Submitted by Helena Bejio (helena.bejio@unioeste.br) on 2018-08-30T01:12:53Z No. of bitstreams: 2 Lorena _Noreto_2018.pdf: 1204647 bytes, checksum: 8be20b04a0a8a1ec5d5fdbe30bb1b6fe (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-08-30T01:12:54Z (GMT). No. of bitstreams: 2 Lorena _Noreto_2018.pdf: 1204647 bytes, checksum: 8be20b04a0a8a1ec5d5fdbe30bb1b6fe (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-02-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The objective of the present study was to determine the minimum basal temperature, growing degree-day and cycle duration, for different phenological stages of wheat development. As well as evaluating the grain yield components and the wheat yield estimation model at different sowing dates and location. The experiments were carried out in the field at COODETEC Research Centers, located in the municipalities of Cascavel and Palotina, in Paraná State. The experimental design used was in randomized blocks in a factorial scheme (7 x 3). The treatments consisted of seven wheat cultivars (CD 108, CD 1104, CD 1440, CD 150, CD 154, CD 1550 e QUARTZO) and three sowing dates for Cascavel (04/22/15, 04/30/15 and 05/21/15) and Palotina (03/31/015, 04/16/15 and 04/27/15), with three repetitions. The variables evaluated were: duration of the periods in days for the intervals of the sowing to the silking and, sowing to the physiological maturation, minimum basal temperature, growing degree-day, number of ears per square meter, number of grains per spike, mass of one thousand grains and grain yield. The reduction in air temperature tends to increase up to 12 days the intervals between sowing and silking, and between sowing and physiological maturation, for both Cascavel and Palotina. For the different cultivars the minimum basal temperature varied from 0°C to 3.7°C for the sowing period to the silking and 5.8°C to 14,1°C for the silking period to the physiological maturation. The thermal requirements for the cultivars reach the reproductive stage (silking), vary from 817 degree-day (CD 108) to 1270 degree-day (QUARTZO). For cultivar CD 108, the sowing period to the ‘physiological maturation was not altered according to the sowing dates in Cascavel. For the other cultivars (CD 1104, CD 1440, CD 150, CD 154, CD 1550 and QUARTZO) there were variations in the sowing period to physiological maturation at different sowing dates. The number of ears per square meter has a greater contribution to increase the grain yield for the cultivars evaluated. The Sowing on 05/21/15 in Cascavel and 04/16/15 in Palotina resulted in grain yield with average of 5391 kg ha-1 and 3409 kg ha-1, respectively. The mathematical model of productivity estimation obtained a performance considered "Good" to estimate the grain yield of cultivars CD 1440 and QUARTZO. / O objetivo do presente estudo foi determinar a temperatura mínima basal, acúmulo de graus-dia e duração do ciclo, para diferentes estádios fenológicos de desenvolvimento do trigo. Além de avaliar os componentes de rendimento de grãos e o modelo de estimativa de produtividade de trigo em diferentes datas e locais de semeadura. Os experimentos foram desenvolvidos a campo, nos Centros de Pesquisas da COODETEC, localizados nos municípios de Cascavel e Palotina, no Estado do Paraná. O delineamento experimental utilizado foi em blocos ao acaso em esquema fatorial (7 x 3). Os tratamentos foram constituídos de sete cultivares de trigo (CD 108, CD 1104, CD 1440, CD 150, CD 154, CD 1550 e QUARTZO) e três datas de semeadura para Cascavel (22/04/15, 30/04/15 e 21/05/15) e Palotina (31/03/015, 16/04/15 e 27/04/15), com três repetições. As variáveis avaliadas foram: duração dos períodos em dias para os intervalos da semeadura ao espigamento e da semeadura a maturação fisiológica, temperatura mínima basal, acúmulo de graus-dia, número espigas por metro quadrado, número de grãos por espiga, massa de mil grãos e rendimento de grãos. A redução na temperatura do ar tende a proporcionar aumento de até 12 dias nos intervalos compreendidos entre a semeadura e o espigamento, e entre a semeadura e a maturação fisiológica, tanto para Cascavel quando para Palotina. Para os diferentes cultivares a temperatura mínima basal variou de 0°C a 3,7°C para o período da semeadura ao espigamento e de 5,8°C a 14,1°C para o período do espigamento a maturação fisiológica. As necessidades térmicas para os cultivares atingirem a fase reprodutiva (espigamento), variaram de 817 graus-dia (CD 108) a 1270 graus-dia (QUARTZO). Para o cultivar CD 108 o período da semeadura a maturação fisiológica não foi alterado em função das datas de semeadura em Cascavel. Enquanto que para os demais cultivares (CD 1104, CD 1440, CD 150, CD 154, CD 1550 e QUARTZO), ocorreu variações na duração do período da semeadura a maturação fisiológica nas diferentes datas de semeadura. O número de espigas por metro quadrado apresenta maior contribuição para aumentar o rendimento de grãos dos cultivares avaliados. As semeaduras em 21/05/2015 em Cascavel e 16/04/2015 em Palotina resultaram em rendimento de grãos com média de 5391 kg ha-1 e 3409 kg ha-1, respectivamente. O modelo matemático de estimativa de produtividade obteve desempenho considerado “Bom” para estimar o rendimento de grão dos cultivares CD 1440 e QUARTZO.

