ISHS Acta Horticulturae 444: III International Symposium on Kiwifruit
WHOLE-PLANT PHOTOSYNTHESIS IN KIWIFRUIT VINES - TEMPORAL CHANGES ON DIURNAL AND SEASONAL SCALES |
| Authors: | J.G. Buwalda, A.J. Greaves |
| Abstract:
Temporal variation in measured photosynthesis (Ac) for kiwifruit vines has been described, on diurnal and seasonal scales. Short-term measurements focused on light (Ac) response described with an asymptotic exponential expression, For vines with leaf area of ca 2.0 - 2.6 m2 m-2, the quantum saturated rate of Ac (Asat) increasing vine leaf area, from 29.0 - 37.8 μmol CO2 m-2 s-1. Longer-term measurements focused on the relationship between diel integrals of Ac (Ad,) and leaf area. Ad increased from -0.7 mol CO2 m-2 day-1 soon after bud burst, to as high 1.4 mol CO2 m-2 day-1 near the summer solstice. A regression of Asat against leaf area indicated that Ad did not peak until leaf area has exceeded ca 2.5 m2 m-2. Diel measurements of Ac have illustrated “mid-day decline”, consisting with feedback inhibition, where Ac early in the day has been relatively high. Maintaining a high ambient CO2 during the day can over-ride the mid-day decline suggesting that source : sink interactions may involved. | |
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