Agriculture Reference
In-Depth Information
Table 14
Percentage of fl orets with more than 80 and 40 pollen grains deposited
on the stigma and number of pollen grains deposited on the stigma.
Cultivar
Florets with
>80%
pollen Grains on
the stigma (%)
Florets with>40%
pollen Grains on
the stigma(%)
Number of pollen
grains deposited
on the stigma
Mean C.V.
Mubouai koku,
Indigenous
Somewake, Indigenous
26.4 ± 21.0
53.3 ± 21.7
59.3 ± 27.7 84.1 ± 5.4
77.3 ± 15.3
97.3 ± 6.0
137.0 ± 23.5 53.9 ±
15.9
204.1 ± 60.2 44.4 ±
7.3
194.6 ± 91.9 48.6 ±
3.5
Homura 3, Breeding
station
Magatama, Breeding
station
97.4 ± 3.5
100.0 ± 0.0
87.8 ± 9.8
100.0 ± 0.0
(After Matsui and Omasa 2002)
Morphologically, large anthers and longer stigmas (Suzuki
1982) contribute to increased tolerance to cold stress during
the booting stage.
Spikelet opening triggers rapid pollen swelling, leading to
anther dehiscence and pollen shedding from the anther's apical
and basal pores (Matsui et al. 1999). Increased basal pore length
in a dehisced anther was found to contribute signifi cantly to
successful pollination (Matsui and Kagata 2003), probably
because of its proximity to the stigmatic surface. Longer stigmas
may also be important for the same reason. After pollination, it
takes about 30 minutes for the pollen tube to reach the embryo
sac. Genotypic differences in pollen number and germinating
pollen on stigma and spikelet fertility was affected by cold
stress.
Low temperatures affect the development of pollen
grains, decreasing the number of engorged ones, preventing
fertilization and causing spikelet sterility, which in turns
lowers grain yields (Lee 2001). Gunawardhana et al. (2003)
