Abstract
To evaluate cowpea genotypic differences in response to inoculation with Bradyrhizobium sp. strains BR 3267 and CB756 in the field, 15 genotypes were assessed for N 2 fixation using 15 N natural abundance and assays of xylem N solutes (ureides, nitrates, and amino-N). Carbon isotope discrimination (δ 13 C) was used as a surrogate for water use efficiency and grain yield determined at maturity. Within each location, the tested cowpeas elicited contrasting responses to inoculation with either Bradyrhizobium strains. For example, inoculating Apagbaala and IT90K-277-2 with strain BR 3267 doubled N-fixed and grain yield at Nyankpala when compared to inoculation of the same genotypes with strain CB756, whereas the inoculation of Padituya with strain CB756 increased those same parameters relative to non-inoculation. Similar contrasting results were also obtained at Savelugu and Gbalahi, where bacterial inoculation with each strain resulted in up to a five-fold increase in N-fixed and a four-fold increase in grain yield depending on the cowpea/inoculant combinations used and the planting location. The main effect of genotype showed that the percent N derived from N 2 fixation (%Ndfa) by the test cowpeas ranged between 74.4 and 89.8%, 11.7 and 50.5%, and 71.9 and 90.3% at Nyankpala, Savelugu, and Gbalahi, respectively. The genotypes grown at Savelugu generally exhibited low %Ndfa which was augmented by greater soil N uptake leading to grain yield increases, a finding supported by significant positive correlations when N-fixed and N content were each plotted against grain yield within locations. The inverse relationship between symbiosis and soil N uptake was also supported by negative correlations between xylem nitrate concentration and relative ureide N abundance (RU-N), and between xylem nitrate concentration and %Ndfa measured from 15 N natural abundance. Some high yielding genotypes also elicited greater water use efficiency (δ 13 C), a trait that could be exploited for increased cowpea production in water limiting environments. This study demonstrates the presence of genotypic differences in cowpea response to inoculation in the field and contributes to the literature regarding the factors influencing legume inoculation response in the tropics.
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Claims 15
Claim · model-written summary
BR 3267 doubled N fixed by Apagbaala and IT90K-277-2 versus CB756 at Nyankpala.
- Taxon
- cowpea
Vigna unguiculatat0 - Material
- Apagbaala and IT90K-277-2e0
- Treatment
- strain BR 3267e0
- Interactor
- strain BR 3267e0symbiont
- Outcome
- N-fixede0
- Direction
- doublede0
- Comparator
- strain CB756e0
- Setting
- Nyankpalae0
Not reportedValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“inoculating Apagbaala and IT90K-277-2 with strain BR 3267 doubled N-fixed and grain yield at Nyankpala when compared to inoculation of the same genotypes with strain CB756”
t0“Cowpea”
Claim · model-written summary
BR 3267 doubled grain yield of Apagbaala and IT90K-277-2 versus CB756 at Nyankpala.
- Taxon
- cowpeaVigna unguiculatat0
- Material
- Apagbaala and IT90K-277-2e0
- Treatment
- strain BR 3267e0
- Interactor
- strain BR 3267e0symbiont
- Outcome
- grain yielde0
- Direction
- doublede0
- Comparator
- strain CB756e0
- Setting
- Nyankpalae0
Not reportedValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“inoculating Apagbaala and IT90K-277-2 with strain BR 3267 doubled N-fixed and grain yield at Nyankpala when compared to inoculation of the same genotypes with strain CB756”
t0“Cowpea”
Claim · model-written summary
CB756 increased N fixed in Padituya versus no inoculation.
- Taxon
- cowpeaVigna unguiculatat0
- Material
- Padituyae0
- Treatment
- strain CB756e0
- Interactor
- strain CB756e0symbiont
- Outcome
- N-fixede0
- Direction
- increasede0
- Comparator
- non-inoculatione0
Not reportedValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“inoculating Apagbaala and IT90K-277-2 with strain BR 3267 doubled N-fixed and grain yield at Nyankpala when compared to inoculation of the same genotypes with strain CB756, whereas the inoculation of Padituya with strain CB756 increased those same parameters relative to non-inoculation”
t0“Cowpea”
Claim · model-written summary
CB756 increased grain yield in Padituya versus no inoculation.
- Taxon
- cowpeaVigna unguiculatat0
- Material
- Padituyae0
- Treatment
- strain CB756e0
- Interactor
- strain CB756e0symbiont
- Outcome
- grain yielde0
- Direction
- increasede0
- Comparator
- non-inoculatione0
Not reportedValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“inoculating Apagbaala and IT90K-277-2 with strain BR 3267 doubled N-fixed and grain yield at Nyankpala when compared to inoculation of the same genotypes with strain CB756, whereas the inoculation of Padituya with strain CB756 increased those same parameters relative to non-inoculation”
t0“Cowpea”
Claim · model-written summary
Inoculation increased N fixed up to fivefold at Savelugu and Gbalahi depending on combination and site.
