Masters Theses

Date of Award

8-2008

Degree Type

Thesis

Degree Name

Master of Science

Major

Plant Sciences

Major Professor

Carl E. Sams

Committee Members

Vincent R Pantalone, Dean Kopsell

Abstract

In recent years consumer interest in edamame increased in part due to reported health benefits associated with vegetable soybeans. Consequently, interest in soybean production has increased steadily. This research consists of three related studies. A spacing and planting date study was performed to compare four soybean lines. This experiment utilized four plant spacings and three planting dates. The lines were grown at the Plateau Research and Education Center in Crossville, TN in 2005 and 2006. Seeds were harvested at the R6 and R8 reproductive stages. Samples were analyzed by HPLC for isoflavone content. Data from the R6 harvest confirmed previously published reports of high isoflavone concentration in line 5601T. At the R8 harvest there was a significant difference among lines for the isoflavone daidzein.

The maturity and force studies were planted together in four row plots during the 2006 and 2007 growing seasons at the East Tennessee Research and Education Center, Knoxville, TN. Isoflavones were extracted from freeze-dried soybeans and measured by HPLC. Samples for the maturity study were harvested from the leftmost inner row. Samples for the force study were harvested from the rightmost inner row. The maturity study measured the concentration of isoflavones in the seed at reproductive stages R4.5, R5, R5.5, R6, R7, and R8. Reproductive stage was significantly different for 9 isoflavones and for total isoflavone concentration. There were differences between lines for 4 isoflavones and for total isoflavone concentration. Line 5601T had the highest isoflavone concentrations. There were also differences in growth stage by line interactions in 3 isoflavones and total isoflavone concentration.

The force study investigated the amount of force needed to remove a pod from the plant in the weeks prior to maturity. Pod removal force was measured using two Imada PS gauges with maximum measurements of 2 kg and 5 kg. The reproductive stages sampled were R5, R5.2, R5.4, R5.6, R5.8, R6, R7, and R8. Pod removal force ranged from 0.055 kg to 2.6 kg. Pod removal force increased linearly from the R5 to R7 stage. There were significant differences due to reproductive stage, line, and combinations of the two (P <.0001).

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