An evaluation of containerized plants for strawberries growing in a subtropical environment.

The productivity of containerized and bare-rooted plants of strawberry (Fragaria * ananassa) was investigated over 4 years in southeastern Queensland, Australia. In the first experiment, plants in small, 75-cm3 cells were compared with bare-rooted plants of 'Festival' and 'Sugarbaby'. A similar experiment was conducted in year 2 with these two cultivars, plus 'Rubygem'. In year 3, plants in large, 125-cm3 cells were compared with small and large bare-rooted plants of 'Festival' and 'Rubygem'. Treatments in each of these experiments were planted on the same date. In the final experiment, plants in large cells and bare-rooted plants of 'Festival' were planted in late March, early April, mid-April, or early May. The plants grown in small cells produced 60% to 85% of the yields of the bare-rooted plants, whereas the yield of plants in large cells was equal to that of the bare-rooted plants. Containerized plants are twice as expensive as bare-rooted plants (A$0.60 vs. A$0.32) (A$=Australian dollar), and gave only similar or lower returns than the bare-rooted plants (A$0.54 to A$3.73 vs. A$1.40 to A$4.09). It can be concluded that containerized strawberry plants are not economically viable in subtropical Queensland under the current price structure and growing system. There was a strong relationship between yield and average plant dry weight (leaves, crowns, and roots) in 'Festival' in the last three experiments, where harvesting continued to late September or early October. Productivity increased by about 18 g for each gram increase in plant dry weight, indicating the dependence of fruit production on vegetative growth in this environment.

Mango Fruit Genomics

Genomics approaches for marker assisted selection of improved mango fruit.

Alternaria Fruit Spot: New Directions

This project determined the identity of causal pathogens, epidemiology and disease cycle of Alternaria leaf blotch and fruit spot in Australian apples and provided a management strategy for both diseases for inclusion in the integrated fruit production manual.

Evaluation of APFIP (apple) varieties

Evaluation of APFIP (apple) varieties.

Alternative fruit fly management for market access for apples

Difficulty with control of Queensland fruit fly with four cultivars of apples on the Granite Belt, Qld. Warnings that the insecticides dimethoate & fenthion might be removed from the market for apples, had been current for several years. Dimethoate was widely used as a post harvest control measure as well as an in-field treatment. Fenthion also had and still has in-field usage. The project attempted to find a replacement for these control measures.

Vapour heat treatment of honey gold mango

Vapour heat treatment of honey gold mango for access to the Japanese market.

Understanding the cropping behaviour of Riberry (Syzygium leuhmannii)

This study highlights the complexity of flowering biology in Syzygium and demonstrates how a basic understanding of a species’ fundamental biology is necessary for successful commercial cultivation. This report brings together useful information from previous international research on Syzygium as well as providing a basic understanding of flower biology, the nature of fruit set and seediness in riberry. Much of these findings have implications for the cultural management of riberry orchards to optimise fruit set and minimise seed set. It raises the possibility of avenues for genetic improvement.

Development of an avocado rapid library tray system for Hass

The aim of the project is to develop a rapid ripening protocol/test which can be used as a reliable library tray system for Hass Avocados. Fruit will be taken from the end of the packing line to reflect both commercial handling quality and intrinsic fruit quality.

Efficient organogenesis of an Australian passionfruit hybrid (Passiflora edulis x Passiflora edulis var. flavicarpa) suitable for gene delivery

An efficient regeneration protocol based on organogenesis from cotyledon explants and suitable for gene delivery has been developed for an Australian passionfruit hybrid. Multiple shoots were regenerated from 30-day-old cotyledon explants on Murashige and Skoog (MS) medium containing 6-benzylvaminopurine (BAP) and coconut water. Media pulsing experiments were conducted to investigate the effect on organogenesis of exposure time of the explants to MS containing 10 mu M BAP and 10% (v/v) coconut water, i.e. passionfruit regeneration medium (PRM). Continuous exposure of these explants to PRM maximised the number of shoots produced to 12.1 per explant. However, periods on hormone-free medium improved the appearance of the shoots and increased the number of explants with shoots from 75 to 84.6%. Further, shoots exposed for 7 days to half-strength MS supplemented with 10 mu M NAA (1-napthalene acetic acid) produced twice as many plantlets than those on half-strength MS alone. Transient GUS histochemical assays indicated delivery of the uidA gene via Agrobacterium tumefaciens.