Memoria para optar al título Profesional de: Ingeniero Agrónomo / En Chile, el trigo candeal (Triticum turgidum L. ssp durum) ha sido desplazado desde el área de riego de la zona central a áreas de secano de la zona centro sur, por frutales y cultivos de mayor rentabilidad. Históricamente, la producción y las investigaciones de este cereal se han llevado a cabo bajo condiciones de riego, labranza tradicional y con sistemas de rotaciones que han sido limitados incurriendo constantemente en monocultivos, situación que afecta negativamente el rendimiento y además la degradación del suelo debido al laboreo, reduciendo el contenido de carbono orgánico. En base a lo anterior, el objetivo de este trabajo fue determinar el efecto de los precultivos de arveja, haba, raps y trigo en el rendimiento y en la calidad del trigo candeal en condiciones de cero labranza. Para ello, se dispuso de 4 precultivos: trigo, arveja, haba y raps; 2 niveles de nitrógeno: 0 kg N ha-1 y 160 kg N ha-1 y 4 repeticiones. Se llevaron a cabo mediciones de información climática, contenido de agua y nitrógeno en el suelo, resistencia a la penetración y a nivel del cultivo se midió fenología, establecimiento, biomasa, rendimiento y sus componentes, contenido de proteína y peso hectolitro. Los rendimientos fueron bajos fundamentalmente en aquellos tratamientos que recibieron fertilización nitrogenada debido al efecto de “Haying off”. No hubo interacción entre nivel de nitrógeno y precultivos para el índice de cosecha, espiga por metro cuadrado, granos por espiga y granos por metro cuadrado. En términos de la calidad del grano, el contenido de proteína fue mayor en los tratamientos en que se aplicó fertilización nitrogenada variando en un rango entre 14-15%. El peso hectolitro tuvo una tendencia opuesta al contenido de proteína, debido a que los tratamientos sin fertilización nitrogenada tuvieron un mayor peso hectolitro debido también al efecto del “Haying off” que generó granos chupados y de bajo peso. La principal variable que influyó en este estudio fue el bajo monto de precipitación (230 mm) durante el periodo de crecimiento del cultivo que generó un estrés hídrico terminal.

