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Daniel J. Miralles - One of the best experts on this subject based on the ideXlab platform.

  • Is the source-sink ratio at anthesis a driver to avoid yield reductions caused by late Foliar disease in wheat?
    Field Crops Research, 2019
    Co-Authors: Román A. Serrago, Patricio Javier Lo Valvo, Daniel J. Miralles
    Abstract:

    Abstract Late Foliar Diseases that appear during the grain filling period reduce radiation interception/absorption decreasing assimilation supply, inducing reductions in grain weight and yield. We hypothesize that crops with higher source-sink ratio (established immediately after anthesis) could have more capacity to avoid reductions in terms of yield, at same level of Foliar disease. Thus, it is speculated that the yield reduction caused by late Foliar Diseases is a complex interaction between current photosynthesis availability per grain and the remobilization capacity according to the sink size determined demand. The objective of the present study was to analyze physiological attributes associated with yield reduction caused by late Foliar Diseases in wheat when source-sink ratio is modified. Experiments were carried out during two consecutive years (2009 and 2010) applying a combination of (i) two disease levels (i.e. healthy and diseased plots), (ii) two different levels of incident radiation applied immediately previous to anthesis, to reduce grain number exclusively (i.e. non-shaded and shaded plots) and (iii) source-sink manipulations during grain filling (i.e. control and trimmed spikes). Shading during pre-anthesis significantly reduced grain number and then, the source-sink ratio was modified between non-shaded and shaded plots, being two fold higher in non-shaded than in shaded plots. In both years and shading treatments, Diseases appeared after anthesis, the diseased plots showing higher values of non-green leaf area than healthy plots, in both shaded and non-shaded treatments. Late Foliar Diseases significantly reduced grain yield in both, 2009 and 2010 mainly due to reductions in grain weight. There was significant interaction in the crop performance to Foliar Diseases between shading treatments and growing seasons. While the reduction caused by late Foliar Diseases was similar between shading treatments during 2009, in 2010 significant differences were observed, being reductions lower in shaded than in non-shaded plots. The source-sink manipulation treatment confirmed these responses, as there were no significant differences in grain weight of trimmed spikes between healthy and diseased crops, confirming that the grain weight reduction due to late Foliar Diseases is driven by the source sink balance.

  • Grain weight response to Foliar Diseases control in wheat (Triticum aestivum L.)
    Field Crops Research, 2011
    Co-Authors: Román A. Serrago, Ramiro Carretero, Marie Odile Bancal, Daniel J. Miralles
    Abstract:

    Foliar Diseases are the main biotic restriction reducing yield in wheat crops affecting both, grain number and/or grain weight, depending on developmental stage at which infection occurs (pre- or post-anthesis, respectively). Grain weight reductions due to Foliar Diseases were widely reported in the literature mostly associated with decreases on radiation interception during the grain filling period. However, different evidences in wheat showed variations on grain weight responses when fungicide was applied during the grain filling period, probably associated with the timing of fungicide application or with the amount of available resources per grain set when fungicides are applied. The present study was designed to determine the causes of grain weight reduction due to Foliar Diseases complex (including leaf rust, Septoria leaf blotch and tan spot) in wheat crops growing under contrasting agronomic and environmental conditions (i.e. different years, locations, cultivars and N supply). The experiments were carried out during 4 years under field conditions in different locations of Argentine and France. Five different commercial wheat cultivars were sown on early and late sowing dates; and two contrasting N availability and two fungicide treatments (protected and unprotected) were applied. Grain number was not affected by Foliar Diseases as their appeared after anthesis. Grain weight was strongly, poorly or not affected by Foliar Diseases and was not associated individually with both, the sink size and the source size. However, when the grain weight response due to fungicide application was plotted against the healthy area absorption per grain (HAAG), a significant negative association (r2 = 0.81; p < 0.0001) was found for the Argentine experiments. When the HAAG was corrected by the grain weight potential (HAAGW) all experiments conduced in Argentine and in France fit well to a common negative linear regression (r2 = 0.74, p < 0.0001) for the relationship between grain weight variation and HAAGW demonstrating that grain weight potential is an important feature to consider in Diseases control programs. Foliar Diseases forced the crop to use the accumulated reserved increasing the utilization rate of the water soluble carbohydrates (WSCUR), depleting as a consequence the water soluble content at physiological maturity (WSCPM) in all experiments. The association between WSCUR and the healthy area absorption per grain corrected by grain weight of healthy crops (HAAGW) suggest that Foliar Diseases in wheat cause source limitation, forcing to the crop to use the WSC reserve which could be insufficient to fill the grains previously formed.

