No description available.

No description available.

USA soybean germplasm has a narrow genetic base that could be augmented by alleles from the wild species Glycine soja which positively influence agronomic traits. The objective of this study was to identify such alleles for yield and yield component QTL (quantitative trait loci). Two populations of 150 BC2F4 lines were generated from a mating between recurrent parent Glycine max 7499 and donor parent Glycine soja PI 245331 with one line in each population tracing back to the same BC2 plant. Population A was used for the QTL identification analysis and population B was used for the QTL verification test. The population A lines were genotyped at 120 SSR marker loci and one phenotype marker, covering a total map length of 1506 cM in 20 linkage groups with an average interval size of 12.5 cM. There were nine putative QTL significantly (Pandlt;0.0001, LODandgt;3.0) associated with yield and yield component traits across 3 environments. One QTL for seed yield was identified using the combined data; the G. soja allele at satt511 on LG-A1 was associated with increased seed yield (LOD=4.3) with an additive yield effect of 190 235 kg ha-1 depending on the QTL analysis method. The phenotypic variance accounted for by the QTL at satt511 was 12%. This QTL also provided a significant yield increase across environments in the validation population; lines that were homozygous for the G. soja allele at satt511 demonstrated a 6.3% (P=0.037) yield increase over lines that were homozygous for the G. max allele. One seed filling period QTL was identified at satt335 (LOD=4.0) on LG-F with an additive effect of +1 day. This QTL also provided a +1 day additive effect (LOD=3.3) on maturity. These results demonstrate the potential of using exotic germplasm to improve soybean yield.

Master of Science / Department of Agronomy / Ignacio Ciampitti / Soybean [Glycine max (L.) Merr.] yields have continuously increased over time. Seed yields are determined by the genotype, environment, and management practices (G × E × M) interaction. Closing yield gaps require a continuous improvement in the use of the available resources, which must be attained via implementation of better management decisions. Linear relationships between seed yield and nitrogen (N) demand are reported in the scientific literature. Main sources of N to the plant are the biological N fixation (BNF) and the soil mineralization processes. On overall, only 50-60% of soybean N demand is met by the BNF process. An unanswered scientific knowledge is still related to the ability of the BNF to satisfy soybean N demand at varying yield levels. Seed N demand not met by N fixation plus soil mineral N, is then fulfilled by the remobilization of N from vegetative organs during the seed filling period. An early remobilization process reduces the photosynthetic activity (leaves) and can limit seed yield. The objectives of this project were to: i) study yield improvements and contribution of N via utilization of contrasting N conditions under historical and modern soybean genotypes, and ii) quantify main seed N sources during the seed filling period. For objective one, four field experiments were conducted during the 2016 and 2017 growing seasons in Kansas, United States (US) and Santa Fe Province, Argentina (ARG). Those experiments investigated twenty-one historical and modern soybean genotypes with release decades from 1980s to 2010s. As for objective two, three field experiments were conducted during the 2015 and 2016 growing seasons in Kansas, US, studying three soybean genotypes: non-roundup ready (RR), released in 1997; RR-1, released in 2009; and RR-2, released in 2014. Across all studies, seeds were inoculated and tested under three N management strategies: i) control without N application (Zero-N); ii) 56 kg N ha-1 applied at reproductive growth stages (Late-N); and iii) 670 kg ha-1 equally split at three timings (Full-N). As for yield improvements and N limitation, soybean yield improvements from the 1980s to 2010s were documented, representing 29% increases in the US and 21% in ARG. Regarding N management, the Full-N fertilization produced a 12% increase in seed yields in the US and 4% in ARG. As for main seed N sources in objective two, remobilization accounted for 59% of seed N demand, and was negatively related to new N uptake occurring during the seed filling period. Seed N demand for greater yields was dependent on both, N remobilization and new N uptake, while for lower yields, seed N demand was mainly supported by the N remobilization process. These results suggest that: a) high seed yields are somehow limited by the availability of N to express their potential, although the question about N application still remains to be fully investigated, as related to the timing and the environment by plant interactions that could promote a N limitation in soybeans; b) remobilization accounts for majority (59%) of N sourced to the seed, and c) high yielding soybean (modern genotypes) rely on diverse N sources: the N remobilization process plus new uptake of N.

