471
© Springer Nature Switzerland AG 2020
B. R. Singh et al. (eds.), Climate Impacts on Agricultural and Natural Resource
Sustainability in Africa, https://doi.org/10.1007/978-3-030-37537-9_27
Exploiting Arbuscular Mycorrhizal FungiRhizobia- Legume Symbiosis to Increase
Smallholder Farmers’ Crop Production
and Resilience Under a Changing Climate
Ezekiel Mugendi Njeru, Morris Muthini, Mercy Martha Muindi,
Omwoyo Ombori, Shem Bonuke Nchore, Steve Runo, and John M. Maingi
Abstract Beneficial soil microbiota, such as arbuscular mycorrhizal fungi (AMF)
and rhizobia, provide essential agroecosystem services in smallholder farming systems. Such microorganisms have great potential to promote crop production and
resilience under a changing climate in sub-Saharan Africa. However, their function
is affected by agronomic management practices, crop genotype and soil quality,
among other factors. In this work, we sought to determine the effect of soil quality
and crop genotype on nodulation, percentage mycorrhizal colonization and growth
of maize and cowpea crops. Soil samples were obtained from ten smallholder
farms with known management history in Embu and Kitui counties of Kenya and
analysed for physicochemical parameters. Greenhouse bioassays were then carried
out, where the samples were put in sterilized pots in four replicates and maintained
in a completely randomized design. Four cowpea and maize genotypes (locally
grown landraces and recommended genotypes from Kenya Agricultural and
Livestock Research Organization) were grown in pots for 40 days. After harvesting, nodulation in the case of cowpea, shoot dry weights and mycorrhizal root
colonization were determined. Remarkably, cowpea genotypes differed significantly (p < 0.0001) in nodule number. The locally cultivated landrace (C2) recorded
the lowest nodulation with 30.4 nodules plant
−1
, compared to the open pollinated
varieties (OPVs): C1, 39.15; C3, 43.70; and C4, 40.6 nodules plant
−1
. Among the
maize genotypes, the locally cultivated landrace (M3) recorded a significantly
(p = 0.008) higher percentage of mycorrhizal root colonization (68.9%) compared
to the OPVs: M1 58.1% and M2 65.3%, while the hybrid (M4) had the lowest root
colonization of 57.8%. Soil characteristics influenced nodulation and mycorrhizal
colonization, where soil P was positively correlated to cowpea nodulation. Soil
organic matter, nitrogen, pH and calcium positively correlated with AMF maize
E. M. Njeru (*) · M. Muthini · M. M. Muindi · S. Runo · J. M. Maingi
Department of Biochemistry, Microbiology and Biotechnology, Kenyatta University,
Nairobi, Kenya
O. Ombori · S. B. Nchore
Department of Plant Sciences, Kenyatta University, Nairobi, Kenya
© Springer Nature Switzerland AG 2020
B. R. Singh et al. (eds.), Climate Impacts on Agricultural and Natural Resource
Sustainability in Africa, https://doi.org/10.1007/978-3-030-37537-9_27
Exploiting Arbuscular Mycorrhizal FungiRhizobia- Legume Symbiosis to Increase
Smallholder Farmers’ Crop Production
and Resilience Under a Changing Climate
Ezekiel Mugendi Njeru, Morris Muthini, Mercy Martha Muindi,
Omwoyo Ombori, Shem Bonuke Nchore, Steve Runo, and John M. Maingi
Abstract Beneficial soil microbiota, such as arbuscular mycorrhizal fungi (AMF)
and rhizobia, provide essential agroecosystem services in smallholder farming systems. Such microorganisms have great potential to promote crop production and
resilience under a changing climate in sub-Saharan Africa. However, their function
is affected by agronomic management practices, crop genotype and soil quality,
among other factors. In this work, we sought to determine the effect of soil quality
and crop genotype on nodulation, percentage mycorrhizal colonization and growth
of maize and cowpea crops. Soil samples were obtained from ten smallholder
farms with known management history in Embu and Kitui counties of Kenya and
analysed for physicochemical parameters. Greenhouse bioassays were then carried
out, where the samples were put in sterilized pots in four replicates and maintained
in a completely randomized design. Four cowpea and maize genotypes (locally
grown landraces and recommended genotypes from Kenya Agricultural and
Livestock Research Organization) were grown in pots for 40 days. After harvesting, nodulation in the case of cowpea, shoot dry weights and mycorrhizal root
colonization were determined. Remarkably, cowpea genotypes differed significantly (p < 0.0001) in nodule number. The locally cultivated landrace (C2) recorded
the lowest nodulation with 30.4 nodules plant
−1
, compared to the open pollinated
varieties (OPVs): C1, 39.15; C3, 43.70; and C4, 40.6 nodules plant
−1
. Among the
maize genotypes, the locally cultivated landrace (M3) recorded a significantly
(p = 0.008) higher percentage of mycorrhizal root colonization (68.9%) compared
to the OPVs: M1 58.1% and M2 65.3%, while the hybrid (M4) had the lowest root
colonization of 57.8%. Soil characteristics influenced nodulation and mycorrhizal
colonization, where soil P was positively correlated to cowpea nodulation. Soil
organic matter, nitrogen, pH and calcium positively correlated with AMF maize
E. M. Njeru (*) · M. Muthini · M. M. Muindi · S. Runo · J. M. Maingi
Department of Biochemistry, Microbiology and Biotechnology, Kenyatta University,
Nairobi, Kenya
O. Ombori · S. B. Nchore
Department of Plant Sciences, Kenyatta University, Nairobi, Kenya