| Summary: | 碩士 === 國立中興大學 === 農藝學研究所 === 84 === A large number of semidwarf high yielding rice varieties ha
ve been developed by using local varieties or artificial mutants. H
owever, semidwarf genes of practical important are limited to s
d-1 locus. In the present study, to evaluate the differences i
n the effects of semidwarf genes at sd-1 locus of
chromosome 1 and the sd-7 locus of chromosome 5 on the
culm length and other agronomic characters by using four isog
enic lines which have the same genetic background of Taichung
65 (abbreviated to T65).
As the result, the plant height of the four
isogenic lines were lower than the recurrent
parent T65, no matter in the first-crop season or in the se
cond-crop season. The range was from 21.5cm to 29.5cm in the
first-crop season and 21.2cm to 36.8cm in the second-crop
season. On the culm length, the four isogenic lines were lower
than the recurrent parent T65 no matter in the first-crop
season or the second-crop season. the range was from 18.6cm to 28.
3cm in the first-crop season and 20cm to 34.2cm in the second-crop season
. It was seggested that the different origin of semidwarf genes can
shorten the plant height and culm length, but they have some diversity
express. The difference in the internode length between each of sem
idwarf lines and its parental cultivar became smaller from the
first to the fourth internodes. However, the percentage of difference t
o the value of each of the parental cultivars in the first internode was
lower than those in the second to fourth internode length. The percent
age of reduction by the genes in the second internode length was similar
to that in the culm.
As for other agronomic characters, in the sd-7 isogenic line t
he panicle length was shorten andthe 1000 grains weight was reduced
no matter in the first-crop season or the second-crop season.In the
sd-1 isogenic lines, the panicle length was shorten, the panicle we
ight was reduced, the spikelets/panicle wasreduced (TLB and TNB in the
first-crop season, TNB in the second-crop season), the seed
setting rate was reduced (TNB and TWB in the second-crop season). As
the result, it was suggested that the three semidwarf isogenic lines
have different express at the sd-1 locus by comparing each agronomic ch
aracter. The agronomic character of TWB was difference with the TLB and
TNB. In comparison with the semidwarf isogenic line TDB which
has a semidwarf gene from D65 with sd-7and other sd-1 isogenic lines,
the TDB had highervalue than TLB and TNB in the plant height, culm lengt
h, the first internode length, the second internod length and panicle we
ight, but no difference with TWB. However, the TDB in the fourth intern
ode length was less than TLB and TNB, and have no difference with TWB
. The TDB and TWB have similar expression in the agronomic characters
except the spikelets per panicle in the second-crop season. It was obser
ved that the semidwarf gene at the same locus expired differently at d
ifferent crop seasons.
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