| Summary: | 碩士 === 國立中興大學 === 植物學系 === 81 === Flooding of bitter melon (Momordica charantia L.), a
flood- intolerant plant, induced several morphological and
physiological changes.Hypocotyl cross sectional area and number
of adventitious roots significantly increased after 4 days of
flooding. On the first day of flooding, root respiration
rate dropped to 42% of control value. Activity of alcohol
dehydrogenase (ADH) and internal ethanol concentrations
increased gradually and reached a maximum level at the third
day of flooding. Furthermore, a new ADH isozyme was induced
as a result of flooding. Continuous flooding lead to death
of seminal root system after 8 days of flooding. The
accumulation of ethanol may result in death of root root
system. Leaves of young seedlings of bitter melon exhibited
reduced leaf carbon dioxide exchange rate (CER), stomatal
conduc- tance, transpiration rate, soluble protein content,
chlorophyll content, ribulose-1,5-bisphosphate carboxylase/
oxygenase(Rubisco) activity and Rubisco content. Stomatal
conductance was positively correlatedwith CER (R square=0.92).
However, the internal carbon dioxide concentration (Ci) of
leaf tissues of flooding-treated plants increased from 240
.mu.bars at day 0 up to 380 .mu.bars at day 6 of flooding.
Furthermore, starch was found to accumulate in chloroplasts of
the flooding-treated leaves. These results indicate that
both stomatal and metabolic factors are responsible for the
reduction in CER during flooding stress. Dark respiration of
leaf increased concomitantly with Ci elevation. Rubisco
activities were shown to linearly correlate with Rubisco
content (R square=0.89) and the percent activation of Rubisco
declined. The elevation of Ci may be involved in lowering
the percent activation of Rubisco during flooding stress.
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