Abstract
Changes in anatomy and receptivity of pistils of strawberry (Fragaria × ananassa Duch.) cv. Ai-Berry and Nyoho after anthesis were investigated.
1. In the cymose truss of the 'Ai-Berry', the distal pistils of the primary (first) flower to open are small and immature, whereas proximal pistils near the base of the receptacle are fully mature and receptive to pollen. In some cases, the stigma of distal pistils are not receptive even 10 days after anthesis. Contrarily, on the tertiary (5th) flowers of 'Ai-Berry' and primary flower of 'Nyoho', the differences in size and the stage of development between the distal and proximal pistils are small and the pistils are equally receptive to pollen at anthesis.
2. The number of undeveloped distal achenes on the fruit decreased if pollination was delayed in 'Ai-Berry', but the stigma on the basal pistils lost their receptivity 4 days after anthesis. Thus, on flowers pollinated 4 or more days after anthesis, the basal pistils failed to set seeds and developed poorly, giving rise to malformed fruits.
3. Malformed fruits in 'Ai-Berry' may be reduced by controlling the timing and the duration of the pollination period, but this is difficult because of the wide range in pistil maturity from the apex to the base of the receptacle. To overcome this problem of malformation in 'Ai-Berry', cultural conditions which might narrow this range during flower development need investigation.
