PLANT RESOURCE CAPTURE AND UTILIZATION: SIMULATION OF SUBTLE CHANGES WITH GREAT EFFECTS
Open Access
- Author:
- Postma, Johannes Auke
- Graduate Program:
- Horticulture
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- May 07, 2011
- Committee Members:
- J P Lynch, Dissertation Advisor/Co-Advisor
Jonathan Paul Lynch, Committee Chair/Co-Chair
Kathleen Marie Brown, Committee Member
Hangsheng Lin, Committee Member
Robert Paul Gallagher Iii, Committee Member - Keywords:
- bean
maize
SimRoot
plant nutrrition
root cortical aerenchyma
phosphorus
nitrogen
potassium
squash
intercropping - Abstract:
- There is a great need for more nutrient efficient and drought tolerant crops, however, targeted breeding for edaphic stress tolerant crops requires scientific knowledge on the function and physiology of the root system. Studying roots in different stressful environments is an enormous task, given the many phenes, phene interactions and environments that need to be studied. In this thesis I present SimRoot, a functional-structural model, which was developed over the course of my dissertation work. SimRoot is specifically designed to study the function of different root architectural phenes for water and nutrient uptake. In chapter 2 I discuss the importance of the development of such a model and focus there on drought. Chapter 3 and 4 present quantitative support for the function of root cortical aerenchyma for growth on low nitrogen, phosphorus and potassium soils. Maize genotypes with high RCA formation may be up to 55, 54 and 72% on low nitrogen, phosphorus or potassium soils respectively. However, the benefit of RCA depends on other phenes, such as lateral branching density. Most soils are characterized by not one but multiple edaphic stresses. Chapter 5 discusses how a single model could simulate uptake and utilization of more than one nutrient simultaneously and presents a small case study on simulation of maize growing on soils with varying nutrient availability of two nutrients. Chapter 6 present simulation results for maize/bean and maize/bean/squash polycultures in comparison to monocultures. The study finds that the polycultures have greater nitrate utilization, but that competition for immobile resources such as phosphorus and potassium is negligible. This dissertation demonstrates the utility of simulation models, in particular functional-structural models, for understanding root function and contributes to a greater understanding of several root architecture traits.