No description available.

No description available.

Synthetic hexaploid wheats, created from a durum (Triticum durum) cross to Aegilops tauschii Coss. (McFadden and Sears, 1946), proved to be an efficient and beneficial source of new genes for common bread wheat (Triticum aestivum L). The purpose of this research was to evaluate the potential and performance of synthetic wheat in Texas. Ten elite primary synthetics from the International Maize and Wheat Improvement Center (CIMMYT), screened for desirable traits, were backcrossed to two Texas cultivars, TAM 111 and TAM 112. Populations were bulked and modified bulked to advance generations. Agronomic traits related to yield were determined on the F4 and F5 Improvement was observed in South Texas and the Blacklands, which have more disease pressure and fewer intermittent dry spells than another two locations at Chillicothe and Bushland in Texas Rolling and High Plains, respectively. Selected bulks were not superior to non-selected bulks. Head number per unit area had the highest correlation with yield and seed weight was the most heritable trait. Synthetic lines combined better with TAM 111 than TAM 112 in high yielding environments. populations across five Texas locations. Similar to crosses with spring wheat, synthetics contributed to yield through an increase in seed weight. Synthetic populations that produced higher grain yield than both TAM 111 and TAM 112 were able to maintain their large seed size and weight while improving their seed per head and head number traits. Poorer performance in environments with harsh winters could be due to a lack of winter-hardiness in the primary synthetics. This clearly demonstrates that improving yield, through utilization of common wheat by synthetic crosses, could result from selecting for larger seed per head and heads per unit area in lines driven from these populations. Introgression of new genes through synthetic backcrosses could contribute to the improvement of wheat in particular regions of Texas. Primary synthetics and recurrent parents combining for superior hybrids were identified.

From the Proceedings of the 1975 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 11-12, 1975, Tempe, Arizona / The response of saltcedar (Tamarix pentandra Pall.) to several antitranspirants was evaluated in laboratory, greenhouse and small -scale field studies using potted plants. Anti - transpirants may provide a treatment alternative to the eradication of saltcedar thickets for water salvage objectives. Transpiration rates were reduced by 23 to 44 percent for 7 to 20 days in the greenhouse, and by 18 to 32 percent for 2 to 8 days in the field. No serious damage to the plants was apparent. One of the most effective antitranspirants considered for a hypothetical saltcedar thicket and a hypothetical operational treatment program, based on estimated cost data, would result in reallocated water costing approximately 55 dollars per acre foot for a single treatment. About 19 acres of saltcedar thicket would have to be treated to provide one acre -foot of reallocated water in this case.

Les défauts récurrents apparaissant dans des contextes particuliers ont un impact non négligeable sur le rendement, lors de la fabrication des noeuds technologiques nanométriques. C'est pourquoi une nouvelle méthode de contrôle du procédé de fabrication in-situ est développée, en vue d'améliorer la performance globale de l'outil de production. Elle se veut complémentaire des techniques d'analyses de défaillance classique, notamment en cas de crise. Le principe est de transformer un circuit de production en un véhicule de test en réutilisant des éléments qui le composent. Le circuit perd alors sa fonctionnalité originale au profit de fonctions de contrôle du procédé de fabrication réalisées uniquement à base de cellules logiques disponibles en grand nombre dans les circuits. Cette transformation, baptisée «échange topologique», implique la modification de certains niveaux de métallisation et nécessite la création d'un flot de conception particulier, basé sur des techniques d'Engineering Change Order (ECO). Comme plusieurs fonctions doivent pouvoir cohabiter ensemble sur un même véhicule, un système de multiplexage a été évalué. La faisabilité est montrée au travers d'un circuit de test réalisé de manière analogue à un circuit en production. Il est transformé pour l'exemple en un système intégré de contrôle d'épaisseur de diélectrique. / Recurrent defects appearing in specific contexts have a significant impact on nanoscale technology nodes manufacturing process yield. Therefore, a new in-situ process monitoring method is developed to improve the overall performance of the production tool. It is complementary to classical failure analysis techniques, especially when a yield crisis occurs. The idea is to transform a production circuit into a test vehicle by reusing its components. The circuit loses its original functionality in favor of process monitoring functions, carried out only with standard cells widely available in circuits. This transformation, called "topological exchange" involves modifying some levels of metallization and requires the creation of a particular design flow, based on Engineering Change Order (ECO) techniques. As several functions must be able to cohabit on the same vehicle, a multiplexing system is evaluated. Feasibility is shown through a test circuit designed analogously to a production circuit. It is transformed for the example into an integrated dielectric thickness control system.