Memoria para optar al título profesional de Ingeniero Agrónomo / En Chile, el trigo candeal (Triticum turgidum L. ssp. durum) está siendo desplazado hacia el secano de la Cordillera de la Costa. Esta zona se caracteriza por poseer una textura arcillosa de permeabilidad lenta favoreciendo problemas de anoxia, escenario que puede ser solucionado con el uso de camellones. Por otro lado, INIA recomienda una dosis de semilla de 200 Kg ha-1, pese a que se puede lograr los mismos rendimientos con bajas dosis de semilla, debido a la compensación de falta de plantas por el aumento de los macollos por planta. El objetivo del presente trabajo fue evaluar el efecto de la dosis de semilla en el rendimiento y la calidad de los granos del trigo candeal sembrado en camellones en condición de secano. Para estudiar dicho efecto, en la temporada 2010-2011 se sembró trigo candeal en plano y camellón con las variedades Llareta INIA y Corcolén INIA en tres dosis de semilla, 30, 100 y 200 kg ha-1, bajo condiciones de secano mediterráneo en la zona central de Chile. El rendimiento de trigo candeal en este experimento fue bajo (687 Kg ha-1), el cual se explica debido a la escasa precipitación (142 mm) durante la temporada del cultivo. Además, se observó un bajo índice de cosecha (0,11) y una alta biomasa (5.906 Kg ha-1) debido a la concentración de la precipitación en el periodo vegetativo del cultivo y el consumo total del agua disponible antes de floración, el cultivo permaneció sin agua durante el llenado de grano. Los resultados mostraron que al disminuir la dosis de semilla, el rendimiento en grano se mantiene constante debido a que la dosis menor registró 2,5 y 5 veces más macollos por plantas y macollos fértiles por planta, respectivamente. Por otro lado, el cultivo sembrado en plano logró un mayor rendimiento en grano (861 Kg ha-1) que el cultivo sembrado en camellón (513 Kg ha-1) debido a que en el cultivo sembrado en camellón se duplico el número de semillas sobre la hilera para mantener la misma dosis de semilla en camellón y en plano ya que en el primero existió un menor número de hileras por superficie, que genero una mayor competencia sobre la hilera y que generó un menor número de plantas establecidas. Se concluye que en clima mediterráneo con baja pluviometría (142 mm) y suelos de textura fina, el rendimiento de trigo candeal, de las variedades Llareta INIA y Corcolén INIA, no cambia con la dosis de semilla. E independiente de la dosis de semilla, el rendimiento disminuye cuando la siembra se realiza en camellones. En cuanto a calidad del grano de trigo candeal, los datos de este trabajo no son concluyentes.

Doctor of Philosophy / Department of Plant Pathology / Bikram S. Gill / Segregation distortion describes the transmission of an allele or alleles of a heterozygous locus at a higher frequency than expected in a Mendelian ratio. From the organism's view, segregation distortion is the preferential retention of chromosomal blocks carrying genes beneficial to its fitness and reproductive viability. In wheat the best studied segregation distortes are those introduced from Aegilops species; these selfish genetic elements are named gametocidal (Gc) genes and the chromosomes carrying them are called Gc chromosomes. This genetic mechanism causes chromosome breakage in gametophytes lacking the Gc carrier chromosome, thus favoring its own retention in the genome. While the mode of action of the Gc genes is not yet known, they have been used extensively in wheat genetics for the development of deletion stocks, a key resource for elucidating the structure of physical regions containing important genes. The objective of this study was to develop the tools necessary to map the Gc2 gene derived from Ae. sharonensis and perform map-based cloning. Extensive physical and genetic mapping located the gametocidal gene on the distal 1% of the 4BL arm present in the T4BS[dot in middle of line]4BL-4S[sh superscript]#1L translocation chromosome. Comparative genomics using rice provided markers distal and proximal to the Gc2 locus; however, synteny broke down at the locus. The characterization of this chromosomal region has provided insight into its recombination frequency, synteny and composition; however, the dynamic architecture of the end of the chromosome has made comparative mapping of this region difficult.

