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When growing kiwifruit, many practices have been utilised to achieve improved fruit quality and maximise productivity through optimised vine performance (Patterson and Currie, 2011). These include planning block layout, ensuring good orchard shelter,

spring and summer trunk girdling, “tip-squeezing” (Max and Currie, 2005), “zero-leaf”

pruning (Gardiner et al., 2005) and fruit thinning (Patterson and Currie, 2011). Preharvest growing conditions and orchard management practices can affect fruit quality at the time of harvest and during subsequent storage. While several orchard and climatic factors have been suggested to influence kiwifruit storage quality, there are few published data demonstrating these effects.

2.1.4.2 Girdling

Trunk girdling, or cincturing, is a technique used to influence cropping, which involves the removal of a ring of the bark around the trunk (Sale, 1990). Fruit growth is dependent on the ability of fruit to compete with vegetative growth for a supply of carbohydrates from leaves (Seager et al., 1995). Girdling interrupts the flow of carbohydrates around the vine by redirecting them to the shoots rather than to the roots, restricting the roots from competing with the fruit to absorb carbohydrates produced by the leaves. Trunk girdling has been widely used in many horticultural products such as grapes, citrus, apple, peach and persimmon to improve fruit size and quality attributes such as DMC and TSS (Goren et al., 2003).

The implementation of girdling within the New Zealand kiwifruit industry was developed to increase orchard yield, fruit size/weight and dry matter concentration (Sale, 1990). Spring trunk girdling practices are used to increase fruit size in both ‘Hayward’

and ‘Hort16A’ whereas summer trunk girdling is applied to facilitate higher dry matter

accumulation by fruit, as well as higher flowering in the spring following application (Patterson and Currie, 2011). Davison (1980) demonstrated that girdling on young

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kiwifruit vines increased flower and fruit numbers. Snelgar and co-workers (Snelgar et al., 1986; Snelgar and Thorp, 1988) reported increased fruit weight with increasing leaf area on girdled vines. Girdling combined with high leaf to fruit ratios were found to improve fruit weight (Seager et al., 1995) and TSS (Seager et al., 1995; Assar et al., 2009). Boyd and Barnett (2011) suggested that extended trunk girdling increased fruit number, improved DMC and resulted in more advanced maturity at harvest. This hastening of maturation of fruit makes girdling an undesirable practice in some cases (Davison, 1990). While much research reports on the effect of girdling on at-harvest kiwifruit quality, little information is available on how girdling affects kiwifruit storage performance (Boyd, 2012). Boyd and Barnett (2011) found that trunk girdling of

‘Hort16A’ (A. chinensis) vines reduced the susceptibility of fruit to develop chilling

injury (CI) during storage.

2.1.4.3 Crop load

Crop load is defined as the fresh weight obtained per canopy hectare. For ‘Hayward’ yields increase from approximately 7 to over 30 t/ha from 1980’s to 2010’s as a result of continued improvements in orchard management, with top-performing orchards producing over 50 t/ha (Thorp et al., 2011). Manipulation of crop load is achieved by light-to-moderate vegetative pruning and flower/fruit thinning. Crop load is important as it affects kiwifruit size and quality in the current season and flower induction for the following season (Sale, 1990). However, over-reduction of crop load compromises orchard yield and in turn profitability (Snelgar et al., 1986; Patterson and Currie, 2011).

Published studies on the effect of crop load on at-harvest kiwifruit quality are somewhat contradictory. While some failed to demonstrate any significant effect of manipulated crop load on fruit weight, FF, DMC and TSS (Snelgar et al., 1998; Broom et al., 2000), others reported high crop load being associated with reduced fruit weight (Patterson and Currie, 2011), higher FF (Boyd and Barnett, 2011) and reduced DMC and total titratable acidity (Famiani et al., 2012) at harvest. The effect of crop load manipulation on kiwifruit storage performance is not well established. Famiani et al. (2012) suggested that high crop load results in reduced TSS and FF after storage for

‘Hayward’. Boyd and Barnett (2011) found that high crop load also increased the

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2.1.4.4 Light

Light is essential for plant growth and fruit production. Vines grown under shaded areas flower poorly in the following season (Davison, 1990). Light intensity also influences photosynthesis rates of leave, growth rate of vines, water uptake and mineral accumulation in the fruit (Buwalda and Smith, 1990; Davison, 1990). Previous studies showed that insufficient light exposure resulted in smaller fruit size, reduced chlorophyll content and calcium accumulation, lower TSS and DMC, and less FF (Tombesi et al., 1993; Antognozzi, 1995; Biasi et al., 1995; Snelgar et al., 1998; Montanaro et al., 2006; Tavarini et al., 2009). In comparison, fruit grown in high light intensity had better quality and longer storability (Tombesi et al., 1993; Antognozzi, 1995).

The use of reflective mulches was discovered in an attempt to increase light availability in the canopies of apple trees (Doud and Ferree, 1980; Mika et al., 2007). Reflective mulches increase light availability by reflecting the light that passes through the canopy and reflecting the light up onto the leaves (Currie et al., 2007). More light allows for warmer air temperatures in various seasons which increase vegetative growth rate (Richardson et al., 2004). Thorp et al (2001) discovered that the use of reflective covers placed underneath ‘Hayward’ kiwifruit vines improved fruit weight and hence fruit yield, and increased flowering in the second year. Costa et al (2003a) confirmed the former study and pointed out a trend for higher TSS and lower FF values before harvest. A research conducted by Currie et al (2007) also suggested higher fruit weight and DMC were found in the fruit from reflective plots.

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2.1.5 Skin properties of kiwifruit