Evaluation of hydroponic systems for the cultivation of Lettuce (Lactuca sativa L., var. Longifolia) and comparison with protected soil-based cultivation (2022)

Table of Contents
Agricultural Water Management Abstract Introduction Section snippets The experimental site Crop performance Conclusions and future work Declaration of Competing Interest Acknowledgments References (76) Land Use Policy Postharvest Biol. Technol. Agric. Water Manag. Sci. Hortic. Glob. Food Secur. Comput. Electron. Agric. Sci. Hortic. Nitrate content in lettuce (Lactuca sativa L) heads in relations to plant spacing, nitrogen form and irrigation level J. Sci. Food Agric. Effect of water regime on growth and yield of Lettuce (Lactuca sativa L.) N Save Nat. Surviv. Effect of phosphorus and plant spacing on the growth and yield of Lettuce Adv. Agric. Biol. Indus water treaty: problems of perception Asian J. Comparison of land, water, and energy requirements of lettuce grown using hydroponic vs. conventional agricultural methods Int. J. Environ. Res. Public Health Groundwater storage variations in India. Groundwater of South Asia Rockwool in horticulture, and its importance and sustainable use in New Zealand. N.Z. J. Crop Hortic. Sci. The opening of Pandora’s box: climate change impacts on soil fertility and crop nutrition in developing countries Plant Soil Yield, fruit quality and mineral composition of grafted melon plants grown under saline conditions J. Hortic. Sci. Biotechnol. Cooling and concentration of nutrient solution in hydroponic lettuce crop Hortic. Bras. Socioeconomic status and esophageal squamous cell carcinoma risk in Kashmir, India Cancer Sci. Potential of vertical hydroponic agriculture in Mexico Sustain Sawdust and bark-based substrates for soilless strawberry production: irrigation and electrical conductivity management PLoS One Smaller, faster stomata: scaling of stomatal size, rate of response, and stomatal conductance J. Exp. Bot. Urban vegetable for food security in cities. A review Agron. Sustain. Dev. Nutrient solution concentration and growing season affect yield and quality of Lactuca sativa L. var. acephala in floating raft culture J. Sci. Food Agric. A relationship between humidity response, growth form and photosynthetic operating point in C3 plants Plant Cell Environ. Economic analysis of agricultural projects Nursery production of Pinus engelmannii Carr. with substrates based on fresh sawdust Forests An economic analysis of soilless culture in gerbera production HortScience Pricing nature: cost-benefit analysis and environmental policy Aeroponic and hydroponic systems for medicinal herb, rhizome, and root crops HortScience Financial analysis: tools and techniques: a guide for managers Nutritional solutions, flow rates and quality of hydroponic lettuce Acta Sci. Agron. Cited by (16) Novel Materials for Urban Farming Effect of biochar amendments on the growth and development of ‘Vera’ crisp lettuce in four soils contaminated with cadmium Differential Metabolic Responses of Lettuce Grown in Soil, Substrate and Hydroponic Cultivation Systems under NH<inf>4</inf><sup>+</sup>/NO<inf>3</inf><sup>−</sup> Application Effect of micro fertilizers on productivity and quality of lactuca-sativa varieties Grocery Waste Compost as an Alternative Hydroponic Growing Medium Recommended articles (6)
ScienceDirect