This is a study of transcriptional gene regulation in wheat (Triticum aestivum, L.) in response to Russian wheat aphid (RWA) (Diuraphis noxia, Kurdjumov) infestation. The Russian wheat aphid feeds on the phloem sap in the leaves of wheat plants, and causes the leaves of susceptible wheat plants to curl. This forms a protective barrier for the RWA from insecticides and natural enemies. Chlorosis also results from the RWA feeding. In cases of high infestation, death of susceptible plants can also occur. Eleven wheat genes that confer resistance to the Russian wheat aphid have been identified, but their mechanism at molecular level is still not clearly understood. Wheat near-isogenic lines (NILs) were used in a genome-wide, transcriptome analysis using cDNA-AFLP technology. RWA-resistant cultivar ‘Tugela DN’ and RWA-susceptible cultivar ‘Tugela’ were infested with the RWA and leaves were collected from the infested plants at different (0-, 1-, 2-, 6-, 12-, 24-, 48- and 120-) hours post infestation. cDNA samples derived from these leaves was then analyzed by cDNA-AFLP which revealed 18 clusters of differential gene regulation between the two NILs. The results of this experiment show that differential regulation of transcripts occur even within the first hour of infestation. All types of regulation were observed within the clusters. Differentially expressed transcript derived fragments (TDFs) that were randomly isolated from PAGE gels and sequenced (41 TDFs) included sequences in the functional groups similar to those observed in the microarray analysis. The functional categories are cell structure and maintenance [protein synthesis (14%), chaperone (2%), protein degradation (2%), transcription factor (5%)]; photosynthesis [sugar metabolism (5%), carbohydrate metabolism (2%), energy related (7%)]; defenserelated [signaling (7%), defense-related (10%)] while the rest did not have any significant homology to any known or characterized proteins. Previous suppressive subtractive hybridization experiments identified transcripts that are differentially expressed in wheat in response to RWA feeding. More transcripts were identified by PCR from cDNA pools derived from RWA-infested plants as having conserved motifs common in pathenogenesis related proteins. The isolated transcripts were used to generate a defense response-biased microarray chip that was used to investigate the regulation of these transcripts during infestation of RWA resistant wheat plants (‘Tugela DN’) in a time trial. Dual hybridization of CyDye labeled probes derived from the induced ‘Tugela DN’ plants to the microarray chips revealed differential regulation of the immobilized transcripts in wheat, at different time points post infestation with the RWA. Statistical analysis of the CyDye intensities on the 380 spots mounted on the cDNA microarray slides showed 29 transcripts to be significantly regulated (P≤0.05) during the time of the experiment. These included ESTs that were grouped into four functional categories, namely cell structure and maintenance (9 ESTs); photosynthesis (8 ESTs); defense-related (4 ESTs) and those with no significant homology found or proteins with unknown function (8 ESTs). Patterns of regulation of these transcripts in all of the functional categories included all types of regulation e.g. mainly down-regulation, mainly up-regulation, and a combination of up-/up-/down-regulation in response to RWA feeding. In conclusion, data obtained utilizing cDNA microarray and cDNA-AFLP analyses in infested wheat suggest that the ability to maintain structures involved in photosynthesis by regulating the relevant transcripts through-out infestation is an important determinant in plant survival during RWA feeding. The timing of regulation is also important as some of the transcripts are also regulated in RWA susceptible ‘Tugela’ plants but not in a timely manner which leads to loss of energy and subsequent death of susceptible plants. / Dissertation (MSc)--University of Pretoria, 2011. / Genetics / unrestricted

Experiments were undertaken to examine the extent of variation for potassium and nitrogen uptake and utilization in wheat and also to address some issues of relevance to the improvement of these traits. These issues included the inheritance of these traits and the difficulties that could arise due to (1) the methodology that is used to measure ion fluxes and utilization, (2) ontogenetic variation in the expression of these traits, and (3) the growth stage at which nutrient utilization is evaluated. To compare varieties developed during different periods in the history of wheat breeding, the varieties were assigned to five groups on the basis of height and origin. Nutrient fluxes were measured either as average net fluxes or short-term net fluxes. Nutrient utilization was expressed as shoot fresh weight per plant, efficiency ratio or utilization efficiency. Substantial variation was observed for all traits except potassium and nitrogen efficiency ratios. Although short-term net potassium fluxes were negatively correlated with root potassium concentration, some of the differences in flux were not associated with differences in root potassium concentration. These differences must therefore be heritable. Due to the complexity of the regulation of nitrate uptake, genotypic differences in short-term net nitrate flux