Seven Vaccinium angustifolium clones were tested for low-temperature tolerance over two dormant seasons. Flower primordia in the pseudoapical bud were damaged at higher temperatures than were stem tissue and primordia of the fourth floral bud. The flower primordia located at the stem tip also reacclimated earlier and seemed to show a stronger response to abrupt spring warming than did other tissues tested. Given the lowest survival temperatures determined and the ambient temperatures recorded, we recommend that the physiological and economic aspects of cryoprotectants and flower-delaying treatments be studied further.
Paul E. Cappiello and Scott W. Dunham
Rizwan Maqbool, David Percival, Qamar Zaman, Tess Astatkie, Sina Adl, and Deborah Buszard
. 108 520 522 Glass, V.M. Percival, D.C. Proctor, J.T.A. 2005 Tolerance of lowbush blueberries ( Vaccinium angustifolium Ait.) to drought stress. I. Soil water and yield component analysis Can. J. Plant Sci. 85 911 917 Ismail, A.A. Smagula, J
Paul E. Cappiello
Lowbush blueberry (Vaccinium angustifolium) is a major fruit crop in costal, Northern New England and Atlantic Canada. One of the factors affecting production is low temperature damage of flower primordia. In addition to mid-winter damage, much of the damage occurs in spring due to late frosts. A study was designed to examine the seasonal variation in the LT50 of fruit buds and to determine the location of the tissue damage.
Field-collected stems were exposed to controlled temperature drops and examined for damage. Three types of damage were identified; destruction of flower primordia, browning of vascular tissue within the fruit-bud, and browning of stem tissue at the base of the bud. The seasonal variation of the occurrence of this damage will be discussed.
Paul E. Cappiello
During the winters of 1993–94 and 1994–95, 54 clones of Vaccinium angustifolium were evaluated for low-temperature tolerance of inflorescence buds. During both seasons, clones were tested periodically, starting right after leaf drop, continuing through mid-winter, and finally through spring loss of low-temperature tolerance. Plants showed greatest variation in lowest survival temperature (LST) during fall and spring sampling dates, and the least variation on the mid-winter dates. In the 1993–94 study, clonal LSTs for November buds ranged from –5 to –27C; January buds showed LST variation of 6C. April buds showed a similar trend to that observed in late November. LST variation is discussed relative to clonal selection for ornamental and commercial use.
V.M. Glass, D.C. Percival, and J.T.A. Proctor
Drought is the most limiting factor of crops worldwide. Sound management of any crop is based on a knowledge of its physiology as well as response to drought. Therefore, water use management has become an agricultural priority, with increased research focusing on plant growth and yield under limited water conditions. The lowbush blueberry (Vaccinium angustifolium Ait.) is the most important horticultural crop in Nova Scotia in acreage, export sales, and value to the economy. A study initiated at the Nova Scotia Wild Blueberry Inst., Debert (45°26′N, 63°27′W), N.S., during the 1998 growing season investigated the effects of water availability on the growth and development of the lowbush blueberry. Treatments consisting of supplemental irrigation (i), drought stress (d), and a control (c) were applied to plants in their cropping phase of production. Net photosynthetic rates (Pn) were highest during bloom (i: 11.9, d: 9.7, c: 9.8 μmol·m-2·s-1) and then declined throughout the season. No significant (P = 0.05) treatment effect on Pn was observed. Stem sample analysis before harvest showed no significant differences (P = 0.05) between stem length, node number, flowering node number, flowering zone length, or number of fruit per stem. Samples from 1-m2 quadrats indicated the drought-stressed plots produced the lowest yield (378 g·m-2) compared with the supplemental irrigation (449 g·m-2) or control (512 g·m-2) plots. Results from this study suggest drought stress on the lowbush blueberry does not produce significant differences in the number of fruit set; it does result in smaller fruit.
