Submitted to: American Institute of Aeronautics and Astronautics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/31/1995
Publication Date: N/A
Interpretive Summary: Changing water supplies and land uses, require plants which are better adapted to changed environments. Improvement of crop adaptation requires an understanding of the way plants interact with their immediate environment. Five Corn hybrids were tested for their ability to grow seedling roots downward at different germination temperatures. One of the five grew more vertically downward than the other four at all temperatures This hybrid is noted for its greater yield stability in the midwest where the soils are deep. Three different patterns of response to different temperatures was observed, suggesting the availability of genetic variation of potential use in breeding. This data will very useful for plant breeders attempting to breed corn hybrids for different types of soil.
Technical Abstract: Seeds of five commercial hybrids of Zea mays were oriented with their embryonic axis perpendicular to gravity and restricted to growth in a vertical plane. Seeds were then placed into growth chambers at either 17.5 C, 20 C, 25 C, or 30 C. Measurements were taken on seedlings for initial shoot angle, final shoot angle, initial tap root angle, and final tap root angle. Both shoots and roots appeared plagiotropic, and angles varied with temperature for some hybrids. Initial shoot angles of three hybrids decreased (became more vertical) with increasing temperature, while two hybrids showed more unusual response patterns. Analyzing final shoot angles, we determined that CG 4327 final shoot angles did not vary with temperature, while the other hybrids showed more vertical final shoot angles with increasing temperatures. Angles of tap root growth were also dependent on temperature. At 20 C, tap roots of all hybrids studied initially grew more horizontally than at other temperatures. Analysis of final root angles indicated that tap roots grew most vertically downward at 25 C and at either lower or higher temperatures became more horizontally oriented. In addition, different hybrids produced different patterns of response, indicating a genetic component. We maintain that there are large genetic differences apparent for root traits even in highly domesticated crops such as corn. In addition, the genetic potential for root growth may be modified by the environment. Genotypes within a species will respond differently to changes in the rhizosphere environment.