were not examined in relation to root nitrate concentration. Therefore, some of the variation in nitrate flux could be due to differences in root nitrate concentration or some other factor(s) which regulates nitrate uptake. Significant differences between groups were also observed. The tall varieties had the highest potassium and nitrate fluxes but were not significantly different from the triple dwarfs. The double dwarfs were the poorest performers for both nutrient uptake and utilization. In general, the tall traditional varieties were more vigorous and hence showed the highest shoot weight per plant and utilization efficiencies. These findings are examined in relation to the contention that plant breeding under high fertility conditions may have resulted in a decline in the ability of plants to acquire and utilize mineral nutrients. The inheritance of short-term net potassium flux, shoot weight per plant, potassium efficiency ratio and potassium utilization efficiency was studied in four crosses. Complex modes of inheritance were observed for all the traits. For one of the crosses significant reciprocal effects were observed for shoot weight per plant, efficiency ratio and utilization efficiency. Narrow sense heritabilities for the two traits most likely to be selected for, namely short-term net potassium flux and shoot weight per plant, indicated that selection for these traits should be carried out amongst families rather than amongst single plants. Diallel analysis for nitrate uptake and utilization indicated that both additive and dominance gene effects are important in the determination of these traits. The effect of developmental changes in potassium uptake and utilization on varietal comparisons and genetic studies was investigated by comparing the performance of six varieties at different stages of growth over a five-week period. The rankings of the varieties for short-term net potassium flux and shoot weight per plant were found to be fairly consistent. Correlations between average net fluxes for different time periods as well between short-term and average net fluxes were poor. These findings indicate that selection for differences in uptake should be based on fluxes obtained from solutions identical in concentration to the growth solution rather than on perturbation fluxes obtained by depletion of a solution much more concentrated than the growth solution. All measures of potassium utilization based on vegetative growth were poorly correlated with performance at the adult stage. Significant negative rank correlations between shoot fresh weight per plant and grain weight per plant were obtained most likely due to differences in harvest index. This finding casts some doubt on the usefulness of vegetative measures of nutrient utilization as indicators of nutrient-use efficiency for a crop in which the economic product consists of grain. / Science, Faculty of / Botany, Department of / Graduate

Germinating uredospores of race C17 of Puccinia graminis f.sp. tritici form characteristic infection structures (appressorium, infection peg, vesicle, infection hypha) in response to a 1.5 h heat shock at 29° C administered 2 h after germination at 19° C. The proportion of sporelings forming infection structures was augmented by nutrients, n-nonyl alcohol and, an appropriately timed heat shock. The heat shock temperature required to induce maximum differentiation had a very precise optimum which varied slightly for each spore lot. Variations one degree above or below this optimum reduced the percent differentiation by greater than 40%. The presence of an inhibitor of protein synthesis, puromycin, in the germination medium: (1) prevented uredosporeling differentiation but had no effect on germination, (2) significantly reduced the proportion of germtubes forming appressoria, and (3) in most cases prevented the division of germtube nuclei. It was concluded that essential differentiation-specific proteins are synthesized from the onset of germination, throughout the formation of appressoria and to the completion of differentiation. These results were consistent with the observed effects of heat shock on the rate of protein hydrolysis. During germination there was a net hydrolysis of protein leading to an increase in size of the endogenous pool of free amino acids and to an increased leakage of amino acids to the germination medium. Heat shock effectively reduced the amount of endogenous free amino acids and the extent to which amino acids were lost to the medium. It was concluded that in heat shocked sporelings protein synthesis was increased relative to protein hydrolysis by comparison with the relative rates of these two processes in germinating (non-shocked) uredosporelings. Moreover, there was no net protein synthesis during the formation of infection structures induced by heat shock. The loss of amino acids to the germination medium was selective, particularly in heat shocked sporelings. / Land and Food Systems, Faculty of / Graduate

