The Experts below are selected from a list of 219 Experts worldwide ranked by ideXlab platform
R. L. Benech Arnold - One of the best experts on this subject based on the ideXlab platform.
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CHANGES IN DORMANCY LEVEL IN Sorghum Halepense SEEDS INDUCED BY WATER STRESS DURING SEED DEVELOPMENT
Functional Ecology, 1992Co-Authors: R. L. Benech Arnold, Michael Fenner, P. J. EdwardsAbstract:Dormancy in Sorghum Halepense seeds as affected by intermittent water stress imposed on the mother plant during seed development was investigated. The drought treatment was imposed in cycles within the maturation period by with-holding water for 5 days, rewatering at the end of each drought cycle and withholding water again. The results showed that two sources of dormancy exist in S. Halepense seeds: one is inherent in the caryopsis itself and is not affected by water stress during seed development (...)
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The role of fluctuating temperatures in germination and establishment of Sorghum Halepense. Regulation of germination at increasing depths
Functional Ecology, 1992Co-Authors: Claudio M. Ghersa, R. L. Benech Arnold, M.a. Martínez-ghersaAbstract:Field and laboratory tests explored the response of Sorghum Halepense seeds to fluctuations in soil temperature, and whether that response serves as a mechanism for sensing depth and regulating seed germination. Seedling production in the field was severely curtailed when seeds were planted at increasing soil depths. Soil-temperature fluctuations were strongly dependent on depth. When soil columns containing seeds were incubated at alternating temperatures of 20 and 30°C, however, seed germination did not diminish with increasing depth, and an evaluation of how soil-surface shading affects the perception of depth by the seeds indicated that soil cover reduced germination of only those seeds in the upper strata of the profile (...)
P. J. Edwards - One of the best experts on this subject based on the ideXlab platform.
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CHANGES IN DORMANCY LEVEL IN Sorghum Halepense SEEDS INDUCED BY WATER STRESS DURING SEED DEVELOPMENT
Functional Ecology, 1992Co-Authors: R. L. Benech Arnold, Michael Fenner, P. J. EdwardsAbstract:Dormancy in Sorghum Halepense seeds as affected by intermittent water stress imposed on the mother plant during seed development was investigated. The drought treatment was imposed in cycles within the maturation period by with-holding water for 5 days, rewatering at the end of each drought cycle and withholding water again. The results showed that two sources of dormancy exist in S. Halepense seeds: one is inherent in the caryopsis itself and is not affected by water stress during seed development (...)
M.a. Martínez-ghersa - One of the best experts on this subject based on the ideXlab platform.
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Seed dispersal, distribution and recruitment of seedlings of Sorghum Halepense (L.) Pers.
Weed Research, 1993Co-Authors: Claudio M. Ghersa, M.a. Martínez-ghersa, Emilio H. Satorre, M. L. Esso, G. ChichotkyAbstract:Summary: Resume: Zusammenfassung Patteras of seed dispersal and seedling recruit ment of Sorghum Halepense (L.) Pers. were compared in abandoned and cultivated fields in Argentina. In both the abandoned and cultivated plots, the greatest concentration of seed fell below, or only a short distance, from the parent plants. A maize combine harvester greatly increased the distance of dispersal of a small part of the seed population. The availability of seed for dispersal, the direction and velocity of wind and the combine harvester were important factors determining the temporal and spatial patterns of seed distribution. The ratio of recruited seedlings to seeds shed was only 1% under the parent plant, but increased to about 100% at a distance of 1.25 m. Soil tilling, which is required for seedling recruitment, and seed density were important factors in determining seedling density as the distance from the parent plants increased. The rate of seedling recruitment was higher in areas where most of the seeds were dispersed late in the season than in those where dispersal occurred early. Dispersion des graines, distribution et reprise des plantules de Sorghum Halepense (L.) Pers. Les schemas de dispersion des graines et de reprise des plantules de Sorghum Halepense (L.) Pers. ont ete compares dans des champs abandonnes et d'autres cultives en Argentine. Tant dans les parcelles abandonnees que cultivees, la plus grande concentration de graines tombe sous ou seulement a une faible distance des plantes parentes. Une moisonneuse a maii a grandement augmente la distance de dispersion d'une petite partie de la population grainiere. La disponibilite des graines pour la dispersion, la direction et la vitesse du vent, et la moissonneuse ont ete d'importants facteurs de determination pour les schemas de distribution spatiale et temporaire. Le ratio de reprise de plantule etait seulement de 1% sous les plantes parentes mais augmentait jusqu'a pres de 100%a une distance de 1, 25 m. Le travail du sol, qui est necessaire pour la reprise des plantules, et la densite grainiere etaient d'importants facteurs dans la determination de la densite des plantules quand la distance des plantes parentes augmente. Le taux de reprise des plantules etait plus eleve dans les zones ou la majorite des graines etait dispersee tard en saison que dans celles ou la dispersion avait eu lieu tot. Ausbreitung der Samen sowie Verbreitung und Entwicklung der Keimpflanzen von Sorghum Halepense (L.) Pers. Ausbreitung der Samen und Entwicklung der Keimpflanzen von Sorghum Halepense (L.) Pers. wurden in Argentinien auf brachliegenden und kultivierten Feldern untersucht. In beiden Situationen fanden sich die grosten Samendichten unter oder nahe der Mutterpflanzen. Mit einem Mais-Mahdrescher wurde ein kleiner Teil der Samenpopulation erheblich ausgebreitet. Die Verfugbarkeit von Samen fur die Ausbreitung, die Windrichtung und-geschwindigkeit und der Mahdrusch waren wichtige Faktoren fur das zeitliche und raumliche Verbreitungsmuster, Unter den Mutterpflanzen keimten die Samen nur zu 1%, aber 1,25 m entfemt zu fast 100%. Bodenbearbeitung und Samendichte bestimmten die Keimpflanzendichte mit zunehmender Entfernung von der Mutterpflanze erheblich. Die Entwichlungsrate spat ansgebreiteter Samen war hoher als die fruh ausgebreiteter.
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The role of fluctuating temperatures in germination and establishment of Sorghum Halepense. Regulation of germination at increasing depths
Functional Ecology, 1992Co-Authors: Claudio M. Ghersa, R. L. Benech Arnold, M.a. Martínez-ghersaAbstract:Field and laboratory tests explored the response of Sorghum Halepense seeds to fluctuations in soil temperature, and whether that response serves as a mechanism for sensing depth and regulating seed germination. Seedling production in the field was severely curtailed when seeds were planted at increasing soil depths. Soil-temperature fluctuations were strongly dependent on depth. When soil columns containing seeds were incubated at alternating temperatures of 20 and 30°C, however, seed germination did not diminish with increasing depth, and an evaluation of how soil-surface shading affects the perception of depth by the seeds indicated that soil cover reduced germination of only those seeds in the upper strata of the profile (...)
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A Field Method for Predicting Yield Losses in Maize Caused by Johnsongrass (Sorghum Halepense)
Weed Technology, 1991Co-Authors: Claudio M. Ghersa, M.a. Martínez-ghersaAbstract:The objective of this research was to modify the senior author's previously developed method for predicting yield losses in maize crops attributable to johnsongrass. The new method is based on the following assumptions: a) relative leaf frequency determiines relative biomass; b) total biomass is constant despite the crop/weed ratio; and c) biomass, and therefore leaf frequency, are related to grain yield. Experiments in Argentina from 1986 to 1989 supported the above hypotheses, and the new method was more accurate than the old for predicting relative species biomass in johnsongrass/maize mixtures. Maize grain yield reductions associated with weed interference were also more accurately predicted. Nomenclature: Maize, Zea mays L.; johnsongrass, Sorghum Halepense (L.) Pers. #3 SORHA. Additional index words: Johnsongrass, yield losses, prediction.
Claudio M. Ghersa - One of the best experts on this subject based on the ideXlab platform.
