No description available.

No description available.

Microsprinkler irrigation offers excellent flexibility for site-specific management of water and nitrogen inputs for citrus orchards in the southwestern United States. Escalating water costs, declining water availability, and increasing regulation of nitrogen (N) fertilizer use are causing growers to adopt practices to improve water and N use efficiency. 'Newhall' navels on 'Carrizo' rootstock were planted in Jan. 1997 and an experiment was initiated. This experiment was continued during 1999. The objective of the experiment was to develop appropriate management guidelines for N fertigation of 3-4 year old microsprinkler-irrigated navel orange trees. Treatments were factorial combinations of three N rates (0.15, 0.30, 0.45 lb N tree⁻¹ yr⁻¹) and three fertigation frequencies (3x/year, monthly, weekly). An untreated control was included. Trunk diameter was not responsive to N rate or fertigation frequency. Leaf N in all treatments, even controls, remained above the critical level (2.5%). However, at each N rate leaf N was highest with the weekly fertigation frequency. Nitrate analyses of soil samples indicate that nitrate leaching was highest with the highest N rate and 3x/year fertigation. Frequent fertigation is recommended because it results in higher leaf N and less nitrate leaching.

Brachiaria brizantha (Hochst ex. A. Rich) Stapf apresenta boa adaptação às condições edafoclimáticas brasileiras e é muito utilizada como planta forrageira em pastagem na produção de bovinos. Apesar de seu potencial na produção de ovinos, ainda são necessárias novas investigações para aperfeiçoar o seu manejo. Objetivou-se com esta pesquisa avaliar as características produtivas, fisiológicas e bromatológicas de um pasto formado por Brachiaria brizantha cv. Marandu, fertilizada com doses de nitrogênio (N) e sob pastejo ovino. O delineamento experimental foi em blocos completos casualizados com 04 repetições e 05 tratamentos experimentais: 0; 90; 180; 270; 360 kg de N.ha-1, totalizando 20 parcelas experimentais. O método de pastejo foi o rotativo, com ciclo de pastejo de 30 dias, sendo 25 dias de descanso e 5 dias de ocupação, como forma de rebaixar o pasto à altura de resíduo de 6 cm. As medições no pasto foram feitas a cada 3 dias em 3 ciclos de pastejo, quando se avaliou: o fluxo de tecidos, a dinâmica de perfilhamento, a produção e a composição bromatológica da planta forrageira. Para massa seca de forragem verificou-se comportamento quadrático nas doses crescentes de N, atingindo o platô em 246 kg.ha-1. As variáveis taxas de senescência foliar, peso médio e densidade populacional de perfilhos não foram influenciados (P>0,05) pela adubação nitrogenada enquanto que a taxa de alongamento e de aparecimento de folhas, a taxa de alongamento de colmo, o número de folhas vivas, o comprimento final de folhas foram influenciados pela adubação nitrogenada (P<0,05). O filocrono e a duração de vida da folha foram mais curtos na presença do N. Em relação às características bromatológicas, o N afetou positivamente nos teores de FDA, FDN, e PB. Pelo manejo imposto aos pastos, a utilização do N teve efeito positivo nas características fisiológicas, produtivas e nutritivas do capim-marandu. / Brachiaria Brizantha (Hochst ex. A. Rich) Stapf is well adapted to Brazilian climatic conditions, and is widely used as a forage grass on pasture production in cattle. Despite its potential for use in the present sheep production, further research studies are still needed to optimize their management. The objective of this research was evaluate yield, physiological and chemical characteristics of a pasture of Brachiaria brizantha cv. Marandu, fertilized with nitrogen and grazing sheep. The experimental design was a randomized complete block with 04 replications and 05 experimental treatments: 0, 90, 180, 270 and 360 kg N.ha-1 totaling 20 experimental plots. The grazing method was rotating with cicle of grazing of 30 days, 25 days of rest and 5 days of occupancy to reach height of pasture residue of 6 cm. Measurements were made in the pasture every 3 days, at,three grazing cycle evaluated. Thus analyzing the flow of plant tissue, the dynamics of tillering, yield and composition chemical of forage. For dry herbage mass there was a quadratic behavior in increasing doses. The increase of N, there was a quadratic behavior, reaching a plateau where the best dose was 270 kg.ha-1. The variables leaf senescence rate, average weight and tiller density were not affected (P>0.05) by use of N, while the variables leaf elongation rate and appearance, stem elongation rate, number of living leaves, final length of leaves were influenced by nitrogen fertilization (P<0.05), Phyllochron and lifetime leaves were shorter in the presence of N. Regarding the chemical caracteristics, the presence of N affected positively the levels of the ADF, NDF and CP, The grazing management imposed, the use of N had a positive effect on the physiological, productive and chemical characteristics of Marandugrass.

