Nutrient and inorganic solute (Na+ and Cl-) content in green onion plants under hydroponic cultivation using brackish water

Abstract

Cultivation using brackish waters can result in nutritional and metabolic imbalances in several plant species, consequently reducing the production of dry matter (DM) and accumulation of toxic ions (Na+ and/or Cl-) in plants. We evaluated the DM production, and nutrient and inorganic solute (Na+ and Cl-) content in green onion plants (cv. Todo Ano Evergreen - Nebuka) under different levels of nutrient solution salinity in combination with circulation frequencies of this solution. Two experiments were conducted in a hydroponic system, using a completely randomized design, in a 6 × 2 factorial scheme, with five replicates: six levels of nutrient solution salinity (1.5, 3.0, 4.5, 6.0, 7.5, and 9.0 dS m-1) and two solution circulation frequencies (twice and thrice a day). In Experiment I, the evapotranspired depth was replaced using brackish water that was used to prepare each of the salinity levels (used exclusively), whereas in Experiment II, brackish water was used only to prepare each of the salinity levels and public water was used (electrical conductivity [ECw] = 0.12 dS m-1) for replacement in all treatments. The increase in the nutrient solution salinity reduced the production of DM and accumulation of nutrients; the reductions were more pronounced when brackish waters were used exclusively (Experiment I). However, the circulation of solutions thrice a day resulted in the harmful effects of the salinity effect. Replacing the evapotranspirated blade with water supply (Experiment II) mitigated the deleterious effects of salinity. Moreover, three circulations of the nutrient solution daily resulted in lower accumulation of inorganic Na+ and Cl- solutes and increased accumulation of nutrients N, P, K+, Ca2+, Mg2+, and S in the culture.

Reuso De Águas Oriundas Da Piscicultura E Seus Efeitos Sob as Trocas Gasosas De Rúcula Hidropônica

“…Diante dos desafios para o reuso de água, sistemas de cultivos que proporcionem menores impactos ambientais são necessários para utilização destes efluentes (John et al, 2022), pois estes podem contaminar lençois freáticos e demais recursos hídricos. Neste sentido, o cultivo hidropônico tem sido cada vez mais utilizado com água de reuso (Silva et al, 2012;Souza, C. D. S. et al, 2020), pois consiste no cultivo de plantas sem a presença do solo, disponibilizando os nutrientes por meio de uma solução nutritiva em perfis. Esse sistema além de se mostrar eficiente para produção de hortaliças, tem o objetivo de reduzir o consumo de água (Silva et al, 2012), tendo em vista que a perda para o meio é diminuída, tornando-se uma solução para escassez hídrica, principalmente em regiões áridas e semiáridas, ambientes em que estratégias para aumentar a eficiência dos sistemas de cultivo se faz necessário (Silva et al, 2016;Lessa et al, 2023).…”