96-20 Minimum Photosynthetically Active Solar Radiation Requirements for Optimum Soybean Yields.



Monday, October 17, 2011
Henry Gonzalez Convention Center, Hall C, Street Level

Landon L. Ries1, Seth L. Naeve1, Wade A. Kent1, James Lee2, Chad Lee3, Kurt Thelen4, Tim Boring4, William J. Ross5 and James Board6, (1)Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN
(2)Iowa State University, Ames, IA
(3)University of Kentucky, Lexington, KY
(4)Michigan State University, East Lansing, MI
(5)Crop, Soil, and Environmental Sciences, University of Arkansas, Little Rock, AR
(6)Louisiana State University Agricultural Center, Baton Rouge, LA
The cumulative amount of photosynthetically active solar (PAR) radiation intercepted by a crop canopy is an integrated measure of the environment where the crop is grown and the production practices employed by a producer (i.e. genotype maturity, planting date, seeding density, row spacing, etc.). Previous research indicates that soybean yield response to cumulative PAR interception is curvilinear; yield increases rapidly until the crop accumulates a critical quantity of PAR, where additional PAR accumulation does not result in greater yield. The objective of this research is to establish a minimum threshold quantity of solar energy (PAR) required by a soybean crop.  Ultimately, development of a PAR threshold will be useful when making soybean management decisions.  To accomplish our objective, collaborators in Minnesota, Michigan, Iowa, Kentucky, Arkansas, and Louisiana (47.8°N to 30.5°N latitude) began a three-year study in 2009 in which accumulated PAR is measured across  six seeding densities (61,750 to 679,250 seeds ha-1) and 2 maturity groups.   Grain yield and yield components were measured at maturity.  For 2009 and 2010, yields were generally maximized with an adapted maturity at a seeding density of 308,750 seeds ha-1which corresponds to approximately 500 MJ m-2 of intercepted PAR.
See more from this Division: C03 Crop Ecology, Management & Quality
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