The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Lisa M Ellsworth - One of the best experts on this subject based on the ideXlab platform.

  • Toward Cost-Effective Restoration: Scaling up Restoration in Ecosystems Degraded by Nonnative Invasive Grass and Ungulates
    Pacific Science, 2017
    Co-Authors: Kelly B. Powell, Lisa M Ellsworth, Creighton M Litton, Kirsten L.l. Oleson, Selita A Ammondt
    Abstract:

    Abstract: Nonnative, invasive grasses displace native plant communities and challenge ecological restoration globally. Ecological monitoring of restoration is typically short term and rarely reassessed to determine if initial findings are indicative of multiyear outcomes, and economic costs of restoration are seldom quantified. To address these knowledge gaps, we resampled a restoration experiment in an invasive Megathyrsus Maximus—dominated ecosystem in Hawai'i to compare success of restoration treatments at 8 and 36 months. We calculated cost to establish and maintain (for 3 yr) experimental field trials (0.13 ha) and management-scale (1 ha and 10 ha) units, estimated 30-yr costs for management-scale units, and determined key drivers of costs. Survival of native outplant species did not differ between 8- (56%) and 36-month (51%) monitoring periods, and M. Maximus cover was lower in restoration treatments than in control plots at both time periods. Cost to establish and maintain the experimental trial wa...

  • improved fuel moisture prediction in non native tropical Megathyrsus Maximus grasslands using moderate resolution imaging spectroradiometer modis derived vegetation indices
    International Journal of Wildland Fire, 2017
    Co-Authors: Creighton M Litton, Lisa M Ellsworth, A P Dale, Tomoaki Miura
    Abstract:

    The synergistic impacts of non-native grass invasion and frequent human-derived wildfires threaten endangered species, native ecosystems and developed land throughout the tropics. Fire behaviour models assist in fire prevention and management, but current models do not accurately predict fire in tropical ecosystems. Specifically, current models poorly predict fuel moisture, a key driver of fire behaviour. To address this limitation, we developed empirical models to predict fuel moisture in non-native tropical grasslands dominated by Megathyrsus Maximus in Hawaii from Terra Moderate-Resolution Imaging Spectroradiometer (MODIS)-based vegetation indices. Best-performing MODIS-based predictive models for live fuel moisture included the two-band Enhanced Vegetation Index (EVI2) and Normalized Difference Vegetation Index (NDVI). Live fuel moisture models had modest (R2=0.46) predictive relationships, and outperformed the commonly used National Fire Danger Rating System (R2=0.37) and the Keetch–Byram Drought Index (R2=0.06). Dead fuel moisture was also best predicted by a model including EVI2 and NDVI, but predictive capacity was low (R2=0.19). Site-specific models improved model fit for live fuel moisture (R2=0.61), but limited extrapolation. Better predictions of fuel moisture will improve fire management in tropical ecosystems dominated by this widespread and problematic non-native grass.

  • restoration impacts on fuels and fire potential in a dryland tropical ecosystem dominated by the invasive grass Megathyrsus Maximus
    Restoration Ecology, 2015
    Co-Authors: Lisa M Ellsworth, Creighton M Litton, James J K Leary
    Abstract:

    Ecological restoration often attempts to promote native species while managing for disturbances such as fire and non-native invasions. The goal of this research was to investigate whether restoration of a non-native, invasive Megathyrsus Maximus (guinea grass) tropical grassland could simultaneously promote native species and reduce fire potential. Megathyrsus Maximus was suppressed with herbicide, and three suites of native species—each including the same groundcover and shrub, and one of three tree species—were outplanted in a randomized, complete block design that also included herbicide control (herbicide with no outplantings) and untreated control treatments. Fuels were quantified 27 months after outplanting, and potential fire behavior (rate of spread and flame length) was modeled with BehavePlus. Compared with untreated controls, native outplant treatments reduced M. Maximus cover by 76–91% and M. Maximus live and dead fuel loads by greater than 92 and 68%, respectively. Despite reductions in M. Maximus fuels, neither treatment-level (grass + native) total fuel loads and fuel moistures, nor modeled fire behavior differed between outplant treatments and controls. The best performing native woody species (Dodonaea viscosa) had significantly lower average individual plant live fuel moisture (84%) than M. Maximus (156%) or other native woody outplant species (201–328%), highlighting the need for careful species selection. These results demonstrate that restoring native species to degraded tropical dry forests is possible, but that ecological restoration will not necessarily alter the potential for fire, at least in the short term, making selection of species with beneficial fuel properties and active fire management critical components of ongoing restoration.

