| Morphological characteristics, Rubisco carboxylase activity, net photosynthetic rate and fruit quality of grafted cucumber seedlings grown in greenhouse after the high-temperature and CO2-rich treatment were tested in this paper, as well as the quality of cucumber fruit. Results showed that:(1)the grafted cucumber in greenhouses with high temperature and elevated CO2grew vigorously,stem height, stem diameter, leaf area and leaf thickness were significantly higher than other treatments.(2)Diurnal changes of RuBPCase activity of grafted cucumber in greenhouses within high temperature and elevated CO2was "Twin Peaks" curve, the first peak appear in around9:00am, the second peak appear in around15:00pm, and13:00to reach a trough in between the two peaks, RuBPCase activities at all time points under high temperature and enriched CO2were significantly higher than other treatments.But the RuBPCase activity can be inhibited only with CO2enrichment treatment under lower temperature (9:00); but with the temperature increasing (13:00and15:00), the RuBPCase activity recovered and finally higher than control. The RuBPCase activity can also be inhibited because of high temperature, but the CO2enrichment treatment can offset the effect and finally increase the enzyme activity.(3) This paper also demonstrated a significant positive correlation between net photosynthetic rate and RuBPCase activity of grafted cucumbers in greenhouses under high temperature and elevated CO2treatment.(4)The high-temperature and CO2-rich treatment can improve the fruit taste and marketability. Contents of soluble sugar, soluble protein, free amino acid and VC of cucumber fruit were significantly increased and much higher than other treatments.That is to say the high-temperature and CO2enrich treatment can enhance the photosynthesis more effectively, thus promoting the growth of the grafted cucumber seedlings and improving its fruit taste. |
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