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Auckland, New Zealand

Palmer J.W.,The New Zealand Institute for Plant and Food Research Ltd | Harker F.R.,Mt Albert Research Center | Tustin D.S.,Hawkes Bay Research Center | Johnston J.,Mt Albert Research Center
Journal of the Science of Food and Agriculture | Year: 2010

In the fresh apple market fruit must be crisp and juicy to attract buyers to purchase again. However, recent studies have shown that consumer acceptability could be further enhanced by improving taste. This study evaluates the use of fruit dry matter concentration (DMC) as a new fruit quality metric for apple. RESULTS: Fruit samples collected at harvest, in the two main fruit growing regions of New Zealand, showed a variation in mean fruit DMC from 130 to 156 g kg-1 with 'Royal Gala' and with 'Scifresh' from 152 to 176 g kg-1. Individual fruit DMC showed a larger range, from 108 to 189 g kg-1 with 'Royal Gala' and from 125 to 201 g kg-1 with 'Scifresh'. Fruit DMC proved a more reliable predictor of total soluble solids after 12 weeks of air storage at 0.5 °C than TSS at harvest for both 'Royal Gala' and 'Scifresh'. Fruit DMC was also positively related to flesh firmness, although this relationship was not as strong as that seen with soluble solids and was more dependent on cultivar. Consumer studies showed that consumer preference was positively related to fruit DMC of 'Royal Gala' apples. CONCLUSION: Fruit DMC can therefore be measured before or at harvest, and be used to predict the sensory potential for the fruit after storage. © 2010 Society of Chemical Industry.

Horner I.,The New Zealand Institute for Plant and Food Research Ltd | Manning M.,Mt Albert Research Center | Casonato S.,Te Puke Research Center
Acta Horticulturae | Year: 2015

Pseudomonas syringae pv. Actinidiae (Psa) causes leaf spotting, cane and leader cankers, or death of kiwifruit vines. Growers require management strategies that minimise the spread of cankers or systemic infection, whilst also minimising canopy loss. This project investigated whether cauterising cankers or pruning beyond the visible canker had any long-term effect in containing progression of the pathogen within the vine. The study included 72 'Zesy002' (commonly known as Gold3) (Actinidia chinensis) vines on one orchard and 87 'Hayward' (A. deliciosa) vines on two orchards, in Te Puke, New Zealand. From one to 30 cane or leader cankers per vine were monitored. Cankers were either left untreated, cauterised using a gas blowtorch, or pruned 40 cm below the lowest symptom. Cankers were delineated initially and canker advance was measured after 1, 3, 7 and 12 months. In 'Hayward', pruning proved to be the most effective, and most pruning wounds callused and healed. Cankers spread only where pruning wounds had not callused and healed. Only 11% and 3% of pruned canes on the two orchards, respectively, showed canker advance after 7 months. In comparison, in cauterised and untreated vines the majority (over 80%) of cankers continued to expand, with no obvious difference between these two treatments, and many instances where cankers expanded beyond the 40-cm mark. In Gold3, canker expansion was greater than in 'Hayward'. Pruning 40 cm below the visible canker margin did not remove the infection from the cane, and cankers continued to expand, in 18.4% of cases. This compares with 27.6 and 27.8% of cankers that expanded beyond the 40-cm mark in the untreated and cauterised vines, respectively, with more than 80% of cankers expanded beyond the original canker margin. The experiments showed that pruning beyond the visible canker reduced the systemic spread of Psa more effectively than cauterising cankers or leaving them untreated.

Viera Arroyo W.,Instituto Nacional Autonomo Of Investigaciones Agropecuarias Iniap | Alspach P.,The New Zealand Institute for Plant and Food Research Ltd | Brewer L.,The New Zealand Institute for Plant and Food Research Ltd | Johnston J.,Mt Albert Research Center | Winefield C.,Lincoln University at Christchurch
European Journal of Horticultural Science | Year: 2013