  • Impact of grazing on fine fuels and potential wildfire behaviour in a non-native tropical grassland
    Pacific Conservation Biology, 2015
    Co-Authors: Edward W. Evans, Lisa M Ellsworth, Creighton M Litton
    Abstract:

    Non-nativegrassinvasionhasincreasedfuelloadsandfirefrequencyinareasthroughoutthetropics,resulting in a non-native grass-wildfire cycle with negative impacts on native biodiversity and ecological processes. Megathyrsus Maximus (guinea grass) invades dry and mesic ecosystems throughout the tropics, increasing fuel loads and wildfire intensity. Eradication of M. Maximus is difficult, making effective wildfire management critical to the protection of adjacent developed areas and remnant native ecosystems. The use of domestic livestock grazing in non-native grass ecosystems may be effective at decreasing fine fuel loads and potential wildfire behaviour. Our objectives were to: (1) quantify live and dead fine fuel loads and moistures in a M. Maximus-dominated ecosystem before and after cattle grazing, and (2) use these data to model potential wildfire behaviour in grazed and ungrazed M. Maximus grasslands with the BehavePlus fire modelling system. Fine fuel loads and moistures, climate variables, and predicted wildfire behaviour werequantifiedatthesamesite(n ¼1)overtwo5-monthperiods(March-July2009,ungrazed;March-July2010,grazed) in the Wai'anae Kai Forest Reserve on the Island of O'ahu, Hawai'i. Strong to conclusive evidence existed that cattle grazing in this system decreased dead and total fuel loads, but did not alter live fuel loads, or live and dead fuel moistures. Modelled wildfire behaviour under both low and average fuel moisture scenarios revealed that grazing decreased the potential rate of spread by 44-52% and flame length by 36-41%. These results demonstrate that cattle grazing may be an effectiveapproachforreducingfuelloadsandpotentialwildfirebehaviourinnon-native-dominatedgrasslandsontropical islands. Additional keywords: BehavePlus fire model, guinea grass, invasive grass, Megathyrsus Maximus, non-native grass-wildfire cycle, tropical dryland ecosystem.

  • Invasive grasses change landscape structure and fire behaviour in Hawaii
    Applied Vegetation Science, 2014
    Co-Authors: Lisa M Ellsworth, Creighton M Litton, Alexander P. Dale, Tomoaki Miura
    Abstract:

    Questions How does potential fire behaviour differ in grass-invaded non-native forests vs open grasslands? How has land cover changed from 1950–2011 along two grassland/forest ecotones in Hawaii with repeated fires? Location Non-native forest with invasive grass understory and invasive grassland (Megathyrsus Maximus) ecosystems on Oahu, Hawaii, USA. Methods We quantified fuel load and moisture in non-native forest and grassland (Megathyrsus Maximus) plots (n = 6) at Makua Military Reservation and Schofield Barracks, and used these field data to model potential fire behaviour using the BehavePlus fire modelling program. Actual rate and extent of land-cover change were quantified for both areas from 1950–2011 with historical aerial imagery. Results Live and dead fuel moisture content and fine fuel loads did not differ between forests and grasslands. However, mean surface fuel height was 31% lower in forests (72 cm) than grasslands (105 cm; P 

Creighton M Litton - One of the best experts on this subject based on the ideXlab platform.

  • Toward Cost-Effective Restoration: Scaling up Restoration in Ecosystems Degraded by Nonnative Invasive Grass and Ungulates
    Pacific Science, 2017
    Co-Authors: Kelly B. Powell, Lisa M Ellsworth, Creighton M Litton, Kirsten L.l. Oleson, Selita A Ammondt
    Abstract:

    Abstract: Nonnative, invasive grasses displace native plant communities and challenge ecological restoration globally. Ecological monitoring of restoration is typically short term and rarely reassessed to determine if initial findings are indicative of multiyear outcomes, and economic costs of restoration are seldom quantified. To address these knowledge gaps, we resampled a restoration experiment in an invasive Megathyrsus Maximus—dominated ecosystem in Hawai'i to compare success of restoration treatments at 8 and 36 months. We calculated cost to establish and maintain (for 3 yr) experimental field trials (0.13 ha) and management-scale (1 ha and 10 ha) units, estimated 30-yr costs for management-scale units, and determined key drivers of costs. Survival of native outplant species did not differ between 8- (56%) and 36-month (51%) monitoring periods, and M. Maximus cover was lower in restoration treatments than in control plots at both time periods. Cost to establish and maintain the experimental trial wa...

