Interactive Effect of Irrigation Volume and Planting Density on Growth and Salt Uptake in Field-Grown Drip-Irrigated Suaeda salsa (L.) Pall.

Abstract

Planting halophytes such as Suaeda salsa (L.) Pall. under drip irrigation is a viable solution for the remediation of saline soils. We conducted this study to investigate the effects of different irrigation volumes and planting densities on the growth and salt uptake of Suaeda salsa under drip irrigation. The plant was cultivated in a field using drip irrigation at various irrigation volumes (3000 m·hm−2 (W1), 3750 m·hm−2 (W2), and 4500 m·hm−2 (W3)) and planting densities (30 plants·m−2 (D1), 40 plants·m−2 (D2), 50 plants·m−2 (D3), and 60 plants·m−2 (D4)) to examine the effects on growth and salt uptake. The study revealed that the amount of irrigation, planting density, and interaction between the two significantly affected the growth characteristics of Suaeda salsa. The plant height, stem diameter, and canopy width increased simultaneously with an increase in the irrigation volume. However, with an increasing planting density and the same irrigation volume, the plant height first increased and then decreased, while the stem diameter and canopy width decreased simultaneously. The biomass of D1 was the highest with the W1 irrigation, while that of D2 and D3 were highest with the W2 and W3 irrigations. The amount of irrigation, planting density, and their interaction significantly affected the ability of Suaeda salsa to absorb salt. The salt uptake increased initially and then decreased with an increasing irrigation volume. At the same planting density, the salt uptake of Suaeda salsa with the W2 treatment was 5.67~23.76% and 6.40~27.10% higher than that with W1 and W3, respectively. Using the multiobjective spatial optimization method, the scientific and reasonable irrigation volume for planting Suaeda salsa in arid areas was determined to be 3276.78~3561.32 m3·hm−2, and the corresponding planting density was 34.29~43.27 plants·m−2. These data can be a theoretical basis for planting Suaeda salsa under drip irrigation to improve saline–alkali soils.