The structure of stigma-style tissues in kiwifruit (Actinidia chinensis Planch. cv. 'Hayward') flowers was examined before, and after, hand-pollination and the course of pollen tube development was followed. At the time of flower opening the style had a well defined canal which opened at its distal end to form a V-shaped stigmatic furrow. The surface of the furrow was covered with unicellular papillae. The exposed wall of each papilla was covered with a cuticle and a distinct pellicle. The papillae were supported by a layer of hypodermal cells and an extensive layer of thin-walled transmitting cells. The transmitting tissue extended from the tip of the style through the stylar canal to its junction with the ovary. A single vascular strand, which extended along the length of the style adjacent to the stylar canal, branched into the stylar parenchyma on each side of the V-shaped furrow. Pollen grains germinated on the stigmatic papillae and grew through the intercellular spaces of the transmitting tissue. Pollen tubes were restricted to the transmitting tissue in the lower half of the canal adjacent to the vascular strand. Starch grains in the stylar parenchyma and transmitting tissue progressively disappeared as the pollen tubes traversed the length of the style. The most rapidly growing pollen tubes reached the base of the style in 3 I hr and fertilisation of some ovules had occurred 42 hr after pollination. Fertilisation continued until 74 hr after pollination.

A number of aqueous solutions were evaluated as possible pollen carriers for the spray pollination of fruit trees. The viability of apple, kiwifruit, oil palm, and plum pollen was markedly reduced after pollen was suspended in water. This loss of viability could be partly overcome by slow hydration of the pollen in moist air before its suspension. The viability of hydrated oil palm and kiwifruit pollen after suspension in calcium nitrate solution of low concentration with or without boric acid, was similar to that of hydrated pollen germinated directly. Similar results were obtained with apple and plum pollens, provided that pentaerythritol was added to the suspension medium. However, the viability of apple , kiwifruit, and plum pollen that had been suspended in these media was substantially reduced during drying on a simulated stigma surface. For kiwifruit, the loss of pollen viability after drying could be partially overcome by the further addition of sodium carboxymethyl cellulose, with or without sodium alginate, to the suspension medium.

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