωτοσυνθετικής συσκευής PItotal) επηρεάστηκαν αρνητικά μετά την προσβολή των στελεχών του σόργου από τις προνύμφες του εντόμου. Η ενδοφυτική παρουσία των μυκήτων B. bassiana και M. robertsii απέτρεψε τις παραπάνω αρνητικές επιδράσεις. Τα αποτελέσματα της παρούσας διατριβής προσφέρουν ισχυρές ενδείξεις για επιτυχή χρησιμοποίηση ορισμένων στελεχών των εντομοπαθογόνων μυκήτων στον έλεγχο των προνυμφών του εντόμου S. nonagrioides τόσο στο εργαστήριο όσο και στο πεδίο. Επίσης, θα ήταν ενδιαφέρουσα η περαιτέρω μελέτη της χρήσης αυτών τωνεντομοπαθογόνων μυκήτων κάτω από συνθήκες μειωμένης διαθεσιμότητας νερού. / The aim of this study was to investigate the effect of entomopathogenic fungi Beauveria bassiana Balsamo (Vuillemin) (Hypocreales: Cordycipitaceae), Metarhizium robertsii (Metchnikoff) Sorokin (Hypocreales: Clavicipitaceae) and Isaria fumosorosea (Wize) Brown & Smith (Hypocreales: Clavicipitaceae), isolated from Greek soils against the main and most damaging pest of sweet sorghum, Mediterranean corn borer Sesamia nonagrioides (Lefebvre) (Lepidoptera: Noctuidae). Laboratory studies were performed to determine the effect of six strains of the above fungi on survival of larvae of S. nonagrioides. All strains of fungi causing high mortality among larvae, killed 78 - 98% of exposed larvae. The most effective were B. bassiana (IGE3), M. robertsii (Elateridae) and I. fumosorosea (Agios Stefanos). These three isolates were selected to examine the effect several conidial suspensions on the mortality of larvae. Recorded mortality was from 7% - 93% depending on the density of conidial suspensions used on larvae. From the above results was found that the capability provided by the entomopathogenic fungi to control the insect was according by the density of the conidial suspensions. Also, the interactions between commercial B. thuringiensis subsp. kurstaki and two entomopathogenic fungi were examined on larvae of S. nonagrioides in 8, 13 and 16 days post-treatment intervals. An overall positive interaction between the pathogens was observed and larval mortality at 16 days was 56–100% exposed to M. robertsii combined with B. thuringiensis subsp. kurstaki, whereas B. bassiana combined with B. thuringiensis subsp. kurstaki killed 54–100 % of exposed larvae. After 8 days, in 6 of the combinations, we found an additive relationship between the pathogens, whereas, a negative interaction was observed in 10 of them. In contrast, after 13 days, we observed a positive interaction in two combinations, which could be considered as synergistic, additive in ten combinations and negative in only four combinations. Finally, after 16 days, in eleven combinations we found an additive interaction, whereas negative interaction was recorded in five of them. We conclude that application of combined pathogens may be more effective for S.nonagrioides control. The strains IGE3, Elateridae and Agios Stefanos of B. bassiana, M. robertsii and I. fumosorosea respectively, were tested for their effectiveness on larval food intake, food consumption and larvae growth at three conidial concentrations. We observed a decrease in food intake by the larvae ranged between 41 and 81%, reduced larvae weight from 29 to 45% and reduced production of wastes from 46 to 81%. We also recorded significant differences in the relative growth rate of larvae, the relative consumption rate of larvae, the index digestibility, the conversion ratio of ingested food and the conversion ratio of assimilated food between infected and control individuals. Therefore, it is possible that infection of larvae by the fungi has an adverse effect on physiological and metabolic processes, which results in larva starvation. Subsequently, we performed experiments in the field, in order to investigate the plant–endophyte association behavior using B. bassiana, M. robertsii and I. fumosorosea, as well as the impact of these associations on larva activity when in planta and under environmental conditions. All three fungal species significantly prevented larvae from entering into plants’ stalk. Statistically significant differences were also observed in the length of tunnels created by larvae in the stem of the plant and in their mortality for individuals infected by the entomopathogenic fungi. These results confirm our findings of the in vitro experiments. Regarding the effect of endophytes on the host plant, a neutral impact was recorded for the development, final biomass and distribution of biomass to the aboveground and underground plant tissues. Temporary changes of chlorophyll concentration and leaf water content stability throughout the experimental period should not be attributed to the presence of endophytes. However, some aspects of the photosynthetic process (net photosynthesis, electron transport rate, as well as parameters of the photosynthetic machinery relative to electron flow round the two photosystems) negatively affected after infection of plants by the larvae. The presence of B. bassiana and M. robertsii ameliorated these adverse effects. The results of this study are strongly indicative of successful usage of certain fungi strains for biological control of S. nonagrioides larvae both in laboratory conditions and in the field.

