Effects of the Elevated Temperature and Carbon Dioxide on Vine Growth and Fruit Quality of 'Campbell Early' Grapevines (Vitis labruscana)

The effects of elevated temperature and CO2 concentration on vine growth and characteristics of fruits of three-year-old 'Campbell Early' grapevine were investigated. The treatment groups consisted of a control group (ambient temperature and 390 mu L.L-1 CO2), an elevated temperature group (ambient temperature + 4.0 degrees C and 390 mu L.L-1 CO2), an elevated CO2 group (ambient temperature and 700 mu L.L-1 CO2), and an elevated CO2/temperature group (ambient temperature + 4.0 degrees C and 700 mu L.L-1 CO2). The average shoot length was 312.6 cm in the elevated CO2/temperature group, which was higher than the other groups; with 206.2 cm in the control group and 255.6 cm and 224.8 cm in the elevated temperature group and elevated CO2 group respectively. However, the shoot diameter showed a tendency of decreasing in the elevated temperature and elevated CO2/temperature groups. The equatorial diameter of berries was increased in the higher carbon dioxide concentration, and the soluble solid content was the highest in the elevated CO2 group, with 14.6 degrees Brix among all treatment groups and the lowest in the elevated temperature group (13.9 degrees Brix). The harvest date was approximately 11 d earlier in the elevated CO2/temperature group and 4 to 2 days earlier in the elevated CO2 group and elevated temperature group, respectively. Regarding the rate of photosynthesis and transpiration during the growth period, higher photosynthetic rates were observed in the elevated CO2 group and the elevated CO2/temperature group during the early stage of growth; however the photosynthetic rate was reduced dramatically in summer, which was contrary to transpiration.