Application of Soil Bacteria as Bioinoculants to Promote Growth of Cowpea (Vigna unguiculata)

Abstract

This work aimed to evaluate the capacity of soil bacteria as bioinoculants (biofertilizers) to promote cowpea (Vigna unguiculata) growth. Three pure bacterial cultures namely Acinetobacter pittii PT1.3.4 (AP), Achromobacter sp.C2.23 (AS), and Achromobacter xylosoxidans N3.4 (AX) were used as bioinoculants to enhance germination and development of cowpea seeds. Pre-decide formulations of single or mixed cultures were prepared, soaked with cowpea seeds, and cultivated on agar in a growth chamber for 7 days at 25°C. Shoot and root length were measured and percentage germination was determined. Similarly, bacterial formulations were prepared in talcum powder and were used as bioinoculants to adhere to cowpea seeds. The inoculated seeds were cultivated in pots for 28 days for the shoot and root length, fresh and dry weight, and percentage germination. Among the tested various formulations, treatment has A. pittii (AP) displayed the highest shoot length (14.67 cm) and fresh weight (0.58 g/plant) of cowpea under laboratory conditions after seven days of inoculation. Similarly, cowpea plants treated with A. pittii (AP) also have the tallest shoots (14.25 cm) under natural conditions after 7 days of inoculation, while the highest root length (10.5 cm) and fresh weight (1.57 g/plant) were recorded from the treatment of Achromobacter sp. (AS). Further, the results of the study also revealed that soil bacteria can survive for one month in talcum powder at 4°C and room temperature storage. These bioinoculants can be used for agricultural application by local farmers to mitigate the cost of chemicals that cause environmental concerns to promote sustainable agriculture in Thailand.