Multivariate analysis of fresh-cut carambola slices stored under different temperatures.

Quality of fresh-cut carambola (Averrhoa carambola L) is related to many chemical and biochemical variables especially those involved with softening and browning, both influenced by storage temperature. To study these effects, a multivariate analysis was used to evaluate slices packaged in vacuum-sealed polyolefin bags, and stored at 2.5 degrees C, 5 degrees C and 10 degrees C, for up to 16 d. The quality of slices at each temperature was correlated with the duration of storage, O(2) and CO(2) concentration in the package, physical chemical constituents, and activity of enzymes involved in softening (PG) and browning (PPO) metabolism. Three quality groups were identified by hierarchical cluster analysis, and the classification of the components within each of these groups was obtained from a principal component analysis (PCA). The characterization of samples by PCA clearly distinguished acceptable and non-acceptable slices. According to PCA, acceptable slices presented higher ascorbic acid content, greater hue angles ((o)h) and final lightness (L-5) in the first principal component (PC1). On the other hand, non-acceptable slices presented higher total pectin content. PPO activity in the PC1. Non-acceptable slices also presented higher soluble pectin content, increased pectin solubilisation and higher CO(2) concentration in the second principal component (PC2) whereas acceptable slices showed lower total sugar content. The hierarchical cluster and PCA analyses were useful for discriminating the quality of slices stored at different temperatures.

Influence of plant traits on production costs and profitability of strawberry in southeast Queensland.

In Queensland the subtropical strawberry ( Fragaria * ananassa) breeding program aims to combine traits into novel genotypes that increase production efficiency. The contribution of individual plant traits to cost and income under subtropical Queensland conditions was investigated, with the overall goal of improving the profitability of the industry through the release of new strawberry cultivars. The study involved specifying the production and marketing system using three cultivars of strawberry that are currently widely grown annually in southeast Queensland, developing methods to assess the economic impact of changes to the system, and identifying plant traits that influence outcomes from the system. From May through September P (price; $ punnet -1), V (monthly mass; tonne of fruit on the market) and M (calendar month; i.e. May=5) were found to be related ( r2=0.92) by the function (SE) P=4.741(0.469)-0.001630(0.0005) V-0.226(0.102) M using data from 2006 to 2010 for the Brisbane central market. Both income and cost elements in the gross margin were subject to sensitivity analysis. 'Harvesting' and 'Handling/Packing' 'Groups' of 'Activities' were the major contributors to variable costs (each >20%) in the gross margin analysis. Within the 'Harvesting Group', the 'Picking Activity' contributed most (>80%) with the trait 'display of fruit' having the greatest (33%) influence on the cost of the 'Picking Activity'. Within the 'Handling/Packing Group', the 'Packing Activity' contributed 50% of costs with the traits 'fruit shape', 'fruit size variation' and 'resistance to bruising' having the greatest (12-62%) influence on the cost of the 'Packing Activity'. Non-plant items (e.g. carton purchases) made up the other 50% of the costs within the 'Handling/Packing Group'. When any of the individual traits in the 'Harvesting' and 'Handling/Packing' groups were changed by one unit (on a 1-9 scale) the gross margin changed by up to 1%. Increasing yield increased the gross margin to a maximum (15% above present) at 1320 g plant -1 (94% above present). A 10% redistribution of total yield from September to May increased the gross margin by 23%. Increasing fruit size increased gross margin: a 75% increase in fruit size (to ~30 g) produced a 22% increase in the gross margin. The modified gross margin analysis developed in this study allowed simultaneous estimation of the gross margin for the producer and gross value of the industry. These parameters sometimes move in opposite directions.

The Application of Near Infrared Spectroscopy for the Assessment of Avocado Quality Attributes, Infrared Spectroscopy. Chapter 14

