Effects of elevated copper levels on biological nitrogen fixation and occurrence of rhizobia in a Tanzanian coffee-cropped soil
| dc.contributor.author | Tindwa, H. | |
| dc.contributor.author | Semu, E. | |
| dc.contributor.author | Msumali, G. P. | |
| dc.date.accessioned | 2016-11-10T11:05:54Z | |
| dc.date.available | 2016-11-10T11:05:54Z | |
| dc.date.issued | 2014 | |
| dc.description | Journal of Agricultural Science and Applications (J. Agric. Sci. Appl.) | en_US |
| dc.description.abstract | A study was conducted to investigate the effects of increasing copper concentration in soil on rhizobial occurrence and the process of biological nitrogen fixation. Two slow-growing bradyrhizobial strains CP, and GM, and two fast-growing rhizobial strains PV, and PV2 were studied by comparing their performance under increasing copper concentrations in greenhouse-based assays involving modified Leonard jar assemblies and potted-soil experiments. Additionally, field samples from soils grown to coffee and subjected to long-term use of copper-based fungicides were analyzed for their total indigenous rhizobial populations using the most probable number-plant infection technique. Results indicated that elevated copper levels in the growth medium had inhibitory effects on nodulation, biological N2 fixation and overall rhizobial numbers in soil. Significant (p= 0.05%) reductions in fresh nodule mass, fresh nodule volume and total shoot nitrogen were recorded when copper concentration was increased from 0 to 100 ppm in both modified Leonard jar assemblies and potted-soil trials. Effective decrements in all the three parameters of fresh nodule mass, fresh nodule volume and total shoot nitrogen were more pronounced with the slow-growing bradyrhizobial strains of CP, and GM, than with the fast-growing PV, and PV2. The MPN-plant infection technique results showed a non-significant (p=0.05) but substantial decrement in rhizobial and bradyrhizobial numbers when the copper-contaminated field soil (82.5 mgCu/g soil) was compared to a control soil (1.8 mgCu/g soil). The study concludes, therefore, that elevated levels of copper in soil could be harmful to free-living rhizobia and their abilities to fix N2 in respective symbiotic associations with legume species. Such negative effects were more pronounced in the slow-growing bradyrhizobial than rhizobial species used. | en_US |
| dc.identifier.uri | https://www.suaire.sua.ac.tz/handle/123456789/890 | |
| dc.language.iso | en | en_US |
| dc.publisher | Sokoine University of Agriculture | en_US |
| dc.subject | Biological nitrogen fixation | en_US |
| dc.subject | Copper contamination | en_US |
| dc.subject | Rhizobia | en_US |
| dc.subject | WPN-plant infection technique | en_US |
| dc.subject | Tanzania | en_US |
| dc.title | Effects of elevated copper levels on biological nitrogen fixation and occurrence of rhizobia in a Tanzanian coffee-cropped soil | en_US |
| dc.type | Article | en_US |