Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title><jats:sec> <jats:title>Aims</jats:title> <jats:p>To evaluate the potential to enhance grain Selenium (Se) concentration in wheat through agronomic innovation practices and exploitation of existing genetic variation.</jats:p> </jats:sec><jats:sec> <jats:title>Methods</jats:title> <jats:p>Grain samples from field experiments carried out as part of the EU projects Nitrogen Use Efficiency (NUE-CROPS), Healthy Minor Cereals (HMC) and Quality Low Input Food (QLIF) were analysed to identify the effects of wheat species/variety, fertiliser type and crop protection regime on grain yield, grain protein and selenium concentrations.</jats:p> </jats:sec><jats:sec> <jats:title>Results</jats:title> <jats:p>Fertiliser type significantly affected grain Se concentration. In the NUE-CROPS and QLIF trials the use of farm-yard manure (FYM) resulted in significantly higher grain Se concentration when compared with mineral fertiliser applied at the same N input level. Similarly, in the HMC trial, FYM and cattle slurry resulted in a significantly higher grain Se concentration compared with biogas digestate and mineral fertiliser. In the QLIF trials, organic crop protection resulted in significantly higher grain Se concentration when compared with conventional crop protection. The NUE-CROPS and HMC trials detected significant differences between varieties of both common wheat (<jats:italic>Triticum aestivum</jats:italic>) and spelt (<jats:italic>T. spelta</jats:italic>). Correlation analyses across the trials identified a negative correlation between yield and grain Se concentration for spelt and positive correlation between plant height and Se concentration for both species.</jats:p> </jats:sec><jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Higher Se concentrations in the taller spelt varieties suggest that there is considerable potential to breed/select for high grain Se by exploiting traits/genetic variation present in older, traditional wheat species (e.g. spelt).</jats:p> </jats:sec>

<jats:title>Abstract</jats:title><jats:sec> <jats:title>Background and aims</jats:title> <jats:p>Iron (Fe) plaque which normally coats rice roots has a strong affinity for phosphorus (P), with a debated effect on plant P uptake. Furthermore, plant responses to P availability shape the rhizospheric environment, possibly affecting the rates of Fe plaque formation and dissolution. The role of Fe plaque to serve as a sink or source of available P may depend on root traits, themselves influenced by P availability. However, the underlying mechanism regulating these interactions remains unclear. In this study, we investigated the effects of P availability on root traits, Fe plaque dynamics and their implications for P uptake and rice plant growth.</jats:p> </jats:sec><jats:sec> <jats:title>Methods</jats:title> <jats:p>Plants were hydroponically grown for 60 days under P-sufficiency or P-deficiency, with or without Fe plaque. Root traits, rhizosphere acidification, and the rates of Fe plaque formation and dissolution were investigated and linked to differences in rice P content and growth.</jats:p> </jats:sec><jats:sec> <jats:title>Results</jats:title> <jats:p>P-deficient conditions stimulated root development and promoted Fe plaque formation on the root surface compared to P-sufficient conditions. However, P limited plants exhibited a faster Fe plaque dissolution, along with increased net proton exudation. After 60 d, P-deficient plants showed higher P uptake in the presence of Fe plaque, whereas the opposite was observed in P-sufficient plants, where Fe plaque limited plant P uptake.</jats:p> </jats:sec><jats:sec> <jats:title>Conclusions</jats:title> <jats:p>The role of Fe plaque in regulating P uptake highly depends on the dynamic nature of this Fe pool that is strictly linked to P availability and regulated by plant responses to P deficiency.</jats:p> </jats:sec>

<jats:title>Abstract</jats:title><jats:sec> <jats:title>Purpose</jats:title> <jats:p>Perennial crops have been suggested as a more sustainable alternative to the currently most common cropping systems. Compared with annual plants, perennial plants produce more biomass and have deeper roots, and are expected to lead to higher soil organic carbon (SOC). This hypothesis, however, has not been well tested for grain crops.</jats:p> </jats:sec><jats:sec> <jats:title>Methods</jats:title> <jats:p>Using perennial intermediate wheatgrass (IWG, <jats:italic>Thinopyrum intermedium</jats:italic>) and annual winter wheat (<jats:italic>Triticum aestivum</jats:italic>) as focal species, and native grassland as reference, we quantified the SOC accumulation via a process-based model, describing water and heat exchanges and carbon-nitrogen cycling in the canopy and soil to a depth of 2 m. The model includes C fixation via photosynthesis, plant biomass growth and litter production, physical protection of SOC, depolymerisation, C mineralisation, nitrification, denitrification, microbial growth, and necromass turnover in the soil. While of general applicability, we considered a sandy loam under warm-summer humid continental climate.</jats:p> </jats:sec><jats:sec> <jats:title>Results</jats:title> <jats:p>Following a conversion from native grassland, IWG reduced SOC losses by at least 38%, especially in the particulate organic carbon (POC) pool, within the top 2 m of soil, compared with annual wheat. Soil microbial biomass and soil respiration were higher in IWG than annual wheat. Shifting from annual wheat to high photosynthetic capacity IWG increased SOC by about 33 g C m<jats:sup>−2</jats:sup> y<jats:sup>−1</jats:sup> (averaged over a 4-year continuous IWG cropping), with a large fraction of SOC gain stemming from restoring POC.</jats:p> </jats:sec><jats:sec> <jats:title>Conclusion</jats:title> <jats:p>Compared with annual grains, perennial grains can increase soil carbon sequestration and maintain SOC at levels nearer to that of native grasslands.</jats:p> </jats:sec>

