Kiwifruit Scion & Rootstock Selection
Kiwifruit cuttings are typically grafted onto seedling rootstock propagated from seed. Although grafting is the primary form of propagation for kiwifruit, specialized rootstock cultivars are not commonly used in California. Instead seedlings of either Bruno or Hayward varieties are grown, then cuttings from known Hayward adults are grafted on to them to ensure the production of desired cultivar traits (Beutel 1990). Some recent research indicates that specialized rootstock varieties can improve the ability of kiwifruit to grow in less than ideal soil conditions and increase cold tolerance (Oliveira and Fraser 2005), however these tolerant rootstocks are not commonly used in California.
The dominant commercial cultivar grown in California is the female ‘Hayward’. It is characterized by large, fuzzy brown-skinned fruit, and adaptability to hot or cool climates. Presently, the most common male pollinator in California is the Cheiftan cultivar. Two other closely related species to A. deliciosa have been grown and marketed commercially, although they are not common in California. A. arguta, also known as the hardy kiwifruit, can withstand severe below-freezing temperatures. It is smooth skinned and much smaller than the “Hayward” fruit (Bliss 1994). Zespri®Gold is a proprietary cultivar, derived from A. chinensis, with yellow flesh and sweeter flavor than the green flesh of Hayward cultivars (Zespri 2012).