Physicochemical properties were assessed for the fruit of 16 saskatoon (Amelanchier alnifolia Nutt.) cultivars harvested in 1998–2000 from replicated trials at two sites (Saskatoon and Moonlake, SK). The cultivars included Bluff, Buffalo, Elizabeth (at Saskatoon only), Forestburg, Honeywood, JB30, Martin, Nelson, Northline, PAR 90, Parkhill, Pearson II, Pembina, Smoky, Success, and Thiessen. Fruit weight and total solids, soluble solids, pH, titratable acidity, anthocyanin content, and colour characteristics of the fruit juice extracts were measured. Fruit of Martin, Thiessen and PAR 90 had the highest fruit weights (mean = 1.63 g), and Success and Bluff the lowest (mean = 0.79 g). Total and soluble solids contents ranged among cultivars from 19.9% and 14.0 °Brix, respectively, for JB30, to 27.9% and 20.1 °Brix, respectively, for Pembina. Fruit pH ranged from 3.65 for Nelson to 4.18 for Parkhill and Smoky. Fruit of Nelson had a titratable acidity (0.63%) that was approximately twice that of Success, Pearson II, Forestburg, Honeywood, Smoky and Parkhill. The soluble solids to titratable acidity ratio (SS/TA) differed greatly among cultivars ranging from 27 for JB30 to 55 for Parkhill. The colour characteristics of the fruit juice extracts differed among cultivars in chroma and L values, but not in hue angle. Anthocyanin analysis by HPLC identified four peaks: cyanidin-3-galactoside, cyanidin-3- glucoside and two unknowns. Total fruit anthocyanin content ranged from 414 µg g-1 for Forestburg to 852 µg g-1 for Nelson. Correlations were found between anthocyanin content and fruit pH, titratable acidity, hue angle and L value. Key words: Amelanchier alnifolia, saskatoon, fruit composition, acidity, anthocyanin content

, and black currant (Ribes nigrum L.) were assessed from fruit harvested from replicated cultivar trials at Saskatoon, SK, and at Yorkton, SK, in 1999 and 2000. Fruit weight, total solids, soluble solids, pH, titratable acidity, percent pit, estimated percent flesh, and Hunterlab colour characteristics were measured. Fruit of the chokecherry cultivars ranged in their 10-fruit weights from 6.6 to 9.2 g, percent pit from 9.4 to 16.0%, estimated percent flesh from 17.2 to 23.7%, and pH from 3.86 to 4.25. Mean total solids and soluble solids contents were 35.2% and 18.3°Brix, respectively, and did not differ among the cultivars. Hue angle, chroma and L values of chokecherry fruit juice extracts ranged from 34.6 to 88.2°, 15.3 to 23.9, and 23.3 to 51.1, respectively. Fruit of the highbush cranberry cultivars ranged in their 10-fruit weights from 4.1 to 7.3 g, percent pit from 4.6 to 9.0%, estimated percent flesh from 10.9 to 14.0%, soluble solids content from 10.2 to 13.3°Brix, and pH from 2.89 to 3.13. The hue angle and L values of the fruit juice extracts of the highbush cranberry cultivars ranged from 16.0 to 18.2°, and from 15.5 to 21.3, respectively. Mean total solids content and L values were 18.9% and 18.0, respectively; both measurements did not differ significantly among the cultivars. Fruit of the black currant cultivars differed only in their 10-fruit weight, pH and titratable acidity which ranged from 7.5 to 12.8 g, 2.85 to 3.04, and 3.04 to 4.03%, respectively. Mean total solids and soluble solids contents of black currant fruit were 22.3% and 15.8 o Brix, respectively. Black currant fruit juice extracts had a mean hue angle, chroma and L values of 13.2°, 12.6 and 9.8, respectively.

We report on a hand-held multiplexed impedance sensor system and show evidence for impedance-based monitoring of the growth of a single bacterium.

The influence of leaf-wetness duration and temperature on infection of Amelanchier alnifolia (saskatoon) by Entomosporium mespili was quantified in controlled-environment studies. Plants were inoculated with a conidial suspension and then subjected to a period of leaf wetness (0, 6, 12, and 24 h), after which they were moved to a growth room set at a fixed temperature (10, 15, 20, 25, and 30°C) for a period of 14 d. Infection levels rose as the leaf-wetness duration increased for combined temperature treatments up to 24 h. Temperatures between 10 and 20°C promoted optimal leaf infection for leaf-wetness periods longer than 6 h. Above the optimal temperature range, mean disease levels decreased. ANOVA with orthogonal contrasts and stepwise regression were used to create a regression equation that describes the relationship of E. mespili infection on saskatoon to both temperature and leaf-wetness duration. Combinations of temperatures between 10 and 25°C and leaf-wetness periods between 6 and 24 h were optimal for lesion development on younger saskatoon leaves.