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In the study, 121 accessions of
Oryza glaberrima were first screened for vegetative stage drought
tolerance. On the basis of visual performance of accessions (leaf
rolling score, leaf drying score, tillering, stress recovery, among
other variables), nineteen tolerant accessions were selected.
Hybridization between selected accessions of O. glaberrima and
O. sativa were undertaken to generate interspecific populations
using conventional breeding methods during 2005. In activity one, 45
fixed lines of F5 and F6, derived from the crosses between TO5681
(upland O. glaberrima) and elite O. sativa, selected
during the wet season 2004 were planted in February 2005 in split plot
design with three replications, to study drought resistance at both
their vegetative and reproductive stages at the Longorola Research
Station. Seeds were seeded in pots and then seedlings were
transplanted. Each line was represented by 1 row of 2 m length. At
vegetative stage, the lines were irrigated for 30 days after
transplanting and then drought was imposed for 4 weeks. At the
reproductive stage (booting), drought was also imposed for 4 weeks. In
activity two, thirteen F2 populations from cross involving a series of
RAMs (floating O. glaberrima from Mali) and elite O. sativa
were also planted in February 2005 for their drought reaction at
vegetative stage. 50 to 300 plants per entry were transplanted with 1
plant/hill and a spacing of 20 cm x 20 cm. Drought stress was imposed
for 4 weeks, 30 days after transplanting. In activity three,
backcrosses and multiple way crosses are made to generate new
populations. Observations on plant height, leaf rolling score, leaf
drying score, recovery ability, days to 50 % flowering and spikelet
sterility are recorded.
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