NDT, a new soilless growing system without substrate suitable for Mediterranean conditions

Ioannis Lycoskoufis,George Mavrogianopoulos

doi:10.15835/nbha48311877

Abstract

Nutrient film technique (NFT) is characterized by the reduction of the dissolved oxygen concentration (DOC) in the recirculating nutrient solution along the gully; this is most intense in warm climates like the Mediterranean region. In this case, plant’s roots at the end of gully suffer from oxygen deficiency. The aim of this study was to develop a new soilless system without substrate which eliminates this NFT drawback and the cost of the substrate. Therefore, a new soilless system was designed. This new system associated the continuous drip irrigation along the gully with the recirculation of the nutrient solution and it was defined as Nutrient Drip Technique (NDT). In addition, the root gully was modified and shaped as W to provide better drainage of the nutrient solution in NDT system compared to NFT system. This system was tested for a tomato crop and compared with an NFT system and for a cucumber crop and compared with a media-based perlite and an NFT system. DOC measurements were taken along the gullies of the different systems. The results indicated that DOC of the nutrient solution along the gullies of NDT was higher and more uniform compared to NFT. Both tomato and cucumber plants grown in NDT system had higher Leaf Area Index (LAI) and were more productive compared to the conventional NFT system. Cucumber crop in NDT system had similar growth and productivity as in the perlite system. Water Use Efficiency (WUE) was higher in NDT compared to NFT system. Consequently, NDT system provides a better control of the root environment and the independence of porous substrates.

Highlights

Growing plants in solution culture, allows accurate control of nutrients and water supplies for plants (Adams, 1981; Epstein and Bloom, 2005)
The results indicated that dissolved oxygen concentration (DOC) of the nutrient solution along the gullies of Nutrient Drip Technique (NDT) was higher and more uniform compared to Nutrient film technique (NFT)
The hydroponic set up The basic features of the new hydroponic system, named Nutrient Drip Technique (NDT) are similar to NFT system and include: (1) a tank of nutrient solution; (2) a pump to deliver the solution, via pipes, to the upper ends of (3) the sloped gullies in which the plants are grown; (4) one irrigation line with emitters, which lay in the middle of each gully, across the length of the gully and (5) a means of collecting the solution as it flows from the lower ends of the drainage water-courses and of returning it to the tank for recirculation

Summary

Introduction

Growing plants in solution culture, allows accurate control of nutrients and water supplies for plants (Adams, 1981; Epstein and Bloom, 2005). It creates less emission, increases water and nutrient use efficiencies and is a more sustainable method than growing in porous substrate. Growing without porous substrate can lead to higher yields, because all conditions can be better controlled. Growing plants without porous substrate exhibits, several advantages, for plant research applications, such as salinity and waterdeficit stresses, which can be applied evenly and accurately to the cultivated plants. Received in revised form: 08 Jul 2020.

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