- Taxon
- cowpeaVigna unguiculatat0
- Treatment
- bacterial inoculatione0
- Outcome
- N-fixede0
- Direction
- increasee0
- Value
- five-folde0
- Qualifier
- depending on the cowpea/inoculant combinations used and the planting locatione0
- Setting
- Savelugu and Gbalahie0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“at Savelugu and Gbalahi, where bacterial inoculation with each strain resulted in up to a five-fold increase in N-fixed and a four-fold increase in grain yield depending on the cowpea/inoculant combinations used and the planting location”
t0“Cowpea”
Claim · model-written summary
Inoculation increased grain yield up to fourfold at Savelugu and Gbalahi depending on combination and site.
- Taxon
- cowpeaVigna unguiculatat0
- Treatment
- bacterial inoculatione0
- Outcome
- grain yielde0
- Direction
- increasee0
- Value
- four-folde0
- Qualifier
- depending on the cowpea/inoculant combinations used and the planting locatione0
- Setting
- Savelugu and Gbalahie0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“at Savelugu and Gbalahi, where bacterial inoculation with each strain resulted in up to a five-fold increase in N-fixed and a four-fold increase in grain yield depending on the cowpea/inoculant combinations used and the planting location”
t0“Cowpea”
Claim · model-written summary
Cowpea Ndfa ranged 74.4–89.8% at Nyankpala.
- Taxon
- cowpeasVigna unguiculatae0
- Outcome
- %Ndfae0
- Value
- 74.4 and 89.8%e0
- Setting
- Nyankpalae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“%Ndfa) by the test cowpeas ranged between 74.4 and 89.8%, 11.7 and 50.5%, and 71.9 and 90.3% at Nyankpala, Savelugu, and Gbalahi, respectively”
Claim · model-written summary
Cowpea Ndfa ranged 11.7–50.5% at Savelugu.
- Taxon
- cowpeasVigna unguiculatae0
- Outcome
- %Ndfae0
- Value
- 11.7 and 50.5%e0
- Setting
- Savelugue0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“%Ndfa) by the test cowpeas ranged between 74.4 and 89.8%, 11.7 and 50.5%, and 71.9 and 90.3% at Nyankpala, Savelugu, and Gbalahi, respectively”
Claim · model-written summary
Cowpea Ndfa ranged 71.9–90.3% at Gbalahi.
- Taxon
- cowpeasVigna unguiculatae0
- Outcome
- %Ndfae0
- Value
- 71.9 and 90.3%e0
- Setting
- Gbalahie0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“%Ndfa) by the test cowpeas ranged between 74.4 and 89.8%, 11.7 and 50.5%, and 71.9 and 90.3% at Nyankpala, Savelugu, and Gbalahi, respectively”
Claim · model-written summary
Low Ndfa at Savelugu was accompanied by greater soil N uptake and higher grain yield.
Verbatim
e0“genotypes grown at Savelugu generally exhibited low %Ndfa which was augmented by greater soil N uptake leading to grain yield increases”
Claim · model-written summary
N fixed correlated positively with grain yield within sites.
- Taxon
- cowpeaVigna unguiculatat0
- Outcome
- grain yielde0
- Direction
- positive correlationse0
- Qualifier
- N-fixede0
- Setting
- locationse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“significant positive correlations when N-fixed and N content were each plotted against grain yield within locations”
t0“Cowpea”
Claim · model-written summary
N content correlated positively with grain yield within sites.
- Taxon
- cowpeaVigna unguiculatat0
- Outcome
- grain yielde0
- Direction
- positive correlationse0
- Qualifier
- N contente0
- Setting
- locationse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“significant positive correlations when N-fixed and N content were each plotted against grain yield within locations”
t0“Cowpea”
Claim · model-written summary
Xylem nitrate concentration correlated negatively with relative ureide N abundance.
- Taxon
- cowpeaVigna unguiculatat0
- Organ / stage
- xyleme0
- Outcome
- relative ureide N abundancee0
- Direction
- negative correlationse0
- Qualifier
- nitrate concentratione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“negative correlations between xylem nitrate concentration and relative ureide N abundance (RU-N)”
t0“Cowpea”
Claim · model-written summary
Xylem nitrate concentration correlated negatively with Ndfa.
- Taxon
- cowpeaVigna unguiculatat0
- Organ / stage
- xyleme0
- Outcome
- %Ndfae0
- Direction
- negative correlationse0
- Qualifier
- nitrate concentratione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“negative correlations between xylem nitrate concentration and relative ureide N abundance (RU-N), and between xylem nitrate concentration and %Ndfa measured from 15 N natural abundance”
t0“Cowpea”
Claim · model-written summary
Some high yielding genotypes showed greater water use efficiency.
Verbatim
e0“Some high yielding genotypes also elicited greater water use efficiency (δ 13 C)”
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