Irrigation and Bradyrhizobium Japonicum Inoculation Effects on Performance of Soybean Production in Tropical Guinea Savanna Zone of Ghana

Abstract

A field experiment was conducted to assess the effect of irrigation regimes and Bradyrhizobium japonicum strains on the performance of soybean cultivar TGX1440-IE. The study was carried out for two consecutive years during the dry season (February-May) at Tono Irrigation Project site in a Guinea Savannah zone of Ghana. Three irrigation regimes based on soybean crop water requirements (full or normal (W0), half (W1) and one and a half (W2) crop water requirements) and two strains of B. japonicum (LS-50 and TAL-120) along with one uninoculated treatments with three replications were laid out in a split-plot randomized complete block design. The LS-50 strain inoculated soybean (I2) had the highest value in the number of nodulation, growth, yield and WUE, followed by the uninoculated (I0) and the TAL-120 (I1) had the least. The LS-50 strain significantly (P<0.01) increased the number of nodulation, growth, yield and WUE by 15 %, 14 %, 10 % and 12 % respectively over the uninoculated soybean. The one and a half irrigation regime (W2) also had the highest values for all crop parameters determined except WUE followed by the full irrigation regime (W0) and the half irrigation (W1) had the least. W1 however, had the highest WUE, followed by W0 and then W2. The one and a half irrigation regime significantly (P<0.01) increased the number of nodulation, growth and yield by 23%,  28% and 10 % respectively but decreased WUE by 65%, over the full irrigation regime.  However, the half irrigation increased the WUE by 36 % over the full irrigation regime. The interaction of LS 50 strain and the one and a half irrigation regime (W2I2) had significant (P<0.05) increase in the growth by 45 % , decrease in WUE by 27 % and insignificant increase in  yield over the interaction of uninoculated and full irrigation regime (W0I0). However the interaction of LS 50 strain and half irrigation regime (W1I2) increased the WUE by 95 % over the interaction of uninoculated and full irrigation regime (W0I0).

Keywords: Soybean cultivar, Tono Irrigation Project, Crop water, LS-50 strain, TAL-120 strain.