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Research from the University of Illinois has shown that sweet corn yields have steadily increased since the 1930s when it is planted at high density. This historical view highlights the importance of planting modern density-tolerant varieties at their optimal densities and offers an opportunity to increase density tolerance.
"Over the years, steady improvements in plant density tolerance have contributed significantly to field corn's genetic yield gains." Our recent research suggests that sweet corn hybrids with high plant density tolerance could be used to increase yield. However, the historical changes in sweet corn plant density tolerance were not known," said Daljeet Dhaliwal (a doctoral student in Crop Sciences at Illinois) and lead author of a Frontiers in Plant Science article.
Marty Williams, a USDA ARS ecologist, and Dhaliwal, an adjunct professor in this department, tested sweetcorn crowding tolerance in hybrids ranging from 1934 to 2014. The marketable ear mass was increased by 2.85 tons per annum over the 80-year period or 0.36 tons per annum per decade when grown at high densities, according to Dhaliwal and Marty Williams.
Williams used his contacts in the sweet corn seed sector to quantify these changes. Companies offered to create the original hybrids from scratch, as many of the original hybrids are no more available.
"The seed industry was willing and able to put in a lot of work to create these hybrids for us at no cost. Williams states that it took five years to put the germplasm together. Without broad industry support, this project wouldn't have been possible. It's an indication of the value that our research program offers, I believe.
Williams and Dhaliwal both grew hybrids that represented each decade at low (4000 plants per acre), and high (32,000 plants/acre) densities for three years. They then measured key characteristics for growers, processors, such as marketable ear mass and crate yield.
Modern hybrids also showed an increase in crate yield, which was in addition to the per-area marketable ears mass improvement in hybrids grown at high densities. The ratio of fresh kernel mass to recovery, which measures how much of an ear is made up by marketable kernels, didn't change over time.
"No improvement in 80 years suggests that there is a breeding goal. How could we improve recovery? Few sweet corn breeding programs had a way to measure recovery until the last ten years. Breeders instead focused on other important traits like eating quality and resistance to disease. Williams states that now we know how much recovery has been improved, it might be worth targeting.
Modern hybrids were more suitable for high density growth, and had fewer tillers than older varieties.
"Plant architecture is becoming more compact. The plants are using less resources to produce vegetative tissue. This means that there is less new biomass and fewer tillers. Modern plants can grow at higher densities, which is good news. It's easier to manage the interference. Dhaliwal says that older hybrids aren't out-yielding if they are planted at low densities.
Williams says, "It is both exciting and humble to conduct a study such as this, which captures a long arc in sweet corn improvement." The incremental advancements of many others have made it possible to get us where we are now.
Continue reading Growing sweet corn at higher density doesn't increase root lodge risk
Further information: Daljeet S. Dhaliwal and colleagues, Historical Trends in Sweet Corn Plant Tolerance Using Era hybrids (19302010s), Frontiers in Plant Science (211). Information from Frontiers in Plant Science Daljeet S. Dhaliwal and colleagues, Historical Trends in Sweet Corn Plant Tolerance Using ERA Hybrids (19302010s), (2021). DOI: 10.3389/fpls.2021.707852