<jats:title>Abstract</jats:title><jats:sec> <jats:title>Background and aims</jats:title> <jats:p>Redox potential is a promising soil health indicator, which integrates the combined effect of chemical oxidation–reduction reactions into a single measurement. However, this method has been tested only on a few soils. The aim of this study was to test redox potential as a soil health indicator, to see if it responds to management practices and to compare it with existing soil health metrics for microbial activity (“CO<jats:sub>2</jats:sub>burst”) and soil structure.</jats:p> </jats:sec><jats:sec> <jats:title>Methods</jats:title> <jats:p>We collected 35 soil samples in agricultural fields from a carbon farming trial, where contrasting management practices have been applied to increase carbon stock. The soil samples were dried, rewetted and analyzed for redox and microbial respiration during rewetting. In addition, soil structure, texture and organic matter content was measured. The data was analyzed for correlations between the indicators and for the differences between management and control fields.</jats:p> </jats:sec><jats:sec> <jats:title>Results</jats:title> <jats:p>Redox was well correlated with microbial activity, structure, and texture. A low redox state was connected to high microbial activity, indicating bioavailable organic matter availability. Soils with good structure had an oxidized redox status, possibly reflecting high gas-transport. The carbon farming practices resulted in lower oxidation, possibly due to build-up of plant residues.</jats:p> </jats:sec><jats:sec> <jats:title>Conclusions</jats:title> <jats:p>The findings supported the use of redox as a soil health indicator, but highlighted further research needs for identifying the shared mechanisms linking structure, redox and microbial activity. As such, redox can be a low-cost additional measurement to map changes in soil health, but it cannot replace existing structure or microbial activity measurements.</jats:p> </jats:sec>

<jats:title>Abstract</jats:title><jats:sec> <jats:title>Background and aims</jats:title> <jats:p>Proteaceae are a prominent plant family in south-western Australia. Most Proteaceae are ‘calcifuge’, occurring exclusively on old phosphorus (P)-impoverished acidic soils, with a few ‘soil-indifferent’ species also found on young P-richer calcareous soils. Calcium (Ca)-enhanced P toxicity explains the calcifuge habit of Proteaceae. However, previous research has so far been focused exclusively on the roles of Ca and P in determining Proteaceae distribution, and consequently there is little knowledge on how other soil-based strategies influence this distribution. We aimed to study the effects of young calcareous soils on four soil-grown Proteaceae and assess differences between calcifuge and soil-indifferent Proteaceae to better understand their natural distribution.</jats:p> </jats:sec><jats:sec> <jats:title>Methods</jats:title> <jats:p>Two calcifuge and two soil-indifferent Proteaceae from south-western Australia were grown in six contrasting soils, including young calcareous, and old acidic soils.</jats:p> </jats:sec><jats:sec> <jats:title>Results</jats:title> <jats:p>When grown in calcareous soils all species showed root growth inhibition, micronutrient deficiency, Ca-enhanced P toxicity, and negative impacts on physiology. Calcifuge species were more sensitive to calcareous soils than soil-indifferent ones, although this varied between genera. Soil-indifferent species tended to produce more cluster roots, release more carboxylates per root mass, and allocate less Ca to their leaves, compared with calcifuges; they also had smaller seeds and were less sensitive to Ca-enhanced P toxicity.</jats:p> </jats:sec><jats:sec> <jats:title>Conclusion</jats:title> <jats:p>We surmise that a combination of these traits allows soil-indifferent species to tolerate calcareous soils. This study provides insight into how Proteaceae respond to young calcareous soils and how this influences their distribution.</jats:p> </jats:sec>

