| Project Title: |
Seed Electrolyte Leakage in Soybean and
Correlation with Seedling Diseases; Evaluation of the Conductivity
Test as a Predictor of Seedling Vigor and
Resistance to Fusarium or Pythium Damage |
|
Project Leader: |
Paul D. Meints, Assistant Professor, Mississippi State University, Starkville, MS |
| Other Participants: | Francis Maideni, Graduate Research Assistant, Mississippi State University, Starkville, MS |
Objective 1. Evaluate seed storage length and accelerated aging on infestation of Fusarium root rot in soybean seed lots.
Three soybean cultivars (Hutcheson, Deltapine 5354, and Hartz 5999) were utilized in this study for both field and laboratory research. Seed was exposed to accelerated aging 45¡ C and 100% relative humidity) for 24 hours to simulate extreme storage stress conditions. Fresh seed and accelerated aged seed were field planted in April, 1998 at North Farm, Starkville, MS and Black Belt Experiment Station, Brooksville, MS. Replicated trials at each location also included seed (Hill) that had been in long term storage. A seed treatment of ambient warehouse storage greater than two years could not be included in the first year from representative cultivars, but will be in subsequent plantings. Each plot consisted of 4 rows 6.1 m (20 feet) long with a row spacing of 0.78 m (30 inches). Seedling emergence was determined by established seedling (first true leaf emerging) count 8 and 15 days after planting. Disease pressure was not observed in field plantings in 1998. Dry conditions and warm soil temperatures contributed to healthy seedling emergence with no evidence of Fusarium induced root rot at either location. Statistical analysis of field emergence data indicated that length of seed storage significantly reduced seedling emergence in all three cultivars independent of seed treatment at both locations in 1998.
Pure cultures of Fusarium oxysporum were isolated and cultured. Growth chamber studies were initiated in fall of 1998 and continue at present. Accelerated aged seed was significantly (p<0. 05) greater in electrolyte leakage and subsequent susceptibility to Fusarium oxysponim induced root rot symptoms followed by long term storage seed and fresh seed from recent harvest in growth chamber culture. Data is currently being collected on this component of the study and thus statistical analysis has not been completed. Preliminary results indicate that seed is most resistant to seedling damage during the first year after harvest and as seed ages deterioration of membrane structure predisposes seed to root rot symptoms and loss. Further data will be used to complete this portion of the study, conduct statistical analysis, and draw final conclusions.
Objective 2. Evaluate single treatment effectiveness of seed treatments against Fusarium damage to seedlings under three seed storage treatments.
Seed treatments utilizing Vitavax 200 or Apron 50W did not significantly affect field emergence due to the lack of disease pressure at Starkville and Brooksville locations in 1998. Field planting will be established in late March or early April as conditions allow in 1999 to exposed seed treatments to greater cool wet soil field stress.
Objective 3. Determine if the conductivity test can be used as a predictor of seed lot performance with respect to Fusarium induced root rot.
Field emergence data from Starkville and Brooksville locations showed that field emergence was not significantly correlated with seed conductivity in 1998 (r = 0.460). Conductivity tests indicated that accelerated seed showed significantly greater (p<0.05) deterioration over seed stored greater than two years and fresh seed from the most recent harvest season.
Growth chamber studies currently in progress indicate that there is a
positive relationship between seed deterioration in storage determined by the
conductivity test, and incidence of root rot symptoms. Fusarium oxysporum culture
applied to soil media into which soybean is planted resulted in greatest
incidence of seedling root rot when seed was aged via accelerated aging,
followed by seed stored greater than two years, followed by fresh seed from the
most recent harvest. Statistical analysis of data has not been completed as the
study is still in progress.
Publication of results will occur as research investigating these objectives is completed during 1999. Growth chamber and laboratory research will conclude by August 1999, and a second year of field studies by November 1999. Results of this research are expected to be published in thesis form and submitted for peer review journal publication by January 2000.
|
Soybeans in
Mississippi |
|
| For information
about this page, contact OAC Webmaster
This site is made possible by the Mississippi Soybean Promotion Board and is maintained by the Office of Agricultural Communications at Mississippi State University. |