Quality and safety evaluation of agricultural products has become an increasingly important consideration in market/commercial viability and systems for such evaluations are now demanded by customers, including distributors and retailers. Unfortunately, most horticultural products struggle with delivering adequate and consistent quality to the consumer. Removing inconsistencies and providing what the consumer expects is a key factor for retaining and expanding both domestic and international markets. Most commercial quality classification systems for fruit and vegetables are based on external features of the product, for example: shape, colour, size, weight and blemishes. However, the external appearance of most fruit is generally not an accurate guide to the internal or eating quality of the fruit. Internal quality of fruit is currently subjectively judged on attributes such as volatiles, firmness, and appearance. Destructive subjective measures such as internal flesh colour, or objective measures such as extraction of juice to measure sweetness (oBrix) or assessment of dry matter (DM) content are also used, although obviously not for every fruit – just a sample to represent the whole consignment. For avocado fruit, external colour is not a maturity characteristic, and its smell is too weak and appears later in its maturity stage (Gaete-Garreton et al., 2005). Since maturity is a major component of avocado quality and palatability, it is important to harvest mature fruit, so as to ensure that fruit will ripen properly and have acceptable eating quality. Currently, commercial avocado maturity estimation is based on destructive assessment of the %DM, and sometimes percent oil, both of which are highly correlated with maturity (Clark et al., 2003; Mizrach & Flitsanov, 1999). Avocados Australia Limited (AAL (2008)) recommend a minimum maturity standard for its growers of 23 %DM (greater than 10% oil content) for the ‘Hass’ cultivar, although consumer studies indicate a preference for at least 25 %DM (Harker et al., 2007).

Effectiveness of Various Artificial Larval Diets for Rearing Bactrocera passiflorae (Froggatt) and B. xanthodes (Broun) in the Laboratory in Fiji

Laboratory colonies of Bactrocera passiflorae (Froggatt) and B. xanthodes (Broun) were established at Koronivia Research Station, Fiji in 1991. Laboratory rearing of the two economically important species was a prerequisite to studies conducted on protein bait spray and quarantine treatment development. To increase the production of laboratory reared fruit flies for this research and also to have a substitute larval diet available, replicated comparisons of the effectiveness of larval diets were carried out using B. passiflorae and B. xanthodes. The diets compared were pawpaw/bagasse, dehydrated carrot and diets used for culturing Mediterranean fruit fly (Ceratitis capitata Wiedemann), Oriental fruit fly (B. dorsalis Hendel), melon fly (B. cucurbitae Coquillett) and B. latifrons (Hendel), pawpaw diet and breadfruit diet. B. passiflorae and B. xanthodes eggs seeded onto the various diets were allowed to develop into larvae, pupae and adults. The percentage egg hatch, number of pupae recovered, percentage pupal mortality, weight of 100 pupae, number of adults and percentage eclosion were used to determine the effectiveness of the diets. Results showed that pawpaw/bagasse and dehydrated carrot diets performed favorably for both species. The pawpaw diet currently used as standard larval diets for both species is the most readily available and easiest to use. Breadfruit diet was tested on B. xanthodes only and showed that it was a suitable substitute for the pawpaw-based diets. Other larval diets, cassava/pawpaw and banana diets, that have been developed and used in the South Pacific areas are also discussed in this paper. When pawpaw or breadfruit are not available, dehydrated carrot diet may be substituted for fruit-based larval diets.

Laboratory-rearing Techniques for Tephritid Fruit Flies in the South Pacific

Laboratory colonies of 15 economically important species of multi-host fruit flies (Diptera:Tephritidae) have been established in eight South Pacific island countries for the purpose of undertaking biological studies, particularly host status testing and research on quarantine treatments. Laboratory rearing techniques are based on the development of artificial diets for larvae consisting predominately of the pulp of locally available fruits including pawpaw, breadfruit and banana. The pawpaw diet is the standard diet and is used in seven countries for rearing 11 species. Diet ingredients are standard proportions of fruit pulp, hydrolysed protein and a bacterial and fungal inhibitor. The diet is particularly suitable for post-harvest treatment studies when larvae of known age are required. Another major development in the laboratory rearing system is the use of pure strains of Enterobacteriaceae bacterial cultures as important adult-feeding supplements. These bacterial cultures are dissected out of the crop of wild females, isolated by sub-culturing, and identified before supply to adults on peptone yeast extract agar plates. Most species are egged using thin, plastic receptacles perforated with 1 mm oviposition holes, with fruit juice or larval diet smeared internally as an oviposition stimulant. Laboratory rearing techniques have been standardised for all of the Pacific countries. Quality control monitoring is based on acceptable ranges in per cent egg hatch, pupal weight and pupal mortality. Colonies are rejuvenated every 6 to 12 months by crossing wild males with laboratory-reared females and vice versa. The standard rearing techniques, equipment and ingredients used in collecting, establishment, maintenance and quality control of these fruit fly species are detailed in this paper.