| dc.description.abstract | Global reserves of phosphorus (P) are continually getting depleted and this poses an
enormous challenge to food production. Phosphorus is one of the major limiting
nutrients for plant productivity. Use of plant-mycorrhizal fungi in relation to
replenishing phosphate is one of the biological techniques being considered. In this
study, the association of Aspilia pluriseta Schweif. with mycorrhizal fungi and their
role in promoting growth and enhancing P availability to gadam sorghum (Sorghum
bicolor L.) was investigated. The main objective of this study was to determine
effects of mycorrhiza in the rhizosphere of Aspilia pluriseta on growth and
phosphorus availability to sorghum crop. The samples were taken from Tunyai and
Gakurungu in Tharaka Nithi County and Kanyuambora in Embu County, Kenya. Soil
samples were taken at depths 0-20cm, 21-40cm and 41-60cm. This was followed by
greenhouse experiments at the University of Embu. The experiments involved use of
potted plants with four treatments; Aspilia pluriseta vegetation covered soils; soil
textural types; soil depth and mycorrhiza fungi inoculated gadam sorghum seeds. The
treatment combinations were carried out in a series of two experiments on a
completely randomized block design on a factorial model replicated thrice. Data
obtained was subjected to ANOVA using SAS Edition 9.2 and differences between
treatment means examined using Least Significant Difference (LSD) at p≤0.05.
Illumina sequencing method was used on the Internal Transcribed Spacer (ITS) region
on the total soil community DNA to capture the genetic fungal community within the
rhizosphere. Analysis of Operational Taxonomic Units (OTUs) was done using
QIIME 1.8.0 and taxonomic classification done using BLASTn on SILVA 119
database. Programming software, R was used for hierarchical clustering. The study
shows that sorghum perfomed better where its seeds were inoculated with
mycorrhiza-soils previously inhabited with Aspilia pluriseta vegetation. Spore counts
varied significantly among silty clay, silt loam and sandy loam soils. The spore
morphotypes was significantly higher at p≤0.05 for soils inhabited by Aspilia
pluriseta compared to those not habited. Three hundred and seventy-three (373)
OTUs were found at 3% genetic distance. Thirty-five fungal taxa were recorded in the
rhizosphere of Aspilia pluriseta. The soil had five main phyla; Glomeromycota
(90.7%), Basidiomycota (3.7%), Ascomycota (3.4%), Chytridiomycota (1.5%), and
unspecified phylum fungi (0.7%). The genera Glomus was the most prevalent in all
soil depths. The association of Aspilia pluriseta and mycorrhiza gave sorghum yield
of 15.2 g per 1000 grains compared to yield of 13.1 g per 1000 grains in soils that did
not have Aspilia pluriseta mycorrhiza association. This was a yield increase of 16%.
Differences between gadam sorghum yields in Aspilia pluriseta soils and gadam
sorghum seeds inoculated with mycrorihza spores was significant at p≤0.05 This
study therefore, recommends use of Aspilia pluriseta in improving sorghum yield. | en_US |
