Masters Theses

Date of Award

5-2007

Degree Type

Thesis

Degree Name

Master of Science

Major

Plant Sciences

Major Professor

Vincent R. Pantalone

Committee Members

Fred Allen, Dennis Deyton, Carl Sam

Abstract

The objectives of this study are three-fold: to determine the within row plant spacing and time of planting that will produce optimal yields and seed isoflavone content, to explore the feasibility of incorporating edamame soybeans [Glycine max (L.) Merrill] in a double-cropping system with strawberries [Fragaria X ananassa], and to study the potential as an edamame soybean of newly identified line TN03-349. Line TN03-349 was planted into raised, plasticulture, irrigated strawberry beds at the University of Tennessee’s East Tennessee Research and Education Center. Five within-row spacings were used (0.08m, 0.15m, 0.30m, 0.60m, and 1.20m) in 2004 and 2005. A second raised bed, irrigated plasticulture experiment was conducted at the Plateau Research and Education Center in Crossville, TN, using four soybean lines (Gardensoy-43, TN00-60, USG 5601T, and TN03-349) and two planting dates (May 24 and June 14, 2005). A final field experiment at the same location used the same four soybean lines, four within-row spacings (0.04m, 0.08m, 0.15m, and 0.30m), and three planting dates (May 24, June 14, and July 6) in 2005 and 2006. All experimental plantings were harvested at both the R6 (green) and the R8 (dry) stages. Analysis of R6 and R8 data, averaged over two years (2004 and 2005), from the East Tennessee location showed that total pod yield was highest up to plant spacing 0.30m (at a mean of 10,450 kg ha-1) and dropped off at the 0.60m (8370 kg ha-1) and 1.20m (5985 kg ha-1) spacings. Similarly, shelled seed yield responded to spacing treatments with 3419 kg ha-1 at 0.30m and decreased to 1880 kg ha-1 at the 1.20m spacing. While seed numbers (per 100 pods) from R6 harvest did not change, seed size did, increasing as space between plants increased with means of 371mg seed-1 for 0.08m and 916mg seed-1 for 1.20m. Seed isoflavone content was not significantly affected by spacing treatment. Analysis of R6 data from the Plateau strawberry bed experiment showed that genotype significantly affected total plot yield (p<0.01) and seed size (p<0.05). While line Gardensoy-43 had the lowest shelled seed yield, it had the largest seeds (1070mg seed-1). The other lines did not differ in shelled seed yield, but TN00-60 and TN03-349 differed from USG 5601T (smallest at 260mg seed-1) in seed size. Planting date did not significantly affect yield or seed size. Analysis of R8 data at Crossville, TN showed line TN03-349 to have significantly higher total yield than all others at 876 kg ha-1 and Gardensoy-43 (lowest yield at 274 kg ha-1) differed from TN00- 60 (549 kg ha-1) and USG 5601T (497 kg ha-1) where p<0.0001. Three isoflavones were significant for genotype: daidzin (p<0.05), malonyl daidzin (p<0.001), and malonyl glycitin (p<0.0001). Total seed isoflavone and oil content were not significantly affected by genotype. Seventeen of eighteen measured amino acids were affected by genotype (p-values varied). Results from the field experiment revealed that genotypic effects were significant (p<0.01) to all measurements across all three planting dates for the R6 development stage. The edamame lines Gardensoy-43 and TN03-349 consistently produced larger seeds and heavier pod weights than the others. Planting date also had a significant effect on seed size (p<0.05) with June giving the largest (mean seed size, 360mg seed-1) and May the smallest (mean seed size, 350mg seed-1) size. Spacing treatment significantly affected seed size (p<0.05), total pod yield (p<0.01), and shelled seed yield (p<0.01). The widest spacing treatment, 0.30m, gave the largest seed size (0.36g) while the closest spacing treatment, 0.04m, yielded the lowest seed size (0.35g). Total pod and shelled seed yields only differed at the widest spacing (0.30m) and were significantly lower than all the other treatments, which did not differ from each other. Analysis of R8 harvested soybeans for 2005 and 2006 revealed that the 2005 experimental plantings produced higher yields than those in 2006 (p<0.0001), which were reduced by deer damage. Genotype played a significant part in R8 seed yield (p<0.0001). Line TN00-60 produced the highest weight (4374 kg ha-1) and differed significantly from the other three lines, which were not different from each other (Gardensoy-43, 2941 kg ha-1; TN03-349, 3373 kg ha-1; USG 5601T, 2970 kg ha-1). Spacing had no significant effect.

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