Needleless shoots and loss of apical dominance in greenhouse-grown loblolly pine (Pinus taeda L.)

Loblolly pine that is winter-sown in the greenhouse and spring-outplanted has been observed to exhibit growth abnormalities in the form of multiple apical and needleless shoots. Seedlings that exhibit growth abnormalities are of questionable value in the evaluation of progeny tests. The use growth data from this seedling material could result in biased and erroneous or invalid conclusions about individual tree or family performance. To determine the causes of growth abnormality development, and to suggest possible remedies, two experiments were initiated. The first experiment examined the effects of raising five Virginia controlled-cross families in two different greenhouses and subsequently outplanting the seedlings on two contrasting sites. The second examined the effects of pre-planting exposure to 0, 4, or 6 weeks of shortened days followed by 0, 400 or 600 hours of chilling and post-planting supplemental water. Experiment one results indicated that abnormalities were more apparent at the better growing site. Further, pre-planting hardening-off likely increased the dormancy status of the seedlings and somewhat alleviated growth abnormalities. It was determined that families varied in the expression of abnormalities. Abnormalities were only observed during the first summer after outplanting; symptoms were alleviated after overwintering. Experiment two results indicated that treatments that influenced the dormancy status of the seedlings influenced the development of growth abnormalities. Pre-planting shortened days resulted in increased needles per total stem units for the second flush. Pre-planting chilling and post-planting supplemental water increased apical dominance.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Forestry

Department dc:contributor.department

Forestry

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1994

Author dc:creator

• Peterson, John A.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

etd-06302009-040512

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/43512