Root Morphological Plasticity in Maize and Its Influence on N Uptake from Patchy Resources.

Soil resources, such as decomposing organic matter, are patchily distributed throughout the soil, resulting in an extremely heterogeneous environment. ‘Root foraging’ encompasses the plastic responses utilized by roots to exploit these patchy resources. One such response is ‘morphological plasticity’, which consists of the alteration of root growth and architecture in response to localized nutrient enrichment. Previous research has demonstrated considerable interspecific variation in root morphological plasticity, which may or may not increase N capture from heterogeneously distributed resources. Thus far, no one has established to what extent intraspecific variation exists in root morphological plasticity. We screened 12 recombinant inbred lines of maize (B73 X Mo17, IBM population) for morphological plasticity within heterogeneously distributed resources. This population has previously been shown to have considerable variation in root architecture. At the University of New Hampshire MacFarlane Greenhouse, we utilized root window boxes as growing containers to facilitate the visualization and measurement of root architectural traits, as well as root proliferation within nutrient patches. We hypothesized that maize lines which produced a greater total number and length of lateral roots would also exhibit greater morphological plasticity, measured as the ratio of root length in nutrient patches to control cores. Additionally, we hypothesized that the maize lines which exhibited the greatest morphological plasticity would capture the most N.  Our results show that maize does exhibit variation in morphological plasticity, and more work is needed to assess the importance of this trait to N uptake under varying soil conditions.