  • Absorbed radiation and radiation use efficiency as affected by Foliar Diseases in relation to their vertical position into the canopy in wheat
    Field Crops Research, 2010
    Co-Authors: Ramiro Carretero, Román A. Serrago, Marie Odile Bancal, Analía E. Perelló, Daniel J. Miralles
    Abstract:

    The impact of Foliar Diseases on crop yield losses is better understood if considering ecophysiological variables together with pathological variables. Although wheat crop losses due to Foliar Diseases have already been studied with an ecophysiological approach, none of these studies analyzed the vertical Diseases distribution into the canopy leaf layers in relation to the canopy size (leaf area index—LAI) and its architecture (light extinction coefficient-k value). Thus, the objectives of the present study were: (i) to understand the importance of the vertical distribution of the Foliar Diseases in relation to radiation absorption efficiency (RAE) for different LAI levels and canopy architectures and; (ii) to analyze and compare two ways of radiation capture estimations, considering LAI as a total or LAI of each leaf layer separately. The wheat cultivar Klein Pegaso was grown in plots under field conditions during three growing seasons using different nitrogen supply levels and a wide range of severity Diseases by using protected and unprotected crops (applying or not fungicides, respectively). Unprotected plots were inoculated with biotrophic and/or necrotrophic pathogens. Biotrophic (Puccinia triticina-leaf rust) and necrotrophic pathogens (Drechslera tritici-repentis-tan spot; Alternaria triticina-leaf blight) constituted the “Diseases complex” with different levels and proportions depending on the year and N treatment. Results showed that Foliar Diseases reduced LAI and GLAI (green leaf area index). GLAI was not only diminished by LAI reductions, but also by increases in NGLAI (non-green leaf area index) due to lesion coverage which reduced light absorption. In spite of the differences observed in LAI between protected and unprotected crops, radiation interception was not affected until LAI dropped down its critical value (i.e. when crop intercept 95% of the maximum radiation possible to be intercepted). The results demonstrated that assuming a uniform distribution of the Diseases, lead to underestimations of accumulated absorbed radiation up to 21%, and as a consequence to overestimations of radiation use efficiency (RUE) up to 29% when Diseases were concentrated in the lower leaf layers into the canopy. Together with the severity of the pathogen, at the time to decide controlling Diseases, farmers should take into account: (i) LAI level, mainly in those crop situations where, during the critical period for yield determination, the LAI is close to or below the critical value; (ii) canopy architecture (k) associated with light distribution into the canopy and (iii) vertical Diseases distribution into the crop

  • Foliar Diseases affect the eco-physiological attributes linked with yield and biomass in wheat (Triticum aestivum L.)
    European Journal of Agronomy, 2009
    Co-Authors: Román A. Serrago, Ramiro Carretero, Marie Odile Bancal, Daniel J. Miralles
    Abstract:

    Abstract Foliar Diseases are the main biotic cause of yield loss in wheat crops ( Triticum aestivum L.) in Argentina and other regions around the world. Most of the studies on Foliar Diseases take a phytopathological perspective, but few studies have analyzed the problem with an eco-physiological approach aimed at the understanding of which crop traits are affected by Foliar Diseases. The present study was designed to determine the effects of a Foliar disease complex (including leaf rust, Septoria leaf blotch and tan spot), on (i) grain yield and (ii) the physiological components of biomass production; intercepted radiation (RI) and radiation use efficiency (RUE), in bread wheat crops growing under contrasting agronomic and environmental conditions (i.e. different cultivars, years, location and nitrogen supply). The experiments were carried out during 4 years in different locations (three in the rolling pampas of Argentina and one in northern of France). Five different commercial wheat cultivars were sown on early (E) and late (L) sowing dates (SD); and two contrasting nitrogen availability and two fungicide treatments (protected and unprotected) were applied. Foliar Diseases appeared during the grain filling period and affected both, leaf area duration (LAD) and healthy area duration (HAD) during that period. Foliar Diseases reduced both, above-ground biomass at harvest (1533 and 1703 g m −2 for unprotected and protected treatments, respectively) and grain yield (646 and 748 g m −2 for unprotected and protected treatments, respectively) without important effects on harvest index. Biomass reductions after anthesis, due to the effects of Foliar Diseases, were associated with a reduced capacity of the canopy to absorb solar radiation more than any effect on RUE. However, RUE was consistently lower—when leaf rust was the predominant disease in the crop, suggesting that this biotrophic pathogen could affect the photosynthetic activity at the leaf or canopy level.

