Potential of Native Rhizobia to Improve Cowpea Growth and Production in Semiarid Regions of Kenya
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Date
2020
Authors
Nyaga, Julian Wanja
Njeru, Ezekiel Mugendi
Journal Title
Journal ISSN
Volume Title
Publisher
Frontiers in Agronomy
Abstract
Cowpea [Vigna unguiculata (L.) Walp] is an important crop for smallholder farmers in
the marginal areas of sub-Saharan Africa. However, the crop growth and production are
affected by low soil fertility due to poor soil management practices. Here, we assessed
the effect of native and commercially available rhizobia inoculants on cowpea nodulation,
growth, and yields on three local cowpea genotypes (K-80, M-66, and KVU 27-1) in the
semiarid areas of Kenya. Field experiments were set in smallholder farms during the 2019
and 2020 cropping seasons. Native rhizobia were isolated from root nodules of cowpea
plants used as trap cultures. The isolates were further assessed for symbiotic efficiency
(SE) in the greenhouse and field experiments carried out during the short and long rain
seasons. Field experiments were laid out in a randomized complete block design with
three replications. The treatments consisted of the commercial inoculant (Biofix), native
isolates, native + Biofix (consortium), and an uninoculated control. In the greenhouse,
the native isolates significantly increased nodule number and dry weight (DW), shoot
DW, and root DW when compared to the uninoculated control. Additionally, 50% of the
isolates recorded SE of >80%, while 35.7 and 14.3% of the isolates had SE of 51–80
and <50%, respectively. In the field, rhizobia inoculation significantly (P < 0.05) increased
nodulation and shoot DW compared to the uninoculated controls. Remarkably, rhizobia
inoculation significantly increased yields where inoculation with native isolates recorded
22.7% increase in yield when compared to uninoculated control in the first season and
28.6% increase in yield in the second season. However, the rhizobia inoculants did
not show a preference for any of the cowpea genotypes, and their performance was
influenced by season and the study location. Our results demonstrate the existence
of superior native isolates with potential to be developed to low-cost biofertilizer for
sustainable cowpea production.
Description
A research article published in Frontiers in Agronomy
Keywords
cowpea, native rhizobia, smallholder, sustainability, nitrogen fixation
Citation
Nyaga JW and Njeru EM (2020) Potential of Native Rhizobia to Improve Cowpea Growth and Production in Semiarid Regions of Kenya. Front. Agron. 2:606293. doi: 10.3389/fagro.2020.606293