Sex-specifically responsive strategies to phosphorus availability combined with different soil nitrogen forms in dioecious Populus cathayana

Abstract

\n \n \n Phosphorus (P) availability and efficiency are especially important for plant growth and productivity. However, the sex-specific P acquisition and utilization strategies of dioecious plant species under different N forms are not clear.\n \n \n \n This study investigated the responsive mechanisms of dioecious Populus cathayana females and males based on P uptake and allocation to soil P supply under N deficiency, nitrate (NO3−) and ammonium (NH4+) supply.\n \n \n \n Females had a greater biomass, root length density (RLD), specific root length (SRL) and shoot P concentration than males under normal P availability with two N supplies. NH4+ supply led to higher total root length, RLD and SRL but lower root tip number than NO3− supply under normal P supply. Under P deficiency, males showed a smaller root system but greater photosynthetic P availability and higher leaf P remobilization, exhibiting a better capacity to adaptation to P deficiency than females. Under P deficiency, NO3− supply increased leaf photosynthesis and P use efficiency (PUE) but reduced RLD and SRL in females while males had higher leaf P redistribution and photosynthetic PUE than NH4+ supply. Females had a better potentiality to cope with P deficiency under NO3− supply than NH4+ supply; the contrary was true for males. These results suggest that females may devote to increase in P uptake and shoot P allocation under normal P availability, especially under NO3− supply, while males adopt more efficient resource use and P remobilization to maximum their tolerance to P deficiency.\n