Date of Award

12-2011

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Horticulture

Advisor

John M. Smagula

Second Committee Member

David Lambert

Third Committee Member

Stephanie Burnett

Abstract

Lowbush blueberry (Vaccinium angustifolium Ait.), and lingonberry ( Vaccinium vitis-idaea L.) are rhizomatous shrubs that are valuable species for use as commercial small fruit crops as well as ornamental landscape plants. A stem cutting propagation study, using the subspecies of lingonberry native to Maine [Vaccinium vitis-idaea L. subsp. minus (Lodd.) Hulten] assessed the optimum time to propagate Maine clones by stem cuttings for optimum rooting and rootball size. Although the cuttings from the 13 June sticking date had a high rooting percentage equivalent to the October dates (2 and 31 October), the cuttings from the two October dates produced rootballs greater than twice the size of the 13 June cuttings. These results indicated that the highest rooting percentage and largest rootballs are produced on lingonberry stem cuttings of current season's growth collected in the fall for Maine clones. Shoot growth of 'Burgundy' lowbush blueberry plants was evaluated in a typical trade gallon container or a wider shallower nursery mum pan with one of four medium compositions. Shoot dry weights of plants growing in both containers were similar, but plants growing in nursery mum pans had a greater shoot growth index. Shoot dry weights of plants grown in both 3:1 and 1:1 sphagnum peat moss and coarse sharp sand container medium compositions were greater than plants grown in the commercial pine bark nursery mix and the commercial pine bark nursery mix with added coir. Plants growing in the 3:1 sphagnum peat moss and coarse sharp sand medium composition had the greatest shoot growth index. The results of this study indicated that optimum nursery container production of lowbush blueberry includes the use of wide shallow containers, and a container medium with sphagnum peat moss (predominantly) and coarse sharp sand. Increasing rhizome growth will benefit commercial growers by filling in bare areas in fields or increasing the rate of establishment of new plantings. Three field studies were conducted to evaluate the effects of plant growth regulators and sucrose on rhizome growth. In 2009, foliar applications of three growth regulators, ethephon (2-chloroethylphosphonic acid), naphthaleneacetic acid [2-(l-naphthyl)acetic acid], and prohexadione-Ca (prohexadione-calcium, calcium 3-oxido-5-oxo-4-propionylcyclohex-3-enecarboxylate), were made once on 17 June when shoots were approximately 4 cm tall. Plants receiving 125 mg·L-1 prohexadione-Ca produced almost three times as many rhizomes as the control. In 2010, foliar applications of prohexadione-Ca were made once on 25 June when most stems were approximately 8 cm tall. Sucrose solution drenches (240 g in 6L water) were made on 7 July and 28 July. In this study, none of the treatment applications were effective at increasing rhizome growth. Stem measurements indicated that applications may have been made too late in the growing season to be effective. In 2011, single applications of prohexadione-Ca at one of two concentrations (125 mg·L-1, 250 mg·L-1) on one of three dates (6 June, 15 June, 27 June) were made to assess the effects of concentration and timing of application on rhizome growth. Plants receiving prohexadione-Ca at 250 mg·L-1 on 27 June produced the greatest number of rhizomes and rhizome tips per treatment plot. The results of the three studies presented here indicated that prohexadione-Ca may be effective at improving rhizome growth of lowbush blueberry, but concentration and timing of application are critical for success.

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