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Seed dispersal, distribution and recruitment of seedlings of Sorghum Halepense (L.) Pers.
Weed Research, 1993Co-Authors: Claudio M. Ghersa, M.a. Martínez-ghersa, Emilio H. Satorre, M. L. Esso, G. ChichotkyAbstract:Summary: Resume: Zusammenfassung Patteras of seed dispersal and seedling recruit ment of Sorghum Halepense (L.) Pers. were compared in abandoned and cultivated fields in Argentina. In both the abandoned and cultivated plots, the greatest concentration of seed fell below, or only a short distance, from the parent plants. A maize combine harvester greatly increased the distance of dispersal of a small part of the seed population. The availability of seed for dispersal, the direction and velocity of wind and the combine harvester were important factors determining the temporal and spatial patterns of seed distribution. The ratio of recruited seedlings to seeds shed was only 1% under the parent plant, but increased to about 100% at a distance of 1.25 m. Soil tilling, which is required for seedling recruitment, and seed density were important factors in determining seedling density as the distance from the parent plants increased. The rate of seedling recruitment was higher in areas where most of the seeds were dispersed late in the season than in those where dispersal occurred early. Dispersion des graines, distribution et reprise des plantules de Sorghum Halepense (L.) Pers. Les schemas de dispersion des graines et de reprise des plantules de Sorghum Halepense (L.) Pers. ont ete compares dans des champs abandonnes et d'autres cultives en Argentine. Tant dans les parcelles abandonnees que cultivees, la plus grande concentration de graines tombe sous ou seulement a une faible distance des plantes parentes. Une moisonneuse a maii a grandement augmente la distance de dispersion d'une petite partie de la population grainiere. La disponibilite des graines pour la dispersion, la direction et la vitesse du vent, et la moissonneuse ont ete d'importants facteurs de determination pour les schemas de distribution spatiale et temporaire. Le ratio de reprise de plantule etait seulement de 1% sous les plantes parentes mais augmentait jusqu'a pres de 100%a une distance de 1, 25 m. Le travail du sol, qui est necessaire pour la reprise des plantules, et la densite grainiere etaient d'importants facteurs dans la determination de la densite des plantules quand la distance des plantes parentes augmente. Le taux de reprise des plantules etait plus eleve dans les zones ou la majorite des graines etait dispersee tard en saison que dans celles ou la dispersion avait eu lieu tot. Ausbreitung der Samen sowie Verbreitung und Entwicklung der Keimpflanzen von Sorghum Halepense (L.) Pers. Ausbreitung der Samen und Entwicklung der Keimpflanzen von Sorghum Halepense (L.) Pers. wurden in Argentinien auf brachliegenden und kultivierten Feldern untersucht. In beiden Situationen fanden sich die grosten Samendichten unter oder nahe der Mutterpflanzen. Mit einem Mais-Mahdrescher wurde ein kleiner Teil der Samenpopulation erheblich ausgebreitet. Die Verfugbarkeit von Samen fur die Ausbreitung, die Windrichtung und-geschwindigkeit und der Mahdrusch waren wichtige Faktoren fur das zeitliche und raumliche Verbreitungsmuster, Unter den Mutterpflanzen keimten die Samen nur zu 1%, aber 1,25 m entfemt zu fast 100%. Bodenbearbeitung und Samendichte bestimmten die Keimpflanzendichte mit zunehmender Entfernung von der Mutterpflanze erheblich. Die Entwichlungsrate spat ansgebreiteter Samen war hoher als die fruh ausgebreiteter.
