| | Planting seeds for a new crop. |
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| | Crop of soybeans ready to harvest. |
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| | Getting field ready to plant new crop. |
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ACCESSION NO: 0201071
SUBFILE: CRIS
PROJ NO: LAB93710
AGENCY: CSREES LA.B
PROJ TYPE: HATCH
PROJ STATUS: NEW
START: 01 JUN 2004
TERM: 31 MAY 2009
FY: 2005
INVESTIGATOR: Board, J. E.; Baur, M.; Sa, D.; Subudhi, P.
PERFORMING INSTITUTION:
AGRONOMY
LOUISIANA STATE UNIVERSITY
BATON ROUGE, LOUISIANA 70893
IMPROVING SOYBEAN PRODUCTION THROUGH CULTIVAR EVALUATION FOR WATERLOGGING TOLERANCE, YIELD COMPENSATION
NON-TECHNICAL SUMMARY: Waterlogging tolerant cultivars and cultivars that yield well at low seeding rates need identification. Farmers need better criteria for insecticide application. This project will identify soybean cultivars having waterlogging tolerance and/or that can yield well at subnormal populations. Aerial photographic methods will be developed for identifying fields requiring insecticide application.
OBJECTIVES: 1. Assess cultivar tolerance to waterlogging stress among all southern public soybean cultivars and some current commercial cultivars. 2. Determine cultivar differences for yield compensation at low plant population among all southern public soybean cultivars. 3. Develop leaf area index and light interception criteria for insecticide application to soybean based on digital aerial photography.
APPROACH: Waterlogging tolerance will be assessed among all public soybean cultivars released in the last 50 years in order to identify tolerant types which can be used in genetic studies. In addition, 30 common commercial soybean cultivars will also be screened for waterlogging tolerance. All selection will be accomplished with a rating system. Soybean cultivars that maintain optimal yield at subnormal populations will be identified using screening criteria derived from previous studies. Criteria for insecticide application to defoliating pests based on digital aerial photography will be developed by comparing vegetation indices made from the photograph with land-based data.
PROGRESS: 2005/01 TO 2005/12
Remote Sensing methods for efficient determination of soybean leaf area index (LAI) and percent canopy light interception (LI) were investigated in a third year of study using land-based methods. The objective of the research is to determine the efficacy of using remotely-sensed canopy reflectance ratios (vegetation indices) as indicators of LAI and LI, crop characteristics that can be used as criteria for insecticide application for defoliating insects of soybean. In 2005, the normalized difference vegetation index (NDVI) was determined by digital photography conducted from a modified pick-up truck. Data were gathered across three soybean cultivars planted near Baton Rouge, LA on three dates. Across the LAI range of 0.0 to 4.00 and the LI range from 15 to 90%, LAI and LI were strongly linked with NDVI in exponential relationships (R2=0.95-0.96). In addition, total vegetative dry matter at R5 (TDM, R5), a benchmark indicator for yield potential, could also be predicted by an exponential equation (R2=0.97). The ability to rapidly and accurately monitor TDM also aids in diagnosis of important stress problems that limit yield. These regression models were successfully validated in an independent study. In summary, three years of field studies support the use of remotely-sensed vegetation indices of soybean as criteria for timing insecticide application to control defoliating insects, determining yield potential, and diagnosis of stress problems. In another study, the yield-enhancing ability of 1-Methylcyclopropene (1-MCP) was investigated. Although no significant yield impact was demonstrated, 1-MCP did significantly (P<0.05) increase node and pod numbers. In a third study, analyses of public southern soybean cultivars released from 1953 to 2001 revealed a positive genetic improvement for yield across this period (0.16 Bu/A.yr). Highest-yielding cultivars were Prichard, Santee, Musen, Lyon, and Clifford, all released between 1993 to 2001 (average yield=2476 kg/ha). Cultivars showing the lowest yields-Lee, Hardee, Davis, Semmes, Bienville, and Mack (average yield=1923 kg/ha)-were released between 1954-1971. In general, yield improvement was more strongly linked with total dry matter (TDM) accumulation (R2=0.64) than harvest index (R2=NS). Increased TDM resulted in greater node, pod, and seed production which contributed to final yield. However, analyses of yield component and TDM interrelationships revealed different yield formation explanations for the top-yielding cultivars. Superior yield for Prichard and Musen occurred clearly from greater TDM resulting in greater numbers of nodes, pods, and seeds. A similar but less clearly-defined process occurred for Santee. In contrast, greater yields for Clifford and Lyon were explained by increased seed size and seed per pod, respectively. Identification of genetically-controlled yield formation processes will aid in providing indirect selection criteria for greater yield in soybean breeding programs.
IMPACT: 2005/01 TO 2005/12
Results from the remote sensing research provides soybean farmers with rapid and inexpensive tools to accurately determine the need for insecticide application to defoliating insects. Results also indicate that remote sensing methods can be used to forecast yield and identify stress problems that limit yield. LAI, LI, and TDM of a crop can be easily monitored during the growing season using a reference area. Used in conjunction with established methods of precision agriculture, this will not only result in higher yields, but also more efficient use of agricultural inputs. The result will be greater profitability for Louisiana soybean farmers. Research with 1-MCP aids in development of a potentially yield-enhancing chemical. Analyses of yield formation within southern public soybean cultivars identify some of the growth dynamic/morphological characteristics breeders have been inadvertently selecting for in the process of cultivar development over the last 50 years. Once these characteristics are verified through further testing, plant breeders can use them as indirect criteria for more rapid and efficient selection for improved yield in breeding programs. Although pod and seed number (resulting from increased dry matter) appeared to play an important role, the data also suggested that seed size or seed per pod were significant in some cases. Since these characteristics are under greater genetic control compared with pod and seed number, they would be better candidates as selection criteria in a breeding program.
PUBLICATIONS: 2005/01 TO 2005/12
1. Board, J.E., and H. Modali. 2005. Dry matter accumulation predictors for optimal yield in soybean. Crop Science 45:1790-1799.
2. Kang, M.S., J.E. Board, N. Aminha, Y. Zhang, O.J. Moreno, and M.G. Balzarini. 2005. Diallel analysis of ear moisture loss rate, SPAD chlorophyll, and harvest index in Maize with the Leafy (Lfy) gene. Journal of New Seeds 7(2):1-16.
3. Board, J.E. 2005. Physiogenetics in soybean: How to identify high-yielding soybean lines in a breeding program. Japanese Journal of Crop Science 74:366-371.
PROJECT CONTACT:
Name: Board, J. E.
Phone: 225-578-1208
Fax: 225-578-1403
Email: jboard@agctr.lsu.edu
URL: www.lsuagcenter.com