Ces travaux visaient à étudier la possibilité de réduire la production de glycérol chezSaccharomyces cerevisiae, afin d’améliorer le rendement éthanol, tout en préservant les capacités decroissance et de production des levures. La production minimale de glycérol nécessaire à la croissancea été déterminée à l'aide d'un modèle de calcul des flux métaboliques. Des souches présentant uneactivité des enzymes de la voie de production du glycérol modulée, afin de s'approcher au plus près del'activité minimale nécessaire estimée in silico, ont été utilisées.Cette stratégie d’ajustement de l’activité de la voie de synthèse du glycérol a permis, encondition aérobie, de réduire de 88 % le rendement glycérol et d'améliorer le rendement éthanol de4,7 % sans modifier la tolérance des mutants à l'éthanol, mais au détriment de la vitesse spécifique decroissance, légèrement réduite. En condition anaérobie, une diminution de 61 % du rendementglycérol et une amélioration de 7 % du rendement éthanol ont pu être obtenues, mais au détriment dela vitesse spécifique de croissance,qui subit une sévère diminution, et de la tolérance à l'éthanol,qui estréduite.L'analyse fine des résultats, grâce à un modèle métabolique, a permis de mettre en évidence,chez les souches mutantes, un besoin accru en énergie, interprété comme la traduction d'une plusgrande difficulté à gérer le stress du procédé et une réorganisation du métabolisme oxydo-réductif,interprétée comme l'impact de la réduction du glycérol sur les voies de réoxydation du cofacteurNADH dans les cellules.Ces résultats ont permis de valider la pertinence de la stratégie de réajustement des fluxmétaboliques, assistée par modélisation stoechiométrique pour l'amélioration des souches, mais aussid'accroître la compréhension du rôle physiologique du glycérol et son intégration au métabolismecellulaire. / This work aimed to assess the possibility of reducing Saccharomyces cerevisiae's glycerolproduction, in order to improve ethanol yield, without altering the abilities of yeasts to grow andproduce ethanol. Minimum glycerol production required for growth was found, thanks to a metabolicflux calculation model. Strains showing a fine tuned activity in the glycerol synthesis pathway enzymeswere used, to get close to the minimum activity established in silico.This fine tuning strategy lead, in aerobiosis, to a 88 % glycerol yield decrease together with a4.7 % ethanol yield increase, with no reduction of mutants'ethanol tolerance, but there is a slightdecrease of the growth rate. In anaerobiosis, a 61 % glycerol yield decrease, together with a 7 %ethanol yield increase were obtained, but mutant strains suffered of a sharp growth rate reduction anda decrease in their ethanol tolerance.A close analysis of the results, with the help of a metabolic model, highlighted both an increaseof mutants' energy requirements, interpreted as an increased difficulty to cope with osmotic stress,and a reorganisation of their oxydo-reductive metabolism, interpreted as glycerol reduction's impacton the NADH cofactor reoxydation pathway.These results validated the relevance of metabolic fine-tuning, assisted with in silicostoichiometric model for strains improvement and they increased the understanding of the integrationof glycerol in cell metabolism as well as its physiological role.