TY - JOUR
T1 - Responses of leaf C:N:P stoichiometry to water supply in the desert shrub Zygophyllum xanthoxylum
AU - Niu, D.
AU - Zhang, C.
AU - Ma, P.
AU - Fu, H.
AU - Elser, J. J.
N1 - Publisher Copyright:
© 2018 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands
PY - 2019/1/1
Y1 - 2019/1/1
N2 - Based on the elemental composition of major biochemical molecules associated with different biological functions, the ‘growth rate hypothesis’ proposed that organisms with a higher growth rate would be coupled to lower C:N, especially lower C:P and N:P ratios. However, the applicability of the growth rate hypothesis for plants is unclear, especially for shrubs growing under different water supply. We performed an experiment with eight soil moisture levels (soil water content: 4%, 6%, 8%, 13%, 18%, 23%, 26% and 28%) to evaluate the effects of water availability on leaf C:N:P stoichiometry in the shrub Zygophyllum xanthoxylum. We found that leaves grew slowly and favored accumulation of P over C and N under both high and low water supply. Thus, leaf C:P and N:P ratios were unimodally related to soil water content, in parallel with individual leaf area and mass. As a result, there were significant positive correlations between leaf C:P and N:P with leaf growth (u). Our result that slower-growing leaves had lower C:P and N:P ratios does not support the growth rate hypothesis, which predicted a negative association of N:P ratio with growth rate, but it is consistent with recent theoretical derivations of growth–stoichiometry relations in plants, where N:P ratio is predicted to increase with increasing growth for very low growth rates, suggesting leaf growth limitation by C and N rather than P for drought and water saturation.
AB - Based on the elemental composition of major biochemical molecules associated with different biological functions, the ‘growth rate hypothesis’ proposed that organisms with a higher growth rate would be coupled to lower C:N, especially lower C:P and N:P ratios. However, the applicability of the growth rate hypothesis for plants is unclear, especially for shrubs growing under different water supply. We performed an experiment with eight soil moisture levels (soil water content: 4%, 6%, 8%, 13%, 18%, 23%, 26% and 28%) to evaluate the effects of water availability on leaf C:N:P stoichiometry in the shrub Zygophyllum xanthoxylum. We found that leaves grew slowly and favored accumulation of P over C and N under both high and low water supply. Thus, leaf C:P and N:P ratios were unimodally related to soil water content, in parallel with individual leaf area and mass. As a result, there were significant positive correlations between leaf C:P and N:P with leaf growth (u). Our result that slower-growing leaves had lower C:P and N:P ratios does not support the growth rate hypothesis, which predicted a negative association of N:P ratio with growth rate, but it is consistent with recent theoretical derivations of growth–stoichiometry relations in plants, where N:P ratio is predicted to increase with increasing growth for very low growth rates, suggesting leaf growth limitation by C and N rather than P for drought and water saturation.
KW - Individual leaf area and mass
KW - individual leaf growth rate
KW - leaf stoichiometry
KW - nitrogen:phosphorus ratio
KW - water supply
UR - http://www.scopus.com/inward/record.url?scp=85053514278&partnerID=8YFLogxK
U2 - 10.1111/plb.12897
DO - 10.1111/plb.12897
M3 - Article
C2 - 30102826
AN - SCOPUS:85053514278
SN - 1435-8603
VL - 21
SP - 82
EP - 88
JO - Plant Biology
JF - Plant Biology
IS - 1
ER -