RegisterSign in

ViewPDF

  • Access throughyour institution

Agricultural Water Management

Volume 245,

28 February 2021

, 106572

Abstract

The expansion of the earth's population has led to the overuse of land and water resources, which has ultimately resulted in their scarcity. Changing climatic conditions and erratic weather behavior over the years has fueled the existing problems of land and water scarcity and continued to exact a toll on agriculture. Utilization of the latest technologies coupled with advanced methods of crop production will no doubt increase our capacity to deal with these modern challenges of the shortages of resources. Soilless or liquid culture may serve as an alternative to conventional soil-based cultivation systems. The present study was conducted to determine the suitability and viability of hydroponic cultivation as an alternative planting system to greenhouse soil-based lettuce cultivation in temperate regions of northern India. In the present study, two hydroponic techniques viz. deep water culture, and nutrient film technique were evaluated and compared to the conventional soil-based cultivation method under protected conditions. Crop performance, water consumption, and economy were the criteria chosen to assess the efficacy of planting techniques using Tukey’s multiple range test at a significance level of 0.05. Deep water culture system was found to be the most desirable concerning the duration of the crop, causing a reduction in the plant growth period by 15 days. Also, higher values of most of the photosynthetic parameters were observed in the deep water culture system, which translated into higher yield/plant for the system. The crop quality also improved under the deep water culture system, which was reflected by the higher values of quality parameters like chlorophyll, total soluble solids, protein, and crude fiber content. Both the hydroponic systems produced significantly higher yield, and nutritionally superior produce in lesser time than the soil-based system (P<0.05). However, there was a significant reduction in the dry matter content under hydroponic conditions. Nutrient film technique resulted in significant water savings of 64% than the other two techniques. According to economic analysis indicators, both hydroponic techniques performed better than the soil-based systems, having benefit-cost ratios greater than 2. Out of the two techniques tested, deep water culture proved to be the most promising system for adoption under protected agriculture owing to its simplicity, ease of operation, higher yield, economic feasibility, and nutritionally superior produce. The results of the study established hydroponic lettuce production as an appropriate and sustainable alternative to conventional soil-based lettuce production.

Introduction

Conventional soil-based agriculture is facing stern challenges in the form of depleted soil productivity in the cultivable areas, poor soil fertility due to continuous cultivation over the years, and most importantly decrease in per capita land availability (Lambin, 2012, Lal, 2015, Lehman et al., 2015). Besides these, there are threats from climate change in the form of rising temperatures, frequent dry periods, the unpredictability of the weather patterns; poor management of water resources within the watershed resulting from overuse of water for irrigation leading to wastage of huge amount of water, unchecked pollution of water bodies and decline in groundwater levels (Clair and Lynch, 2010, Dhawan, 2017, Bhanja et al., 2018). These challenges are a serious threat to conventional soil-based agriculture systems due to which producing food nowadays is becoming a real challenge. Therefore, the traditional soil-based agricultural practices need to be complemented by more productive and ecologically-sustainable forms of modern agriculture (Lambin and Meyfroidt, 2011). These modern forms of agriculture should take into cognizance the modern-day challenges of reduced soil productivity, depleted nutrient reserves of soil, limited availability of water for irrigation, and also help face the challenges of climate change. One approach to tackle these modern challenges is to espouse cultivation systems that are not reliant on soils. Soilless or liquid culture techniques possibly could serve as complementary cultivation systems to provide a conceivable solution to the current problems of scarcity of fertile arable lands and water, while minimizing the risks associated with soil-based cultivation systems. Hydroponics or liquid culture is one such specialized technique that involves the growth of plants without soil. Although artificial, it is based upon the same principles that nature has set up as the pattern of life and therefore is not an unnatural crop production method (Texier, 2013).

Hydroponics may be perceived as an engineered way of growing plants that utilizes a soil-less growing medium and a nutrient solution that is optimized to deliver the calculated resources essential for plant growth and development (Savvas, 2003). With regard to water management, it can be viewed as the art of managing water, infusing it with the nutrition vital to plants, and delivering it to their thirsty roots on an as-needed basis so that the highest yields can be achieved in the same sized space while using much less water and labor (Eigenbrod and Gruda, 2015). Plants grown hydroponically receive a well-balanced diet due to which these plants are healthier than their soil-grown counterparts (Bugbee, 2004, Hayden, 2006). Hydroponics, unlike conventional agriculture, facilitates complete control over the nutrition of the crop thus using no more than the amount of nutrients and water required by each crop leading to more efficient nutrient regulation and better water management (Rouphael et al., 2004, Tomasi et al., 2014). Due to the reasons aforementioned, hydroponics is usually considered a superior form of agriculture in virtually all the countries of the world (Schmilewski, 2009). Hydroponic studies aimed at improving crop productivity of hydroponic systems and resolving their limitations have increased exponentially over the past several decades in the developed nations, especially the US and China. The technology is being increasingly implemented in the developed world and hydroponic cultivation of several crops, including lettuce, cucumbers, tomatoes, etc. has been studied (Lee and Lee, 2015). However, the technique is still in its juvenile phase in the developing nations and demands extensive research on various aspects before its adoption in crop production. In India particularly, the continued population growth has rendered a market that is willing to purchase locally grown hydroponic produce. But the technique is far from enactment due to lack of evidence and research on the various aspects of the technology that would address the concerns of the growers while providing an insight into the production technique.

