Greaves & Buwalda--Photosynthetic gas exchange in kiwifruit

New Zealand Journal of Crop and Horticultural Science abstracts

Observations of diurnal decline of photosynthetic gas exchange in kiwifruit and the effect of external CO2 concentration

A. J. GREAVES

The Horticulture and Food Research
Institute of New Zealand
Ruakura Research Centre
Private Bag 3123
Hamilton, New Zealand

J. G. BUWALDA

Ministry of Research, Science, and Technology
P. O. Box 5336
Wellington, New Zealand

Abstract The prevalence of diurnal decline of photosynthesis in field-grown kiwifruit (Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson var. deliciosa `Hayward') and the effects of elevated CO2 concentration during decline were studied. During the seasonal period from soon after fruit set to harvest, marked diurnal reductions of photosynthesis rate were found that could not be correlated with levels of photosynthetically active radiation (PAR), temperature, and transpiration. Declines of photosynthesis were observed only on clear days characterised by benign environmental conditions other than sustained irradiance at saturating or near saturating levels. Elevation of CO2 concentration to 200 umol/mol above ambient during photosynthesis decline overcame the decline effect, allowing photosynthesis to track irradiance levels throughout the day. Possible mechanisms generating the diurnal decline and the alleviation by elevation of CO2 concentration are discussed.

Keywords Actinidia deliciosa; kiwifruit; photosynthesis; elevated CO2; diurnal decline of photosynthesis; mid-day depression

New Zealand Journal of Crop and Horticultural Science, 1996, Vol. 24: 361-369

0114-0671/96/2404-0361 $2.50/0 (c) The Royal Society of New Zealand 1996

PDF file of entire paper: medium quality (626K); (scanned from paper original: notes about this process)

This year's abstracts | Journal home page | All abstracts | Publishing home page