Native Rhizobia Improve Plant Growth, Fix N<sub>2</sub>, and Reduce Greenhouse Emissions of Sunnhemp More than Commercial Rhizobia Inoculants in Florida Citrus Orchards
Sunnhemp (<i>Crotalaria juncea</i> L.) is an important legume cover crop used in tree cropping systems, where there is increased interest by growers to identify rhizobia to maximize soil nitrogen (N) inputs. We aimed to isolate and identify native rhizobia and compare their capabilities...
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| Format: | Article |
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MDPI AG
2022-11-01
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| Series: | Plants |
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| Online Access: | https://www.mdpi.com/2223-7747/11/22/3011 |
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| author | Antonio Castellano-Hinojosa Christoph Mora Sarah L. Strauss |
| author_facet | Antonio Castellano-Hinojosa Christoph Mora Sarah L. Strauss |
| author_sort | Antonio Castellano-Hinojosa |
| collection | DOAJ |
| description | Sunnhemp (<i>Crotalaria juncea</i> L.) is an important legume cover crop used in tree cropping systems, where there is increased interest by growers to identify rhizobia to maximize soil nitrogen (N) inputs. We aimed to isolate and identify native rhizobia and compare their capabilities with non-native rhizobia from commercial inoculants to fix atmospheric dinitrogen (N<sub>2</sub>), produce and reduce nitrous oxide (N<sub>2</sub>O), and improve plant growth. Phylogenetic analyses of sequences of the 16S rRNA and <i>recA</i>, <i>atpD,</i> and <i>glnII</i> genes showed native rhizobial strains belonged to <i>Rhizobium tropici</i> and the non-native strain to <i>Bradyrhizobium japonicum</i>. Plant nodulation tests, sequencing of <i>nodC</i> and <i>nifH</i> genes, and the acetylene-dependent ethylene production assay confirmed the capacity of all strains to nodulate sunnhemp and fix N<sub>2</sub>. Inoculation with native rhizobial strains resulted in significant increases in root and shoot weight and total C and N contents in the shoots, and showed greater N<sub>2</sub>-fixation rates and lower emissions of N<sub>2</sub>O compared to the non-native rhizobium. Our results suggest that native rhizobia improve plant growth, fix N<sub>2</sub>, and reduce greenhouse emissions of sunnhemp more than commercial rhizobia inoculants in Florida citrus orchards. |
| first_indexed | 2024-03-09T18:04:17Z |
| format | Article |
| id | doaj.art-c167532676144d9897a91357feb4b617 |
| institution | Directory Open Access Journal |
| issn | 2223-7747 |
| language | English |
| last_indexed | 2024-03-09T18:04:17Z |
| publishDate | 2022-11-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Plants |
| spelling | doaj.art-c167532676144d9897a91357feb4b6172023-11-24T09:38:11ZengMDPI AGPlants2223-77472022-11-011122301110.3390/plants11223011Native Rhizobia Improve Plant Growth, Fix N<sub>2</sub>, and Reduce Greenhouse Emissions of Sunnhemp More than Commercial Rhizobia Inoculants in Florida Citrus OrchardsAntonio Castellano-Hinojosa0Christoph Mora1Sarah L. Strauss2Southwest Florida Research and Education Center, Department of Soil, Water, and Ecosystem Sciences, Institute of Food and Agricultural Sciences, University of Florida, 2685 State Rd. 29N, Immokalee, FL 34142, USASouthwest Florida Research and Education Center, Department of Soil, Water, and Ecosystem Sciences, Institute of Food and Agricultural Sciences, University of Florida, 2685 State Rd. 29N, Immokalee, FL 34142, USASouthwest Florida Research and Education Center, Department of Soil, Water, and Ecosystem Sciences, Institute of Food and Agricultural Sciences, University of Florida, 2685 State Rd. 29N, Immokalee, FL 34142, USASunnhemp (<i>Crotalaria juncea</i> L.) is an important legume cover crop used in tree cropping systems, where there is increased interest by growers to identify rhizobia to maximize soil nitrogen (N) inputs. We aimed to isolate and identify native rhizobia and compare their capabilities with non-native rhizobia from commercial inoculants to fix atmospheric dinitrogen (N<sub>2</sub>), produce and reduce nitrous oxide (N<sub>2</sub>O), and improve plant growth. Phylogenetic analyses of sequences of the 16S rRNA and <i>recA</i>, <i>atpD,</i> and <i>glnII</i> genes showed native rhizobial strains belonged to <i>Rhizobium tropici</i> and the non-native strain to <i>Bradyrhizobium japonicum</i>. Plant nodulation tests, sequencing of <i>nodC</i> and <i>nifH</i> genes, and the acetylene-dependent ethylene production assay confirmed the capacity of all strains to nodulate sunnhemp and fix N<sub>2</sub>. Inoculation with native rhizobial strains resulted in significant increases in root and shoot weight and total C and N contents in the shoots, and showed greater N<sub>2</sub>-fixation rates and lower emissions of N<sub>2</sub>O compared to the non-native rhizobium. Our results suggest that native rhizobia improve plant growth, fix N<sub>2</sub>, and reduce greenhouse emissions of sunnhemp more than commercial rhizobia inoculants in Florida citrus orchards.https://www.mdpi.com/2223-7747/11/22/3011legumessunnhempcover cropsorchardscitrusbiofertilizers |
| spellingShingle | Antonio Castellano-Hinojosa Christoph Mora Sarah L. Strauss Native Rhizobia Improve Plant Growth, Fix N<sub>2</sub>, and Reduce Greenhouse Emissions of Sunnhemp More than Commercial Rhizobia Inoculants in Florida Citrus Orchards Plants legumes sunnhemp cover crops orchards citrus biofertilizers |
| title | Native Rhizobia Improve Plant Growth, Fix N<sub>2</sub>, and Reduce Greenhouse Emissions of Sunnhemp More than Commercial Rhizobia Inoculants in Florida Citrus Orchards |
| title_full | Native Rhizobia Improve Plant Growth, Fix N<sub>2</sub>, and Reduce Greenhouse Emissions of Sunnhemp More than Commercial Rhizobia Inoculants in Florida Citrus Orchards |
| title_fullStr | Native Rhizobia Improve Plant Growth, Fix N<sub>2</sub>, and Reduce Greenhouse Emissions of Sunnhemp More than Commercial Rhizobia Inoculants in Florida Citrus Orchards |
| title_full_unstemmed | Native Rhizobia Improve Plant Growth, Fix N<sub>2</sub>, and Reduce Greenhouse Emissions of Sunnhemp More than Commercial Rhizobia Inoculants in Florida Citrus Orchards |
| title_short | Native Rhizobia Improve Plant Growth, Fix N<sub>2</sub>, and Reduce Greenhouse Emissions of Sunnhemp More than Commercial Rhizobia Inoculants in Florida Citrus Orchards |
| title_sort | native rhizobia improve plant growth fix n sub 2 sub and reduce greenhouse emissions of sunnhemp more than commercial rhizobia inoculants in florida citrus orchards |
| topic | legumes sunnhemp cover crops orchards citrus biofertilizers |
| url | https://www.mdpi.com/2223-7747/11/22/3011 |
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