Abstract
New Zealand Asian Pear/nashi growers have experienced variable crop loads between years in the export cultivar 'Housui'. Normal practice is for pollination to be achieved via bees placed in the orchard during flowering. The purpose of this study was to determine which pollen type would be an effective pollen source for 'Housui' if artificial pollen were to be applied. Pollen was applied to bagged ‘Housui’ flowers at Ohaupo, Waikato, New Zealand in 1998, 1999 and 2000. Pollen types used were a range of fresh and frozen Asian pear pollens, European pear pollen, apple pollen, crab apple pollen and crushed bee-collected pellets. Fruit set due to bee pollination of unbagged flowers decreased each year from 1998 to 2000. It was found that a single application to bagged flowers of highly viable nashi pollen, either fresh or frozen, increased fruit set compared to bee pollination by up to 20%. There was a noticeable trend whereby pollen with higher in vitro germination percentages resulted in better fruit set. Pollen could be frozen and stored for one year at -18°C without significantly reducing fruit set provided there was no warming of the pollen during storage. ‘Kousui’ pollens collected in the high crop load years (1997 and 1999) had highest viability and significantly better fruit set than any other pollen type (mean 58%). The other fresh and frozen nashi pollens and the European pear pollens had significantly lower fruit set (mean 37%). Fruit set from these pollens was similar to that from bee pollinated flowers in 1998 and 1999. The lowest fruit set was obtained from apple, crab apple, bee collected pellets, 'Pollenaid' and 'Housui'. Fruit set from these pollens was similar to self-pollination (<20%). This suggests that a suitable pollen for artificial application would be 'Kousui' collected in a high crop load years and used in the alternate low crop load year.
Published Version
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