Abstract
Densities of single and multiple macro- and micronutrients were estimated in the mature kernels of 1348 accessions in 13 maize genotypes. The germplasm belonged to stiff stalk (SS) and non-stiff stalk (NS) heterotic groups (HGs) with one (S1) to four (S4) years of inbreeding (IB), or open pollination (OP), and with opaque or translucent endosperm (OE and TE, respectively). Indices were calculated for macronutrients (M-Index), micronutrients (m-Index) and an index based on Fe and Zn densities (FeZn-Index). The objectives were to (1) build predictive models and quantify multivariate relationships between single and multiple nutrients with physical and biochemical constituents of the maize kernel; (2) quantify the effects of IB stages and endosperm textures, in relation to carbon and nitrogen allocation, on nutrients and their indices; and (3) develop and test the utility of hierarchical multi-way classification of nutrients with kernel color space coordinates. Differences among genotypes and among IB stages accounted for the largest amount of variation in most nutrients and in all indices, while genotypic response to IB within HGs explained 52.4, 55.9, and 76.0% of variation in the M-Index, m-Index, and FeZn-Index, respectively. Differences in C and N allocation among HGs explained more variation in all indices than respective differences in allocation among endosperm (E) textures, while variation decreased with sequential inbreeding compared to OP germplasm. Specific color space coordinates indicated either large macronutrient densities and M-Index, or large micronutrient densities, m-Index, and FeZn-Index. These results demonstrated the importance of genotypes and the C:N ratio in nutrient allocation, as well as bivariate and multiple interrelationships.
Highlights
Human manipulation of carbon and nitrogen partitioning, such as the selective concentration of carbohydrates and storage proteins in larger kernels of maize (Zea mayz L.) during domestication from its wild progenitor [1], is evident from the earliest examples of crop domestication [2]
Recent research-based evidence indicated that abiotic stresses trigger shifts of the ionome of plants exposed to elevated CO2 and drought [6,7] and may compromise future nutrient availability
Was dominated, in decreasing order, by [K, P, Mg and S] densities, whereas [Fe and Zn] densities dominated for micronutrients
Summary
Human manipulation of carbon and nitrogen partitioning, such as the selective concentration of carbohydrates and storage proteins in larger kernels of maize (Zea mayz L.) during domestication from its wild progenitor [1], is evident from the earliest examples of crop domestication [2] This process was concomitant with the manipulation of key physical, biochemical, and nutrient traits of the maize kernel [3]. Recent research-based evidence indicated that abiotic stresses trigger shifts of the ionome of plants exposed to elevated CO2 and drought [6,7] and may compromise future nutrient availability In grain crops, such as maize, the mature seed represents a distinct developmental end point that summarizes the life history and genetic composition of a particular genotype [8]. Nutrients are not distributed uniformly throughout the seeds of grain crops: some elements are concentrated
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