What was done
Kiwifruit (Actinidia deliciosa) vines were grown in controlled environment chambers receiving ambient and enriched (ambient plus 200 ppm) atmospheric CO2 concentrations for three growing seasons to determine the effects of elevated CO2 on gas exchange in this important fruit-bearing species.

What was learned
Leaves of vines growing in ambient air displayed a daily decline in photosynthetic rate beginning around 0900 hours.  In contrast, leaves of vines growing in CO2-enriched air exhibited no sign of photosynthetic depression and continued to display increasing photosynthetic rates with increasing light levels.  In fact, during periods of peak irradiance and temperature, the photosynthetic rates of the CO2-enriched vines were 75% greater than those of the vines growing in ambient air.

What it means
As the air's CO2 content rises, photosynthetic rates of kiwifruit leaves will likely rise too, providing developing fruit with greater carbohydrate supplies for facilitating growth.  Consequently, fruit yields on mature kiwifruit vines are likely to rise dramatically with future increases in the air's CO2 content.