Kashmir valley has undergone a steady transition of lands from agricultural to non-agricultural uses over the past few decades. Reports reveal that in the last half-decade alone, over 20% of the farmlands have been converted for commercial or residential purposes (Rising Kashmir, 2019). This depletion in the reserves of arable land has hurt agricultural productivity in the state of Jammu and Kashmir, which is reflected by the decrease in the Gross Domestic Product of the state from 28% in 2004–05–16.05% in 2017–18 (Jammu and Kashmir Economic Survey Report, 2017–18). In addition, the Indus water treaty between India and Pakistan also poses an exceptional challenge to agriculture in the Kashmir valley. Under the treaty, the construction of reservoirs or dams and irrigation facilities is restricted unless there is prior approval of Pakistan. India's storage entitlement on river basins which are subjected to Indus waters treaty provisions viz. Sindh, Jhelum, and Chenab are just 0.25, 0.50, and 0.50 million-acre feet, respectively, due to which less than 45% of the state has access to irrigation (Bansal, 2013). Consequentially, these river basins are entirely dependent for their survival on the snowfall received in winter months. However, there are fears for the future, particularly with receding glaciers and their impact on river flows. Investigations revealed that glaciers in Kashmir Himalaya have shrunk by 17%, which, if continued, will have an adverse effect on the stream flows, water supplies, other dependent sectors in the region and will further decrease the availability of water for irrigation (Murtaza and Romshoo, 2017). Using this limited available water efficiently and effectively for supporting agriculture will be the main challenge faced by the farming communities in the region in the near future.

Apart from this, depletion in productivity of soil as a consequence of the use of traditional soil-based production systems with inefficient irrigation methods, lack of proper drainage practices, and excessive fertilizer application coupled with various environmental factors like soil erosion, waterlogging and development of salinity have undesirably impacted crop production in the region. In order to increase the productivity of conventional agriculture systems, farmers of Kashmir valley have resorted to the widespread use of pesticides and other agrochemicals as a result of which the overall incidence of cancer is on the rise in the valley (Dar et al., 2013, Wani et al., 2014). Hydroponic systems may be widely used in the valley to produce food with limited growing space and water, especially during the harsh winters when the valley is mostly cut off from the rest of the world. However, the acceptance of this capital-intensive technology amongst growers depends on its profitability and commercial viability.

Although there are quite a few studies that have proven the better performance of hydroponic systems over traditional systems, only a handful of studies drawing comparisons between the different hydroponic growing models have been conducted so far. In addition, hydroponic establishments are combined with protected cultivation, so no separate growth trends for hydroponic systems are available (De Anda and Shear, 2017). Researchers have concluded that hydroponic production can result in different outcomes under different crops and environmental conditions (Gashgari et al., 2018). Lettuce is a cool-season crop of high economic importance due to its potential to return revenue and is extensively grown worldwide, predominantly in temperate and subtropical regions (Mou, 2008, Kumar et al., 2010). Due to its nutritional value, it can command higher market prices and therefore has been commercialized internationally (Abu-Rayyan et al., 2004). Lettuce cultivation under protected conditions is being promoted in recent years but the crop production techniques for lettuce have not been standardized yet (Kadayifci et al., 2004, Spehia et al., 2018). The major challenge in greenhouse lettuce production is to standardize the growing systems that improve the quality and quantity of the produce, ensure judicious water management and reduce environmental impacts (Schwarz et al., 2009, Acharya et al., 2013). Lettuce (Lactuca sativa L.) cultivation under several hydroponic models particularly water culture and nutrient film technique has been extensively studied all over the world (Kaiser and Ernst, 2012, Safaei et al., 2015). These studies confirm that hydroponic growing systems result in increased leaf yield (Barbosa et al., 2015, Petropoulos et al., 2016). However, there are concerns amongst consumers about the nutritional quality, water consumption, and economics that thwart expansion into the commercial sector.

