Title page for ETD etd-07022001-083225


Type of Document Master's Thesis
Author Clarke, Jodie Johnson
URN etd-07022001-083225
Title Development of a Greenhouse Tobacco Seedling Performance Index
Degree Master of Science
Department Crop and Soil Environmental Sciences
Advisory Committee
Advisor Name Title
Reed, Thomas David Committee Chair
Jones, James L. Committee Member
Welbaum, Gregory E. Committee Member
Wilkinson, Carol A. Committee Member
Keywords
  • tobacco
  • seedling performance
  • emergence
  • digital imaging analysis
Date of Defense 2001-05-02
Availability unrestricted
Abstract
Tobacco seed performance is traditionally measured as percentage

germination at 14 d under controlled laboratory conditions. However, under

greenhouse conditions, seed lots with equal 14-d germination may exhibit

substantial differences in uniformity of early seedling growth and spiral root

incidence that impact the number of usable transplants. A seedling performance

index (SPI) was developed to quantitatively describe greenhouse tobacco seedling

performance. The 14-d emergence, relative leaf area uniformity, and seedling leaf

area determined by computer image analysis were used to calculate the index.

Greenhouse tobacco seed trials demonstrated that seed with the Rickard pellet had

higher emergence, but the higher spiral root incidence associated with the Rickard

pellet lowered the SPI compared to the Cross Creek pellet. Primed seed lots of

flue-cured cultivars (NC 72 and NC 71) had a significantly higher SPI than the

nonprimed seed lots at one location but not at a second location. Seed lots sown

in Premier Pro-Mix TA commercial medium had a higher spiral root incidence,

which resulted in a lower SPI compared to Carolina Choice, Carolina Gold, and

Sunshine LP5 commercial media. The index quantitatively determined

differences in seedling performance under greenhouse conditions not reflected by

standard germination tests. Significant differences in the SPI were observed

among seed lots with certified 90% germination. The SPI is a simple method to

describe seedling performance because the data used to calculate the SPI is

obtained from one seed tray image. In contrast, frequent counting and seedling

evaluations are involved with standard germination and vigor tests.

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