Effect of Electrical Conductivity on Growth, Yield and Quality of Broccoli Grown in Hydroponic System

Abstract

An experiment was conducted to identify the electrical conductivity (EC) in the nutrient solution that optimizes broccoli's growth, yield, and quality (Brassica oleracea var. italica L.) during cultivation. The experiment involved five EC treatments: T1 = EC 1.5, T2 = EC 2.0, T3 = EC 2.5, T4 = EC 3.0, and T5 = EC 3.5. These treatments were implemented in a deep water culture (DWC) hydroponic production system, which is a soilless cultivation method. The study was conducted at Patuakhali Science and Technology University, Bangladesh. Parameters such as plant biomass production, yield, quality variables, and tissue mineral content were measured. The results revealed that both high (3.5 dsm-1) and low (1.5 dsm-1) EC treatments led to a decrease in plant biomass, yield and quality of broccoli. But at EC level 3.0 dsm-1 (T4), the highest number of leaves per plant (16.3), leaf area (352.5 cm2), shoot length (28.0 cm), root length (49.33 cm), head/curd diameter (14.67 cm), head fresh weight (257.53 g), and dry weight (29.0 g) were recorded at 60 days after transplanting (DAT). Additionally, lower levels head/curd tissue micronutrients such as manganese (Mn), zinc (Zn), copper (Cu), and iron (Fe) content (59.63, 34.57, 29.43 and 136.67 ppm respectively) were found in lower EC level (1.5 dsm-1), while higher EC level (3.5 dsm-1) showed higher levels of those minerals (68.53, 45.80, 38.53 and 163.0 ppm respectively). Phosphorus (P) and Sulphur (S) content was non-significant in respect of different EC treatments. Conversely, nitrogen (N) and potassium (K) content were higher (3.16 % and 2.42 %) in lower EC treatments and lower (1.56 % and 1.64 %) in higher EC treatments. Mn, Zn, Cu, and Fe content of broccoli head/curd tissue increased progressively with higher EC treatments, while N and K content decreased. Based on this study’s growth and quality criteria, the optimal EC treatment for broccoli in a deep water culture hydroponic production system was found best at EC 3.0 (T4). It was found that both high and low EC levels induced nutrient stress, negatively affecting broccoli's quality, growth, and yield.