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Home HortScience Kiwifruit Survives Feast and Famine Treatments
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AUCKLAND, NEW ZEALAND—To meet high consumer demand, kiwifruit growers are challenged to find ways to produce consistently high yields. Kiwifruit grow on vines, requiring producers to use careful canopy management techniques. Traditionally used vine management practices include trunk girdling, summer pruning, and growing fruit on older, less vigorous wood. These techniques help to minimize competition for resources between fruit and new, rapidly growing shoots.

In New Zealand, research scientists Linda M. Boyd and Andrew M. Barnett undertook a long-term study of on mature, field-grown  kiwifruit vines using different techniques (e.g., pruning, fruit thinning, and girdling) to modify whole-vine resource allocation. According to Boyd and Barnett, the aim of their research was to determine how the treatments affected vine productivity, fruit dry matter concentration (DMC), and storage performance over several seasons. The study results appeared in HortScience.

The scientists combined high croploads with badly timed and excessive pruning to intentionally deplete whole-vine carbohydrate status (famine treatment), and conversely used low croploads with high leaf-to-fruit numbers to provide abundant carbohydrates to fruit (feast treatment). Extended trunk girdling (ETG) was used to isolate the canopy from the roots for extended periods of time. "The famine and ETG treatments were designed to identify any problems that may occur if growers channel too much assimilate into fruit production," Boyd and Barnett explained.

The researchers found that that whole-vine treatments that allocate a greater proportion of carbohydrates to fruit than to root or shoot growth also affect vine productivity and fruit quality. Extended trunk girdling produced fruit with higher dry matter concentration and typically advanced maturity compared with ungirdled control vines carrying the same cropload and harvested on the same date. Fruit from the trunk-girdled vines were more susceptible to physiological pitting and less susceptible to low temperature breakdown than fruit from the control vines.

"Each season the ETG vines became relatively more productive than the control vines, resulting in increasingly large numbers of fruitlets being thinned to obtain realistic croploads," the scientists wrote. "In contrast, the relatively high croploads, low leaf numbers, and increased competition between growing shoots and fruit in the famine vines reduced vine productivity by almost 40% compared with vines having lower croploads and higher leaf-to-fruit ratios."

The researchers noted that although the treatments affected productivity, fruit DMC, and storage performance, there was no evidence of decline in kiwifruit quality and productivity after 4 years of treatment application.


The complete study and abstract are available on the ASHS HortScience electronic journal web site:

Founded in 1903, the American Society for Horticultural Science (ASHS) is the largest organization dedicated to advancing all facets of horticultural research, education, and application. More information at


Original Article:

Manipulation of Whole-vine Carbon Allocation Using Girdling, Pruning, and Fruit Thinning Affects Fruit Numbers and Quality in Kiwifruit
Linda M. Boyd and Andrew M. Barnett
HortScience 46:590–595. [Abstract][Full Text][PDF]

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