Hayward to move south

The most com­monly grown va­ri­ety of ki­wifruit around Te Puke will not be com­mer­cially vi­able in the area by the end of the cen­tury, say sci­en­tists.

The Orchardist - - PlanFor Climate Change -

A study into how cli­mate change will af­fect pro­duc­tion of the Hayward cul­ti­var in the Bay of Plenty – the com­mon bright green ki­wifruit – has been pub­lished in the New Zealand Jour­nal of Crop and Hor­ti­cul­tural Sci­ence.

Lead au­thor, NIWA sci­en­tist Dr An­drew Tait, says it is glob­ally recog­nised that the ef­fects of cli­mate change is an emerg­ing risk to the eco­nomic value of fruit crops, es­pe­cially those grown in warm, tem­per­ate re­gions such as ki­wifruit.

“Our study shows that ki­wifruit pro­duc­tion around Te Puke steadily de­creases over com­ing decades. It will be mar­ginal by 2050 and most likely not vi­able by 2100 un­der all but the most strin­gent of global green­house gas emis­sion op­tions.”

How­ever, the good news is that other parts of New Zealand will be­come suit­able for ki­wifruit pro­duc­tion as tem­per­a­tures in­crease.

About 90% of New Zealand’s ki­wifruit in­dus­try is based in the Bay of Plenty and more than half of that around Te Puke. Pro­duc­tion is mostly the Hayward va­ri­ety which is suited to the cli­mate and soils of the area, in­clud­ing warm springs, mild sum­mers and au­tumns and high sun­shine hours. Ki­wifruit needs suf­fi­cient “win­ter chilling” between May and July to pro­duce high flower num­bers in spring that re­sult in fruit. High win­ter chilling, or colder sus­tained tem­per­a­tures over this pe­riod, gen­er­ally re­sults in more flow­ers and an ear­lier flow­er­ing pe­riod.

Pro­duc­tiv­ity sig­nif­i­cantly in­creased between 1980 and 2010 due to tech­nol­ogy changes and the in­tro­duc­tion of a chem­i­cal sprayed on the vines in late win­ter to im­prove the ef­fects of win­ter chilling. New Zealand ki­wifruit ex­ports were worth $1558 mil­lion in the year end­ing June 2016 – up from $930 mil­lion the pre­vi­ous year. But the use of the chem­i­cal, hy­dro­gen cyanamide, may be re­stricted or banned in fu­ture.

“As air tem­per­a­tures in New Zealand con­tinue to rise, the po­ten­tial for more years with mar­ginal or poor win­ter chilling con­di­tions steadily in­creases. This could put sig­nif­i­cant stress on the ki­wifruit in­dus­try in the Te Puke area, par­tic­u­larly if hy­dro­gen cyanamide is banned,” Dr Tait says.

“If this hap­pens soon then there is an ur­gent need to con­sider the vi­a­bil­ity of Hayward ki­wifruit pro­duc­tion in other ar­eas of the coun­try, along­side ge­netic im­prove­ment.”

NIWA tem­per­a­ture data and high res­o­lu­tion map­ping abil­i­ties showed ar­eas fur­ther in­land in the Bay of Plenty as well as Can­ter­bury and Cen­tral Otago had po­ten­tial as Hayward ki­wifruit grow­ing re­gions.

“The good news is that through good plan­ning, the New Zealand ki­wifruit in­dus­try is very likely to re­main vi­able for many decades to come,” Dr Tait says.

“As air tem­per­a­tures in New Zealand con­tinue to rise, the po­ten­tial for more years with mar­ginal or poor win­ter chilling con­di­tions steadily in­creases. This could put sig­nif­i­cant stress on the ki­wifruit in­dus­try in the Te Puke area, par­tic­u­larly if hy­dro­gen cyanamide is banned.”

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