Quantitative flowering of kiwifruit
(Actinidia deliciosa (A. Chev.) C. F. Liang et A.
R. Ferguson var. deliciosa) was investigated in 25
North Italian kiwifruit orchards to evaluate frost
resistance following a severe cold spell in January
1985, when air temperatures dropped as low as
- 23 ° C. The percentage of fruitful shoots in female
cultivar 'Hayward' began to decrease at -11°C;
at about -18°C very few reproductive buds burst
the following spring. As temperatures decreased,
the proportion of vegetative shoots, arising from
meristems in the basal axils of winter buds,
increased. The male cultivar, 'Matua' reacted in a
similar way to 'Hayward', but 'Matua' was more
tolerant to frost injury. The same reduction in
flowering shoots, resulting from a fall in
temperature, was obtained at about - 1.2 to
-1.8 °C lower in male than in female plants in the
range from -II to -18°C. In no case was plant
death observed. Acutely damaged plants were
capable of regrowth from adventitious buds either
of the leaders or of the trunk.