Román A. Serrago - One of the best experts on this subject based on the ideXlab platform.

  • Is the source-sink ratio at anthesis a driver to avoid yield reductions caused by late Foliar disease in wheat?
    Field Crops Research, 2019
    Co-Authors: Román A. Serrago, Patricio Javier Lo Valvo, Daniel J. Miralles
    Abstract:

    Abstract Late Foliar Diseases that appear during the grain filling period reduce radiation interception/absorption decreasing assimilation supply, inducing reductions in grain weight and yield. We hypothesize that crops with higher source-sink ratio (established immediately after anthesis) could have more capacity to avoid reductions in terms of yield, at same level of Foliar disease. Thus, it is speculated that the yield reduction caused by late Foliar Diseases is a complex interaction between current photosynthesis availability per grain and the remobilization capacity according to the sink size determined demand. The objective of the present study was to analyze physiological attributes associated with yield reduction caused by late Foliar Diseases in wheat when source-sink ratio is modified. Experiments were carried out during two consecutive years (2009 and 2010) applying a combination of (i) two disease levels (i.e. healthy and diseased plots), (ii) two different levels of incident radiation applied immediately previous to anthesis, to reduce grain number exclusively (i.e. non-shaded and shaded plots) and (iii) source-sink manipulations during grain filling (i.e. control and trimmed spikes). Shading during pre-anthesis significantly reduced grain number and then, the source-sink ratio was modified between non-shaded and shaded plots, being two fold higher in non-shaded than in shaded plots. In both years and shading treatments, Diseases appeared after anthesis, the diseased plots showing higher values of non-green leaf area than healthy plots, in both shaded and non-shaded treatments. Late Foliar Diseases significantly reduced grain yield in both, 2009 and 2010 mainly due to reductions in grain weight. There was significant interaction in the crop performance to Foliar Diseases between shading treatments and growing seasons. While the reduction caused by late Foliar Diseases was similar between shading treatments during 2009, in 2010 significant differences were observed, being reductions lower in shaded than in non-shaded plots. The source-sink manipulation treatment confirmed these responses, as there were no significant differences in grain weight of trimmed spikes between healthy and diseased crops, confirming that the grain weight reduction due to late Foliar Diseases is driven by the source sink balance.

  • Grain weight response to Foliar Diseases control in wheat (Triticum aestivum L.)
    Field Crops Research, 2011
    Co-Authors: Román A. Serrago, Ramiro Carretero, Marie Odile Bancal, Daniel J. Miralles
    Abstract:

    Foliar Diseases are the main biotic restriction reducing yield in wheat crops affecting both, grain number and/or grain weight, depending on developmental stage at which infection occurs (pre- or post-anthesis, respectively). Grain weight reductions due to Foliar Diseases were widely reported in the literature mostly associated with decreases on radiation interception during the grain filling period. However, different evidences in wheat showed variations on grain weight responses when fungicide was applied during the grain filling period, probably associated with the timing of fungicide application or with the amount of available resources per grain set when fungicides are applied. The present study was designed to determine the causes of grain weight reduction due to Foliar Diseases complex (including leaf rust, Septoria leaf blotch and tan spot) in wheat crops growing under contrasting agronomic and environmental conditions (i.e. different years, locations, cultivars and N supply). The experiments were carried out during 4 years under field conditions in different locations of Argentine and France. Five different commercial wheat cultivars were sown on early and late sowing dates; and two contrasting N availability and two fungicide treatments (protected and unprotected) were applied. Grain number was not affected by Foliar Diseases as their appeared after anthesis. Grain weight was strongly, poorly or not affected by Foliar Diseases and was not associated individually with both, the sink size and the source size. However, when the grain weight response due to fungicide application was plotted against the healthy area absorption per grain (HAAG), a significant negative association (r2 = 0.81; p < 0.0001) was found for the Argentine experiments. When the HAAG was corrected by the grain weight potential (HAAGW) all experiments conduced in Argentine and in France fit well to a common negative linear regression (r2 = 0.74, p < 0.0001) for the relationship between grain weight variation and HAAGW demonstrating that grain weight potential is an important feature to consider in Diseases control programs. Foliar Diseases forced the crop to use the accumulated reserved increasing the utilization rate of the water soluble carbohydrates (WSCUR), depleting as a consequence the water soluble content at physiological maturity (WSCPM) in all experiments. The association between WSCUR and the healthy area absorption per grain corrected by grain weight of healthy crops (HAAGW) suggest that Foliar Diseases in wheat cause source limitation, forcing to the crop to use the WSC reserve which could be insufficient to fill the grains previously formed.

