Assessing The Efficiency Of Soybean [Glycine Max (L.) Merrill] Genotypes In Phosphorus Uptake And Nitrogen Fixation

ABSTRACT

An experiment was conducted at Ilonga Agricultural Research Institute during the 2013 cropping season in order to assess the efficiency of soybean genotypes in phosphorus uptake and nitrogen fixation. The study was conducted between March 2013 and July 2013. The experiment was designed as 4 x 7 factorial experiments in randomized complete block and laid out in split-plots arrangement with three replications. The main plots were four P fertilizer levels (0, 15, 30 and 45 kg P ha-1 ), while seven soybean genotypes (TGX 1895-33F, TGX 1895-4F, TGX 1954-1F, TGX 1871-12E, TGX 1844-4E, TGX 1440-1E and Bossier) constituted the sub-plots. The N fertilizer at a rate of 10 kg N ha-1 was applied in all experimental plots as a starter dose. Plant height, days to 50% flowering, P and N uptake, number of nodules, number of active nodules and reduced ethylene were measured at full flowering. Number of pods per plant, seeds per pod, 100 seeds weight and grain yield were obtained at harvest. Results showed that TGX 1895-33F and TGX 1954-1F were identified as high P uptake genotypes with 0.4064 and 0.3831 mg P/plant, respectively. Also they were identified as efficient in N2 fixation with the highest amounts of reduced acetylene from detached nodules with 7.14 and 6.96 μ mol C2H4 h-1 g-1, respectively. The high yielding genotypes were identified to be TGX 1954-1F, TGX 1844-4E and TGX 1440-1E (P ≤ 0.05) which had grain yield of 1706, 1892 and 1863 kg ha-1, respectively. Based on the results from this study, it is recommended that genotypes TGX 1895-33F, TGX 1954-1F and TGX 1844-4E be used in the breeding programmes at the Institute.