New Zealand Journal of Crop and Horticultural Science abstracts

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Flowering of kiwifruit (Actinidia deliciosa) is reduced by long photoperiods

W. P. Snelgar
M. J. Clearwater

The Horticulture and Food Research Institute of New Zealand Ltd
No. 1 Road, RD 2
Te Puke, New Zealand
email: bsnelgar@hortresearch.co.nz

E. F. Walton

The Horticulture and Food Research Institute of New Zealand Ltd
Private Bag 92 169
Auckland, New Zealand

Abstract Mature kiwifruit (Actinidia deliciosa ‘Hayward’) vines grown under standard orchard management were exposed to 16-h photoperiods from the longest day in summer until after leaf fall in autumn. Photoperiod extension was achieved with tungsten halogen lamps that produced 2–8 µmols m–2 s–1 photosynthetically active radiation. Long day treatments did not affect fruit dry matter or fruit weight at harvest during the growing season that the treatments were applied or during the following growing season. However, flowering was reduced by 22% during the spring following treatment application. As this reduction in flowering was not accompanied by a decrease in budbreak, the long day effect is not consistent with a delay in the onset of winter chilling. It is suggested therefore, that the observed reduction in flowering may be because of a diminution of floral evocation.

Keywords winter chilling; floral evocation; floral commitment; flowering; Actinidia

New Zealand Journal of Crop and Horticultural Science, 2007, Vol. 35: 33–38
0014–0671/07/3501–0033      © The Royal Society of New Zealand 2007
H06017; Online publication date 19 February 2007. Received 2 March 2006; accepted 24 November 2006

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