Does the Application Flow Rate of Nutrient Solutions Prepared in Brackish Water Affect Coriander Production?

Abstract

Flow rates for applying nutrient solutions in hydroponic systems are empirically known, yet uncertainties remain regarding whether brackish water affects the optimal flow rate and, consequently, biomass production and allocation. This study evaluated whether variations in application flow rate affect coriander biomass when brackish water is used to prepare the nutrient solution. Two consecutive greenhouse cycles were conducted: In the first, salinity was adjusted using NaCl, and in the second, CaCl 2 ·2H 2 O. A completely randomised design (4 × 4) was adopted, comprising four electrical conductivities (1.7, 3.0, 4.5 and 6.0 dS m −1 ) and four flow rates (1.0, 2.0, 3.0 and 4.0 L min −1 ), totalling 64 experimental units per cycle. Fresh and dry mass partitioning and dry mass allocation were analysed. Lower flow rates (> 1 and ≤ 2 L min −1 ) increased shoot fresh mass even under elevated salinity, whereas higher flow rates (> 2 L min −1 ) favoured root biomass. Increasing salinity reduced the shoot dry mass ratio but raised the overall percentage of dry matter, irrespective of the predominant cation (Na + or Ca 2+ ). A flow rate between 1 and 2 L min −1 is recommended, even when using brackish water to prepare the nutrient solution, as this range promotes greater shoot biomass in coriander plants.

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