| Summary: | 碩士 === 國立中興大學 === 植物學系 === 85 === Our research focused on soybean cultivar Kaohsuing Sel.
10(Glycine max (L.) Merr. cv. Kaohsuing Sel. 10) and vegetable
soybean cultivar Kaohsuing 3 (Glycine max (L.) Merr. cv.
Kaohsuing 3). We treated the samples with different amounts of
nitrogen fertilization using urea as a nitrogen source, and
analyzed its effects on the carbon and nitrogen metabolism of
the leaves during the flowering stage and seed filling
period. The
experimental results showed that there were different levels of
influence of nitrogen treatment to different cultivars and their
growth stages.The effectsof the addition of nitrogen treatment
affected leaf CO2 assimilatory rates more on the soybean than
the vegetable soybean. The addition of nitrogen led to a
decrease of respiratory rate of both soybean and vegetable
soybean leaves,which resulted in discrepancy of carbon skeleton
and thus the consequential biochemical reactions.
In addition,the yield was affected by assimilate translocation
and distribution. Twofold and threefold nitrogen
treatments raised the ratio of assimilates partitioning to
the soybean pod while there were no obvious effects of which to
the assimilates partitioning in vegetable soybean.But, there
were noobvious effects on the harvest index,perhaps being
attributed to of both soybeanand vegetable soybean under
different amounts of nitrogen fertilization.It mightbe the
failure of efficient translocation of assimilates to pods.
During the flowering and seed filling stages, the glutamate
dehydrogenase activity of soybean and vegetable soybean
leaves was higher than the glutamine synthetase activity. The
addition of nitrogen fertilization increased the glutamine
synthetase activity and yet it was unable to increase the
glutamate dehydrogenase,therefore under the high nitrogen
situation, soybean and vegetablesoybean used glutamine
synthetase pathway to metabolise ammonium in leaves.Otherthan
this, during the flowering and seed filling stages, the
glutamate contents were higher than glutamine inside the soybean
and vegetable soybean leaves.Whichindicated that glutamate
dehydrogenase took part in metabolising the ammonium. During
the flowering and seed filling stages, asparagine, the highest
quantityamino acid could be used to synthesize other amino acids
through transamination without consuming too much energies. This
was beneficial to the developing pods.Soybean seeds contain a
large amount of protein (about 33.1% to 49.2%),therefore, during
the seed filling stage, it was beneficial to protein synthesis
as the asparagine contained in the soybean leaves to transport
to the seeds. We found that addition of nitrogen
fertilization raised the photosynthetic rate in both soybean
and vegetable soybean and yet it had little effects in the
nitrogen assimilation and thus was unable to translocate the
ample nitrogen contained in the leaves to the pods.
Therefore, there was no trivial correlationbetween the nitrogen
assimilation and the yields. Further studies about the
correlation of seed growth and the nitrogen content in the
leaves must be done in order to understand that whether the
assimilation and partioning efficiency of soybean and vegetable
soybean is a restrictive factor to the seed growth.
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