Abstract
Ionomics is the study of elemental accumulation in living organisms using high-throughput elemental profiling. In the present study, we examined the ionomic responses to nutrient deficiency in maize grown in the field in long-term fertilizer trials. Furthermore, the available elements in the field soils were analyzed to investigate their changes under long-term fertilizer treatment and the ionomic relationships between plant and soil. Maize was cultivated in a field with the following five long-term fertilizer treatments: complete fertilization, fertilization without nitrogen, without phosphorus, without potassium, and no fertilization. Concentrations of 22 elements in leaves at an early flowering stage and in soils after harvest were determined. The fertilizer treatments changed the availabilities of many elements in soils. For example, available cesium was decreased by 39 % and increased by 126 % by fertilizations without nitrogen and potassium, respectively. Effects of treatments on the ionome in leaves were evaluated using the translocation ratio (the concentration in leaves relative to the available concentration in soils) for each element. Nitrogen deficiency specifically increased the uptake ability of molybdenum, which might induce the enhancement of nitrogen assimilation and/or endophytic nitrogen fixation in plant. Potassium deficiency drastically enhanced the uptake ability of various cationic elements. These elements might act as alternatives to K in osmoregulation and counterion of organic/inorganic anions. Two major groups of elements were detected by multivariate analyses of plant ionome. Elements in the same group may be linked more or less in uptake and/or translocation systems. No significant correlation between plant and soil was found in concentrations of many elements, even though various soil extraction methods were applied, implying that the interactions between the target and other elements in soil must be considered when analyzing mineral dynamics between plant and soil.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-015-1562-x) contains supplementary material, which is available to authorized users.
Highlights
Nitrogen (N), phosphorus (P), and potassium (K) are the three major fertilizer nutrients, and adequate fertilization is one of the most important factors in plant production (Mengel and Kirkby 2001)
N, P, and K fertilizers were applied as ammonium sulfate, superphosphate, and potassium sulfate, respectively (100 kg N, P2O5, K2O ha−1), once before sowing
Differences in concentration of total and exchangeable K were almost constant among all the fertilizer treatments (Table 1)
Summary
Nitrogen (N), phosphorus (P), and potassium (K) are the three major fertilizer nutrients, and adequate fertilization is one of the most important factors in plant production (Mengel and Kirkby 2001). Fertilization may affect the availability of elements other than those applied to soils. Malhi et al (1998) continuously applied ammonium nitrate at different rates for 27 years and determined the chemical properties of the soils (thin Black Chernozem, Typic Boroll). They found that ammonium nitrate application reduced soil pH, increased KCl-extractable aluminum (Al) and diethylenetriaminepentaacetic acid (DTPA) extractable iron (Fe), and affected the concentration of DTPA-extractable manganese (Mn) and zinc (Zn). Li et al (2007) performed long-term fertilizer trials with the three major nutrients for 16 years and compared DTPA-extractable Fe, Mn, Zn, and copper (Cu) in soils among treatments. The soil contains various elements of the periodic table (Tyler and Olsson 2001)
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