  • Absorbed radiation and radiation use efficiency as affected by Foliar Diseases in relation to their vertical position into the canopy in wheat
    Field Crops Research, 2010
    Co-Authors: Ramiro Carretero, Román A. Serrago, Marie Odile Bancal, Analía E. Perelló, Daniel J. Miralles
    Abstract:

    The impact of Foliar Diseases on crop yield losses is better understood if considering ecophysiological variables together with pathological variables. Although wheat crop losses due to Foliar Diseases have already been studied with an ecophysiological approach, none of these studies analyzed the vertical Diseases distribution into the canopy leaf layers in relation to the canopy size (leaf area index—LAI) and its architecture (light extinction coefficient-k value). Thus, the objectives of the present study were: (i) to understand the importance of the vertical distribution of the Foliar Diseases in relation to radiation absorption efficiency (RAE) for different LAI levels and canopy architectures and; (ii) to analyze and compare two ways of radiation capture estimations, considering LAI as a total or LAI of each leaf layer separately. The wheat cultivar Klein Pegaso was grown in plots under field conditions during three growing seasons using different nitrogen supply levels and a wide range of severity Diseases by using protected and unprotected crops (applying or not fungicides, respectively). Unprotected plots were inoculated with biotrophic and/or necrotrophic pathogens. Biotrophic (Puccinia triticina-leaf rust) and necrotrophic pathogens (Drechslera tritici-repentis-tan spot; Alternaria triticina-leaf blight) constituted the “Diseases complex” with different levels and proportions depending on the year and N treatment. Results showed that Foliar Diseases reduced LAI and GLAI (green leaf area index). GLAI was not only diminished by LAI reductions, but also by increases in NGLAI (non-green leaf area index) due to lesion coverage which reduced light absorption. In spite of the differences observed in LAI between protected and unprotected crops, radiation interception was not affected until LAI dropped down its critical value (i.e. when crop intercept 95% of the maximum radiation possible to be intercepted). The results demonstrated that assuming a uniform distribution of the Diseases, lead to underestimations of accumulated absorbed radiation up to 21%, and as a consequence to overestimations of radiation use efficiency (RUE) up to 29% when Diseases were concentrated in the lower leaf layers into the canopy. Together with the severity of the pathogen, at the time to decide controlling Diseases, farmers should take into account: (i) LAI level, mainly in those crop situations where, during the critical period for yield determination, the LAI is close to or below the critical value; (ii) canopy architecture (k) associated with light distribution into the canopy and (iii) vertical Diseases distribution into the crop

  • Foliar Diseases affect the eco-physiological attributes linked with yield and biomass in wheat (Triticum aestivum L.)
    European Journal of Agronomy, 2009
    Co-Authors: Román A. Serrago, Ramiro Carretero, Marie Odile Bancal, Daniel J. Miralles
    Abstract:

    Abstract Foliar Diseases are the main biotic cause of yield loss in wheat crops ( Triticum aestivum L.) in Argentina and other regions around the world. Most of the studies on Foliar Diseases take a phytopathological perspective, but few studies have analyzed the problem with an eco-physiological approach aimed at the understanding of which crop traits are affected by Foliar Diseases. The present study was designed to determine the effects of a Foliar disease complex (including leaf rust, Septoria leaf blotch and tan spot), on (i) grain yield and (ii) the physiological components of biomass production; intercepted radiation (RI) and radiation use efficiency (RUE), in bread wheat crops growing under contrasting agronomic and environmental conditions (i.e. different cultivars, years, location and nitrogen supply). The experiments were carried out during 4 years in different locations (three in the rolling pampas of Argentina and one in northern of France). Five different commercial wheat cultivars were sown on early (E) and late (L) sowing dates (SD); and two contrasting nitrogen availability and two fungicide treatments (protected and unprotected) were applied. Foliar Diseases appeared during the grain filling period and affected both, leaf area duration (LAD) and healthy area duration (HAD) during that period. Foliar Diseases reduced both, above-ground biomass at harvest (1533 and 1703 g m −2 for unprotected and protected treatments, respectively) and grain yield (646 and 748 g m −2 for unprotected and protected treatments, respectively) without important effects on harvest index. Biomass reductions after anthesis, due to the effects of Foliar Diseases, were associated with a reduced capacity of the canopy to absorb solar radiation more than any effect on RUE. However, RUE was consistently lower—when leaf rust was the predominant disease in the crop, suggesting that this biotrophic pathogen could affect the photosynthetic activity at the leaf or canopy level.

