Anthony J. Shorter

Heat treatment injury of mango fruit revealed by nondestructive magnetic resonance imaging

Abstract Proton magnetic resonance imaging (MRI) was used to observe disinfestation heat treatment-induced injury in the mesocarp of ripening mango cv. Kensington Pride. Injured areas were characterised by relatively low water levels (low signal intensity) corresponding to air filled cavities and “islands” of starchy mesocarp. Heat treatment-induced lesions started to develop on the day of treatment (day 0) and were maximally evident in fruit held at 22°C by day 4. Nondestructive proton MRI was shown to be a sensitive method for detecting and monitoring the progress of heat treatment-induced injury in mango fruit.

A simple non-destructive method for laboratory evaluation of fruit firmness

Summary. Devices which offer simple, inexpensive, reliable and non-destructive objective measurement of fruit firmness assist in the monitoring of quality. For the present study, the Analogue CSIRO Tomato Firmness Meter (AFM), which measures fruit deformation under a 500 g load applied for 30 s was modified by replacing the analogue displacement gauge with a digital gauge and by using a laboratory jack for positioning the fruit in the vertical dimension. Non-destructive measurements of tomato fruit softening during ripening and determined with the Digital Firmness Meter (DFM) were strongly correlated with both firmness measured with the AFM (r2 = 0.96, n = 19) and with firmness determined subjectively by hand pressure (r2 = 0.93, n = 19). Similarly, mango fruit softening during ripening was monitored and DFM and hand firmness measurements were well correlated (r2 = 0.95, n = 10). The firmness of individual fruit could be measured around 20% faster with the DFM than with the AFM, and displacement was easier to read from the digital than from the analogue display. The DFM proved to be a suitable device for measuring fruit firmness in postharvest laboratory studies and warrants evaluation under commercial packing and handling conditions.

Effect of partial pressure infiltration of calcium into ‘Kensington’ mango fruit

Summary.‘Kensington’ mango fruit harvested at the mature green stage were partial pressure (vacuum) infiltrated with calcium (4 g Ca 2+/L as CaCl2) at 3 reduced pressure levels (–33, –66 and –99 kPa). Concentrations of Ca2+ in unripened calcium-treated fruit were about 1-, 2- and 3-fold higher, respectively, than Ca2+ concentrations in the skin and flesh of control (untreated; i.e. not vacuum infiltrated) fruit. For example, skin tissue Ca2+ concentrations of control fruit and of those treated at –33, –66 and –99 kPa were 1.51, 1.93, 3.42 and 5.01 mg Ca2+/g dry weight, respectively. Concentrations of Ca2+ in the skin of both control fruit and of Ca2+ -treated fruit were consistently higher, by about 2-fold, than those in the fruit flesh. Compared with the –33 kPa infiltration treatment, Ca2+ levels in the fruit flesh were increased by only about 2-fold by further reductions in the partial pressure infiltration levels to –66 or –99 kPa. Infiltration of Ca2+ into mango fruit was apparently via lenticels and along xylem conduits open at the cut pedicel. These infiltration pathways were revealed by inclusion of Brilliant Blue dye in the Ca2+ solution. Undyed and dyed lenticels were separately excised for Ca2+ analysis. Dark (dyed) lenticels had higher Ca2+ concentrations (1.86 ± 0.11 mg Ca2+/g dry weight) than light (undyed) lenticels (0.83 ± 0.19 mg Ca2+/g dry weight). Partial pressure infiltration of Ca2+ at any of the 3 subatmospheric pressure levels did not result in shelf life extension. Fruit infiltrated at –66 and –99 kPa exhibited injuries, which included exacerbated lenticel blackening and anaerobic off-odour and taste evident at the end of shelf life. In comparison, both control (untreated) mango fruit and those infiltrated with Ca2+ at –33 kPa ripened normally.

Vase life characteristics of selected Grevillea

Grevillea is a large genus containing many species, forms and hybrids bearing inflorescences with desirable cut flower characteristics. Nineteen different Grevillea spp. and forms (7), and 39 hybrids (including 11 repeat collections) were assessed for vase life. Longevity varied 3-fold, from 3 days for G. wickhamii to 9 days for a G. whiteana accession. Species with comparatively long vase lives included G. pteridifolia, G. sessilis and G. whiteana. These genotypes may be useful for cut flower production and/or in breeding programs aimed at producing new cut flower Grevillea.

Effect of ethylene absorption on the storage of Granny Smith apples held in polyethylene bags

Abstract Granny Smith apples grown in Western Australia are highly susceptible to the physiological disorders bitter pit and superficial scald, after short periods of storage. Granny Smith apples were held in sealed polyethylene bags with and without an ethylene absorbent Purafil (potassium permanganate on aluminium oxide). In two seasons the ethylene levels were markedly reduced with the use of potassium permanganate while the severity of bitter pit and superficial scald were also reduced. These effects of ethylene removal may be due to the delaying of fruit senescence.

Long term, low temperature storage injures kangaroo paw cut flowers

Abstract Cut kangaroo paw ( Anigozanthos spp.) inflorescences are regarded as having poor storage potential. Storage for up to 4 weeks at temperatures between 0 and 10°C was investigated. Post-storage vase life and chlorophyll fluorescence data collected for the hybrids ‘H1’ and ‘Bush Dawn’ showed that this crop is chilling sensitive. There was a marked drop in quality at

A triazole compound extends the vase life of Geraldton waxflower

A triazole compound, triadimenol, and metluidide were evaluated as vase solution ingredients for Geraldton waxflower. It was anticipated, on the basis of published literature, that these chemicals might induce endogenous abscisic acid (ABA) accumulation and associated stomatal closure, thereby providing an improved water balance. Triadimenol (10 mg/L) generally extended both foliage and flower vase life for the 3 cultivars of Geraldton waxflower studied. However, the increased longevity was associated with greater, rather than less, vase solution usage. Therefore, stomatal closure was not induced, and the beneficial effect was evidently not a function of significantly increased endogenous ABA levels. Mefluidide did not extend the vase life of Geraldton waxflower.