Optimization of Nutrient Solution Electrical Conductivity for Growth Response of Red Amaranths (Amaranthus cruentus) under Vertical Hydroponic System

Abstract

The present study was conducted to optimise nutrient solution electrical conductivity (EC) to improve the growth and yield of red amaranths (Amaranthus cruentus) variety Arka Arunima under a vertical Nutrient Film Technique (NFT) hydroponic system. The experiment was carried out in a naturally ventilated polyhouse at Dr. NTR College of Agricultural Engineering, Bapatla, Andhra Pradesh. Four nutrient concentration treatments based on total dissolved solids (TDS), namely T1 (650 ppm), T2 (750 ppm), T3 (850 ppm) and T4 (950 ppm), were evaluated in a Completely Randomised Design (CRD) with three replications. Fifteen-day-old seedlings were transplanted into vertical A-frame NFT units using hydrotons as the growing medium. The pH of the nutrient solution was maintained between 6.0 and 6.5 throughout the crop period. Growth parameters, including plant height, number of branches, number of leaves, root length, stem diameter and yield, were recorded at 10, 20 and 30 days after transplantation (DAT) and analysed statistically using ANOVA. The results showed significant differences among treatments for most growth parameters at 20 and 30 DAT. Among the treatments, T2 (750 ppm) recorded the highest plant height (26.4 cm), number of leaves (24), root length (24.72 cm), stem diameter (6.14 mm) and yield (7.04 kg). The lowest yield (4.67 kg) was observed in T4 (950 ppm), indicating that higher nutrient concentrations adversely affected crop growth and productivity. Regression and optimisation analysis confirmed that a nutrient concentration of approximately 750 ppm (EC ≈ 1.5 dS/m) was optimal for achieving higher yield and efficient nutrient utilisation under NFT hydroponics.