Catching more light for higher soybean yields
Oct. 4, 2005Contact Information:
Burl Seversike, Department of Crop, Soil and Environmental Sciences
479-575-2354 / tsevers@uark.edu
Dr. Larry Purcell, Department of Crop, Soil and Environmental Sciences
479-575-3983 / lpurcell@uark.edu
By Fred Miller, University of Arkansas Division of Agriculture
479-575-5647 / fmiller@uark.edu
Graduate student Burl Seversike of Olympia, Wash., monitors pod set in test plots of ultra-early maturing soybeans. Seversike is working with Dr. Larry Purcell to determine if experimental soybean varieties with seven leaves, rather than the more common three, improves yields in plants with a very short growing season.
Graduate student Burl Seversike of Olympia, Wash., adjusts irrigation sprinklers in test plots of ultra-early maturing soybeans. Seversike is working with Dr. Larry Purcell to determine if experimental soybean varieties with seven leaves, rather than the more common three, improves yields in plants with a very short growing season.
FAYETTEVILLE, Ark. — University of Arkansas graduate student Burl Seversike seeks a novel solution to a yield problem with ultra-early maturing soybeans.
Seversike, of Olympia, Wash., grows experimental soybeans with clusters of seven leaflets, rather than the more common three. He expects an improvement in how well early-maturing plants use solar power that will result in higher yields.
“Ultra-early maturity group soybeans have certain advantages over those varieties that mature later,” said Dr. Larry Purcell, crop physiologist for the Arkansas Agricultural Experiment Station and Seversike’s graduate advisor. “They can be ready for harvest before the hottest, driest time of summer, saving water and the cost of pumping it for irrigation. They are also very flexible for double-cropping systems.
“But their short life cycle means the leaf canopy doesn’t grow as full as later maturing varieties,” Purcell said. “They have a smaller accumulation of light that has an impact on yield.”
To compensate for a shorter cropping season, Purcell said growers have to plant ultra-early soybeans at a higher seed rate — adding expense to put in a larger quantity of seed per acre — in order to obtain yields comparable to later maturity group soybeans.
Some livestock producers grow seven-leaflet soybeans as a forage crop, Purcell said. He and Dr. Pengyin Chen, UA soybean breeder, crossed the seven-leaflet trait into several ultra-early varieties, producing the experimental plants Seversike uses in his test plots at the Arkansas Agricultural Research and Extension Center in Fayetteville.
“My hypothesis is that plants with seven lealets will have greater leaf surface and intercept more sunlight than plants with three leaflets,” Seversike said. “If this helps the plant produce higher yield, growers can buy less seed to get the same yields.”
Seversike shoots digital images of the plots and runs them through a program that measures the amount of green, sunlight-trapping surface in the plots. He compares the results from the experimental soybean lines with those of conventional, three-leaflet varieties to determine if seven leaves intercept a greater amount of light. He monitors the growth stages in the plots to compare the hybrids with the more conventional varieties.
Anticipating a positive result, Seversike extracts DNA from the hybrid plants and screens for the gene that controls the seven-leaflet trait.
“If closing the leaf canopy earlier helps improve yield for early maturing soybeans, it may also improve yields for later maturing varieties,” he said. “Knowing which gene controls the leaf trait will help breed improved varieties in other maturity groups that can take advantage of greater light interception.”