  • improved fuel moisture prediction in non native tropical Megathyrsus Maximus grasslands using moderate resolution imaging spectroradiometer modis derived vegetation indices
    International Journal of Wildland Fire, 2017
    Co-Authors: Creighton M Litton, Lisa M Ellsworth, A P Dale, Tomoaki Miura
    Abstract:

    The synergistic impacts of non-native grass invasion and frequent human-derived wildfires threaten endangered species, native ecosystems and developed land throughout the tropics. Fire behaviour models assist in fire prevention and management, but current models do not accurately predict fire in tropical ecosystems. Specifically, current models poorly predict fuel moisture, a key driver of fire behaviour. To address this limitation, we developed empirical models to predict fuel moisture in non-native tropical grasslands dominated by Megathyrsus Maximus in Hawaii from Terra Moderate-Resolution Imaging Spectroradiometer (MODIS)-based vegetation indices. Best-performing MODIS-based predictive models for live fuel moisture included the two-band Enhanced Vegetation Index (EVI2) and Normalized Difference Vegetation Index (NDVI). Live fuel moisture models had modest (R2=0.46) predictive relationships, and outperformed the commonly used National Fire Danger Rating System (R2=0.37) and the Keetch–Byram Drought Index (R2=0.06). Dead fuel moisture was also best predicted by a model including EVI2 and NDVI, but predictive capacity was low (R2=0.19). Site-specific models improved model fit for live fuel moisture (R2=0.61), but limited extrapolation. Better predictions of fuel moisture will improve fire management in tropical ecosystems dominated by this widespread and problematic non-native grass.

  • restoration impacts on fuels and fire potential in a dryland tropical ecosystem dominated by the invasive grass Megathyrsus Maximus
    Restoration Ecology, 2015
    Co-Authors: Lisa M Ellsworth, Creighton M Litton, James J K Leary
    Abstract:

    Ecological restoration often attempts to promote native species while managing for disturbances such as fire and non-native invasions. The goal of this research was to investigate whether restoration of a non-native, invasive Megathyrsus Maximus (guinea grass) tropical grassland could simultaneously promote native species and reduce fire potential. Megathyrsus Maximus was suppressed with herbicide, and three suites of native species—each including the same groundcover and shrub, and one of three tree species—were outplanted in a randomized, complete block design that also included herbicide control (herbicide with no outplantings) and untreated control treatments. Fuels were quantified 27 months after outplanting, and potential fire behavior (rate of spread and flame length) was modeled with BehavePlus. Compared with untreated controls, native outplant treatments reduced M. Maximus cover by 76–91% and M. Maximus live and dead fuel loads by greater than 92 and 68%, respectively. Despite reductions in M. Maximus fuels, neither treatment-level (grass + native) total fuel loads and fuel moistures, nor modeled fire behavior differed between outplant treatments and controls. The best performing native woody species (Dodonaea viscosa) had significantly lower average individual plant live fuel moisture (84%) than M. Maximus (156%) or other native woody outplant species (201–328%), highlighting the need for careful species selection. These results demonstrate that restoring native species to degraded tropical dry forests is possible, but that ecological restoration will not necessarily alter the potential for fire, at least in the short term, making selection of species with beneficial fuel properties and active fire management critical components of ongoing restoration.

  • Impact of grazing on fine fuels and potential wildfire behaviour in a non-native tropical grassland
    Pacific Conservation Biology, 2015
    Co-Authors: Edward W. Evans, Lisa M Ellsworth, Creighton M Litton
    Abstract:

