2024-03-28T10:29:58Zhttps://www.tdx.cat/oai/requestoai:www.tdx.cat:10803/3004342017-08-29T20:34:50Zcom_10803_1col_10803_12
nam a 5i 4500
Cereals
Cereales
Isòtops estables en ecologia
Isótopos estables en ecología
Stable isotopes in ecological research
Resistència de les plantes a la sequera
Resistencia de las plantas a la sequía
Drought tolerance of plants
Arrels (Botànica)
Raíces (Botánica)
Roots (Botany)
Teledetecció
Teledetección
Remote sensing
Novel phenotyping and monitoring approaches to assess cereal performance under abiotic stress conditions = Nuevos enfoques de fenotipeado y monitoreo de cultivos para evaluar el rendimiento de cereales cultivados en diferentes condiciones de estrés abiótico
[Barcelona] :
Universitat de Barcelona,
2015
Accés lliure
http://hdl.handle.net/10803/300434
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Khaled Elazab, Abdelhalim,
autor
1 recurs en línia (245 pàgines)
Tesi
Doctorat
Universitat de Barcelona. Departament de Biologia Vegetal
2015
Universitat de Barcelona. Departament de Biologia Vegetal
Tesis i dissertacions electròniques
Araus Ortega, José Luis,
supervisor acadèmic
Serret Molins, M. Dolors,
supervisor acadèmic
Araus Ortega, José Luis,
supervisor acadèmic
TDX
Cereals are the basis of the normal diet in most Mediterranean countries and it is estimated that they account for 35-50% of the regional populations’ dietary energy consumption. Water deficit is the main constraint limiting cereal productivity in the Mediterranean regions. Crop management and breeding may improve the performance of cereals under such stress conditions. However, the lack of efficient tools to monitor the performance of agronomical practices or to undertake appropriate phenotyping in breeding programs limits the efficiency of both avenues.
Novel tools to monitor the cereals (durum wheat and maize) performance in the thesis are:
1. Stable isotopes
In C3 plants the carbon isotope composition (δ13C) measured in plant tissues is considered as one of the most promising secondary traits in wheat (and other C3 cereals) when breeding for drought resilience. The δ13C has been reported to negatively correlate with Ci/Ca (the ratio of leaf intercellular to ambient CO2 concentration) and positively correlated with A/E (the ratio of net assimilation to water evaporated from the transpiring organs). Therefore, the δ13C is positively related to WUE, which is considered as the biomass produced per unit of water transpired. Correlations between δ13C and GY and/or aerial biomass (AB) may be either negative or positive according to the plant tissue sampled and environmental conditions tested. In the case of a C4 plant like maize, variations in the δ13C in response to water conditions are small in compared to C3 plants like wheat, but they are still adequate for use in maize as an indicator of water conditions during growth. The oxygen isotope composition (δ18O) of plant tissues is known to reflect the evaporative conditions throughout the crop cycle and thus it has been proposed as a proxy method for measuring transpiration as well as an indicator of genotypic differences in stomatal conductance (gs) in C3 and C4 plants.
2. Root traits
Plant roots are the key organs in the plant responsible for the absorption of water and nutrients. Concerning root traits, their response to drought stress is still a challenging subject for research. The laborious work required for the study of the root system has prevented the adoption of root characteristics as routinely phenotyping traits for crop breeding. The root weight density (RWD) and root length density (RLD) are frequently used in root studies to describe the root weight and root length, respectively, within a soil volume and they reflect the capacity of roots to extract water and nutrients. The specific root length (SRL) is considered another of the most important and commonly measured morphological traits. Previous studies showed that a high SRL facilitates nutrient uptake in low-nutrient environments and makes plants more competitive for soil nutrient uptake.
3. The use of proximal (remote) sensing
The assessment of AB is important for monitoring crop growth because it could reflect the effect of stresses on crop growth and senescence. Thus, a number of studies have revealed that spectral reflectance techniques have the potential to provide precise, non-destructive instantaneous quantitative estimates of AB. The Normalized Difference Vegetation Index (NDVI) has been used as an indicator of AB and GY in cereals. In recent years the use of digital Red-Green-Blue (RGB) images has been proposed as an alternative to develop vegetation indices that may replace spectroradiometrical based NDVI. The price, size, and the easy use of conventional digital cameras make them viable alternatives to assess AB and GY in cereals. A number of studies have used digital RGB imaging to measure different colour parameters such as: greenness; intensity of green, red and blue; and derived normalized indices from the green, red and blue bands.
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