The effective pollination period was determined in kiwifruit [Actinidia deliciosa (Chev.) Liang and Fergusonl and the factors affecting it were evaluated. The effective pollination period, measured as the capability to set fruit after hand-pollinating flowers of different ages, was 4 days; 5 days after anthesis fruit set decreased and 2 days later it was nil. Pollen tube growth did not appear to he a limiting factor since pollen tubes grew quickly and reached the base of the style 2 days after pollination and reached the ovules 1 day later. Ovules appeared viable for the 7 days following anthesis, and visibly degenerated within the following 3 days. Stigmatic receptivity was determined by the ability to sustain pollen germination after hand pollinating flowers of different ages. The duration of stigmatic receptivity closely fit the effective pollination period determined through fruit set. Thus, it appears that stigma receptivity is the main factor responsible for the short effective pollination period.

Stigmatic receptivity is a major factor limiting fruit set in kiwifruit (Actinidia deliciosa). The aim of this work was to know what determines the cessation of stigmatic receptivity in this species. Stigmatic receptivity has been analysed in kiwifruit through the capacity of the stigma to sustain pollen germination and has been related to stigmatic development and degeneration.The stigma of kiwifruit flowers has a papillate surface which from anthesis is covered with an abundant exudate. Papillae are unicellular and contain a number of phenolic deposits. During the lifetime of the flower these papillae gradually lose turgidity, while stigmatic secretion increases until 5 d after anthesis when papillae start rupturing and the papillar content is liberated into the germination medium. Stigmatic receptivity is high at anthesis and lasts for the next 4 d. However, it drastically decreases 5 d after anthesis and it is nil 2 d later. The pattern of stigmatic receptivity closely fits that of papillar integrity, indicating that stigmatic receptivity relies on this integrity. Since papillar integrity can easily be evaluated in stigmatic arms, this criterion can be used as a quick method to estimate stigmatic receptivity.