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Peter J. Stoffella and Mike F. Fleming

Cabbage [Brassica oleracea L. (Capitata Group) cv. Bravo] transplants were grown on raised beds at Fort Pierce, Fla., during Fall 1987 and 1988. Plants were spaced at 8, 15, 23, 30, and 38 cm within rows or populations equivalent to 123,000, 61,500, 41,000, 30,800, and 24,600 plants/ha. Individual root weights, total plant weights, and core length increased linearly as within-row spacing (WRS) increased in both experiments. Untrimmed head weights, trimmed head weights, head height, head width, and core width increased quadratically as WRS increased in both experiments. Head shape and core index did not differ among WRS in either experiment, except for a quadratic increase in the head height: bead width ratio (head shape) as WRS increased in the 1988 experiment. Coefficients of variability (cv) for most measured variables decreased as WRS increased, indicating a reduction in plant-to-plant variation. Optimum marketable cabbage head size (>1 kg) and lower plant-to-plant variation (cv < 20%) were obtained at WRS of 23 cm or wider. However, trimmed cabbage yields decreased linearly as WRS increased in both experiments. In this study, a lower plant population (WRS > 23 cm) was more conducive to a once-over cabbage harvest since plant-to-plant variation in head size and other yield and quality characteristics was reduced.

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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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Shahrokh Khanlzadeh, Michel J. Lareau, and Deborah Buszard

During 1987-90, nineteen strawberry cultivars and one selection from Agriculture Canada/McGill University were evaluated for their fruiting and other plant characteristics. Based upon an index of potential return which Integrates percent yield at each harvest date and total yield, the following cultivars listed in decreasing order of desirability (early productivity) are recommended: `Chambly', `Annapolis', `Honeoye', `Kent' and `Cavendish'. `Lina', `Lester', SJ83OR-2, `Bounty' and `Settler' have the most concentrated ripening period based upon an index of concentration. Highest yields were obtained with `Honeoye', SJ83OR-2, `Chambly', `Kent', Glooscap` and `Oka'. All had large, medium-firm fruit. Because of their tolerance to the herbicide terbacil and their large, medium-firm fruit, `Chambly', `Oka' and SJ830R-2 appear to be potential replacements for the commercial cultivars `Kent', `Honeoye' and `Glooscap' and are recommended for trials in Quebec. `Cornwallis', `Settler', `Midway', `Cavendish' and `Redcoat' had the lowest yield variability of the cultivars on trial.

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Babak Talebpour, Maksut Barış Eminoğlu, Uğur Yegül, and Ufuk Türker

) measured per-tree yield variability in a highly productive pear orchard using site-specific management procedures and estimated the variability of profit per tree yield. Rey Pedro (1995) determined the spatial and temporal variability of olive trees to

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Patrick L. Byers, Andrew L. Thomas, and Margaret Millican

uniformly in the cymes, and are resistant to shattering. Berry weight ranges from 52 to 111 mg ( Finn et al., 2008 ). Yield variability was noted between the Mountain Grove and Mount Vernon sites with Mountain Grove plots producing higher yields but smaller

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Arthur Villordon, Julio Solis, Don LaBonte, and Christopher Clark

; Somasundaram and Mithra, 2008 ). Such models represent an important step in further understanding the complex interactive nature of management and agroclimatic variables on sweetpotato storage root yield variability. These phenology-driven models specified that

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Jongtae Lee, Byeonggyu Min, Heedae Kim, Juyeon Kim, Young-Seok Kwon, and George E. Boyhan

formation, resulting in decreased marketable bulb yield. Onion bulb yield variability has been largely explained by both short-term extreme precipitation and temperature variability (drought-heat stress) for long-day onions in the Czech Republic ( Potopova

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Charles E. Barrett, Lincoln Zotarelli, Lucas G. Paranhos, Peter Dittmar, Clyde W. Fraisse, and John VanSickle

indicate the limitations of the reduced data set for the bare ground system as compared with the plasticulture system and depict the yield variability seen in both systems. The bimodal distribution in yield seen for the bare ground system would be expected

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Russell Galanti, Alyssa Cho, Amjad Ahmad, and Javier Mollinedo

(1992) reported a reduction in macadamia tree growth when N leaf concentrations were less than 1.22% and is implicated in yield variability ( Stephenson and Cull, 1986 ). The current practice of collecting leaf samples is time-consuming and expensive

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Samir C. Debnath

affecting yield (berry size, number of berries per cluster, and stem density) results in great yield variability within a field. The genetic diversity between wild clones has been verified by molecular techniques ( Debnath, 2009 ). The variability in fruit