Memoria para optar al título profesional de Ingeniero Agrónomo / En Chile, el trigo candeal (Triticum turgidum L. ssp. durum) está siendo desplazado hacia el secano de la Cordillera de la Costa. Esta zona se caracteriza por poseer una textura arcillosa de permeabilidad lenta favoreciendo problemas de anoxia, escenario que puede ser solucionado con el uso de camellones. Por otro lado, INIA recomienda una dosis de semilla de 200 Kg ha-1, pese a que se puede lograr los mismos rendimientos con bajas dosis de semilla, debido a la compensación de falta de plantas por el aumento de los macollos por planta. El objetivo del presente trabajo fue evaluar el efecto de la dosis de semilla en el rendimiento y la calidad de los granos del trigo candeal sembrado en camellones en condición de secano. Para estudiar dicho efecto, en la temporada 2010-2011 se sembró trigo candeal en plano y camellón con las variedades Llareta INIA y Corcolén INIA en tres dosis de semilla, 30, 100 y 200 kg ha-1, bajo condiciones de secano mediterráneo en la zona central de Chile. El rendimiento de trigo candeal en este experimento fue bajo (687 Kg ha-1), el cual se explica debido a la escasa precipitación (142 mm) durante la temporada del cultivo. Además, se observó un bajo índice de cosecha (0,11) y una alta biomasa (5.906 Kg ha-1) debido a la concentración de la precipitación en el periodo vegetativo del cultivo y el consumo total del agua disponible antes de floración, el cultivo permaneció sin agua durante el llenado de grano. Los resultados mostraron que al disminuir la dosis de semilla, el rendimiento en grano se mantiene constante debido a que la dosis menor registró 2,5 y 5 veces más macollos por plantas y macollos fértiles por planta, respectivamente. Por otro lado, el cultivo sembrado en plano logró un mayor rendimiento en grano (861 Kg ha-1) que el cultivo sembrado en camellón (513 Kg ha-1) debido a que en el cultivo sembrado en camellón se duplico el número de semillas sobre la hilera para mantener la misma dosis de semilla en camellón y en plano ya que en el primero existió un menor número de hileras por superficie, que genero una mayor competencia sobre la hilera y que generó un menor número de plantas establecidas. Se concluye que en clima mediterráneo con baja pluviometría (142 mm) y suelos de textura fina, el rendimiento de trigo candeal, de las variedades Llareta INIA y Corcolén INIA, no cambia con la dosis de semilla. E independiente de la dosis de semilla, el rendimiento disminuye cuando la siembra se realiza en camellones. En cuanto a calidad del grano de trigo candeal, los datos de este trabajo no son concluyentes. / Durum Wheat (Triticum turgidum L. ssp. durum) is being displaced to the dry lands of the coastal mountain range in Chile. The main features of this area are clay soil textures with slow permeability for irrigation and anoxic problems during rainy seasons, this background can be solved using raised bed. On the other hand, INIA advises a 200 kg ha-1 seed rate, despite that, identical yields can be obtained with lower seed rate due to plant compensation of the lower plant number by increasing the plant tillers. The main objective of the present work was the evaluation of the seed rate into the final yield and quality of the durum wheat grain sown in raised bed in dry lands. In order to study that effect, durum wheat was sown in the season 2010 – 2011 in flat lands and in raised bed with Llareta INIA and Corcolen INIA varieties in three seed rates, 30, 100 and 200 kg ha-1, under Mediterranean dry land in central Chile. Durum wheat yield in this field assay was low (687 kg ha-1), explained by the lower rainfall during the crop season (142 mm). Moreover a low harvest index (0.11) and high biomass values (5.906 kg ha-1) were observed due to the concentration of the precipitation during the crop vegetative stage and due pre-floration total water consumption, this caused that the crop remained without water during grain filling. The result showed that lowering the seed rate, the grain yield remains constant due to minor rate registered 2.5 to 5 times more tillering by plant and fertile tiller per plant respectively. On the other hand the crop sown in a flat soil surface reached a higher grain yield (861 kg ha-1) than the crop sown in a raised bed soil surface (513 kg ha-1) because at the crop sown on ridge doubled the number of seeds on the line to keep the same amount of seed in ridge and flat as it existed in the first fewer rows per surface, generating more competition on row and generated a smaller number of plants established. It is concluded that in Mediterranean climate with lower precipitation rate (142 mm) and fine textured soils, the durum wheat yield from the Llareta INIA and Corcolen INIA varieties does not change with the seed rate. Independent of the seed dose, the yield diminishes when the sowing is performed in raised bed soil surfaces. No conclusive data was found in this work for the quality of the durum wheat.

Memoria para optar al título Profesional de Ingeniero Agrónomo / El alto vigor inicial, definido a través de un mayor área foliar temprana (Zadoks 12 - 13) y del peso de semilla, es ventajoso al asociarse con una mayor biomasa y área foliar durante el estado de crecimiento en condiciones de medioambiente Mediterráneo, donde las precipitaciones son abundantes en etapas tempranas en el desarrollo del cultivo y ausentes al final del ciclo productivo. Debido a lo anterior, éste estudio analizó y comparó el efecto del vigor inicial en el rendimiento y crecimiento de trigo candeal (Triticum turgidum L. var. durum) en un ambiente Mediterráneo y en condiciones de secano, además de asociar el rasgo a la interceptación de radiación.

