Physiological traits and genetic controls associated with heat adaptation of bread wheat

High temperatures affect plant growth and reduce crop productivity. Notwithstanding the extensive research on the effects of heat stress on plant development, to date, the basis of wheat tolerance to high temperatures is unknown. Currently, physiological crop breeding for improved wheat adaptation to heat stress is driven by the utilization of cumulative traits useful under those environments. However many of these traits have yet to be fully exploited. This study is focused on three key components of heat adaptation: I) the significance of root development for hot irrigated environments in comparison to drought stressed environments and its relation with canopy temperature, II) the contribution and genetic basis of the staygreen attribute to heat adaptation of bread wheat, and III) The relevance of leaf respiration for plant productivity under hot environments. Chapter 1 presents a literature review focused on providing a general background for the three following publications included in the forthcoming chapters. The relevance of heat stress for the wheat crop is discussed with focus on recent publications that describe the current situation and forecasts for the upcoming years and effect of climate change. The genetic and physiological basis of heat tolerance is also addressed, presenting a generic conceptual model currently applied in wheat breeding for improved heat adaptation. In Chapter 2, the significance of optimal root development under hot-irrigated environments is addressed and compared with the performance observed in the same germplasm grown under water-limited conditions. This journal publication discusses the association of QTL for canopy temperature with deep and abundant radicular systems. A subset of a Seri/Babax mapping population was evaluated for root distribution patterns and residual soil moisture across the soil profile from surface to 120 cm depth. Results from this study endorse canopy temperature as a valuable tool for assessing expression of plant’s water uptake and hence root development under both, hot-irrigated and drought environments. In Chapter 3, the potential value of the staygreen attribute in breeding for heat adaptation of wheat is addressed. This journal publication estimated a number of parameters associated with the staygreen phenotype including (but not limited to) the rate of senescence, the percentage of greenness decay and the area under the curve of the normalized difference vegetation index measured over time. The greenness decay of each genotype was fitted to linear or non- linear models to describe their patterns. And finally these staygreen parameters together with other physiological and agronomical parameters were analysed for QTL to aid understanding of the genetic basis of the staygreen attribute in the Seri/Babax population. Chapter 4 presents a descriptive study on leaf respiration rates of a diverse wheat germplasm set grown under high temperatures during the 2010, 2011, 2012 and 2013 seasons. Agronomic and physiological phenotyping was performed including detailed observations for biomass production, carbohydrates content recorded in a subset during the last year of experiments. The study evaluated the effect of different temperatures and plant stages in leaf respiration rates and also made a comparison between five wheat classes. Results from this study showed genetic diversity for leaf respiration and also genotypic differences between leaf temperature and leaf age (determined by developmental plant stage). Interesting associations were observed between physiological traits, yield and leaf respiration rates. Finally, Chapter 5 presents general conclusions and future direction of the work. The work described in the thesis suggests that tolerance to high temperature in wheat can be improved by the translation of physiological traits into the breeding process. Three approaches explored in this thesis: canopy temperature, staygreen traits and leaf respiration. The evidence collected support the idea that a strategic, physiological breeding approach can lead to important gains in wheat yield under hot-irrigated conditions and this outcome will be important for the adaptation of wheat to global warming.Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 201

Reseña

Lovera, José Rafael. Vida de hacienda en Venezuela, siglos xviii al xx. Caracas: Fundación Bigott,Colección Bigotteca, SerieHistoria, 2009. 316pp

Changes in microphytobenthos fluorescence over a tidal cycle: implications for sampling designs

Intertidal microphytobenthos (MPB) are important primary producers and provide food for herbivores in soft sediments and on rocky shores. Methods of measuring MPB biomass that do not depend on the time of collection relative to the time of day or tidal conditions are important in any studies that need to compare temporal or spatial variation, effects of abiotic factors or activity of grazers. Pulse amplitude modulated (PAM) fluorometry is often used to estimate biomass of MPB because it is a rapid, non-destructive method, but it is not known how measures of fluorescence are altered by changing conditions during a period of low tide. We investigated this experimentally using in situ changes in minimal fluorescence (F) on a rocky shore and on an estuarine mudflat around Sydney (Australia), during low tides. On rocky shores, the time when samples are taken during low tide had little direct influence on measures of fluorescence as long as the substratum is dry. Wetness from wave-splash, seepage from rock pools, run-off, rainfall, etc., had large consequences for any comparisons. On soft sediments, fluorescence was decreased if the sediment dried out, as happens during low-spring tides on particularly hot and dry days. Surface water affected the response of PAM and therefore measurements used to estimate MPB, emphasising the need for care to ensure that representative sampling is done during low tide

Hantavirus Infection in Anajatuba, Maranhão, Brazil

In 2000, the first outbreak of hantavirus pulmonary syndrome was recognized in the Brazilian Amazon (Maranhão State). An epidemiologic study identified a 13.3% prevalence of hantavirus-specific immunoglobulin G. The analysis of risk factors suggests that persons are occupationally exposed to infected rodents in the crop fields

EVALUACION DE VIDA DE ANAQUEL DE PAPA (Solanum tuberosum) ALMACENADA TRATADA CON ACIDO SALICILICO, ACIDOS CARBOXILICOS Y CALCIO (Frito Xcell)

Tesis de Licenciatur

Reseña

Lovera, José Rafael. Vida de hacienda en Venezuela, siglos xviii al xx. Caracas: Fundación Bigott,Colección Bigotteca, SerieHistoria, 2009. 316pp

Evaluación del programa de capacitación para asesores educativos "saber para todos", de INEA Tlalpan, a través del modelo CIPP

Licenciatura en Psicología Educativ