    Non-nativegrassinvasionhasincreasedfuelloadsandfirefrequencyinareasthroughoutthetropics,resulting in a non-native grass-wildfire cycle with negative impacts on native biodiversity and ecological processes. Megathyrsus Maximus (guinea grass) invades dry and mesic ecosystems throughout the tropics, increasing fuel loads and wildfire intensity. Eradication of M. Maximus is difficult, making effective wildfire management critical to the protection of adjacent developed areas and remnant native ecosystems. The use of domestic livestock grazing in non-native grass ecosystems may be effective at decreasing fine fuel loads and potential wildfire behaviour. Our objectives were to: (1) quantify live and dead fine fuel loads and moistures in a M. Maximus-dominated ecosystem before and after cattle grazing, and (2) use these data to model potential wildfire behaviour in grazed and ungrazed M. Maximus grasslands with the BehavePlus fire modelling system. Fine fuel loads and moistures, climate variables, and predicted wildfire behaviour werequantifiedatthesamesite(n ¼1)overtwo5-monthperiods(March-July2009,ungrazed;March-July2010,grazed) in the Wai'anae Kai Forest Reserve on the Island of O'ahu, Hawai'i. Strong to conclusive evidence existed that cattle grazing in this system decreased dead and total fuel loads, but did not alter live fuel loads, or live and dead fuel moistures. Modelled wildfire behaviour under both low and average fuel moisture scenarios revealed that grazing decreased the potential rate of spread by 44-52% and flame length by 36-41%. These results demonstrate that cattle grazing may be an effectiveapproachforreducingfuelloadsandpotentialwildfirebehaviourinnon-native-dominatedgrasslandsontropical islands. Additional keywords: BehavePlus fire model, guinea grass, invasive grass, Megathyrsus Maximus, non-native grass-wildfire cycle, tropical dryland ecosystem.

  • Invasive grasses change landscape structure and fire behaviour in Hawaii
    Applied Vegetation Science, 2014
    Co-Authors: Lisa M Ellsworth, Creighton M Litton, Alexander P. Dale, Tomoaki Miura
    Abstract:

    Questions How does potential fire behaviour differ in grass-invaded non-native forests vs open grasslands? How has land cover changed from 1950–2011 along two grassland/forest ecotones in Hawaii with repeated fires? Location Non-native forest with invasive grass understory and invasive grassland (Megathyrsus Maximus) ecosystems on Oahu, Hawaii, USA. Methods We quantified fuel load and moisture in non-native forest and grassland (Megathyrsus Maximus) plots (n = 6) at Makua Military Reservation and Schofield Barracks, and used these field data to model potential fire behaviour using the BehavePlus fire modelling program. Actual rate and extent of land-cover change were quantified for both areas from 1950–2011 with historical aerial imagery. Results Live and dead fuel moisture content and fine fuel loads did not differ between forests and grasslands. However, mean surface fuel height was 31% lower in forests (72 cm) than grasslands (105 cm; P 

A P De Souza - One of the best experts on this subject based on the ideXlab platform.

  • high resolution linkage map with allele dosage allows the identification of regions governing complex traits and apospory in guinea grass Megathyrsus Maximus
    Frontiers in Plant Science, 2020
    Co-Authors: R C U Ferreira, L Jank, Leticia Aparecida De Castro Lara, Aline Da Costa Lima Moraes, Alessandro Alvespereira, F A De Oliveira, A A F Garcia, M F Santos, A P De Souza
    Abstract:

    Forage grasses are mainly used in animal feed to fatten cattle and dairy herds, and guinea grass (Megathyrsus Maximus) is considered one of the most productive of the tropical forage crops that reproduce by seeds. Due to the recent process of domestication, this species has several genomic complexities, such as autotetraploidy and aposporous apomixis. Consequently, approaches that relate phenotypic and genotypic data are incipient. In this context, we built a linkage map with allele dosage and generated novel information of the genetic architecture of traits that are important for the breeding of M. Maximus. From a full-sib progeny, a linkage map containing 858 single nucleotide polymorphism (SNP) markers with allele dosage information expected for an autotetraploid was obtained. The high genetic variability of the progeny allowed us to map 10 quantitative trait loci (QTLs) related to agronomic traits, such as regrowth capacity and total dry matter, and 36 QTLs related to nutritional quality, which were distributed among all homology groups (HGs). Various overlapping regions associated with the quantitative traits suggested QTL hotspots. In addition, we were able to map one locus that controls apospory (apo-locus) in HG II. A total of 55 different gene families involved in cellular metabolism and plant growth were identified from markers adjacent to the QTLs and APOSPORY locus using the Panicum virgatum genome as a reference in comparisons with the genomes of Arabidopsis thaliana and Oryza sativa. Our results provide a better understanding of the genetic basis of reproduction by apomixis and traits important for breeding programs that considerably influence animal productivity as well as the quality of meat and milk.