Barley is one of the important crops in many of the irrigated regions of the world. It is an important crop in Iran for both human consumption and livestock feed. In the United States and Europe it is used for livestock feed and beverages. The income from this crop is moderate in comparison to that from other major agricultural products. Barley production has a definite place in the economy of the region, because it requires only a small amount of care. It can be readily grown on poor lands. One of the factors contributing to the increased acreage of barley in many countries is the tolerance and adaptability of this plant to salt and poor or second class land. Yields have been increased materially in recent years with the development of new varieties superior to the standard varieties previously used. Better cultural practices are improving yields, but much remains to be done in this phase of the work.

Les nanoparticules (NP) comportent au moins une dimension entre 1 et 100 nm. Les nanoparticules de dioxyde de cérium (NPCeO2) sont largement utilisées au niveau industriel, en particulier comme additif au carburant diesel, mais font aussi l’objet d’étude en cancérologie. L’OCDE a placé les NPCeO2 dans la liste des nanomatériaux nécessitant une évaluation urgente de leur toxicité.Plusieurs études ont démontré le passage de NP métalliques dans les gonades après exposition in vivo chez l’animal, mais très peu de données sont disponibles concernant les NPCeO2.L’objectif de ce travail a été dans un premier temps d’étudier la génotoxicité des NPCeO2 sur spermatozoïdes et ovocytes murins par exposition in vitro, ainsi que leur impact sur la fécondation in vitro (FIV) murine. Nous avons dans un second temps étudié leur génotoxicité sur spermatozoïdes humains in vitro.Nous avons montré une diminution significative des taux de fécondation chez la souris, lors des FIV réalisées en présence de NPCeO2 à faible concentration (0,01 mg/l). Nous avons également montré une génotoxicité significative des NPCeO2 à faibles doses sur ovocytes, spermatozoïdes de souris, et spermatozoïdes humains par le test des comètes. En microscopie électronique à transmission, nous n’avons pas retrouvé de NP dans les milieux de culture à 0,01 mg/l, mais observé une endocytose dans les cellules du cumulus entourant les ovocytes à forte concentration (100 mg/l) et une accumulation des NP le long des membranes des spermatozoïdes et des zones pellucides des ovocytes. Ces résultats apportent des informations nouvelles et importantes sur les mécanismes d’actions suspectés. / The fast development of nanotechnology gives rise to questions regarding the potential risks on human health. Cerium oxide nanoparticles (CeO2NP) are widely used, as diesel additive, as well as promising therapeutic in cancerology, yet scarce data are currently available on their toxicity. It has been shown that metal nanoparticles can cross biological barriers and accumulate into various organs including the gonads after in vivo exposure. Our objectives were to investigate CeO2NP’s genotoxicity on mouse spermatozoa and oocytes, human spermatozoa, and to study their possible impact on murine IVF.We showed a significant decrease of fertilization rate, during IVF carried out in culture medium containing CeO2NP at very low concentration (0.01mg/l). We also showed significant DNA damage induced in vitro by CeO2NP on mouse spermatozoa and oocytes at 0.01 mg/l using Comet assay. TEM did not detect any nanoparticles in the IVF samples at 0.01 mg/l, but showed, at high concentration (100 mg/l), their endocytosis by the cumulus cells surrounding oocytes and their accumulation along spermatozoa plasma membranes and oocytes zona pellucida. We showed significant DNA damage induced by CeO2NP on human spermatozoa. The genotoxicity was inversely proportional to the concentration. At 0.01 mg/l, the genotoxicity mechanisms involved oxidative stress and close interactions between spermatozoa and CeO2NP.We demonstrate for the first time the impact of CeO2NP on in vitro fertilization, as well as their genotoxicity on mouse gametes and human sperm, at very low nanoparticle concentration exposure. These results support several publications on metal nanoparticles reprotoxicity.

