As global temperatures rise with climate change, the risk of insufficient winter chilling for kiwifruit grown in Te Puke increases. This spurs a need for thoughtful planning from the industry to ensure the sustainability of kiwifruit in New Zealand.

These matters are examined in ‘Potential impact of climate change on Hayward kiwifruit production viability in New Zealand,’  by Andrew Tait, Vijay Paul, Abha Sood and Alistair Mowat features in the latest issue of New Zealand Journal of Crop and Horticultural Science Volume 46.3.

The article cautions that production viability of the Hayward kiwifruit is set to decrease steadily over the coming years. The model used shows the Hayward kiwifruit industry in Te Puke becoming non-viable by the end of the century under all but the strictest of global greenhouse gas emissions pathways.

The kiwifruit industry is predicted to contribute $6.14 billion to New Zealand’s gross domestic product by 2030. More than half of Aotearoa’s kiwifruit crop is grown in the Bay of Plenty, including the popular Hayward kiwifruit cultivar predominantly in Te Puke township, just southeast of Tauranga.

The town of Te Puke in the Western Bay of Plenty is one of the world’s kiwifruit hot-spots. In addition to the enormous fibreglass Kiwifruit straddling the roadside of SH2 into the town, Te Puke is proud to boast the title of ‘Kiwifruit capital of New Zealand’.

The climate and soils of Te Puke have historically been well-suited to growing kiwifruit as it sits within an ideal temperature range, has good winter chilling, warm springs, and mild summers and autumns. When you add lots of hours of sunshine and just the right amount of rain on deep, free-draining volcanic soils, it creates the perfect environment for growing bounties of fresh, tangy and sweet kiwifruit.

As global temperatures rise with climate change, this idyllic kiwifruit environment in Te Puke could be severely altered by the middle of the century. Commercial viability of the industry in the area could dwindle to nothing by 2080.

The use of the chemical hydrogen cyanamide (known commercially as Hi-Cane) greatly enhances the long-term viability of kiwifruit production in Te Puke. The use of Hi-Cane encourages budbreak and boosts the number of fruit on vines. It can also substitute about 2⁰C of winter chilling benefit in warm winters (basically the natural budbreak will yield the same number of flowers as untreated vines in a winter that is 2⁰C colder). Concern from the community regarding the toxicity and environmental effects of Hi-Cane mean that its use is increasingly being restricted or banned.

The possible banning of Hi-Cane spraying means there is an urgent need to consider other areas in the country for kiwifruit production, alongside possible genetic improvements to kiwifruit cultivars (for example, introducing low winter chill requirement traits). Other advancements made by growers to mitigate climate change in their vine management practices (like plant breeding) and some other factors which determine kiwifruit viability have not been included in the model discussed in the study.

The aim of the study was to develop a simple model for assessing current and future Hayward kiwifruit production viability in Te Puke, drawing on a wealth of previous research on the topic. The relative simplicity of the model ensures that it is easy to use with simulated temperature data output from climate models, and is easy to understand and interpret.

From this study it appears Te Puke’s perfect climate for kiwifruit orchards is set to change alongside global warming. However the authors conclude there are many other areas in New Zealand that show a potential increase in kiwifruit production viability over the next century.

Such areas include more inland parts of the Bay of Plenty and colder places like Canterbury and Central Otago. Through good future planning, the fruitful New Zealand kiwifruit industry is very likely to remain viable for many decades to come.

* The article ‘Potential impact of climate change on Hayward kiwifruit production viability in New Zealand‘ is available to read in full at Taylor & Francis Online. Articles included also discuss the effects of low pressure storage on zucchini quality, decreasing storage defects in persimmons and other important topics relating to crop science in the latest issue of the New Zealand Journal of Crop and Horticultural Science.

Source: Royal Society of New Zealand