  • high resolution linkage map with allele dosage allows the identification of an apomixis region and complex traits in guinea grass Megathyrsus Maximus
    bioRxiv, 2019
    Co-Authors: R C U Ferreira, L Jank, Leticia Aparecida De Castro Lara, Aline Da Costa Lima Moraes, Alessandro Alvespereira, F A De Oliveira, A A F Garcia, M F Santos, A P De Souza
    Abstract:

    Forage grasses are mainly used in animal feed to fatten cattle and dairy herds. Among tropical forage crops that reproduce by seeds, guinea grass (Megathyrsus Maximus) is considered one of the most productive. This species has several genomic complexities, such as autotetraploidy and apomixis, due to the process of domestication. Consequently, approaches that relate phenotypic and genotypic data are incipient. In this context, we built a linkage map with allele dosage and generated novel information about the genetic architecture of traits that are important for the breeding of M. Maximus. From a full-sib progeny, a linkage map containing 858 single nucleotide polymorphism (SNP) markers with allele dosage information expected for an autotetraploid was obtained. The high genetic variability of the progeny allowed us to map ten quantitative trait loci (QTLs) related to agronomic traits, such as regrowth capacity and total dry matter, and 36 QTLs related to nutritional quality, which were distributed among all homology groups (HGs). Various overlapping regions associated with the quantitative traits suggested QTL hotspots. In addition, we were able to map one locus that controls apospory (apo-locus) in HG II. A total of 55 different gene families involved in cellular metabolism and plant growth were identified from markers adjacent to the QTLs and apomixis locus by using the Panicum virgatum genome as a reference in comparisons with the genomes of Arabidopsis thaliana and Oryza sativa. Our results provide a better understanding of the genetic basis of reproduction by apomixis and traits important for breeding programs that considerably influence animal productivity as well as the quality of meat and milk.

Yuseika Olivera - One of the best experts on this subject based on the ideXlab platform.

  • influencia de la fertilizacion en las propiedades fisico quimicas de un suelo dedicado a la produccion de semilla de Megathyrsus Maximus
    Pastos y Forrajes, 2015
    Co-Authors: J Ramirez, Yousi Fernandez, P J Gonzalez, Xiomara Salazar, J M Iglesias, Yuseika Olivera
    Abstract:

    Se estudio la influencia que ejercen diferentes fuentes de fertilizante en las propiedades fisico-quimicas de un suelo Gley Nodular ferruginoso, dedicado a la produccion de semilla de Megathyrsus Maximus (guinea) cv. Likoni. El diseno fue de bloques al azar, con cuatro replicas, y se evaluaron los tratamientos siguientes: testigo; 3, 6 y 9 t de humus de lombriz por hectarea; 20, 40 y 60 t de estiercol vacuno por hectarea; y 180-50-75 kg de NPK por hectarea. La densidad real y aparente fluctuo entre los tratamientos; pero, en sentido general, fue superior (p ≤ 0,05) en el testigo y en el NPK, para las profundidades de 0-10 y 10-20 cm, respectivamente. La humedad natural fue superior (p ≤ 0,05) al aplicar 9 t de humus y 60 t de estiercol; mientras que la porosidad no difirio entre los tratamientos. La materia organica se incremento, y el mejor resultado (p ≤ 0,05) se obtuvo en el tratamiento de 9 t de humus. El rendimiento de semilla con 9 t de humus fue similar al de NPK (entre 41,0 y 91,3 kg de SPG/ha); sin embargo, la ganancia por concepto de venta de semillas y la ganancia por hectarea fueron superiores en el tratamiento con 9 t de humus, lo que propicio un menor costo de produccion (10,30 vs. 16,50 pesos/kg de semilla para humus y NPK, respectivamente). Se concluye que es factible, desde el punto de vista productivo y economico, el uso de abonos organicos en los sistemas de produccion de semillas de guinea.

