Appropriate nitrogen addition regulates reproductive strategies of Leymus chinensis

Nitrogen(N) addition can significantly improve the aboveground productivity of plants. The responses of reproductive strategies to N addition remain elusive for Leymus chinensis. Here, we examined the vegetative growth and clonal and sexual reproduction of a rhizome clonal grass, Leymus chinensis (Trin.) Tzvel, in response to N addition rates of 0, 2, 4, 8, 16, 32, and 64 g N m−2. N addition altered the reproductive strategy and allometric growth patterns of L. chinensis along the N addition gradient. N addition generally promoted higher investment in the biomass of vegetative and clonal organs, and a lower investment in sexual organs. N addition rates of 16 and 32 g N m−2 were key thresholds; 16 g N m−2 was the optimal rate for sexual reproduction and 32 g N m−2 was optimal for vegetative growth and clonal reproduction. At an addition rate of 16 g N m−2, the sexual reproductive capacity of L. chinensis was highest. Resource allocation to sexual reproduction increased with N addition, but decreased at rates>16 g N m−2. The growth and clonal reproduction of L. chinensis decreased at N concentrations>32 g N m−2. Our findings highlight that the reproductive strategy of L. chinensis varies with N addition rate, and the growth, sexual reproduction, and clonal reproduction strategies of L. chinensis are plastic, which has important implications for production.