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Brian A. Birrenkott and Elden J. Stang

Selective flower removal was used in 1987 and 1988 to evaluate intraplant competition or inhibition within flowering uprights of `Searles' cranberry (Vaccinium macrocarpon Ait.). The lowest two flowers were removed from uprights at various stages of plant development in 1987. With one or both of the two earliest, i.e., lowest, flowers developing `into fruit, 25% of the remaining flowers matured into fruit. Removal of the earliest two flowers at preblossom or late blossom resulted in ≈ 46% fruit set for the remaining flowers. Slightly fewer upper flowers set (36%) when the earliest flowers and fruit were removed at early fruit development. In 1988, the lowest two flowers were removed at preblossom and natural insect pollination was supplemented by hand pollination. Hand-pollinated (upper) flowers set 58% when the lowest two flowers were removed, compared to 17% for the unthinned control. Yield and fruit numbers were lowered slightly as a result of flower thinning in both years. A significant amount of variation in fruit production was explained by the number of flowering uprights per unit of production area in both years.

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Herbert D. Stiles

Static-V trellis increases raspberry yield, but fruiting shoots grow toward its center making harvest difficult. Shading causes early leaf abscission and it favors fungus diseases inside the V. Static training of floricanes and primocanes to opposite sides of a V trellis prevents neither harvest difficulty, nor primocane injury during harvest. In 1988-89 harvest difficulties were reduced by bloom-time shifting of floricanes on a V-trellis. Over 90% of fruiting shoots were oriented to the trellis ' exterior, but primocane shading and early leaf abscission continued. The 'bent fence' trellis was designed and tested in 1989. It shifts floricanes from horizontal orientation to an upright position on one side of a V-shaped trellis, thus retaining outward display of fruiting shoots and achieving unobstructed display of primocanes on the opposite side. Harvest efficiency, disease reduction, accurate deposition of pesticides, avoidance of solar injury (sun scald), and adaptation of mechanical pest control procedures are potentiated by this system. It also reduces impediments to studies of carbohydrate partitioning, photosynthetic efficiency, yield efficiency, and intraplant competition.

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Susannah Amundson, Dennis E. Deyton, Dean A. Kopsell, Walt Hitch, Ann Moore, and Carl E. Sams

correspond to the findings of Papadopoulos and Ormrod (1990) . They found that with a narrow plant spacing, yield per plant declined but yield per area increased. This can be explained by the increased interplant and intraplant competition that is imposed

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Pedro Brás de Oliveira, Maria José Silva, Ricardo B. Ferreira, Cristina M. Oliveira, and António A. Monteiro

, carbohydrate reserves remained at a similar level at the end of the cycle regardless of intraplant competition. Also at the end of the growing cycle, starch concentration was replenished to the initial level. This pattern of variation was already described for

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Katherine F. Garland, Stephanie E. Burnett, Michael E. Day, and Marc W. van Iersel

. At lower DLI, petiole length of the uppermost fully expanded leaf increased, allowing plants to reduce intraplant competition for light ( Fig. 5A ). Phytohormones play a key role in such plant responses to changing light conditions ( Stamm and Kumar