Nutrient Solution Temperature Affects Growth and °Brix Parameters of Seventeen Lettuce Cultivars Grown in an NFT Hydroponic System

Dharti Thakulla,Niels Maness,Bizhen Hu,Carla Goad,Bruce Dunn

doi:10.3390/horticulturae7090321

Dharti Thakulla, Niels Maness + Show 3 more

Open Access

https://doi.org/10.3390/horticulturae7090321

Copy DOI

Journal: Horticulturae	Publication Date: Sep 17, 2021
Citations: 14	License type: CC BY 4.0

Affiliation: Oklahoma State University

Abstract

Nutrient solution temperature in a hydroponic system affects °Brix and yield of lettuce; thus, it is important to maintain the water temperature within an appropriate range. Nutrient-film technique (NFT) trials were conducted to investigate the effects of different water temperatures (18.3 °C, 21.1 °C, and ambient) on growth and °Brix of 17 cultivars from five different types (Loose leaf, Romaine, Butterhead, Salanova, and Batavian) of lettuce. The average daily water temperature for ambient treatment was recorded to be 20 to 26.5 °C. The study was conducted in a split-plot design with three replications over time. Results indicated that water temperature affected root and shoot fresh and dry weight, plant width, and °Brix for lettuce. Lettuce grown at 21.1 °C were 15% greater for shoot fresh weight than plants grown at ambient conditions. All the growth and quality parameters of lettuce were found to be affected by cultivars, with “Coastal Star” showing the best results in both growth and °Brix parameters. All the cultivars of the Romaine type showed greater growth and °Brix, while Salanova lettuce did not perform well in all treatments compared to other lettuce types. For CO2 assimilation, the interaction between water temperature and cultivars was significant, with “Parris Island” having the greatest rate at ambient water temperature. These results suggested that maintaining water temperature at 21.1 °C produced lettuce with greater growth and biomass but had 26% lower °Brix than lettuce grown at 18.3 °C.

Highlights

Published: 17 September 2021Hydroponics is a technique of growing plants by placing the roots in a nutrient solution with or without mechanical root support [1]
The objectives of our research were to identify the optimum water temperature needed for the greatest ◦ Brix and yield of five different types of lettuce grown in Nutrient-film technique (NFT) hydroponic systems
Lettuce grown at 21.1 ◦ C chilled water were greater in terms of shoot fresh and dry weight as well as root fresh and dry weight compared to

Summary

Introduction

Hydroponics is a technique of growing plants by placing the roots in a nutrient solution with or without mechanical root support [1]. It is referred to as “controlled environment agriculture”, or CEA, since raising plants hydroponically requires control of various environmental factors such as water temperature, light intensity and duration, humidity, and pH of the solution and mineral nutrients [2]. An important characteristic of hydroponic cultivation is the need and ability to control the temperature of the nutrient solution or of the root system using heaters or a cooling spiral. Studies have shown that when the temperature is above or below an optimum level, it may influence plant metabolic activities, including the accumulation of different metabolites such as phenolic compounds, nutrient uptake, chlorophyll pigment formation, photosynthesis, and the growth and development of the plant [5].

Objectives

Methods

Results

Conclusion