Memoria para optar por el título profesional de Ingeniera Agrónoma Mención en Fitotécnia / El uso de las rotaciones de cultivo bajo condiciones de secano es una alternativa empleada en la agricultura para generar sistemas agrícolas más sustentables y productivos. De estas se puede obtener beneficios como el aporte de nitrógeno al suelo y la interrupción en el ciclo de enfermedades. En la temporada 2010 se sembró trigo candeal variedad Llareta INIA posterior a arveja (Pisum sativum L.), haba (Vicia faba L.), raps (Brassica napus L.) y trigo candeal con el fin de estudiar el efecto de precultivos en la calidad y rendimiento de trigo candeal (Triticum turgidum L. ssp. durum) en condiciones de secano mediterráneo de la zona central de Chile. La precipitación alcanzó 230 mm durante el ciclo del cultivo. Para aislar el efecto del precultivo asociado a nitrógeno se aplicó 2 dosis de fertilizante nitrogenado (0 y 160 Kg N ha -1 ). Los resultados mostraron que haba fue la leguminosa que aportó más nitrógeno a la siembra (44,4 kg N ha -1 ). El rendimiento se vio afectado de manera negativa principalmente por las bajas precipitaciones de la temporada y la aplicación de N, produciéndose un fenómeno de “haying-off”. El tratamiento de 160 Kg N ha -1 produjo una mayor biomasa, que se reflejó en mayor número de espigas por superficie, pero bajo rendimiento, producto de un menor peso de granos y menos granos por espiga. Los tratamientos sin fertilización nitrogenada tendieron a conservar más agua en el suelo durante la temporada, mientras que los distintos precultivos no generaron diferencias en el contenido de agua del suelo. Los precultivos sólo generaron diferencias significativas en el peso de los granos y el mayor peso se obtuvo con el precultivo haba, debido a un menor número de granos por superficie. Todos los tratamientos superaron el 12% de proteína, mínimo exigido por la industria, mientras que para peso del hectolitro sólo los tratamientos sin fertilización nitrogenada superaron 78 kg hL -1 que bonifica la industria. Se concluye que, bajo las condiciones extremadamente secas de la temporada el uso de precultivos no provocó diferencias en el rendimiento ni en la calidad del trigo candeal. El uso de haba como precultivo aportó el mayor contenido de nitrógeno disponible previo a la siembra de trigo candeal. La metodología aplicada no permitió detectar si el uso de precultivos tuvo efecto en el contenido de agua del suelo. / The use of crop rotations under rainfed conditions is an alternative used in agriculture to generate more sustainable agricultural and productive systems. The benefits that are generated from them may be soil nitrogen input and disrupt disease cycle. Season 2010 the variety Llareta INIA was planted after pea (Pisum sativum L.), faba bean (Vicia faba L.), canola (Brassica napus L.) and durum wheat to study the effect of precultures in the quality and yield of wheat (Triticum turgidum L. ssp. durum) under central rainfed Mediterranean condition in Chile. The rainfall reached 230 mm during the crop cycle. To isolate the effect of pre-culture not associated with nitrogen was applied 2 doses of nitrogen fertilizer (0 and 160 kg N ha -1 ). The results showed that the legume faba bean provided more nitrogen at pre sowing (44,4 kg N ha -1 ). Yield was negatively affected mainly by low rainfall of the season and the application of N, leading to a phenomenon of "haying-off". The treatments of 160 kg N ha -1 produced greater biomass, which was reflected in a greater number of spikes per surface, but low yield, due to a lower grain weight and fewer grains per spike. Treatments without nitrogen fertilization tended to keep more water in the soil during the season, whereas preculture treatments didn’t generate different in soil water content. The precultures only generated significant differences in grain weight and greater weight was obtained with faba bean, due to a lower number of kernels per area. All treatments exceeded 12% of protein, minimum required by the industry, but only treatments without nitrogen fertilization exceeding 78 Kg hL -1 , that the industry subsidizes. Finally we can conclude that, under the extremely dry conditions of the season, the use of precultures did not improve the durum wheat yield nor the quality. The use of faba bean as preculture contributed the highest content of available nitrogen before sowing of wheat. The methodology applied does not allow detecting if the use of precultures causes effects in the soil water content.