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Pollen
behaviour and fertililization impairment in Bambara
groundnut
(Vigna subterrenea
[L.] Verdc.)
Oyiga Benedict Chijioke*, Uguru Michael
Ifeanyi and Aruah Chinenye Blessing
Department of Crop Science, University of Nigeria, Nsukka,
Nigeria.
*Corresponding
author.
E-mail:
ceejaybeecee@yahoo.com.
Tel:+2348037317861.
Accepted 1 December, 2009 |
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Two field experiments were conducted in April and August,
2007 cropping season at the Department of Crop Science
research farm, University of Nigeria, Nsukka, to evaluate
the pollen germination potentials and the pollen tube growth
of thirteen bambara groundnut cultivars. The harvested
pollen grains were exposed for 0, 5, 10 and 15 min durations
to ambient conditions before in vitro germination.
Pollen germination and
pollen
tube growth were tested using a medium containing
10 g sucrose, 100 mg/l
boric acid and 300 mg/l
calcium
nitrate
made up to 100 ml with deionized water.
The results showed that cultivars, had significant effect on
the pollen germination only at the late planting. The early
and late planting results showed that pollens
incubated
immediately after harvest
had
the highest germination percentage, while
pollen exposed for five minutes prior to germination
showed
very poor
germination.
Pollens exposed beyond five minutes after harvest did not
germinate. The cultivars significantly (P < 0.05) affected
the pollen tube growth at both early and late planting
dates. The pollen tube growth decreased drastically with
increase in duration of pollen exposure. The pollen tube had
an exponential growth rate at the on set of the pollen tube
growth, followed by lag and stationary growth phases in the
pollen tube growth curves. The
exponential,
logistic and Gomperzt growth models were used to estimate the best fit
model for the pollen tube growth in bambara groundnut
cultivars. In the early planting, the average straightness
(R2)
value of these models for growth estimate were 98.4, 98.6
and 98.5%, respectively. During the late planting, the
average R2 values were 91.5, 96.6 and 96.6%,
respectively. The three models are therefore considered
suitable for the computation of the pollen tube growth
rates. The
principal
component
and cluster analyses were used to group
the cultivars in relation to the levels
of
pollen
survival under ambient conditions.
At early planting, cultivar
Bg-01
had moderate
surviving pollen
grains
while Bg-08,
Bg-09,
Bg-10
and Bg-11
were found to
have
poor surviving pollens.
At late planting, cultivar Bg-04
and Bg-07 had
high survival pollens
while
Bg-01 had poor pollen survival.
Key words:
Pollen behaviour, pollination, fertilization, Bambara
groundnut, Vigna subterranea (L.) Verdc. |