Jun Gu Lee*, Jong Nam Lee, Eung Ho Lee, and Byoung Yil Lee
Lowbush blueberry (Vaccinium angustifolium Ait.) have some potential agricultural benefits for soil covering and high nutritive antioxidant fruit production in highland of South Korea. As a preliminary research step to introduce and to rapidly propagate the lowbush blueberry in South Korea, we evaluated the cutting propagation efficiency under several cutting conditions. The pH of peatmoss media were adjusted to five target values of 4.5, 5.0, 5.5, 6.0, and control with air-slaked lime. Peat-moss were mixed with perlite at five levels of volume ratios in separate experimental design. The cuttings were also prepared with the three cutting regions from mother stock shoots and the number of nodes per cutting. The rooting of V. angustifolium cuttings initiated at 50 days after cutting in nursery bed, and at 70 days after cutting, shallow root ball were developed by 0.5 cm diameter. The rooting rate and root ball development were favorable in the pH 4.5 and nonadjusted control (pH 4.15) while the mixed ratio of perlite did not affect on rooting efficiency ranging from 30% to 50% mixed treatment. Terminal and intermediate region from newly developed shoot performed higher cutting efficiency compared to the basal region, and four to six nodes per each cutting showed favorable shoot growth and root ball development compared to the 2-node cutting. Thus the cutting of upper shoot region having four to six nodes in acidic peatmoss nursery containing 30% to 50% perlite might be suitable preliminary screened conditions. The cutting propagation efficiency of the five lowbush blueberry clones were also evaluated depending on the summer and early spring cutting.
Youzhi Chen, John M. Smagula, Walter Litten, and Scott Dunham
In a managed field of native Vaccinium angustifolium Ait. clones, the effect of fall foliar sprays of B at 345 g·ha-1 and/or Ca at 3,450 g·ha-1 in remedying tissue deficiency of B varied among 12 clones, as seen in pollen germinability and on individual stems as seen in flower number, fruit set, and number of harvestable berries. With Ca applied alone, increased berry size did not overcome yield reduction due to fewer flowers and berries per stem. Berry diameter and mass correlated better to number of seeds of germinable size than to total number of seeds. Pollen germination averaged 17.4% on stigmata from untreated clones, and all three treatments (B, Ca, B + Ca) increased that average by 8%. More seeds per berry with the B-alone treatment implies more ovules fertilized when B deficiency is remedied. No relation was found between in vitro and in vivo pollen germination.
Scott N. White, Nathan S. Boyd, and Rene C. Van Acker
production regions such as Maine will be important for assessing the applicability of the models outside of Nova Scotia. Literature Cited Aalders, L.E. Hall, I.V. 1964 A comparison of flower-bud development in the lowbush blueberry, Vaccinium angustifolium
Paul E. Cappiello and Scott Dunham
Commercial lowbush blueberry production involves management of what have long been considered highly diverse populations of naturally occurring clones. Wide phenotypic variation evident in fields has often been anecdotally equated with variation in yield, cultural requirements, etc., however this has not been tested rigorously. Interest in selection of clones with superior low-temperature tolerance prompted this study to estimate population-wide variation within the species. Thirty six clones of Vacciniun angustifolium exhibiting most of the typical phenotypic classes were selected from two commercial production fields in Maine. Plants were evaluated for low-temperature tolerance of reproductive and vascular tissues on a monthly basis from November through April. In addition, variation in relative time of anthesis, flower structure, and floral low-temperature tolerance were determined. Results are discussed with respect to potential for selection of superior clones for both fruit production and ornamental use.
Sharon Morrison, John M. Smagula, and Walter Litten
For accelerating the filling in of bare areas in native lowbush blueberry fields or converting new areas to production, micropropagated plantlets rooted after three subcultures outperformed seedlings and rooted softwood cuttings. After 2 years of field growth, they averaged 20.3 rhizomes each of average dry weight 3.5 g, as compared with 5.7 rhizomes of average dry weight 1.1 g for rooted softwood cuttings. After 1 year of field growth, seedlings produced on average 3.3 vs. 0.4 rhizomes from micropropagated plants that had not been subcultured and 0.3 rhizomes from stem cuttings. Apparently, subculturing on cytokinin-rich media induces the juvenile branching characteristic that provides micropropagated plants with the desirable morphologies and growth habits of seedlings. These characteristics favor rhizome production while the benefits of asexual reproduction are retained. The advantage in rhizome production of micropropagation over stem cuttings varied among clones.