Scientists take pains over developing new kiwifruit varieties
The statistics are mind-numbing: every year Plant & Food Research NZ breeds 100,000 kiwifruit varieties, which it narrows down to 8000 to develop into a fruit with wide appeal. But this is only the start of the selection process. It will be at least 10 years before a new variety will finally hit the supermarket shelves.
Once these 8000 bear fruit the results are tasted and tested to see whether they have the right attributes. It’s not just a question of taste: the new varieties have to be the right shape, highly productive, and resistant to pests and diseases. Only a handful ever make it through the screening process. Plant & Research kiwifruit breeding team leader Luis Gea says the programme is unusual compared to others in that it is consumer driven.
Zespri asks consumers what they look for in fruit and works backwards using that information. “We let the consumer drive where we are going,” says Gea. Thanks to the efforts of researcher Dr Ross Ferguson, who rescued plants before the Three Gorges dam drowned them forever, Plant & Food Research has the largest collection of kiwifruit parent plants outside of China – about 22,000.
China might be regarded as the “home” of kiwifruit, but the plant also occurs naturally in Russia, Korea, and Japan, and plants from these countries are also used in the breeding programme. Some of the fruit from these are no larger than a small plum, some have smooth skin, while others are pale and covered with downy fur.
Each year scientists screen the collection for the best potential parents and breed them up. After two years, using molecular markers, the best seedlings are selected for further development.
“It’s like choosing your lotto numbers in the lottery. Picking the winner is not simple because you have to have all your markers right.
“Instead of using statistics to choose the numbers we are using markers to say this one has the science attributes we are looking for. We are using genetic markers to identify the winner and the one we want to propagate,” says Gea.During years 3-5 the seedlings are planted in the orchard and further selected, based on what consumers like. At the same time the fruit is tested to make sure it will travel thousands of kilometres to markets without spoiling.
By year 7 the best plants are selected for planting at different sites around the country to make sure they perform well in a variety of locations. Main kiwifruit growing areas are the Bay of Plenty, Northland and Nelson.
With Zespri, the scientists develop orchard management and post-harvest protocols before the “right” cultivar is released on the market. In the case of SunGold, the cultivar that replaced Hort3 which proved to be vulnerable to the disease Psa, development took close to 20 years.
At present Zespri has a red and a green kiwifruit cultivar in pre-commercial trials, with commercialisation considered from 2017.
A red kiwifruit is one of the researchers’ Holy Grails – Asian consumers especially are attracted by red-coloured fruit but so far the varieties developed are small-sized which do not store well and are susceptible to Psa.
Work also continues on developing a high-yielding, good-tasting green kiwifruit with strong health benefits. Three new varieties were commercialised by Zespri in 2010 – SunGold, Sweet Green and Charm. Sweet Green has been described as “stunning if you get it right” by organic grower Jeff Roderick, and sold mainly to Japan and China.
Charm is an example of a variety that went all to way to commercialisation but its poor keeping qualities held against it and it was “de-commercialised” in 2015. Even so, Roderick has kept several vines on his orchard “for my grandkids” because he regards it so highly. Overall, annual R&D investment (including research into markets and health benefits) is $35 million or 1.5 per cent of revenue. Between them Zespri, Plant & Food Research and the Government spend about $15m a year on cultivar research.
That investment pays off, if the example of gold kiwifruit is anything to go by. Since their commercialisation, the Hort16A and SunGold varieties have added more than $4 billion added to the New Zealand economy.
* The writer travelled courtesy of Zespri