Determination of Increase in Yield of Tropical Grasses Inoculated with Spirillum lipoferum
N. N. Ngerebara
Department of Science Laboratory Technology, School of Applied Sciences, Kenule Beeson Saro-Wiwa Polytechnic, P.M.B. 20, Bori, Nigeria.
L. O. Amadi *
Department of Microbiology, Faculty of Science, Rivers State University, P.M.B. 5080, Nkpolu-Oroworukwo, Port Harcourt, Nigeria.
G. C. Vincent
Department of Science Laboratory Technology, School of Applied Sciences, Kenule Beeson Saro-Wiwa Polytechnic, P.M.B. 20, Bori, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Increase in yield of tropical grasses viz. digit grass (Digitaria decumbens), guinea grass (Panicum maximum) and pearl millet (Penisetum americanum) inoculated with tropical nitrogen-fixing bacterium, Spirillum lipoferum was investigated. The study was carried out for three consecutive years (2016-2018). Dry matter yields and protein content of the three tropical grasses were used for the assessment. In 2017, pearl millet (Penisetum americanum) and guinea grass (Panicum maximum) produced significantly higher protein content and dry matter yields. Projected yields using regression analysis of both pearl millet and guinea grass indicated that about 40kgN ha-1 yr-1 were replaced by inoculation. Although, protein production of guinea grass was lower during 2018, dry matter yield responses were similar to those of 2017. This research has shown that inoculation with Spirillum lipoferum, a tropical nitrogen-fixing bacterium reduced acetylene and increased yields or reduced nitrogen fertilizer requirement of the tropical grasses as well as replacement of up to 40KgN ha-1. This amount is agro-economically important and suggests the viability and potential for grass-bacteria systems.
Keywords: Spirillum lipoferum, guinea grass, pear millet, digit grass, nitrogen fixation