Drip irrigation effect on seed yield, quality, and water use of Artemisia sphaerocephala

Artemisia sphaerocephala, a xerophyte shrub from the Compositae family, has gained significant attention in ecological restoration and various industries. However, limited knowledge of agricultural practices for its seed production hinders the development and use of this species. In a 5-year field experiment, we investigated the effects of four surface drip irrigation treatments (W0, W1, W2, and W3 with 0, 80, 160, and 240 mm, respectively) on seed yield, quality, and water use efficiency (WUE) in A. sphaerocephala. Higher irrigation levels significantly increased seed yield, with annual averages of 37, 85, 140, and 195 kg/ha for W0, W1, W2, and W3, respectively. Additionally, increased irrigation improved germination percentage and reduced median water potential (${\psi }_{50(g)}$). However, the effect of irrigation on WUE varied from year to year. Therefore, we recommend total irrigation of 240 mm, distributed as 80 mm each during winter, regreening, and full flowering stages, to optimize A. sphaerocephala seed production, particularly in arid regions. A structural equation model identified seeds per flower (SF) as the most significant contributor to seed yield, highlighting SF as a key trait for breeding programs aimed at improving A. sphaerocephala seed yield. Our study provides valuable insights for implementing effective agronomic measures to enhance seed yield in A. sphaerocephala and similar semi-shrubs.