Inoculation with highly effective and persistent rhizobium strains is a possible approach for enhancing the productivity of groundnut in Ghana. Therefore, a 2 × 9 factorial experiment which resulted in 18 treatments in total was set up in three farmers’ fields across northern Ghana to evaluate the response of two groundnut varieties to indigenous rhizobium isolates and their persistence after a year of introduction. The persistence study was carried out under greenhouse conditions. Randomised complete block design (RCBD) and completely randomised design (CRD) with three replications were used for the field and greenhouse studies respectively. Experimental treatments included two varieties of groundnut (Samnut 22 and Chinese), five native isolates, three positive controls (Biofix, BR 3267 and +N) and a negative control without inoculation. Isolate 53e caused significant (P ≤ 0.05) increase in nodule dry weight on Samnut 22 at both Cheshegu and Tanina, while isolate 9d was the best at Binduri. Chinese variety on the other hand produced nodules with increased (P ≤ 0.05) weight following inoculation with isolates 9g at both Cheshegu and Tanina. At Binduri, the isolate 9d produced the highest nodule dry weight. Grain yield of Samnut 22 was significantly (P ≤ 0.05) increased by inoculation with isolate 53e at both Cheshegu and Tanina. All except isolate 91a caused significant (P ≤ 0.05) increase in grain yield at Binduri. The Chinese variety also produced increased grain yields following inoculation with isolate 9g at Cheshegu and Tanina. At Binduri, increased grain yield was caused by isolate 9d. Results from the persistence study indicated that the test isolates increased the native rhizobium population with subsequent improvement in N2 fixation after the eight (8) months fallow period. Results from the study showed that the rhizobium isolates are potential elite strains which could be used for the production of groundnut inoculants upon further studies and characterisation.
MSc and Bcs thesis, internship reports