  • influencia de la fertilizacion en las propiedades fisico quimicas de un suelo dedicado a la produccion de semilla de Megathyrsus Maximus influence of fertilization on the physical and chemical properties of a soil dedicated to the production of megat
    2015
    Co-Authors: J Ramirez, Yousi Fernandez, P J Gonzalez, Xiomara Salazar, J M Iglesias, Yuseika Olivera, Estacion Experimental De Pastos
    Abstract:

    The influence exerted by different fertilizer doses on the physical and chemical properties of a ferruginous Gley Nodular soil, dedicated to the production of Megathyrsus Maximus (Guinea grass) cv. Likoni seed, was studied. The design was randomized blocks, with four replications, and the following treatments were evaluated: control (without fertilizer); 3, 6 and 9 t of earthworm humus per hectare; 20, 40 and 60 t of cattle manure per hectare; and 180-50-75 kg of NPK per hectare. The values of the real and apparent density fluctuated among the treatments; but, in general, they were at the end higher (p ≤ 0,05) in the control and in NPK, for the depths 0-10 and 10-20 cm, respectively. The natural humidity was higher (p ≤ 0,05) when applying 9 t of humus and 60 t of manure; while porosity did not differ among the treatments. The organic matter increased, and the best result (p ≤ 0,05) was obtained in the treatment of 9 t of humus. The seed yield with 9 t of humus was similar to that of NPK (between 41,0 and 91,3 kg of PGS/ha); however, the profit for the sale of seeds and the profit per hectare were higher in the treatment with 9 t of humus, which propitiated a lower production cost (10,30 vs. 16,50 pesos/kg of seed for humus and NPK, respectively). It is concluded that the use of organic fertilizers in the systems of Guinea grass seed production is feasible, from the productive and economic point of view.

L Jank - One of the best experts on this subject based on the ideXlab platform.

  • morphogenetic and structural characteristics of Megathyrsus Maximus cv centenario under defoliation intensities
    Research Society and Development, 2020
    Co-Authors: Newton De Lucena Costa, L Jank, Joao Avelar Magalhaes, A B Bendahan, B H N Rodrigues, Francisco Jose De Seixas Santos
    Abstract:

    The effect of defoliation intensities (20, 30, 40 and 50 cm above soil level) on green dry matter (GDM) yield and morphogenetic and structural characteristics of Megathyrsus Maximus cv. Centenario were evaluated under field conditions in Roraima´s savannas. The effects of defoliation intensities on the GDM yields, leaf area index and leaf elongation rates was adjusted to the quadratic regression model and maximum values recorded with cutting at 35.8; 44.9 and 30.2 cm above soil level, respectively. The tiller population density, number of leaves tiller -1 and leaf appearance rate was inversely proportional to the intensity of defoliation, while the opposite occurred for to average leaf length and leaf senescence rate. Apical meristem removal percentage was higher with increasing defoliation intensity. Vigor regrowth showed close negative correlation with defoliation intensity level. Pastures of M. Maximus cv. Centenario managed under 30 to 35 cm residue provides higher forage productivity, larger efficiency of forage utilization, greater tissue renewal and canopy structure more favorable to grazing.

  • high resolution linkage map with allele dosage allows the identification of regions governing complex traits and apospory in guinea grass Megathyrsus Maximus
    Frontiers in Plant Science, 2020
    Co-Authors: R C U Ferreira, L Jank, Leticia Aparecida De Castro Lara, Aline Da Costa Lima Moraes, Alessandro Alvespereira, F A De Oliveira, A A F Garcia, M F Santos, A P De Souza
    Abstract:

    Forage grasses are mainly used in animal feed to fatten cattle and dairy herds, and guinea grass (Megathyrsus Maximus) is considered one of the most productive of the tropical forage crops that reproduce by seeds. Due to the recent process of domestication, this species has several genomic complexities, such as autotetraploidy and aposporous apomixis. Consequently, approaches that relate phenotypic and genotypic data are incipient. In this context, we built a linkage map with allele dosage and generated novel information of the genetic architecture of traits that are important for the breeding of M. Maximus. From a full-sib progeny, a linkage map containing 858 single nucleotide polymorphism (SNP) markers with allele dosage information expected for an autotetraploid was obtained. The high genetic variability of the progeny allowed us to map 10 quantitative trait loci (QTLs) related to agronomic traits, such as regrowth capacity and total dry matter, and 36 QTLs related to nutritional quality, which were distributed among all homology groups (HGs). Various overlapping regions associated with the quantitative traits suggested QTL hotspots. In addition, we were able to map one locus that controls apospory (apo-locus) in HG II. A total of 55 different gene families involved in cellular metabolism and plant growth were identified from markers adjacent to the QTLs and APOSPORY locus using the Panicum virgatum genome as a reference in comparisons with the genomes of Arabidopsis thaliana and Oryza sativa. Our results provide a better understanding of the genetic basis of reproduction by apomixis and traits important for breeding programs that considerably influence animal productivity as well as the quality of meat and milk.

