Multi-Dimensional Plant Element Stoichiometry—Looking Beyond Carbon, Nitrogen, and Phosphorus

Abstract

Nutrient elements are important for plant growth. Element stoichiometry considers the balance between different nutrients and how this balance is affected by the environment. So far, focus of plant stoichiometry has mainly been on the three elements carbon (C), nitrogen (N), and phosphorus (P), but many additional elements are essential for proper plant growth. Our overall aim is to test the scaling relations of various additional elements (K, Ca, Mg, S, Cu, Zn, Fe, Mn), by using ten data sets from a range of plant functional types and environmental conditions. To simultaneously handle more than one element, we define a stoichiometric niche volume as the volume of an abstract multidimensional shape in n dimensions, with the n sides of this shape defined by the plant properties in question, here their element concentrations. Thus, a stoichiometric niche volume is here defined as the product of element concentrations. The volumes of N and P (V NP ) are used as the basis, and we investigate how the volume of other elements (V Oth ) scales with respect to V NP¸w ith the intention to explore if the concentrations of other elements increase faster (scaling exponent > 1) or slower (<1) than the concentrations of N and P. For example, scaling exponents >1 suggest that favorable conditions for plant growth, i.e., environments rich in N and P, may require proportionally higher uptake of other essential elements than poor conditions. We show that the scaling exponent is rather insensitive to environmental conditions or species and ranges from -3.804 to 1.976 (average 0.384) in nine out of ten data sets. For single elements,Mg has the smallest scaling exponent (0.524) and Mn the largest (2.666). In two of the ten data sets the scaling exponent is negative but positive in the other eight sets. Comparison between laboratory determined stoichiometric relations and field observations suggest that element uptake in field conditions often exceeds the minimal physiological requirements. The results provide evidence for the view that the scaling relations previously reported for N and P can be extended to other elements; and that N and P are the driving elements in plant stoichiometric relations. The stoichiometric niche volumes defined here could be used to predict plant performances in different environments.

Shoot and Root Traits Underlying Genotypic Variation in Early Vigor and Nutrient Accumulation in Spring Wheat Grown in High-Latitude Light Conditions

“…Some genotypes, notably ‘Quarna’ and ‘Rohan’, increased their P pools strongly in proportion to N (strong P accumulators), whilst other genotypes, e.g., ‘Happy’ and ‘Alderon’, showed much weaker P accumulation in proportion to N (weak P accumulators) ( Figure 6 A). This indicates that there is genetic variation in the proportion of P to N accumulation across the plant material investigated here; and the negative scaling exponent for the niche volumes of N and P vs. the other nutrients [ 42 ] indicates that there is genetic variation also with respect to the proportional accumulation of other elements. It is interesting that the genotype ‘Happy’, with a weak P accumulation in proportion to N, and consequently the strongest deviation from an optimal P-to-N ratio ( Figure 7 C), was also the one with the smallest slope in the relationship between root and leaf development ( Figure 3 ).…”

“…The relationship between whole plant biomass and N and P productivities (as the inverses of mass-based N and P concentrations) were analyzed by non-linear regression. The scaling relation between the stoichiometric niche volume of N and P on the one hand, and the volume of other nutrient elements on the other hand, were analyzed with reduced major axes (RMA) regression [ 42 , 65 ].…”

“…The proportional acquisition of nutrients in relation to each other can also be evaluated using products of element concentrations and the calculation of scaling exponents. This allows to explore for example if the concentrations of the other elements increase faster or slower than the concentrations of N and P [ 42 ].…”

Multielemental Stoichiometry in Plant Organs: A Case Study With the Alpine Herb Gentiana rigescens Across Southwest China

“…In addition, the core central tendency in N:P ratio is similar among observations in different biota, which could be due to the similar biochemical investment across all biota (Zhang and Elser, 2017). Apart from C, N, and P, a more complete understanding of homeostasis necessitates the consideration of other elements, especially the nutrient elements for plant growth (Jeyasingh et al, 2017;Ågren and Weih, 2020). Potassium (K) is the second most abundant nutrient in plant photosynthetic tissues and is required for many functions, such as the maintenance of electrical potentials across cell membranes (Britto and Kronzucker, 2008;Sardans and Peñuelas, 2015).…”

Identification of species traits enhancing yield in wheat-faba bean intercropping: development and sensitivity analysis of a minimalist mixture model

“…2). Note that the maximum nitrogen concentration is larger than the critical nitrogen concentration, which allows M 3 to consider that crops can take up more nitrogen then they need to reach their maximum relative growth rate (Greenwood et al 1990;Justes et al 1994;Van Wijk et al 2003;Ågren 1988;Ågren and Weih 2020). If the crop nitrogen concentration drops below a so-called minimum nitrogen concentration, the actual daily biomass production is reduced to zero.…”