Influence of planting density on growth performance, salt dynamics, and nitrogen uptake in Suaeda salsa L

Optimal planting density (PD) is a critical agronomic practice that directly influences plant growth and yield. Suaeda salsa L. can absorb salts from saline soils and accumulate them in its tissues, thereby playing a significant role in saline-alkali soil remediation. However, studies on the effects of S. salsa PD on soil improvement are limited.

In this study, a pot experiment was conducted with three planting densities, two plants per pot (D1), four plants per pot (D2), and six plants per pot (D3), to determine their effects on the growth and salt accumulation in S. salsa. The soil moisture in each pot was maintained at 80% of the field capacity and was continuously controlled throughout the growing period using a weighing method.

The results showed that PD significantly influenced the morphological traits and salt removal capacity. Throughout the growing season, plant height, leaf area, and biomass were highest under D2, exceeding those under D1 by 29-78% and those under D3 by 1-6%. Nitrogen accumulation first increased and then decreased with increasing PD, reaching its maximum under D2 treatment. Although the shoot Na⁺ concentration decreased over time, the overall biomass continued to increase, resulting in a gradual increase in total salt accumulation, which peaked at the fruiting stage. Under D2, the highest salt removal was observed, reaching nearly 4.17 g pot^-1 (84.44 g m^-2).

The optimal density for S. salsa was 4 plants per pot (81 plants m^-2), which led to greater salt removal and higher biomass accumulation.