Shade tolerance is a highly desirable trait when breeding new bermudagrass(Cynodon spp.)lines,but current screening methods can take many years to complete.There is a clear need for large-scale turfgrass breeding prog...Shade tolerance is a highly desirable trait when breeding new bermudagrass(Cynodon spp.)lines,but current screening methods can take many years to complete.There is a clear need for large-scale turfgrass breeding programs to reliably,accurately,and quickly predict shade tolerance in their germplasm.The objectives of this research were to:(i)build custom chambers to reproducibly estimate photosynthetic characteristics from turfgrass canopies at different light intensities and(ii)determine which photosynthetic characteristics are indicative of past shade performance.A custom-built chamber was constructed to determine average photosynthetic characteristics for the whole plant by studying the turfgrass canopy at natural leaf angles for light interception.Shade tolerant(11-T-56)and shade sensitive(Tifway)bermudagrass cultivars were used to examine the effectiveness of the chamber within an array of photosynthetic characteristics when the grasses were grown in full-sun and 73%shade environments.Light compensation point,chlorophyll content,quantum yield,dark respiration rate,and maximum quantum yield of photosystem II were evaluated in this trial.Based on the results of this study,the authors recommend that light compensation point or maximum quantum yield be further evaluated as an accurate indicator of shade tolerance when performed in the field on spring days with grasses grown in full sun or 73%shade environments.Lower Rd rates and ambient temperatures on spring days appear to minimize unexplained variance in the data,which would allow researchers to better detect genotypic differences during this season.展开更多
Background:The incorporation of legumes,specifically alfalfa(Medicago sativa L.),into bermudagrass(Cynodon spp.)-based pasture systems in the southeastern United States has increased in recent years as an alternative ...Background:The incorporation of legumes,specifically alfalfa(Medicago sativa L.),into bermudagrass(Cynodon spp.)-based pasture systems in the southeastern United States has increased in recent years as an alternative to synthetic nitrogen(N)fertilization.Methods:A small plot evaluation was conducted in Shorter,Alabama,and Tifton,Georgia,USA,to evaluate the impact of harvest height(HH)and harvest frequency(HF)on agronomic characteristics of alfalfa+bermudagrass mixtures in southeastern United States.Results:Results from both locations revealed that the longer the HF and the shorter the HH,the greater the alfalfa retention was in the stand(p<0.01).HH did not impact any of the reported nutritive value parameters,while longer HF resulted in lower total digestible nutrients,lower crude protein,higher acid detergent fiber,and lower 48 h in vitro dry matter digestibility(p<0.01).Both HH and HF impacted forage accumulation at both locations(p<0.01).HH resulted in different trends at each location,while longer frequencies generally increased forage accumulation.Conclusions:This research confirmed recent findings from comparable evaluations in the southeastern United States,in that increasing HH and decreasing HF improved alfalfa retention while having a negligible effect on nutritive value or forage accumulation.展开更多
Bermudagrass(Cynodon dactylon(L.)Pers.)is one of the primary perennial forages in the southeastern USA.Newer hybrid cultivars have superior production and nutritive value compared to common ecotypes.However,there are ...Bermudagrass(Cynodon dactylon(L.)Pers.)is one of the primary perennial forages in the southeastern USA.Newer hybrid cultivars have superior production and nutritive value compared to common ecotypes.However,there are many challenges facing bermudagrass production in the region.First,the bermudagrass stem maggot(BSM;Atherigona reversura Villeneuve)has severely damaged bermudagrass throughout the region.Strategically timed pyrethroid applications significantly reduce adult BSM populations,but efforts are needed to develop integrated pest management plans.Second,an increasing number of producers are noting challenges with green-up following winter dormancy.This may be attributed to disease,unbalanced soil fertility,and weed pressure.Perhaps one of the most limiting factors for continued production is the deficit of sprigs and trained personnel to sprig hybrid bermudagrasses.This research is critically important as the need for cold-tolerant bermudagrass is increasing as tall fescue(Lolium arundinaceum(Schreb.)S.J.Darbyshire)is declining due to changes in temperature and precipitation throughout the northern parts of the region.Plant breeders are investigating hybrid bermudagrass at latitudes>35°with respect to freeze or cold tolerance.Despite the many challenges facing hybrid bermudagrass in the southeastern USA,researchers are working to ensure its persistence,productivity,and availability for the future.展开更多
Background Bermudagrass(Cynodon spp.)is one of the most common perennial warm-season forages grown in the Southeastern United States.The incorporation of alfalfa(Medicago sativa)into bermudagrass pastures could serve ...Background Bermudagrass(Cynodon spp.)is one of the most common perennial warm-season forages grown in the Southeastern United States.The incorporation of alfalfa(Medicago sativa)into bermudagrass pastures could serve as an alternative source of nitrogen(N)while also improving the nutritive value of the forage base.Methods A 2-year grazing evaluation arranged in a randomized complete block design was conducted from May to September 2018(Year 1)and May–August 2019(Year 2)in Tifton,GA,USA.The objective was to compare the production of alfalfa–bermudagrass mixed pastures(BGA)with bermudagrass monoculture pastures with(BGN)or without(BG)the application of synthetic nitrogen on forage production and stocker cattle performance.Results Differences were observed for average daily gain(p=0.10),gain per hectare(p=0.02)and stocking rate(p=0.01),in that BGA was greatest compared to BGN and BG,which did not differ from each other.Furthermore,BGA had increased forage crude protein(p=0.01)and total digestible nutrients(p=0.01)compared to BGN and BG.Finally,BGA provided the greatest economic return per hectare compared to BG or BGN.Conclusions These data illustrate improved animal performance and forage nutritive value using alfalfa–bermudagrass systems and offer a viable option for producers seeking alternatives to synthetic N sources for bermudagrass pastures in the Southeastern United States.展开更多
