Effects of conservation versus elimination of growing points on yield, C: N: P stoichiometry, and root morphology of Leymus chinensis

The conservation and elimination of the growing point of Leymus chinensis (Trin.) Tzvel. are two common contrasted scenarios during grazing. However, the biomass and nutrient allocation in L. chinensis, as well as their contribution to yield under these conditions are unclear. Therefore, a simulated grazing experiment was conducted using a factorial design that combined two defoliation heights (conservation versus elimination of growing points) and four plant heights (18, 24, 31, and 35 cm) during two growing seasons (2020 and 2021), resulting in eight treatments. Additionally, the experiment also included two identical control treatments with a single mowing in mid-August. The results demonstrated that conservation treatments for the growing point increased the regeneration time of L. chinensis during the entire growing season in both years compared to elimination treatments for the growing point, due to the alteration in biomass allocation priority and C: N: P stoichiometric ratio between stems and leaves of L. chinensis, as well as root morphological traits. The growth strategy in the treatment with 17 cm defoliation height at 35 cm plant height demonstrated the optimal combination, resulting in stabling the accumulated DM yield of L. chinensis in both years. The findings emphasize the significance of comprehending the correlation between the growing point of L. chinensis and its yield, providing a pioneering approach to guide sustainable grazing practices for L. chinensis grassland.