Phenotypic Plasticity, Plant Height, and Phenology in Winter Wheat: A Simulation Study.

The objective of this effort was to simulate plant height in winter wheat (Triticum aestivum L.) across a range of environments in Nebraska using genetic information. Plant height is influenced by major genes that are discrete and well characterized genetically and phenotypically. Although plant height is a complex trait, it is far simpler than many traits. Two data sets were used in this study, one from a PhD dissertation where final plant heights were measured at five locations across Nebraska over two years and another study where plant height was measured 13 times before anthesis in one year at one location for one genotype. The crop simulation model CropSyst was modified by incorporating a different phenology algorithm and adding a plant height algorithm. The plant height algorithm was based on the ratio of the mean optimum final height of a height class (tall semidwarf, semidwarf, short semidwarf) to the mean optimum final heights for two tall cultivars, an environmental index based on the fraction of transpirable water, and the development stage. Final plant heights were simulated reasonably well for the different height classes with a root mean square error of 3.4 cm. For the second data set, although the final plant height was well predicted and there was a very good correlation between observed and simulated intermediate heights (r² = 0.99), the absolute height values did not agree well. These results were related to the phenology algorithm and unusual weather during the growing season.