Background:Alfalfa(Medicago sativa L.)and bermudagrass(Cynodon spp.)mixtures(ABG)can be effectively managed in Southeastern United States under cut and graze management systems.However,there is still a need to investi...Background:Alfalfa(Medicago sativa L.)and bermudagrass(Cynodon spp.)mixtures(ABG)can be effectively managed in Southeastern United States under cut and graze management systems.However,there is still a need to investigate the influence that bermudagrass cultivar has under these harvest management strategies(HMS)grown in this mixture.Methods:A 2-year trial evaluated bermudagrass cultivars(“Russell”or“Tifton 85”)interseeded with alfalfa(“Bulldog 805”)under three contrasting HMS(cut only[CO],graze only[GO],or cut and graze[GC])in Tifton,Georgia,USA.All data were analyzed for animal performance,forage,and total system performance using the PROC MIXED procedure in SAS.An economic benefit-costs analysis was performed to compare the returns to each HMS on a per-hectare and a per-head basis.Results:Bermudagrass cultivar and HMS did not interact in any parameters evaluated(p>0.35).Overall,HMS affected the responses more than bermudagrass cultivar.Forage and animal productivity were generally greater during the in-season grazing period compared to the deferred grazing period.Cutting management maximized total system performance(p<0.01).Economic analysis of computer simulated feeding outcomes indicated a net return of$2831 and$1295 ha^(-1)yr^(-1)for CO and GC systems,respectively,compared to an actually achieved return of$209 ha^(-1)yr^(-1)for the GO system.Conclusions:Based on computer-simulated feeding results,addition of cutting management to the forage system,whether CO or in addition to grazing,provided better agronomic and economic returns compared to only grazing ABG mixtures.Future research should test the feasibility of the computer-simulated results and evaluate how ecosystem services are impacted when utilizing these HMS in other ABG mixture combinations.展开更多
基金funded in part by the University of Georgia College of Agriculture&Environmental Sciences,and by the National Institute of Food and Agriculture,U.S.Department of Agriculture,under award number 2010-51181-21064.
文摘Shade tolerance is a highly desirable trait when breeding new bermudagrass(Cynodon spp.)lines,but current screening methods can take many years to complete.There is a clear need for large-scale turfgrass breeding programs to reliably,accurately,and quickly predict shade tolerance in their germplasm.The objectives of this research were to:(i)build custom chambers to reproducibly estimate photosynthetic characteristics from turfgrass canopies at different light intensities and(ii)determine which photosynthetic characteristics are indicative of past shade performance.A custom-built chamber was constructed to determine average photosynthetic characteristics for the whole plant by studying the turfgrass canopy at natural leaf angles for light interception.Shade tolerant(11-T-56)and shade sensitive(Tifway)bermudagrass cultivars were used to examine the effectiveness of the chamber within an array of photosynthetic characteristics when the grasses were grown in full-sun and 73%shade environments.Light compensation point,chlorophyll content,quantum yield,dark respiration rate,and maximum quantum yield of photosystem II were evaluated in this trial.Based on the results of this study,the authors recommend that light compensation point or maximum quantum yield be further evaluated as an accurate indicator of shade tolerance when performed in the field on spring days with grasses grown in full sun or 73%shade environments.Lower Rd rates and ambient temperatures on spring days appear to minimize unexplained variance in the data,which would allow researchers to better detect genotypic differences during this season.
基金National Institute of Food and Agriculture,Grant/Award Number:2017-70005-27089。
文摘Background:The incorporation of legumes,specifically alfalfa(Medicago sativa L.),into bermudagrass(Cynodon spp.)-based pasture systems in the southeastern United States has increased in recent years as an alternative to synthetic nitrogen(N)fertilization.Methods:A small plot evaluation was conducted in Shorter,Alabama,and Tifton,Georgia,USA,to evaluate the impact of harvest height(HH)and harvest frequency(HF)on agronomic characteristics of alfalfa+bermudagrass mixtures in southeastern United States.Results:Results from both locations revealed that the longer the HF and the shorter the HH,the greater the alfalfa retention was in the stand(p<0.01).HH did not impact any of the reported nutritive value parameters,while longer HF resulted in lower total digestible nutrients,lower crude protein,higher acid detergent fiber,and lower 48 h in vitro dry matter digestibility(p<0.01).Both HH and HF impacted forage accumulation at both locations(p<0.01).HH resulted in different trends at each location,while longer frequencies generally increased forage accumulation.Conclusions:This research confirmed recent findings from comparable evaluations in the southeastern United States,in that increasing HH and decreasing HF improved alfalfa retention while having a negligible effect on nutritive value or forage accumulation.