Marie Odile Bancal - One of the best experts on this subject based on the ideXlab platform.

  • Grain weight response to Foliar Diseases control in wheat (Triticum aestivum L.)
    Field Crops Research, 2011
    Co-Authors: Román A. Serrago, Ramiro Carretero, Marie Odile Bancal, Daniel J. Miralles
    Abstract:

    Foliar Diseases are the main biotic restriction reducing yield in wheat crops affecting both, grain number and/or grain weight, depending on developmental stage at which infection occurs (pre- or post-anthesis, respectively). Grain weight reductions due to Foliar Diseases were widely reported in the literature mostly associated with decreases on radiation interception during the grain filling period. However, different evidences in wheat showed variations on grain weight responses when fungicide was applied during the grain filling period, probably associated with the timing of fungicide application or with the amount of available resources per grain set when fungicides are applied. The present study was designed to determine the causes of grain weight reduction due to Foliar Diseases complex (including leaf rust, Septoria leaf blotch and tan spot) in wheat crops growing under contrasting agronomic and environmental conditions (i.e. different years, locations, cultivars and N supply). The experiments were carried out during 4 years under field conditions in different locations of Argentine and France. Five different commercial wheat cultivars were sown on early and late sowing dates; and two contrasting N availability and two fungicide treatments (protected and unprotected) were applied. Grain number was not affected by Foliar Diseases as their appeared after anthesis. Grain weight was strongly, poorly or not affected by Foliar Diseases and was not associated individually with both, the sink size and the source size. However, when the grain weight response due to fungicide application was plotted against the healthy area absorption per grain (HAAG), a significant negative association (r2 = 0.81; p < 0.0001) was found for the Argentine experiments. When the HAAG was corrected by the grain weight potential (HAAGW) all experiments conduced in Argentine and in France fit well to a common negative linear regression (r2 = 0.74, p < 0.0001) for the relationship between grain weight variation and HAAGW demonstrating that grain weight potential is an important feature to consider in Diseases control programs. Foliar Diseases forced the crop to use the accumulated reserved increasing the utilization rate of the water soluble carbohydrates (WSCUR), depleting as a consequence the water soluble content at physiological maturity (WSCPM) in all experiments. The association between WSCUR and the healthy area absorption per grain corrected by grain weight of healthy crops (HAAGW) suggest that Foliar Diseases in wheat cause source limitation, forcing to the crop to use the WSC reserve which could be insufficient to fill the grains previously formed.

  • Absorbed radiation and radiation use efficiency as affected by Foliar Diseases in relation to their vertical position into the canopy in wheat
    Field Crops Research, 2010
    Co-Authors: Ramiro Carretero, Román A. Serrago, Marie Odile Bancal, Analía E. Perelló, Daniel J. Miralles
    Abstract:

    The impact of Foliar Diseases on crop yield losses is better understood if considering ecophysiological variables together with pathological variables. Although wheat crop losses due to Foliar Diseases have already been studied with an ecophysiological approach, none of these studies analyzed the vertical Diseases distribution into the canopy leaf layers in relation to the canopy size (leaf area index—LAI) and its architecture (light extinction coefficient-k value). Thus, the objectives of the present study were: (i) to understand the importance of the vertical distribution of the Foliar Diseases in relation to radiation absorption efficiency (RAE) for different LAI levels and canopy architectures and; (ii) to analyze and compare two ways of radiation capture estimations, considering LAI as a total or LAI of each leaf layer separately. The wheat cultivar Klein Pegaso was grown in plots under field conditions during three growing seasons using different nitrogen supply levels and a wide range of severity Diseases by using protected and unprotected crops (applying or not fungicides, respectively). Unprotected plots were inoculated with biotrophic and/or necrotrophic pathogens. Biotrophic (Puccinia triticina-leaf rust) and necrotrophic pathogens (Drechslera tritici-repentis-tan spot; Alternaria triticina-leaf blight) constituted the “Diseases complex” with different levels and proportions depending on the year and N treatment. Results showed that Foliar Diseases reduced LAI and GLAI (green leaf area index). GLAI was not only diminished by LAI reductions, but also by increases in NGLAI (non-green leaf area index) due to lesion coverage which reduced light absorption. In spite of the differences observed in LAI between protected and unprotected crops, radiation interception was not affected until LAI dropped down its critical value (i.e. when crop intercept 95% of the maximum radiation possible to be intercepted). The results demonstrated that assuming a uniform distribution of the Diseases, lead to underestimations of accumulated absorbed radiation up to 21%, and as a consequence to overestimations of radiation use efficiency (RUE) up to 29% when Diseases were concentrated in the lower leaf layers into the canopy. Together with the severity of the pathogen, at the time to decide controlling Diseases, farmers should take into account: (i) LAI level, mainly in those crop situations where, during the critical period for yield determination, the LAI is close to or below the critical value; (ii) canopy architecture (k) associated with light distribution into the canopy and (iii) vertical Diseases distribution into the crop

  • Foliar Diseases affect the eco-physiological attributes linked with yield and biomass in wheat (Triticum aestivum L.)
    European Journal of Agronomy, 2009
    Co-Authors: Román A. Serrago, Ramiro Carretero, Marie Odile Bancal, Daniel J. Miralles
    Abstract:

    Abstract Foliar Diseases are the main biotic cause of yield loss in wheat crops ( Triticum aestivum L.) in Argentina and other regions around the world. Most of the studies on Foliar Diseases take a phytopathological perspective, but few studies have analyzed the problem with an eco-physiological approach aimed at the understanding of which crop traits are affected by Foliar Diseases. The present study was designed to determine the effects of a Foliar disease complex (including leaf rust, Septoria leaf blotch and tan spot), on (i) grain yield and (ii) the physiological components of biomass production; intercepted radiation (RI) and radiation use efficiency (RUE), in bread wheat crops growing under contrasting agronomic and environmental conditions (i.e. different cultivars, years, location and nitrogen supply). The experiments were carried out during 4 years in different locations (three in the rolling pampas of Argentina and one in northern of France). Five different commercial wheat cultivars were sown on early (E) and late (L) sowing dates (SD); and two contrasting nitrogen availability and two fungicide treatments (protected and unprotected) were applied. Foliar Diseases appeared during the grain filling period and affected both, leaf area duration (LAD) and healthy area duration (HAD) during that period. Foliar Diseases reduced both, above-ground biomass at harvest (1533 and 1703 g m −2 for unprotected and protected treatments, respectively) and grain yield (646 and 748 g m −2 for unprotected and protected treatments, respectively) without important effects on harvest index. Biomass reductions after anthesis, due to the effects of Foliar Diseases, were associated with a reduced capacity of the canopy to absorb solar radiation more than any effect on RUE. However, RUE was consistently lower—when leaf rust was the predominant disease in the crop, suggesting that this biotrophic pathogen could affect the photosynthetic activity at the leaf or canopy level.

  • Modelling wheat growth and yield losses from late epidemics of Foliar Diseases using loss of green leaf area per layer and pre-anthesis reserves
    Annals of Botany, 2007
    Co-Authors: Marie Odile Bancal, Corinne Robert, Bertrand Ney
    Abstract:

    Background and Aims Crop protection strategies, based on preventing quantitative crop losses rather than pest outbreaks, are being developed as a promising way to reduce fungicide use. The Bastiaans' model was applied to winter wheat crops (Triticum aestivum) affected by leaf rust (Puccinia triticina) and Septoria tritici blotch (STB; Mycosphaerella graminicola) under a range of crop management conditions. This study examined (a) whether green leaf area per layer accurately accounts for growth loss; and (b) whether from growth loss it is possible to derive yield loss accurately and simply. Methods Over 5 years of field experiments, numerous green leaf area dynamics were analysed during the post-anthesis period on wheat crops using natural aerial epidemics of leaf rust and STB. Key Results When radiation use efficiency (RUE) was derived from bulk green leaf area index (GLAI), RUEbulk was hardly accurate and exhibited large variations among diseased wheat crops, thus extending outside the biological range. In contrast, when RUE was derived from GLAI loss per layer, RUElayer was a more accurate calculation and fell within the biological range. In one situation out of 13, no significant shift in the RUElayer of diseased crops vs. healthy crops was observed. A single linear relationship linked yield to post-anthesis accumulated growth for all treatments. Its slope, not different from 1, suggests that the allocation of post-anthesis photosynthates to grains was not affected by the late occurring Diseases under study. The mobilization of pre-anthesis reserves completely accounted for the intercept value. Conclusions The results strongly suggest that a simple model based on green leaf area per layer and pre-anthesis reserves can predict both growth and yield of wheat suffering from late epidemics of Foliar Diseases over a range of crop practices. It could help in better understanding how crop structure and reserve management contribute to tolerance of wheat genotypes to leaf Diseases.

Ramiro Carretero - One of the best experts on this subject based on the ideXlab platform.

  • Grain weight response to Foliar Diseases control in wheat (Triticum aestivum L.)
    Field Crops Research, 2011
    Co-Authors: Román A. Serrago, Ramiro Carretero, Marie Odile Bancal, Daniel J. Miralles
    Abstract:

    Foliar Diseases are the main biotic restriction reducing yield in wheat crops affecting both, grain number and/or grain weight, depending on developmental stage at which infection occurs (pre- or post-anthesis, respectively). Grain weight reductions due to Foliar Diseases were widely reported in the literature mostly associated with decreases on radiation interception during the grain filling period. However, different evidences in wheat showed variations on grain weight responses when fungicide was applied during the grain filling period, probably associated with the timing of fungicide application or with the amount of available resources per grain set when fungicides are applied. The present study was designed to determine the causes of grain weight reduction due to Foliar Diseases complex (including leaf rust, Septoria leaf blotch and tan spot) in wheat crops growing under contrasting agronomic and environmental conditions (i.e. different years, locations, cultivars and N supply). The experiments were carried out during 4 years under field conditions in different locations of Argentine and France. Five different commercial wheat cultivars were sown on early and late sowing dates; and two contrasting N availability and two fungicide treatments (protected and unprotected) were applied. Grain number was not affected by Foliar Diseases as their appeared after anthesis. Grain weight was strongly, poorly or not affected by Foliar Diseases and was not associated individually with both, the sink size and the source size. However, when the grain weight response due to fungicide application was plotted against the healthy area absorption per grain (HAAG), a significant negative association (r2 = 0.81; p < 0.0001) was found for the Argentine experiments. When the HAAG was corrected by the grain weight potential (HAAGW) all experiments conduced in Argentine and in France fit well to a common negative linear regression (r2 = 0.74, p < 0.0001) for the relationship between grain weight variation and HAAGW demonstrating that grain weight potential is an important feature to consider in Diseases control programs. Foliar Diseases forced the crop to use the accumulated reserved increasing the utilization rate of the water soluble carbohydrates (WSCUR), depleting as a consequence the water soluble content at physiological maturity (WSCPM) in all experiments. The association between WSCUR and the healthy area absorption per grain corrected by grain weight of healthy crops (HAAGW) suggest that Foliar Diseases in wheat cause source limitation, forcing to the crop to use the WSC reserve which could be insufficient to fill the grains previously formed.

  • Absorbed radiation and radiation use efficiency as affected by Foliar Diseases in relation to their vertical position into the canopy in wheat
    Field Crops Research, 2010
    Co-Authors: Ramiro Carretero, Román A. Serrago, Marie Odile Bancal, Analía E. Perelló, Daniel J. Miralles
    Abstract:

