Patient science unlocks kiwifruit gold

By ROSALIE SMITH

Plant breeder Dr Alan Seal likens plant breeding to steering a fully laden oil tanker.

"You set your direction, you build up momentum, and you don't try to alter your course," he said.

"If you change direction you slow your progress."

He should know. He has been breeding new varieties, mostly of kiwifruit, first for the old Department of Scientific and Industrial Research (DSIR) and then for HortResearch, for the past 18 years.

Based at the Te Puke Research Centre, he is now leader of HortResearch's new varieties team of 80 scientists.

Fourteen of the team are working on kiwifruit and some have been on the job even longer than Seal. They have a total of 150 years of plant breeding experience among them.

"Plant breeding is a slow business," said Seal.

"The breeder is fortunate if the result of a first-generation selection yields a winner. More usually, the breeder has to carry out further crosses and selections, each generation of kiwifruit taking five years to complete fruit assessment.

"Plant breeders have to be patient but it is important they are also impatient to find shortcuts, to trim six months or a year off a programme.

"The exciting time for breeders is the annual harvest when we assess the results of our crosses. We like to think we can predict the results but sometimes there are disappointments and sometimes exciting surprises.

"Choosing the female parent is easy because you can see its fruit, but only experience can tell you the likely characteristics to arise from the male parent. That is where experience proves its value.

"The ultimate reward is to breed a commercially successful selection, which will make a difference to the industry and perhaps also the country."

The yellow-fleshed Zespri Gold, or Hort16A, is the biggest success to come from the breeding programme and is the result of selection from Actinidia chinensis.

It came out of a joint programme between HortResearch and the kiwifruit industry organisation, Zespri.

HortResearch owns the variety and Zespri markets the fruit exclusively under the trademark Zespri Gold kiwifruit.

Zespri has licensed growers in Italy, France and California to produce Zespri Gold for it to sell in New Zealand's off-season and it can take legal action against anyone stealing Hort16A plant material.

It has also been able to control production within New Zealand, licensing growers to plant only enough to meet its estimated market demand.

Zespri Gold has been well received. Retired Zespri chief executive Tony Marks told the last annual meeting that Gold was "a winner ... outselling green in many markets three to one ... and the lead product blazing the trail for the bulk volume sales of the classic green fruit".

It took Seal and his colleagues more than 20 years to breed the gold-fleshed kiwifruit.

Seeds of Actinidia chinensis were imported from China in 1979 and 1981; in 1987, crosses between selected male and female seedlings were made; in 1991, Hort16A was selected; in 1997, the first 4000 trial trays were exported; and in 2001, 5.2 million trays were sent overseas following its commercial release.

It has a competitor in Jintao, an Actinidia chinensis selection made in China in 1981 and sold to an Italian consortium. It is now grown commercially in Italy, but Seal says he would be surprised if it matched the eating quality of Zespri Gold.

Seal says virtually no kiwifruit breeding is being undertaken in the United States and the main French kiwifruit breeding programme has shut up shop, though there is some breeding research in Italy, China, Japan and Korea.

In New Zealand, about $2.2 million a year is invested in kiwifruit plant breeding, 60 per cent coming from Government sources and 40 per cent from the industry.

Zespri holds details of the kiwifruit breeding programme close to its chest, but the situation was different in the late 1980s when I edited the industry magazine, New Zealand Kiwifruit.

Then I was able to write about the work being undertaken in the search for gold and red-fleshed selections and for early-maturing Hayward kiwifruit. One cover of the magazine sported a picture showing fruit of many shapes and colours from the range of varieties held by the DSIR.

The closed-book approach is understandable. Back in the 1970s the industry could not stop nurseries from exporting New Zealand plant material to countries that soon became competitors. Now it can protect its new varieties.

It is now 99 years since the first kiwifruit seeds were brought from China. The most significant plant selection was made in the 1920s when nurseryman Hayward Wright selected the variety to carry his name.

Several named selections were being grown in the early years of commercial production in Te Puke but eventually the Hayward kiwifruit won over the rest because of its larger size and longer storage life. It was first grown commercially in the late 1930s and increasingly from the 1950s, although other varieties were still being exported in the 1970s.

The DSIR's first entry into kiwifruit breeding began in 1955 when Actinidia arguta plant material was imported from England.

Varietal improvement began in earnest in the 1970s and accelerated after the Kiwifruit Marketing Licensing Authority was formed in 1978.

Achievements so far have included breeding improved green-fleshed fruit to augment or replace the Hayward cultivar, still the predominant kiwifruit in international trade.

One new selection, Tomua, was of an earlier-maturing, green-fleshed fruit to compete with the Chilean crop, which was a few weeks earlier than New Zealand's.

After a lengthy selection process and field trials, growers were encouraged to plant Tomua in the 1990s but it did not find favour with marketers.

Storage problems showed up and new techniques had been developed to get Hayward fruit to the market earlier.

Tomua's initial promise was not confirmed and Zespri pulled the plug on its production.

Growers received compensation for losses but the decision to withdraw Tomua led to division and ill-feeling in the industry - some Tomua growers felt the compensation offered was inadequate and some Hayward growers felt too much of their money was being spent on compensation.

The male cultivar Chieftain, developed by HortResearch, is now widely used for pollination, offering improved seed set and better sychronisation of flowering.

A new rootstock, Kaimai, has sometimes proved very hard to graft budwood onto, but leads to more flowers on Hayward vines where there is little winter chilling.

Interest in Actinidia arguta, or baby kiwifruit, is growing. Its fruit has been described as being about the size of an English gooseberry, with a smooth skin and very juicy flesh.

Its sophisticated flavour is somewhat sharper than that of green kiwifruit.

The fruit hang in loose bunches. Marketable fruit weighs 6g to 22g.

Peter Berry, at present industry liaison officer for Zespri, is an arguta enthusiast.

He became interested in the 1980s when he was chairman of the industry scientific research committee. At that time the DSIR was growing a large seedling population of arguta in its plant selection programme.

Selection has continued and now the best three have emerged and are being evaluated in the field on two sites. Private breeders have also made improved selections.

Berry and three kiwifruit growers have formed a partnership and planted 6ha of arguta vines near Katikati. Their first significant harvest will be in the next few weeks.

More than 40 New Zealand growers have planted some 25ha and have formed a growers' association chaired by Berry.

Last year Zespri set up the Arguta Product Group, also with Berry in the chair, bringing together growers, exporters, packers and HortResearch under the Zespri umbrella. It has given permission for some exporters to handle arguta because the volumes so far available for export are comparatively small.

Arguta kiwifruit go by up to 25 different names, but US growers are marketing their fruit as baby kiwi so New Zealand has decided to follow suit.

Pay a visit to the Te Puke Research Centre and you may see rows of closely spaced kiwifruit seedlings. But you will not be allowed anywhere near the most promising selections. And you certainly will not be given information about the next new kiwifruit likely to be released on world markets.

The New Zealand kiwifruit industry has the edge on all its competitors in its new varieties and is not going to give away information or plant material worth millions of dollars to the country and its kiwifruit growers.