Chapters authored
Silicon Use in the Integrated Disease Management of Wheat: Current Knowledge
Silicon (Si) is a benefic element for higher plants such as wheat (Triticum aestivum) in which it is accumulated in the shoot tissues. In this crop, leaf diseases and spike diseases are the cause of yield losses, and therefore several studies had been conducted under field and greenhouse conditions to demonstrate that plants supplied with Si reduced most of the diseases damage due to the amelioration of the plant defenses. However, the benefits of Si depend on its accumulation in the plant’s tissue, which is influenced by the availability of the element in the soil as well as the up-take ability of the wheat cultivar. In this chapter we present the current knowledge about the mechanisms of Si absorption and its accumulation in different tissues of the wheat plant, the most studied options for silicate fertilization, and the benefits of Si on grain yield. We also present some insight of the effect of Si-supply in wheat on the reduction of main leaf and ear diseases, bringing evidence and explanation of the defense mechanisms involved. In addition, we provide an overview of the Si effect on the physiology (gas exchange, chlorophyll a fluorescence and carbohydrate metabolism) of the wheat plant. Finally, questions have been raised about the Si uses as fertilizer that still needs to be answered. We recognized that some studies have enhanced our understanding of Si providing evidence of the Si use as disease management strategy, but further research is needed to make the Si uses a simple task for wheat growers under field condition.
Part of the book: Current Trends in Wheat Research
Chlorophyll a Fluorescence: A Method of Biotic Stress Detection
Plant diseases are a major threat to food security, causing drastic alterations in plant metabolism upon infection by pathogens. This often results in decreased biomass accumulation, slowed growth rates, and diminished yield components. Pathogens, through various lifestyles such as biotrophic, necrotrophic, and hemibiotrophic, disrupt photosynthesis, the primary metabolic process, via functional and structural damages. Furthermore, the CO2 assimilation in plants is severely altered by pathogens regardless of their lifestyles. Photosynthetic determinations allow us to establish a perspective about the physiological impairment caused by pathogens related to alterations in the CO2 flow from the atmosphere to carboxylation sites, stomatal limitations, and photosynthetic performance of photosystem II (PSII). From the changes in the energy, dissipation is possible to establish the functional status of the photochemistry machinery under stress conditions. For the above, chlorophyll a fluorescence (CF) and CF imaging (CFI) arose as a method highly sensible to determine the damage caused by pathogens in plants. This review shows a practical perspective on CF tools using visual method and rapid fluorescence induction kinetics (OJIP-test), for disease detection associated with plant-pathogen interaction studies from the physiological viewpoint, their implications for plant pathology research, applications for the plant phenotyping field, and biotic stress detection.
Part of the book: Challenges in Plant Disease Detection and Recent Advancements [Working title]