Olubukola Olayemi OLUSOLA–MAKINDE1 and Olumide Solomon ODAMO1
Department of Microbiology, the Federal University of Technology, Akure, NIGERIA.
Corresponding author: ooolusola–firstname.lastname@example.org; Tel.: +234 8035665156
Abstract. Nigeria is the largest producer of soybean in sub–Saharan Africa plus soybean is one of the cheapest sources of protein in the developing world. Hence, substantial raise in soybean cultivation in Nigeria is pertinent. This study aims at evaluating in–vitro inoculation technology for soybean cultivation using local charcoal ($0.02 per hectare) against popularly imported peat ($3.00 per hectare) as carriers. Bradyrhizobium japonicum USDA110 was assayed for caseinase, lysine decarboxylase, citrate, lipase, and starch hydrolysis then scaled–up in yeast mannitol broth. Charcoal and peat carriers were prepared, inoculated, cured for 15 days at 28 °C and analysed on congo red agar. Soybean seeds were treated with inoculated charcoal and peat using gum Arabic, and cultivated on sterilized loamy soil samples. Untreated seeds served as negative control. Bradyrhizobium japonicum USDA110 was positive to bromothymol blue, catalase and oxidase, but negative to caesinase, lysine decarboxylase and starch hydrolysis. The height of the cultivated soybean plants was 37.10 ± 2.94 cm, 35.00 ± 1.27 cm and 17.70 ± 1.33 cm for the peat carrier, charcoal carrier and untreated seeds respectively, and the number of root nodules formed were 24.00 ± 1.00, 23.00 ± 1.00 and 5.00 ± 1.00 and for peat carrier, charcoal carrier and untreated seeds accordingly. There was no significant difference between the number of root nodules formed in charcoal and peat carrier plants at p < 0.05 value. This study reveals potentials for greener and economic soybean production in Nigeria.
Keyword: Bradyrhizobium japonicum USDA110 inoculation, charcoal carrier, peat carrier, soybean agronomy