Seed carbohydrate reserves influence the optimal seminal root number of maize

Open Access
- Author:
- Perkins, Alden
- Graduate Program:
- Horticulture
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- May 15, 2020
- Committee Members:
- Jonathan Paul Lynch, Thesis Advisor/Co-Advisor
Kathleen Marie Brown, Committee Member
Tom Richard, Committee Member
Erin L Connolly, Program Head/Chair - Keywords:
- maize
root architecture
soils
domestication
teosinte - Abstract:
- Maize (Zea mays ssp. mays) has several major morphological differences from its wild progenitor, Mexican annual teosinte (Z. mays ssp. parviglumis). While maize landraces typically form between two and six seminal roots that emerge from the seed in addition to the radicle, teosinte generally does not form seminal roots. The structural-functional plant model OpenSimRoot was used to construct seedling root architectural models of teosinte and a maize landrace by measuring model parameters on plants grown in mesocosms between 0 and 25 days after planting. The contribution of seminal roots to nutrient acquisition was simulated in a low-phosphorus environment, several low-nitrogen environments, and a variety of planting densities. Seminal roots and their lateral roots contributed approximately 35% of the nitrogen and phosphorus acquired by the maize landrace in the 25 days following germination. Increased seminal root number improved phosphorus acquisition for the maize landrace, as has been previously reported, and it improved the acquisition of nitrogen in soils with multiple textural classes, initial nitrogen fertilization rates, and precipitation regimes. Seminal roots were not beneficial to teosinte growth under low-nitrogen conditions because teosinte had insufficient seed carbohydrate reserves to support their development. Maize seeds are approximately ten times larger than those of teosinte, so selection for seed size during domestication may have increased the optimal seminal root number. The results may have implications for improving seedling nutrient acquisition efficiency, informing de novo domestication efforts, and understanding the selective pressures that shape seed size in teosinte.