The present investigation was undertaken to determine whether hydroponic cultivation presents a suitable and viable alternative to greenhouse soil-based lettuce cultivation in the temperate regions of northern India, on the basis of the performance of two hydroponic techniques viz. deep water culture, and nutrient film technique for greenhouse lettuce cultivation. Crop performance, water consumption, and economic analysis were chosen as indicators of suitability and viability for this study. The study also aimed to evaluate the overall performance of deep water culture, nutrient film technique in terms of the suitability and viability indicators, and make a direct comparison of hydroponically grown lettuce with the soil-based lettuce under protected conditions.

Section snippets

The experimental site

The crop experiments were carried out under protected conditions in a plastic poly-house with a North-South orientation at the Experimental farm of College of Agricultural Engineering, Sher-e-Kashmir University of Agricultural Sciences and Technology, Kashmir, Northern India. It is situated at 34° 08' 30.5" N latitude and 74° 51' 42.0" E longitude and an elevation of 1605m above mean sea level. Inside the poly-house, the only source of light was natural solar radiation, while the relative

Crop performance

Data on the growth, photosynthetic, yield, and quality parameters were recorded from the sample plants during the course of the experiment. Out of the three growing systems tested, it was observed that growing systems had a significant influence on the performance of the plants. Crop duration, photosynthetic, growth, and quality parameters were significantly influenced by the growing method.

Conclusions and future work

It can be concluded from the results of comparative analysis that the hydroponic systems studied were suitable for lettuce production under the temperate conditions of Northern India. The deep water culture and nutrient film technique proved to be promising hydroponic techniques that delivered nutritionally superior and higher yields as compared to the protected soil-based cultivation system. This study has efficaciously quantified the overall performance of deep water culture and nutrient film

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

This research was financially supported by the All India Coordinated Research Project (AICRP) on Plasticulture Engineering and Technology. The authors of this study gratefully acknowledge Dr. Omar Fayaz Khan and Er. Mehraj Din Dar for their guidance and comments on the manuscript. We would also like to thank Dr. Rohitashw Kumar for his technical advice.

References (76)

  • S.V. Souza et al.Economic viability for deploying hydroponic system in emerging countries: a differentiated risk adjustment proposal

    Land Use Policy

    (2019)

  • M.V. Selma et al.Sensory quality, bioactive constituents and microbiological quality of green and red fresh-cut lettuces (Lactuca sativa L.) are influenced by soil and soilless agricultural production systems

    Postharvest Biol. Technol.

    (2012)

  • J.F. Maestre-Valero et al.Producing lettuce in soil-based or in soilless outdoor systems. Which is more economically profitable?

    Agric. Water Manag.

    (2018)

  • S. Lee et al.Beneficial bacteria and fungi in hydroponic systems: types and characteristics of hydroponic food production methods

    Sci. Hortic.

    (2015)

  • E.F. LambinGlobal land availability: malthus versus Ricardo

    Glob. Food Secur.

    (2012)

  • D.S. Domingues et al.Automated system developed to control pH and concentration of nutrient solution evaluated in hydroponic lettuce production

    Comput. Electron. Agric.

    (2012)

  • G.E. Barrett et al.Achieving environmentally sustainable growing media for soilless plant cultivation systems – a review

    Sci. Hortic.

    (2016)

  • A. Abu-Rayyan et al.

    Nitrate content in lettuce (Lactuca sativa L) heads in relations to plant spacing, nitrogen form and irrigation level

    J. Sci. Food Agric.

    (2004)

  • S.K. Acharya et al.

    Effect of water regime on growth and yield of Lettuce (Lactuca sativa L.)

    N Save Nat. Surviv.

    (2013)

  • A.S.H.I.K. Alahi et al.

    Effect of phosphorus and plant spacing on the growth and yield of Lettuce

    Adv. Agric. Biol.

