| In this experiment. Jin You NO.37 was selected as the material to explore the change of photosynthesis, carbohydrate metabolism and related enzyme activity in order to provided theoretical basis for the high quality and yield cultivation of cucumber. The results showed that:1. The plant height. stem diameter and leaf area of cucumber was significantly decreased under the high temperature stress, CO2 fertlization could promote the growth of cucumber, The plant height, stem diameter and leaf area was higher than CK respectively 20.60%ã€7.12%ã€27.66% under treatment with elevated CO2 at high temperature after 29 days of treatment, while treatment with elevated CO2 at ambient temperature was 7.20%ã€1.80%ã€9.46% respectively, the increasing effect decreased as treatment time prolonged.2. The net photosynthesis rate of high temperature treatment was the lowest during the whole experiment and reached at the peak after 22 days of high temperature treatment; CO2 fertlization could promote the net photosynthesis rate of cucumber, and treatment with elevated CO2 at high temperature was better than that treatment with elevated CO2 at ambient temperature, The net photosynthesis rate reached at the peak after 29 days of treatment with elevated CO2 at ambient temperature, and reached at the peak after 36 days of treatment with elevated CO2 at high temperature, which significantly prolonged the spike of net photosynthesis rate.3. Trend of starch content was first decreased then increased. Content of starch became higher than CK after treatment of 36 days with elevated CO2 at high temperature condition, leaves of cucumber became aging as time prolonged and the content of starch also increased at the same time:Content of starch with elevated CO2 at ambient temperature started to increase after treatment of 22 days, of which was earlier than the other treatments and CK in terms of the starting time of the starch accumulation,but its net photosynthesis was lower than CK after treatment of 36 days, starch content and net photosynthetic rate had significant negative correlation relationship, which turned out that the accumulation of starch made a feedback to photosynthesis in cucumber leaves.4. Carbohydrate content presented the opposite changes with content of starch, and treatment with elevated CO2 maintained at a high level 36 days ago, it turned out that the increasment of carbohydrate content was from the decompotision of starch combined with the change of starch content:High temperature could promote the decompotision of starch, reduce the starch accumulation of cucumber leaves; Change of sucrose content was consistented with soluble sugar content.5. Trend of SS activity was first increased then decreased, high temperature treatment reached at the peak after treatment of 29 days while the other three treatments reached at the peak after treatment of 36 days; Trend of SPS activity was first increased then decreased. SPS activity of high temperature treatment appeared to be lowest reached at the peak after treatment of 22 days, treatment with elevated CO2 at ambient temperature reached at the peak after treatment of 29 days while CK and treatment with elevated CO2 at high temperature reached at the peak after treatment of 36 days, whose peak of the starting time significantly later than the other two treatments.6. Trend of AI activity was first increased then decreased, high temperature treatment and treatment with elevated CO2 at high temperature reached at the peak after treatment of 22 days while CK reached at the peak after treatment of 29 days, whose peak appeared to be a little earlier; Trend of NI activity was first decreased then increased, the high temperature treatment and treatment with elevated CO2 at ambient temperature reached the minimum after treatment of 22 days while the other two treatments reached the minimum after treatment of 29 days, AI activity of treatment with elevated CO2 at ambient temperature was highest after treatment of 29 days.7. Sucrose content had a relationship with SPS and AI activity under condition of treatment with elevated CO2 at ambient temperature, while sucrose content had a relationship with SPS and NI activity under condition of treatment with elevated CO2 at high temperature. |
