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Patricia A. Lindsey and Nina L. Bassuk

The development of a rapid, accurate, yet nondestructive technique for expressing whole-tree leaf area would be extremely useful in studying various growth phenomena in trees. The objective of this research was to evaluate the accuracy of an image analysis process adapted for estimating the leaf surface area of four broad-leafed tree species (Amelanchier L. `Robin Hill Pink', Tilia americana L. `Redmond', Sophora japonica L. `Regent', Fraxinus americana L. `Autumn Purple' and Fraxinus pennsylvanica Marsh.). Video images of photographs taken of each tree canopy were quantified by an image analyzer into unitless surface area values or silhouette areas. The relationship between estimated leaf area as calculated from silhouette area and actual leaf area of these trees as determined by a leaf area meter was highly correlated. Use of this technique would enable a researcher, simply from serial photographs of the canopy, to retroactively estimate leaf or canopy area at crucial interim periods.

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Malcolm W. Smith, Mark D. Hoult, and Jeremy D. Bright

Low yields and high harvesting costs are long-standing problems in mango (Mangifera indica L.) cultivation. In an effort to increase productivity in the scion 'Kensington Pride' we examined the impact of nine different rootstocks over a 10-year period. Rootstock effects on fruit production were significant in most seasons, and cumulative yields (nine seasons of cropping) for the best treatment ('Sg. Siput') exceeded those of the poorest treatment ('Sabre') by 141%. Yield efficiencies (expressed on both a trunk cross-sectional area and canopy silhouette area basis) were also significantly affected by rootstock. Rootstock effects on yield and yield efficiency were generally consistent across seasons, despite large seasonal variations in yield. Harvest rates were also influenced by rootstock, and were poorly correlated with tree size. These results demonstrate possibilities for manipulating mango scion productivity through rootstock genotype.

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Malcolm W. Smith, Jeremy D. Bright, Mark D. Hoult, Richard A. Renfree, Tony Maddern, and Neil Coombes

capture and analysis methods were used and a projected canopy silhouette area (CSA) value obtained for each tree ( Smith et al., 2003 ). The start of fruit harvesting in each season was determined by testing flesh dry matter content and normally occurred