Growth Characteristics of Bell Pepper and Tomato Hydroponically Cultivated in Growth Media Containing Different NaCl Concentrations in Raw Water on Reclaimed Lands

Abstract

Reclaimed land used as arable land can improve low food self-sufficiency or export competitiveness through large-scale controlled-environment agriculture. However, high salinity in reclaimed land can cause diseases and decrease yields during crop cultivation. This study was conducted to understand the growth characteristics of bell pepper and tomato hydroponically cultivated in rockwool and coir media reflecting changes in electrical conductivity (EC) and NaCl concentrations in the raw water of reclaimed lands. For bell pepper, Machai varieties (C. annuum L. cv. Machai) were used. For tomatoes, TY TRUST varieties (S. lycopersicum L. cv. TY TRUST) were used. NaCl was supplemented into the nutrient solution once a week to construct a treatment group based on EC. For bell pepper and tomato, NaCl was supplied at the following levels: none (CON), EC 4.0 (T1), EC 4.5 (T2), EC 5.0 (T3), and EC 5.5 dS·m-1 (T4). The plant height, leaf area, leaf fresh weight, leaf dry weight, stem fresh weight, stem dry weight, and fruit yield of bell pepper and tomato were investigated as indicators of growth characteristics of crops. For bell peppers, the growth index decreased with an increase in the stage as the NaCl concentration was increased, regardless of the type of media used. The use of coir media could secure bell pepper production yields without a significant effect of the NaCl concentration at the levels used in this study. However, for tomatoes, the leaf area was significantly decreased when NaCl concentrations were applied compared to that of the control group. Also, most other growth indicators were significantly decreased at NaCl concentrations above T2. The effects of the NaCl concentration were reduced when tomatoes were cultivated in coir media instead of rockwool media. Therefore, for hydroponically cultivated bell peppers and tomatoes, if raw water containing NaCl is supplied, it may be possible to maintain the crop yield if coir media are used.