    The impact of Foliar Diseases on crop yield losses is better understood if considering ecophysiological variables together with pathological variables. Although wheat crop losses due to Foliar Diseases have already been studied with an ecophysiological approach, none of these studies analyzed the vertical Diseases distribution into the canopy leaf layers in relation to the canopy size (leaf area index—LAI) and its architecture (light extinction coefficient-k value). Thus, the objectives of the present study were: (i) to understand the importance of the vertical distribution of the Foliar Diseases in relation to radiation absorption efficiency (RAE) for different LAI levels and canopy architectures and; (ii) to analyze and compare two ways of radiation capture estimations, considering LAI as a total or LAI of each leaf layer separately. The wheat cultivar Klein Pegaso was grown in plots under field conditions during three growing seasons using different nitrogen supply levels and a wide range of severity Diseases by using protected and unprotected crops (applying or not fungicides, respectively). Unprotected plots were inoculated with biotrophic and/or necrotrophic pathogens. Biotrophic (Puccinia triticina-leaf rust) and necrotrophic pathogens (Drechslera tritici-repentis-tan spot; Alternaria triticina-leaf blight) constituted the “Diseases complex” with different levels and proportions depending on the year and N treatment. Results showed that Foliar Diseases reduced LAI and GLAI (green leaf area index). GLAI was not only diminished by LAI reductions, but also by increases in NGLAI (non-green leaf area index) due to lesion coverage which reduced light absorption. In spite of the differences observed in LAI between protected and unprotected crops, radiation interception was not affected until LAI dropped down its critical value (i.e. when crop intercept 95% of the maximum radiation possible to be intercepted). The results demonstrated that assuming a uniform distribution of the Diseases, lead to underestimations of accumulated absorbed radiation up to 21%, and as a consequence to overestimations of radiation use efficiency (RUE) up to 29% when Diseases were concentrated in the lower leaf layers into the canopy. Together with the severity of the pathogen, at the time to decide controlling Diseases, farmers should take into account: (i) LAI level, mainly in those crop situations where, during the critical period for yield determination, the LAI is close to or below the critical value; (ii) canopy architecture (k) associated with light distribution into the canopy and (iii) vertical Diseases distribution into the crop

  • Foliar Diseases affect the eco-physiological attributes linked with yield and biomass in wheat (Triticum aestivum L.)
    European Journal of Agronomy, 2009
    Co-Authors: Román A. Serrago, Ramiro Carretero, Marie Odile Bancal, Daniel J. Miralles
    Abstract:

    Abstract Foliar Diseases are the main biotic cause of yield loss in wheat crops ( Triticum aestivum L.) in Argentina and other regions around the world. Most of the studies on Foliar Diseases take a phytopathological perspective, but few studies have analyzed the problem with an eco-physiological approach aimed at the understanding of which crop traits are affected by Foliar Diseases. The present study was designed to determine the effects of a Foliar disease complex (including leaf rust, Septoria leaf blotch and tan spot), on (i) grain yield and (ii) the physiological components of biomass production; intercepted radiation (RI) and radiation use efficiency (RUE), in bread wheat crops growing under contrasting agronomic and environmental conditions (i.e. different cultivars, years, location and nitrogen supply). The experiments were carried out during 4 years in different locations (three in the rolling pampas of Argentina and one in northern of France). Five different commercial wheat cultivars were sown on early (E) and late (L) sowing dates (SD); and two contrasting nitrogen availability and two fungicide treatments (protected and unprotected) were applied. Foliar Diseases appeared during the grain filling period and affected both, leaf area duration (LAD) and healthy area duration (HAD) during that period. Foliar Diseases reduced both, above-ground biomass at harvest (1533 and 1703 g m −2 for unprotected and protected treatments, respectively) and grain yield (646 and 748 g m −2 for unprotected and protected treatments, respectively) without important effects on harvest index. Biomass reductions after anthesis, due to the effects of Foliar Diseases, were associated with a reduced capacity of the canopy to absorb solar radiation more than any effect on RUE. However, RUE was consistently lower—when leaf rust was the predominant disease in the crop, suggesting that this biotrophic pathogen could affect the photosynthetic activity at the leaf or canopy level.

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  • Effects of tillage, row width, and cultivar on Foliar Diseases of double-crop soybean.
    Plant Disease, 1993
    Co-Authors: J. A. Wrather, S. H. Anderson, N. C. Wollenhaupt, S. C. Anand, S. R. Kendig
    Abstract:

    Experiments were conducted over two years, 1985 and 1986, to determine the effect of tillage systems, row widths, and soybean cultivars on Foliar Diseases in double-crop soybean. The soybean cultivars Pershing, susceptible to bacterial blight, and Avery, resistant to bacterial blight, were each planted in 38-cm and 75-cm row widths in soil under conventional tillage or no-tillage following winter wheat. There was a significant interaction (P=0.0001) between tillage and cultivar for the severity of bacterial blight and a significant interaction (P=0.001) for tillage, cultivar, and year for the severity of brown spot. Tillage did not influence bacterial blight severity on Avery; however, disease severity was higher on Pershing soybean in tilled plots