| dc.description.abstract | Potato is the second most important food crop after maize in Kenya hence it plays an important
role in regional food security in the country. Low yields are realized because of lack of certified
clean seed potato, poor agronomic practices and diseases such as bacterial wilt and late blight.
Seed production and marketing in the country has been greatly affected by poor management,
limited knowledge of farmers on use of clean seed potato, availability and high prices of certified
seed potatoes. For quality seeds to be produced minitubers (pre-basic seed) are multiplied 3-6
times in the field to produce certified seed potato. Each multiplication requires a season thus it
takes several years for the clean and certified seed potatoes to be produced. Use of Plant Growth
Promoting Rhizobacteria (PGPR) could potentially increase the number of minitubers produced
and reduce the time it takes to produce clean seed potatoes. This study was conducted to
investigate the effect of PGPR inoculants on growth and yield of disease free tissue culture
potato plantlets grown in the greenhouse at Kabete field Station, University of Nairobi and miniaeroponic system at KARI-Tigoni research station. A total of 128 rhizobacterial isolates
comprising of Azotobacter (35), Bacillus (40) and Pseudomonas (53) spp. were isolated from
soils from major potato growing counties in Kenya and subjected to in-vitro tests to determine
the best performing isolates for use in the greenhouse trials. The measurable parameters
monitored included number and size of tubers, weight of tubers, shoot height, shoot and root
biomass. Isolate B19 was most effective in suppressing growth of Ralstonia. solanacearum invitro. There were significant (p < 0.05) differences in growth characteristics between the uninoculated control plants and inoculated plants. Isolate P79 from Keiyo South subcounty was
most promising in enhancing growth parameters. In mini-aeroponic experiment, isolates B8 and
B86 from Molo and Kieni East subcounties, significantly (p < 0.05) increased tuber numbers and
weight when compared to the control. In conclusion, rhizobacteria P79, B19, B8 and B86 were
the most effective in enhancing crop growth (biofertilizers) and suppression of disease
(biocontrol) thus should be subjected to extensive assessments for use in seed potato production. | en_US |
