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ARS Home » Midwest Area » Ames, Iowa » Corn Insects and Crop Genetics Research » Research » Publications at this Location » Publication #322292
Title: Effects of plant density on plant growth before and after recurrent selection in maize

Author
item STEIN, MICHAEL - Iowa State University
item MIGUEZ, FERNANDO - Iowa State University
item Edwards, Jode

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2015
Publication Date: 6/30/2016
Citation: Stein, M.J., Miguez, F., Edwards, J.W. 2016. Effects of plant density on plant growth before and after recurrent selection in maize. Crop Science. doi:10.2135/cropsci2015.09.0599.

Interpretive Summary: Continued increases in maize grain yield will require hybrids adapted to growing at higher plant densities. During the entire hybrid maize era, new hybrids sold to farmers have become consistently adapted to growing at higher plant densities over time, which has led to higher grain yield per acre. While plant density response for grain yield has been well studied, our understanding of how plants have become better adapted to higher plant densities is still lacking. Better biological understanding is critical to evaluating future water and Nitrogen needs at higher plant densities, row-width requirements, and potential impacts of climate change. Researchers in ARS undertook a study to evaluate growth of different plant organs throughout the season to better understand the impact of high plant density. Researchers found that improved maize populations better maintained ear growth at high plant density whereas the timing of growth in stalk and tassel was more delayed at high plant density. The relative proportion of mass in ears to whole plant (harvest index) was maintained across densities in improved populations. The work shows the density impacted timing of growth more than the size of ear in relation to plant. This understanding will help breeders identify traits to emphasize for high throughput phenotyping approaches (such as remote sensing) to improve adaptation to even higher plant densities.

Technical Abstract: Breeding for higher grain yield in Maize (Zea mays L.) has produced varieties that are adapted to grow at higher population densities. While the effects of density on final grain yield and plant phenotypes are well known, how density affects the early development of the plant has been less studied. The objective of this experiment was to examine the effects of high planting density on the development of the reproductive and vegetative structures in unselected Iowa Stiff Stalk Synthetic (BSSS) and Iowa Synthetic Corn Borer No. 1 (BSCB1) and populations that have been selected for high grain yield via a reciprocal recurrent selection program. The selected and unselected populations were planted at four densities ranging from 3.23 to 12.92 plants m-2 at three locations around Ames, IA over two years. High planting density slowed the growth rate and delayed the development of ears, shoots, and tassels. High planting density affected the populations differently, with a reduced rate of ear length increase occurring in BSCB1 but not BSSS, and a delay in ear shoot and tassel biomass accumulation in BSSS but not BSCB1. Selection reduced or eliminated the growth rate reductions and delays caused by high plant densities. This experiment showed that selection did change how plants reacted to high density, and that it is possible to use early-season phenotyping to model the growth.