No description available.

No description available.

The cellular and molecular environment of the uterus during the pre - and peri - implantation period of early pregnancy is critical for implantation success and optimal fetal and placental development. Perturbations to this environment not only have consequences for the success of pregnancy and neonatal health and viability, but can also drive adverse health outcomes in the offspring after birth, particularly the development of metabolic disorders such as obesity, hypertension and insulin resistance. The influence of seminal plasma on the cytokine and immune uterine environment has been previously well characterised in mice, however the effects of disruption in uterine seminal plasma exposure for pregnancy outcome have not been investigated. The studies described in this thesis employed the use of surgical seminal vesicle ablation in males and embryo transfer experiments to investigate the physiological significance of uterine seminal plasma exposure on programming fetal and neonatal outcomes, and growth and metabolic status in adult offspring. We demonstrate that in the absence of seminal plasma, oocyte fertilisation and embryo implantation are reduced, showing that seminal plasma acts primarily to facilitate fertilisation, possibly by promoting sperm transport and survival in the reproductive tract. In addition we show that pregnancies initiated in the absence of seminal plasma give rise to offspring which display accelerated growth after birth and increased adiposity in adulthood, compared to those developed in a tract exposed to seminal plasma at the time of conception. Offspring conceived in the absence of seminal plasma also displayed alterations in serum leptin and adiponectin content, similar to those known to be associated with obesity in the mouse. Using embryo transfer experiments, we showed that some, but not all aspects of the perturbed postnatal development are recapitulated when embryos fertilised in the presence of what semen are transferred to a recipient tract which has not been exposed to seminal plasma. More severe perturbations were seen in 2 - cell transfer than in blastocyst transfer experiment. Additionally, there was a significant effect of the embryo transfer procedure, irrespective of seminal plasma exposure, on fetal and postnatal development that confounded interpretation of these experiments. In addition, we investigated the potential mechanisms by which the influence of seminal plasma is exerted. Mediators of pre - implantation embryo development, implantation and the modulation of the maternal immune response to pregnancy were all assessed for regulation by seminal plasma using QRT - PCR. It was demonstrated that seminal plasma exposure induces the up - regulation of key embryotrophic factors, LIF, GM - CSF and IL - 6, in the oviduct following insemination. Factors important in tissue remodelling required for implantation and angiogenesis, MMP - 2, MMP - 3 and VEGF - C, were also shown to be increased at the time of implantation after seminal plasma exposure. Additionally the generation of T - regulatory cells in uterine tissues, demonstrated by the up - regulation of the transcription factor FOXp3 was shown to be dependent on semen exposure. The influence of seminal plasma on embryonic development, implantation and modulation of the maternal immune response to pregnancy may therefore be mechanisms which contribute to the adverse outcomes seen in pregnancies initiated in the absence of seminal plasma. Together these experiments show a role for seminal plasma signalling at the time of insemination in influencing the pre - implantation embryo to program later fetal and neonatal development, thereby impacting on the metabolic health of offspring. We conclude that seminal plasma is not simply a transport medium for sperm, but acts also as a key regulator of a female tract environment providing optimal support for the developing embryo. / Thesis (Ph.D.)--School of Paediatrics and Reproductive Health, 2006.

"December 2003" / Includes bibliographical references (leaves 183-224) / xvii, 236 leaves : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Obstetrics and Gynaecology, 2004