Influence of deficit irrigation and kaolin particle film on grape composition and volatile compounds in Merlot grape (Vitis vinifera L.).

The effect of deficit irrigation and a kaolin-based, foliar reflectant particle film (PF) on grape composition and volatile compounds in Merlot grapes was investigated over two growing seasons in semi-arid, south-western Idaho. Vines were provided with differential amounts of water based on their estimated crop evapotranspiration (ET(c)) throughout berry development, and particle film was applied to half of the vines in each irrigation main plot. Free and bound volatile compounds in grapes were analyzed using stir bar sorptive extraction-gas chromatography-mass spectrometry (SBSE-GC-MS). The concentrations of free C(6) compounds (hexanal, trans-2-hexenal, and 1-hexanol) decreased, and bound terpene alcohols (nerol and geraniol) and C(13)-norisoprenoids (ß-damascenone, 3-hydroxy-ß-damascenone, 1,1,6-trimethyl-1,2-dihydronaphthalene, and 3-oxo-α-ionol) increased in berries each year in response to severity of vine water stress. Concentrations of C(13)-norisoprenoids and bound forms of nerol and geraniol were positively correlated with their concentrations in the corresponding wines. Particle film application had minimum effect on free and bound volatile composition in the grapes, and there was no interactive effect between particle film and deficit irrigation. However, particle film application enhanced the total amount of berry anthocyanins.

Reduction of Green Mold on Grapefruit after Hot Forced-Air Quarantine Treatment.

Lesions on grapefruit developing from wounds inoculated with a spore suspension of Penicillium digitatum just prior to heating for 300 min in 46°C moist, forced air developed less rapidly during 4 days of storage at 21°C than lesions formed from inoculations made after the fruit were heated, or lesions on non-heated fruit. Since the lesion size on fruit inoculated after heating was similar to that on fruit that were not heated, induced host resistance via lignification or accumulation of phytoalexins probably did not occur. Results from this research demonstrate that development of green mold on grapefruit caused by P. digitatum is inhibited by time and temperature regimes of moist, forced air that are known to provide quarantine security against Mexican fruit fly.