基金National Institute of Food and Agriculture,Grant/Award Number:2017-70005-27089Georgia Seed DevelopmentGeorgia Beef Commission。
文摘Bermudagrass(Cynodon dactylon(L.)Pers.)is one of the primary perennial forages in the southeastern USA.Newer hybrid cultivars have superior production and nutritive value compared to common ecotypes.However,there are many challenges facing bermudagrass production in the region.First,the bermudagrass stem maggot(BSM;Atherigona reversura Villeneuve)has severely damaged bermudagrass throughout the region.Strategically timed pyrethroid applications significantly reduce adult BSM populations,but efforts are needed to develop integrated pest management plans.Second,an increasing number of producers are noting challenges with green-up following winter dormancy.This may be attributed to disease,unbalanced soil fertility,and weed pressure.Perhaps one of the most limiting factors for continued production is the deficit of sprigs and trained personnel to sprig hybrid bermudagrasses.This research is critically important as the need for cold-tolerant bermudagrass is increasing as tall fescue(Lolium arundinaceum(Schreb.)S.J.Darbyshire)is declining due to changes in temperature and precipitation throughout the northern parts of the region.Plant breeders are investigating hybrid bermudagrass at latitudes>35°with respect to freeze or cold tolerance.Despite the many challenges facing hybrid bermudagrass in the southeastern USA,researchers are working to ensure its persistence,productivity,and availability for the future.
文摘Background Bermudagrass(Cynodon spp.)is one of the most common perennial warm-season forages grown in the Southeastern United States.The incorporation of alfalfa(Medicago sativa)into bermudagrass pastures could serve as an alternative source of nitrogen(N)while also improving the nutritive value of the forage base.Methods A 2-year grazing evaluation arranged in a randomized complete block design was conducted from May to September 2018(Year 1)and May–August 2019(Year 2)in Tifton,GA,USA.The objective was to compare the production of alfalfa–bermudagrass mixed pastures(BGA)with bermudagrass monoculture pastures with(BGN)or without(BG)the application of synthetic nitrogen on forage production and stocker cattle performance.Results Differences were observed for average daily gain(p=0.10),gain per hectare(p=0.02)and stocking rate(p=0.01),in that BGA was greatest compared to BGN and BG,which did not differ from each other.Furthermore,BGA had increased forage crude protein(p=0.01)and total digestible nutrients(p=0.01)compared to BGN and BG.Finally,BGA provided the greatest economic return per hectare compared to BG or BGN.Conclusions These data illustrate improved animal performance and forage nutritive value using alfalfa–bermudagrass systems and offer a viable option for producers seeking alternatives to synthetic N sources for bermudagrass pastures in the Southeastern United States.
基金National Institute of Food and Agriculture,Grant/Award Number:2019-70005-30360。
文摘Background:Alfalfa(Medicago sativa L.)and bermudagrass(Cynodon spp.)mixtures(ABG)can be effectively managed in Southeastern United States under cut and graze management systems.However,there is still a need to investigate the influence that bermudagrass cultivar has under these harvest management strategies(HMS)grown in this mixture.Methods:A 2-year trial evaluated bermudagrass cultivars(“Russell”or“Tifton 85”)interseeded with alfalfa(“Bulldog 805”)under three contrasting HMS(cut only[CO],graze only[GO],or cut and graze[GC])in Tifton,Georgia,USA.All data were analyzed for animal performance,forage,and total system performance using the PROC MIXED procedure in SAS.An economic benefit-costs analysis was performed to compare the returns to each HMS on a per-hectare and a per-head basis.Results:Bermudagrass cultivar and HMS did not interact in any parameters evaluated(p>0.35).Overall,HMS affected the responses more than bermudagrass cultivar.Forage and animal productivity were generally greater during the in-season grazing period compared to the deferred grazing period.Cutting management maximized total system performance(p<0.01).Economic analysis of computer simulated feeding outcomes indicated a net return of$2831 and$1295 ha^(-1)yr^(-1)for CO and GC systems,respectively,compared to an actually achieved return of$209 ha^(-1)yr^(-1)for the GO system.Conclusions:Based on computer-simulated feeding results,addition of cutting management to the forage system,whether CO or in addition to grazing,provided better agronomic and economic returns compared to only grazing ABG mixtures.Future research should test the feasibility of the computer-simulated results and evaluate how ecosystem services are impacted when utilizing these HMS in other ABG mixture combinations.
