Leaf stoichiometry and resorption of N and P in Lucerne at different growth stages under different water supplies

Abstract

Drought affects not only nutrient cycling but also the internal cycling in the plant. We conducted a greenhouse experiment with lucerne at low, moderate and high soil water levels (LW, MW and HW). Green-leaf N:P (N:P_gr) decreased at squaring and flowering stages as water supply increased, while senesced-leaf N:P (N:P_sen) increased mostly. N:P_gr increased with the growth at LW and MW, while hardly changed at HW. N:P_sen increased and then decreased with the growth at LW and HW, but increased at MW. Water supply may affect soil N or P limitation in a growth stage-specific way. Water supply barely affected leaf N resorption of lucerne, while enhanced leaf P resorption. P resorption was positively correlated with soil P limitation, while there was no relationship of N resorption with N limitation. Therefore, increased water supply would lead to enhanced P resorption to ameliorate the restriction of soil P limitation to lucerne growth.

Keywords:

• alfalfa
• leaf nutrient concentration
• leaf nutrient resorption efficiency
• stoichiometry
• soil nutrient limitation
• water addition

Additional information

Funding

This work was supported by the grants from National Natural Science Foundation of China (31572460), National Key Research and Development Program of China (2016YFC0400302) and Fundamental Research Funds for the Central Universities of China (lzujbky-2017-ot01).