<jats:title>Abstract</jats:title><jats:sec> <jats:title>Background</jats:title> <jats:p>Suboptimal nitrogen availability is a primary constraint for crop production in low-input agroecosystems, while nitrogen fertilization is a primary contributor to the energy, economic, and environmental costs of crop production in high-input agroecosystems. In this article we consider avenues to develop crops with improved nitrogen capture and reduced requirement for nitrogen fertilizer.</jats:p> </jats:sec><jats:sec> <jats:title>Scope</jats:title> <jats:p>Intraspecific variation for an array of root phenotypes has been associated with improved nitrogen capture in cereal crops, including architectural phenotypes that colocalize root foraging with nitrogen availability in the soil; anatomical phenotypes that reduce the metabolic costs of soil exploration, improve penetration of hard soil, and exploit the rhizosphere; subcellular phenotypes that reduce the nitrogen requirement of plant tissue; molecular phenotypes exhibiting optimized nitrate uptake kinetics; and rhizosphere phenotypes that optimize associations with the rhizosphere microbiome. For each of these topics we provide examples of root phenotypes which merit attention as potential selection targets for crop improvement. Several cross-cutting issues are addressed including the importance of soil hydrology and impedance, phenotypic plasticity, integrated phenotypes, in silico modeling, and breeding strategies using high throughput phenotyping for co-optimization of multiple phenes.</jats:p> </jats:sec><jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Substantial phenotypic variation exists in crop germplasm for an array of root phenotypes that improve nitrogen capture. Although this topic merits greater research attention than it currently receives, we have adequate understanding and tools to develop crops with improved nitrogen capture. Root phenotypes are underutilized yet attractive breeding targets for the development of the nitrogen efficient crops urgently needed in global agriculture.</jats:p> </jats:sec>

<jats:title>Abstract</jats:title><jats:sec> <jats:title>Aims</jats:title> <jats:p>Little research has been conducted to quantify the atmosphere-plant-soil interaction in urban environments due to a lack of understanding of plant water use characteristics and the limited availability of high-quality field data. This research aims to quantify the drying effect of root systems of two Australian native tree species on soil water dynamics and ground movement using high-quality field measurement data.</jats:p> </jats:sec><jats:sec> <jats:title>Methods</jats:title> <jats:p>A long-term field monitoring on soil moisture variation and ground movement close to <jats:italic>C. maculata</jats:italic> and <jats:italic>M. styphelioides</jats:italic>, was conducted for up to 45 months in Melbourne, Australia. The water requirement of each tree was monitored using sap flow sensors. Laboratory soil testing was conducted to obtain soil properties and develop profiles of soil suction and water content. The intercorrelation between soil water dynamics and tree soil water use was established.</jats:p> </jats:sec><jats:sec> <jats:title>Results</jats:title> <jats:p>Tree roots could no longer extract water from the soil when total soil suction exceeded a wilting point of approximately 1000 kPa. The soil profile differences between the two sites were a significant factor causing substantial differences in tree water consumption.</jats:p> </jats:sec><jats:sec> <jats:title>Conclusions</jats:title> <jats:p>At the <jats:italic>C. maculata</jats:italic> site, tree-induced soil desiccation occurred to a depth of 1.1 m, while at the <jats:italic>M. styphelioides</jats:italic> site, it extended down to 2.2 m depth. The tree root-soil interaction analysis shows that water uptake of 10.64 kL by tree roots partially contributes to a 5% decline in soil water content and a 270 kPa rise in soil suction, resulting in a continuous soil settlement of 22 mm.</jats:p> </jats:sec>

<jats:title>Abstract</jats:title><jats:sec> <jats:title>Background and aims</jats:title> <jats:p>The root barrier to radial O<jats:sub>2</jats:sub> loss is a trait induced during soil flooding restricting oxygen loss from the roots to the anoxic soil. It can also restrict radial water loss, potentially providing tolerance towards drought during conditions of water deficit. Several root traits (aerenchyma and xylem vessels area) respond in a similar way to soil flooding and low soil water potentials. Therefore, we hypothesised that root acclimations to soil flooding prime plants to withstand conditions of water deficit.</jats:p> </jats:sec><jats:sec> <jats:title>Methods</jats:title> <jats:p>We raised plants in hydroponics mimicking contrasting soil water conditions (aerated controls for well-watered soils; stagnant, deoxygenated solutions for flooded soils, and aerated solutions with different PEG6000 concentrations to mimic conditions of water deficit). We used O<jats:sub>2</jats:sub> microsensors and gravimetric measurements to characterize the formation of a barrier to radial O<jats:sub>2</jats:sub> loss during conditions of water deficit, and measured key anatomical root traits using light microscopy.</jats:p> </jats:sec><jats:sec> <jats:title>Results</jats:title> <jats:p>Several root traits were induced in stagnant conditions as well as in conditions of water deficit, including the barrier to radial O<jats:sub>2</jats:sub> loss. The tightness of the barrier to water loss was similar in both stagnant and PEG6000 treatments. Moreover, plants growing in stagnant conditions tolerated a following severe condition of water deficit, whereas those growing in mimicked well-watered conditions did not.</jats:p> </jats:sec><jats:sec> <jats:title>Conclusions</jats:title> <jats:p>We demonstrated that plants growing in stagnant conditions can withstand following severe conditions of water deficit. We propose that key root traits, such as the barrier to radial O<jats:sub>2</jats:sub> loss, which are induced in stagnant conditions as well as mild conditions of water deficit, prime the plants for a following severe condition of water deficit.</jats:p> </jats:sec>