Fruit quality and flavour are important targets in all pear breeding programmes. Perceived sweetness is directly influenced by the amount and type of sugar accumulated in fruit. Limited information is available on sugar composition in pear fruit and published studies have been completed using cultivars rather than breeding populations. The objective of this research was to determine the quantitative genetic parameters of sugar content in fruit of interspecific hybrids from families making up a pear breeding population. Glucose, fructose, sucrose and sorbitol contents were measured in mature fruit. Most of the sugars, except for sorbitol, showed genetic variability and a relatively high (i.e., > 0.5) ratio between the estimated additive genetic variance and the total variance. Sorbitol showed a high negative genetic correlation (-0.65) with fructose. It could be suggested that the main product of sorbitol conversion was fructose. Sucrose showed a negative genetic correlation with glucose (-0.37) and fructose (-0.16), which would be expected given that sucrose is metabolised into fructose and glucose. Two parents with 100 % European parentage showed the highest empirical breeding values (eBV)s for fructose and total sugars. The parent with 100 % Asian parentage showed the lowest eBV for sorbitol. The mean percentages of the sugars across the entire population were: glucose 13 %, fructose 59 %, sucrose 8 % and sorbitol 20 %, indicating fructose was the main sugar with sucrose less prominent. © Verlag Eugen Ulmer KG, Stuttgart.

Beatson R.A.,The New Zealand Institute for Plant and Food Research Ltd | Alspach P.A.,The New Zealand Institute for Plant and Food Research Ltd | Currie A.J.,The New Zealand Institute for Plant and Food Research Ltd | Harris-Virgin P.M.,The New Zealand Institute for Plant and Food Research Ltd | White A.,Mt Albert Research Center
Acta Horticulturae | Year: 2011

The genus Actinidia contains many species that have an array of novel traits of potential commercial interest. We have initiated an interspecific hybridisation programme to introgress some of these novel traits into commercial kiwifruit. Thus we need to have an understanding of the genetic behaviour of interspecific hybrids. We report on the fruiting characteristics of two interspecific Actinidia hybrid populations. Plants were harvested over five seasons (2006-2010). Key traits measured included average fruit weight, estimated yield, dry matter, soluble solids, fruit firmness, titratable acidity and vitamin C content. A mixed modelling approach for the analysis of data was used to derive estimates of narrow sense heritability for four traits and the genetic correlations between them. In addition, empirical breeding values were obtained for each genotype and selection indices developed. The implications of these estimates in breeding for improved commercial cultivars of Actinidia species are discussed.

Henriod R.E.,Horticulture and Food Research Institute of New Zealand Ltd | Tustin D.S.,Horticulture and Food Research Institute of New Zealand Ltd | Breen K.C.,Horticulture and Food Research Institute of New Zealand Ltd | Oliver M.,Horticulture and Food Research Institute of New Zealand Ltd | And 5 more authors.
Acta Horticulturae | Year: 2011

This study investigated the effects of both crop load and time of thinning on harvest fruit size, yield and quality of 'Scifresh' (Jazz™) apple at experimental orchards in Hawke's Bay (HB) and in Nelson (NEL), New Zealand. Six-year-old 'Scifresh' trees were thinned to low, medium and high crop loads (targets of 4, 8 and 12 fruit per trunk cross sectional area (TCA), respectively) at either 0, 30, 60 or 90 days after full bloom. Fruit were assessed at harvest after 16 weeks storage at 0.5°C and 7 days at 20°C. Trees thinned early in the season to a target crop load of 4 fruit per TCA produced considerably larger fruit at harvest (mean 203 g in HB and 183 g in NEL), being approximately 9.4% (HB) and 12.1% (NEL) larger than on trees thinned to a target of 12 fruit per TCA. Allowing trees to carry a low versus a high crop load resulted in the additional fruit quality benefits of higher mean soluble solids content (13.3 v 12.5%), titratable acidity (0.62 v 0.54%) and firmness (9.7 v 8.8 kgf) at harvest. The drawbacks from reduced crop load, however, were a substantial reduction in mean yield per tree (max. 59 kg/tree down to 34.5 kg/tree) and an increased potential of up to 3.6% in post-storage bitter pit expression. Earlier timing of thinning had the benefits of increasing fruit size without overly compromising total yield per tree, and in slightly increasing (by 1.1%) mean soluble solids content (max. 13.7%). Thinning timing had minimal effect on firmness and acidity. The drawbacks from early rather than late thinning, however, were a slight reduction in mean blush coverage (by 8.1%) and a higher incidence of mean internal bitter pit (max. 5.3%). In general, superficial scald incidence overall was highest (up to 23%) in fruit from HB compared with NEL when thinning occurred early and late in the season. Thus, a medium crop load of 8 fruit per TCA employed early to mid-season is likely to provide the most favourable trade-off for production of adequate yield without unduly compromising fruit size, eating quality and disorder incidence.

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