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The role of fluctuating temperatures in germination and establishment of Sorghum Halepense. Regulation of germination at increasing depths
Functional Ecology, 1992Co-Authors: Claudio M. Ghersa, R. L. Benech Arnold, M.a. Martínez-ghersaAbstract:Field and laboratory tests explored the response of Sorghum Halepense seeds to fluctuations in soil temperature, and whether that response serves as a mechanism for sensing depth and regulating seed germination. Seedling production in the field was severely curtailed when seeds were planted at increasing soil depths. Soil-temperature fluctuations were strongly dependent on depth. When soil columns containing seeds were incubated at alternating temperatures of 20 and 30°C, however, seed germination did not diminish with increasing depth, and an evaluation of how soil-surface shading affects the perception of depth by the seeds indicated that soil cover reduced germination of only those seeds in the upper strata of the profile (...)
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A Field Method for Predicting Yield Losses in Maize Caused by Johnsongrass (Sorghum Halepense)
Weed Technology, 1991Co-Authors: Claudio M. Ghersa, M.a. Martínez-ghersaAbstract:The objective of this research was to modify the senior author's previously developed method for predicting yield losses in maize crops attributable to johnsongrass. The new method is based on the following assumptions: a) relative leaf frequency determiines relative biomass; b) total biomass is constant despite the crop/weed ratio; and c) biomass, and therefore leaf frequency, are related to grain yield. Experiments in Argentina from 1986 to 1989 supported the above hypotheses, and the new method was more accurate than the old for predicting relative species biomass in johnsongrass/maize mixtures. Maize grain yield reductions associated with weed interference were also more accurately predicted. Nomenclature: Maize, Zea mays L.; johnsongrass, Sorghum Halepense (L.) Pers. #3 SORHA. Additional index words: Johnsongrass, yield losses, prediction.
Nathan L. Tintle - One of the best experts on this subject based on the ideXlab platform.
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Transcriptome assembly and annotation of johnsongrass (Sorghum Halepense) rhizomes identify candidate rhizome-specific genes.
Plant direct, 2018Co-Authors: Nathan Ryder, Kevin M. Dorn, Mark Huitsing, Micah Adams, Jeff Ploegstra, Lee R. Dehaan, Steve R. Larson, Nathan L. TintleAbstract:: Rhizomes facilitate the wintering and vegetative propagation of many perennial grasses. Sorghum Halepense (johnsongrass) is an aggressive perennial grass that relies on a robust rhizome system to persist through winters and reproduce asexually from its rootstock nodes. This study aimed to sequence and assemble expressed transcripts within the johnsongrass rhizome. A de novo transcriptome assembly was generated from a single johnsongrass rhizome meristem tissue sample. A total of 141,176 probable protein-coding sequences from the assembly were identified and assigned gene ontology terms using Blast2GO. Estimated expression analysis and BLAST results were used to reduce the assembly to 64,447 high-confidence sequences. The johnsongrass assembly was compared to Sorghum bicolor, a related nonrhizomatous species, along with an assembly of similar rhizome tissue from the perennial grain crop Thinopyrum intermedium. The presence/absence analysis yielded a set of 98 expressed johnsongrass contigs that are likely associated with rhizome development.
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Transcriptome assembly and annotation of johnsongrass (Sorghum Halepense) rhizomes identifies candidate rhizome-specific genes
bioRxiv, 2018Co-Authors: Nathan Ryder, Kevin M. Dorn, Mark Huitsing, Micah Adams, Jeff Ploegstra, Lee R. Dehaan, Steve R. Larson, Nathan L. TintleAbstract:Rhizomes facilitate the wintering and vegetative propagation of many perennial grasses. Sorghum Halepense (johnsongrass) is an aggressive perennial grass that relies on a robust rhizome system to persist through winters and reproduce asexually from its rootstock nodes. This study aimed to sequence and assemble expressed transcripts within the johnsongrass rhizome. A de novo transcriptome assembly was generated from a single johnsongrass rhizome meristem tissue sample. A total of 141,176 probable protein-coding sequences from the assembly were identified and assigned gene ontology terms using Blast2GO. The johnsongrass assembly was compared to Sorghum bicolor, a related non-rhizomatous species, along with an assembly of similar rhizome tissue from the perennial grain crop Thinopyrum intermedium. The presence/absence analysis yielded a set of 259 johnsongrass contigs that are likely associated with rhizome development.