Genotypic variation in phosphorus requirement and utilization in nodulated common beans (phaseolus vulgaris l.)
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Date
1992
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Sokoine University of Agriculture
Abstract
A study to investigate the genotypic variations in phosphorus requirement and utilization by four common bean genotypes AA/2/5/6xK-2; 86EP 5091-B-2; EP 3-2 and Selian wonder, referred to as C2' C4' C5 and C8 respectively, inoculated with a locally produced Rhizobium strain, PV1, was carried out at the Sokoine University of Agriculture, Morogoro, Tanzania in a glasshouse pot experiment. The soil used as the growth medium was an Oxic Haplustult with low levels of total nitrogen and Bray-1 phosphorus with a slight acid reaction. phosphorus applied were 0, The 5, 10, 20, 40, 160mgP/kg soil as kh,poa Z 4 extractable levels of 80, 120 and and these rates were each replicated six times for each common bean genotype. The increases in the number of nodules, (hence nodulation), nodule weights, shoot dry weights, root dry weights, pod production, seed production, percent N in the shoots and percent P in the shoots with increasing rates of applied phosphorus were significant and these plant parameters were positively and significantly correlated to one another, suggesting the vital role of phosphorus in symbiotic nitrogen fixation. The variations in phosphorus requirement and utilization based on the above plant parameters were attributed to the inherent genetic characteristics of the four common bean genotypes. The genotypes most tolerant to low levels of Bray-1 extractable phosphorus fixed more nitrogen symbiotically and accumulated more dry matter. The genotypes' tolerance phosphorus followed to low levels of the order different phosphorus rates C5 > C4 > for optimum symbiotic nitrogen fixation for each C2 extractable > C8‘yields individual. The and common bean genotype should be established in a similar investigation under field conditions. The ability of the genotypes to form nodules hence fix inoculated with the Rhizobium nitrogen, strain PV1 indicate when the ability of the Rhizobium strain PV1 to tolerate low levels of Bray-1 extractable phosphorus. Based on the results and C4 inoculated obtained in this study, the genotypes C5 with Rhizobium strain PV1 can be grown in soils deficient in available phosphorus without any effect on reducing seed yield.
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Dissertation
Keywords
Genotypic variation phosphorus, Phosphorus requirement, Nodulated common beans, Phaseolus vulgaris l.