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- Author or Editor: Emily Hoover x
- Journal of the American Society for Horticultural Science x
The grape species Vitis labruscana Bailey and V. riparia Michx. were subjected to a decreasing photoperiod at constant moderate temperatures to determine whether acclimation occurred in response to a shortening photoperiod. Cane growth, periderm development, killing temperature of the primary bud, and bud dormancy were measured in vines receiving a natural photoperiod (ND), a simulated long photoperiod of 15 hours (LD), and shorter photoperiods of 14, 13, or 12 hours (SD). The LD treatment was effective at maintaining growth and inhibiting periderm development and the onset of bud dormancy in V. labruscana. Cane growth rate with all SD treatments decreased as compared to the LD regime. A significant increase in periderm development occurred with the 12-hour SD treatment. Similarly, the onset of bud dormancy was promoted by the 12-hour SD in V. labruscana. The primary bud killing temperature was 1C lower in V. labruscana under the 12-hour SD than under the LD treatment. In contrast, the LD treatment neither maintained growth nor fully inhibited periderm development and the onset of dormancy in V. riparia. The decrease in the cane growth rate upon exposure to SD was significantly greater in V. riparia than V. labruscana. Periderm development was observed in both the SD and its respective LD-treated V. riparia vines. However, the rate of periderm development was significantly greater in the SD vines than in the LD vines. The onset of bud dormancy was promoted by 13-hour SD in V. riparia. Similarly, the primary bud killing temperature was 2 to 3C lower in V. riparia upon exposure to SD. Vitis riparia has a longer critical photoperiod than V. labruscana and appears to be more sensitive to changes in light intensity or light quality. While the change in freezing tolerance in response to short photoperiods is small, the photoperiod response at a longer critical photoperiod, when combined with lower temperatures, will promote an earlier and possibly more rapid cold acclimation in V. riparia than in V. labruscana.
Abstract
Selection criteria to identify primocane-fruiting red raspberry seedlings (Rubus idaeus L.) with high, early yield are desirable in regions with short growing seasons. To identify possible parents contributing these desirable characteristics, ‘Heritage’, ‘Redwing’, and two genotypes from the Minnesota breeding program were subjected to yield component analysis. In all genotypes, yield was determined by canes/meter of row, fruit per node, and fruit weight. Over the 3-year period, ‘Heritage’ had the highest yield/meter of row, yield per cane, fruit per cane, and number of fruit per fruiting node among all genotypes. Component compensation was highest for ‘Redwing’, while MN 652 had the greatest degree of independence among components. In selecting seedlings for early fruiting and high yield, high cane densities and/or large fruit size will be needed.