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Influence of flooding on
bambara groundnut (Vigna subterranea L.) germination:
Effect of temperature, duration and timing
A. Sesay
Department of Crop Science and Production, Botswana College
of Agriculture, Faculty of Agriculture, University of
Botswana P/B 0027, Gaborone, Botswana.
E-mail:
abusesay@yahoo.com .
Accepted 14 January, 2009 |
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To evaluate the response of bambara groundnut seeds to
flooding stress a laboratory study (experiment 1) and a
greenhouse study (experiment 2) were conducted. In the
laboratory study seeds of a brown-coloured local bambara
groundnut landrace were completely immersed in distilled
water (pre-sowing soaking) for 2, 4, 6 and 8 d in an
incubator at 20, 25, 30 and 35°C. In the greenhouse study
flooding stress was imposed on seeds of the uniswa red
landrace at 1, 3, 5 or 7 d after start of imbibition. In
experiment 1 pre-sowing soaking enhanced germination rate,
but final germination percentage decreased drastically as
the duration of soaking increased beyond 2 days. There was a
significant flooding duration x temperature interaction on
final germination percentage. The germination ability of
bambara groundnut seeds was reduced by 60 and 80% when seeds
were soaked for 6 days at 20 and 30°C, respectively, and a
complete loss in germination occurred when seeds were soaked
for 6 days at 35°C, and for 8 days at all temperatures used
in the study. However, seeds germinated well (68%) even
after 6 days of soaking at 25°C. In experiment 2, flooding
bambara groundnut seed for 1 or 12 h at 1, 3, 5 or 7 days
after start of imbibition did not reduce germination
percentage significantly. However, flooding at any time for
24 or 48 h significantly reduced germination percentage,
compared with non-flooded seed. These results suggest that,
at least for the two landraces used in this experiment,
short-term flooding of fields during the germination phase
of bambara groundnut is detrimental to germination and
uniform emergence, but that the response is influenced by
the duration of flooding, temperature, germination stage and
the interaction between flooding duration and temperature.
Key words: Bambara groundnut,
Vigna subterranea, seed flooding tolerance, pre-sowing
hydration, germination.
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