  • high resolution linkage map with allele dosage allows the identification of an apomixis region and complex traits in guinea grass Megathyrsus Maximus
    bioRxiv, 2019
    Co-Authors: R C U Ferreira, L Jank, Leticia Aparecida De Castro Lara, Aline Da Costa Lima Moraes, Alessandro Alvespereira, F A De Oliveira, A A F Garcia, M F Santos, A P De Souza
    Abstract:

    Forage grasses are mainly used in animal feed to fatten cattle and dairy herds. Among tropical forage crops that reproduce by seeds, guinea grass (Megathyrsus Maximus) is considered one of the most productive. This species has several genomic complexities, such as autotetraploidy and apomixis, due to the process of domestication. Consequently, approaches that relate phenotypic and genotypic data are incipient. In this context, we built a linkage map with allele dosage and generated novel information about the genetic architecture of traits that are important for the breeding of M. Maximus. From a full-sib progeny, a linkage map containing 858 single nucleotide polymorphism (SNP) markers with allele dosage information expected for an autotetraploid was obtained. The high genetic variability of the progeny allowed us to map ten quantitative trait loci (QTLs) related to agronomic traits, such as regrowth capacity and total dry matter, and 36 QTLs related to nutritional quality, which were distributed among all homology groups (HGs). Various overlapping regions associated with the quantitative traits suggested QTL hotspots. In addition, we were able to map one locus that controls apospory (apo-locus) in HG II. A total of 55 different gene families involved in cellular metabolism and plant growth were identified from markers adjacent to the QTLs and apomixis locus by using the Panicum virgatum genome as a reference in comparisons with the genomes of Arabidopsis thaliana and Oryza sativa. Our results provide a better understanding of the genetic basis of reproduction by apomixis and traits important for breeding programs that considerably influence animal productivity as well as the quality of meat and milk.

  • resposta de pastagens de Megathyrsus Maximus cv zuri a frequencia de desfolhacao
    Research Society and Development, 2019
    Co-Authors: Newton De Lucena Costa, L Jank, Joao Avelar Magalhaes, B H N Rodrigues, Francisco Jose De Seixas Santos
    Abstract:

    With the objective to evaluate the effect of defoliation frequency (14, 21, 28, 35, 42 and 49 days) on green dry matter (GDM) yield, chemical composition and morphogenetic and structural characteristics of Megathyrsus Maximus cv. Zuri pastures were carried out an experiment under natural field conditions at Roraima´s savannas. The reduction in the frequency of defoliation resulted in higher yields of GDM and regrowth vigor, however, it resulted in significant decreases in nitrogen, phosphorus, calcium, magnesium and potassium contents. The leaf appearance and leaf expansion rates are inversely proportional to the defoliation frequency, occurring the inverse for number of leaves tiller -1 , average leaf length, leaf area index and foliar senescence rate. Maximum GDM yields, regrowth yields, number of leaves tiller -1 , average leaf length and leaf area index, they were obtained with defoliation frequencies at 40.3; 44.9; 36.9; 42.4 and 39.0 days, respectively. These data suggest the frequency of defoliation more adequate for pastures of M. Maximus cv. Zuri, aiming to reconcile production, regrowth vigor, quality and efficiency of forage utilization, tissue renewal and canopy structure more favorable to grazing, is between 35 and 42 days.

  • caracteristicas morfogenicas e estruturais de Megathyrsus Maximus cv tanzânia 1 sob intensidades de desfolhacao
    PUBVET, 2018
    Co-Authors: Newton De Lucena Costa, L Jank, Joao Avelar Magalhaes, Antonio Neri Azevedo Rodrigues, Fabiola Helena Dos Santos Fogaca, Amaury Burlamaqui Bendahan, Francisco Jose De Seixas Santos
    Abstract:

    O efeito de intensidades de desfolhacao (20, 30, 40 e 50 cm acima do solo) sobre a producao de forragem e caracteristicas morfogenicas e estruturais de Megathyrsus Maximus cv. Tanzânia-1 foi avaliado nos cerrados de Roraima.