Made available in DSpace on 2014-06-11T19:32:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-06-05Bitstream added on 2014-06-13T20:43:09Z : No. of bitstreams: 1 silva_la_dr_jabo.pdf: 667095 bytes, checksum: f07b680dee9ab27fcd76f2d412bb2029 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O trabalho objetivou identificar e classificar linhagens de sorgo, eficientes e ineficientes ao P avaliadas em ambientes com estresse e sem estresse de P, identificar a importância relativa da eficiência de aquisição e a eficiência de utilização em relação à eficiência de uso de P, obter as estimativas dos coeficientes de correlação genética e fenotípica, realizar análise de trilha e identificar os componentes principais. Avaliou-se 243 linhagens de sorgo e duas testemunhas adicionais divididas em três látices 9x9 com três repetições. Avaliaram-se as seguintes características nos ambientes com e sem estresse de P: florescimento, altura de plantas e produtividade de grãos. As características teor de fósforo nos grãos, eficiência de aquisição, eficiência de utilização interna de P, eficiência de uso de P, índice de colheita de P e quociente de utilização, foram avaliadas somente no ambiente com estresse de P. Foram identificadas e classificadas 107 linhagens eficientes ao P e 138 linhagens ineficientes avaliadas em ambientes com e sem estresse de P. Na importância relativa das eficiências o índice eficiência de aquisição foi o que melhor se relacionou com a eficiência uso de fósforo. De acordo com os resultados das correlações fenotípicas e genotípicas o índice de eficiência de uso de fósforo pode ser avaliado indiretamente, pela avaliação da produtividade de grãos em ambiente com estresse de P. Dentre as variáveis explicativas na análise de trilha, o teor de P total na planta foi a que melhor explicou os efeitos diretos nas variáveis básicas de eficiência de aquisição e uso de P. Foram identificados três componentes principais (PCA 1, 2 e 3), que juntos explicaram 81% da variação original dos dados / This study aimed to identify and classify sorghum lines for P efficiency in environments with high and low P, to identify the relative importance of acquisition efficiency and utilization efficiency in relation to P use efficiency, to obtain the estimates of correlation coefficients and evaluate genetic and phenotypic path analyzes through the development of the direct and indirect effects of independent variables on the dependent variables, and identify the major components. Two hundred forty-three sorghum lines and two additional controls divided into three 9x9 lattices with three replications. Flowering, plant height and grain yield were evaluated in low and high P environments. Phosphorus content in the grain, P acquisition efficiency, P utilization efficiency of internal P, P use efficiency, harvest index and P utilization quotient were evaluated in the low P environment. One hundred and seven lines were identified and classified as P efficient and 138 lines as P inefficient. The relative efficiency of the P acquisition index was the most highly correlated with the efficiency of phosphorus use. These results suggest that the phenotypic correlation index of phosphorus use efficiency can be evaluated indirectly by the assessment of grain yield in P environments total P content in plant was the variable that best explained the direct effects, in the path analysis, of variables in the basic efficiency of acquisition and use. Three main components; 1, 2 and 3, together explained 81% of the variation of the original data