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  • Author or Editor: David K. Wildung x
  • Journal of the American Society for Horticultural Science x
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Abstract

Three seedling populations of lingonberries from Fairbanks, Alaska, Oulu, Finland, and the Pasvik River Valley, Norway were exposed to 0, 170, 344, 513, 681, 843, 1013, and 1185 hours of continuous chilling temperatures (4 ± 1°C) to determine chilling requirements necessary to satisfy rest. Both the Finnish and Alaskan populations required at least 681 hours of chilling to obtain maximum terminal vegetative budbreak. Continuous chilling for 1185 hours was insufficient to obtain maximum budbreak in the Norwegian population. In the Finnish and Alaskan populations neither the percentage of stems exhibiting lateral budbreak nor the number of lateral branches per stem differed among chilling treatments. Plants from Norway showed significantly greater lateral budbreak in the 513- and 681-hour treatments than in all other treatments. At least 681 hours of chilling were necessary to achieve normal flowering in the Finnish population.

Open Access

Abstract

‘Northblue’ blueberry (Vaccinium corymbosum L.) plants propagated by tissue culture (TC) have a branching pattern and growth rate different from plants propagated by leaf-bud cuttings. Two to 3 times more basal branches were formed on tissue culture-derived plants by the time they were 27 to 34 weeks old. These basal branches were maintained on older plants in the field, where lateral branching was also twice as high. The growth rate of the young TC-derived plants was 3 times the rate of young leaf-bud, cutting-propagated (ST) plants. However, lateral branch length of older plants in the field was similar for both groups of plants, indicating a reduction in the growth rate of TC-derived plants from 34 to 82 weeks after propagation. Pruning and chilling methods reduced basal branch length and the number of lateral branches produced in the field, while enhancing the length of lateral branches and total buds per lateral branch. Although TC-derived blueberry plants had numbers of total flower buds and total buds per lateral branch similar to ST-derived plants, they produced more flower buds per plant. The enhanced branching framework of TC-derived plants, composed of rapidly forming basal and lateral branches, may increase photosynthesis at an early age and hasten fruit production.

Open Access

Plants of `Northblue' blueberry, propagated in tissue culture (TC) or from softwood, single-node cuttings (ST), were evaluated in field plantings established in 1984 at Becker and Grand Rapids, in central and northern Minnesota, respectively. Plantings were observed from 1987 through 1994 to determine the persistence of such effects as increased vigor, more spreading growth habit, and higher yield observed for TC plants during the initial 3 years after planting. TC plants had significantly higher yields at Grand Rapids in 1989 and 1994. At Grand Rapids, the consistently greater plant spread (bearing area) of TC plants resulted in higher yields of TC plants over all years combined. At Becker, TC and ST plants did not differ for plant height or spread after 10 years and, in 2 of 5 years, ST plants had heavier average berry weights. At Grand Rapids, TC plants did not differ consistently in height, or subjective ratings of the amount of bloom or crop. The effects of propagation method on yield and growth habit of `Northblue' are limited to early years in warmer locations, but can be of longer-term significance in colder areas with shorter growing seasons and lower winter temperatures, where plant spread is a more important factor than plant height in determining yield.

Free access