Selection of irrigation regime for seed production of native plant <i>Lespedeza potaninii</i> in desert steppe.

It is of great significance to establish a suitable irrigation regime for the artificial propagation of native plant <i>Lespedeza potaninii</i> in arid areas. Taking the wild excellent herbage <i>L. potaninii</i> from desert steppe of Ningxia as test material, we set up an experiment with nine irrigation regimes (three irrigation times of 2, 3, and 4 times, crossed with three irrigation quotas of 150, 250, and 350 m³·hm^-2) to select the best regime by investigating the effects of different irrigation regimes on the agronomic characteristics related to seed production, seed yield and quality, as well as water use efficiency. We found that the irrigation time and quota had significant effect on plant height, branch number, reproductive branch number, inflorescence number, pod number, pod seed number, and the thousand-seed weight. The highest seed yield was obtained in the T₃ treatment (irrigating 2 times, 350 m³·hm^-2 for each time), which was 49.4% higher than that of the T₈ treatment (irrigating 4 times, 250 m³·hm^-2 for each time). The T₄ treatment (irrigating 3 times, each time 150 m³·hm^-2) had the highest water use efficiency. The germination rate and the germination potential of seeds under the T₃ treatment were the highest, reaching 88.0% and 84.7%, respectively. The T₃ treatment was the suitable irrigation regime for the artificial propagation of <i>L. potaninii</i> seeds based on a comprehensive evaluation using the entropy weight-TOPSIS method.