| dc.description.abstract | Maize is staple food in Kenya and is grown in almost all agro-ecological zones. The average
maize yield in the highlands is about 3.5 t/ha while that for the arid and semi arid (ASALs) low
altitude areas is less than 1.3 t/ha. Arid and semi arid areas constitute about 82% of the total land
area and supports about 20% of the country’s human population. The demand for more food
culminating from the population increase and the migration of people from high potential areas
to semi arid lowlands has led to maize growing in marginal areas. Kenya’s ASALs are home to
the very rural poor who practice subsistence farming as a livelihood. Local landraces of maize
are an important livelihood resource in these areas. The objective of the study was to characterize
selected Kenyan local maize landraces for drought tolerance and resistance to larger grain borer
in storage. The characterization for drought tolerance was carried out using secondary traits that
exhibit high heritability for drought tolerance such as grain yield, anthesis-silking interval (ASI),
tassel size, ears per plant and leaf rolling. The experiment was laid out in a lattice design
(unbalanced) each with sixty-four maize genotypes. A second experiment to evaluate drought
tolerance was conducted for landraces that exhibited favorable tolerance characteristics. This
experiment was laid out in a split plot (RCBD) design with water levels (water stressed and
unstressed, at flowering) as the main plots and germplasm as the sub plots. Irrigation was
withheld one week to tasseling and resumed forty days later in water stressed plots. The wellwatered plots had continuous irrigation. The field experiments were carried out at KARIMasongaleni field station in Kibwezi district, which falls under agro-ecological zone VI. Among
the characters evaluated, a low ASI (1-6 days) was associated with a high level of drought
tolerance and low yield losses under moisture stress. Drought stress resulted in 17% to 81%
relative grain yield losses. Germplasm GBK-032419, DT/BT/1470.DT and GBK-034659
exhibited lowest grain yield losses of 28%, 22% and 17% while KTL N 70140-4, KTL N 10162-
1 and Makueni Dry Land Composite (control) exhibited high grain yield losses of 81%, 70% and
68%, respectively. However, Katumani inbred lines DT/BT/1917.DT and DG/BT/2443.DT,
though exhibiting the shortest ASI of about 1 day experienced about 50% grain yield loss under
moisture stress. In general, an increase in number of ears per plant, 100-seed weight, increased
plant height, high shelling %, reduced leaf rolling and low ASI were associated with yield
increases under water stress. Germplasm that exhibited favorable drought tolerance
characteristics were CML-492, DT/BT/1917.DT, DT/BT/1470.DT, DG/BT/2443.DT, GBK044593, GBK-032419, GBK-032423, GBK-34659, KTL N 701104 and GBK-032357. The most
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susceptible germplasm (ASI between 12-17 days) were KTL N 70133-3, KTL N 10168-1,
Katumani Composite B, Makueni Dry Land Composite, KTL N 10168-2, GBK-043227, GBK034711 and GBK-027054. The germplasm that exhibited drought tolerance characteristics were
further evaluated for resistance to larger grain borer (LGB) damage in storage. This experiment
was done at CIMMYT field laboratory-Kiboko. Samples were laid out in complete randomized
design and replicated three times. Although no absolute resistance existed, most landraces
exhibited higher levels of resistance to LGB than the control variety H614. The germplasm with
the highest resistance level was CML-492, while GBK-043731 had the lowest level. Germplasm
CML-492, DT/BT/1971.DT, DT/BT/1470.DT, DG/BT/2443.DT, GBK-044593, GBK-032419,
GBK-032423, GBK-34659 and GBK-032357 exhibited tolerance to drought and also resistance
to LGB relative to control H614. Katumani Composite B, though exhibiting susceptibility to
drought, had a high level of resistance to LGB than most local landraces. It was concluded that
some Kenyan local landraces exhibit drought tolerance characteristics and also resistance to
LGB. According to factor analysis, the phenotypic characteristics evaluated for drought tolerance
accounted for 68% of the total variation. | en_US |
