Identification and characterization of Sorghum (sorghum bicolor (l.) Moench) landraces and improvement of on-farm seed production in Eastern Kenya
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Date
2014-08-19
Authors
Muui, Catherine W.
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Abstract
Sorghum (Sorghum bicolor (L.) Moench) is an under-utilized crop that is
tolerant to drought, flooding, saline-alkaline, infertile soils and high
temperature. Farmers maintain landraces through preference selection and
obtain seed from different sources. Local germplasm provides greater genetic
variability and may provide useful traits to broaden the genetic base. Decline in
use may erode the genetic base, preventing use of distinctive traits in crop
adaptation and improvement which may result in their disappearance. There is
also lack of information on on-farm seed production strategies leading to lack
of quality seeds, information on use and improved cultural management. The
objectives of this research were to identify and determine the key sorghum
landraces grown in lower eastern Kenya, establish their diversity, quality levels
for seed used by farmers, come up with pre and post harvest handling methods
that could be used by farmers to improve on-farm seed quality. A baseline
survey was conducted and landraces collected in various agro-ecological zones
of lower eastern Kenya. Morphological and molecular characterization, varietal
assessment in different ecozones and seed quality tests were done. Two
varieties were used to test the effect of location of seed on different panicle
sections, storage containers, and seed drying at different times of the day for
different duration on seed quality. Results showed that farmers maintain a
diversity of landraces unique in adaptation, food quality, grain yield, quality of
harvested products and biotic stress resistance. They obtain seed for planting
from informal systems of which 36% recorded low viability and 38% low vigor
with 85% of seed samples contaminated with either Fusarium sp., Penicillium
sp., Rhizorpus sp., Aspergillus niger and Aspergillus flavurs. The landraces
recorded low heterozygosity indicating high level of stability in the population.
Landraces clustering based on geographical locations was distinct with some
overlaps across the locations. Variations were observed for leaf and mid rib
colour, panicle compactness, awns and seed colour. A wide range of
quantitative characters was observed between the accessions. The lower third
part of the panicle recorded the highest seed viability and vigor indicating
deterioration had not occurred compared to other panicle parts. The highest
seed viability and vigor was realized in seed stored in the gourds and the seed
stored for four weeks. Significant differences (P=0.05) were observed in leaf
area, leaf, shoot and root length, and in dry matter accumulation among the
seeds sampled after one month, two months and three months after storage.
The seed viability and vigor decreased with increase in time the seed was sun
dried but had no negative effect on seed dried in the seed drier. Farmers
maintain a diversity of landraces, and since the region has a high agricultural
potential, productivity for better food security could be improved by use of
locally available germplasm adapted to this particular environment. Sorghum
production may be effectively increased by use of improved production
technologies and teaching farmers the importance of the crop to increase the
production area. Seeds used by farmers to plant their crop are of poor quality in
relation to germination, vigor and pathogen infestations
Description
Doctor of Philosophy in agronomy, 2014