    (2014)

  • A. Bansal

    Indus water treaty: problems of perception

    Asian J.

    (2013)

  • G.L. Barbosa et al.

    Comparison of land, water, and energy requirements of lettuce grown using hydroponic vs. conventional agricultural methods

    Int. J. Environ. Res. Public Health

    (2015)

  • S.N. Bhanja et al.

    Groundwater storage variations in India.

    Groundwater of South Asia

    (2018)

  • Bugbee, B., 2004. Nutrient management in recirculating hydroponic culture, in: South Pacific Soilless Culture...
  • W.T. Bussell et al.

    Rockwool in horticulture, and its importance and sustainable use in New Zealand.

    N.Z. J. Crop Hortic. Sci.

    (2004)

  • S.B. Clair et al.

    The opening of Pandora’s box: climate change impacts on soil fertility and crop nutrition in developing countries

    Plant Soil

    (2010)

  • G. Colla et al.

    Yield, fruit quality and mineral composition of grafted melon plants grown under saline conditions

    J. Hortic. Sci. Biotechnol.

    (2006)

  • N.N. Cometti et al.

    Cooling and concentration of nutrient solution in hydroponic lettuce crop

    Hortic. Bras.

    (2013)

  • N.A. Dar et al.

    Socioeconomic status and esophageal squamous cell carcinoma risk in Kashmir, India

    Cancer Sci.

    (2013)

  • J. De Anda et al.

    Potential of vertical hydroponic agriculture in Mexico

    Sustain

    (2017)

  • C. Depardieu et al.

    Sawdust and bark-based substrates for soilless strawberry production: irrigation and electrical conductivity management

    PLoS One

    (2016)

  • Dhawan, V., 2017. Water and agriculture in India: background paper for the South Asia expert panel during the Global...
  • P.L. Drake et al.

    Smaller, faster stomata: scaling of stomatal size, rate of response, and stomatal conductance

    J. Exp. Bot.

    (2013)

  • C. Eigenbrod et al.

    Urban vegetable for food security in cities. A review

    Agron. Sustain. Dev.

    (2015)

  • C. Fallovo et al.

    Nutrient solution concentration and growing season affect yield and quality of Lactuca sativa L. var. acephala in floating raft culture

    J. Sci. Food Agric.

    (2009)

  • P.J. Franks et al.

    A relationship between humidity response, growth form and photosynthetic operating point in C3 plants

    Plant Cell Environ.

    (1999)

  • Gashgari, R., Alharbi, K., Mughrbil, K., Jan, A., Glolam, A., 2018. Comparison between growing plants in hydroponic...
  • Gonnella M., Serio F., Conversa G., Santamaria P., 2003. Yield and quality of lettuce grown in floating system using...
  • J.P. Gittinger

    Economic analysis of agricultural projects

    (1982)

  • M.M. González-Orozco et al.

    Nursery production of Pinus engelmannii Carr. with substrates based on fresh sawdust

    Forests

    (2018)

  • I. Grafiadellis et al.

    An economic analysis of soilless culture in gerbera production

    HortScience

    (2000)

  • N. Hanley et al.

    Pricing nature: cost-benefit analysis and environmental policy

    (2009)

  • A.L. Hayden

    Aeroponic and hydroponic systems for medicinal herb, rhizome, and root crops

    HortScience

    (2006)

  • E.A. Helfert

    Financial analysis: tools and techniques: a guide for managers

    (2001)

  • Jammu and Kashmir Economic Survey Report 2017–18...
  • Jensen, M.H., 2002. Controlled Environment agriculture in deserts, tropics and temperate regions-A World Review. in:...
  • C.H. Junior et al.

    Nutritional solutions, flow rates and quality of hydroponic lettuce

    Acta Sci. Agron.

    (2007)

  • Cited by (16)

    View all citing articles on Scopus

    Recommended articles (6)

    • Research article

      Optimizing irrigation schedule in a large agricultural region under different hydrologic scenarios

      Agricultural Water Management, Volume 245, 2021, Article 106575

      Irrigation schedule is essential for improving crop production and allocating water resources in agricultural regions that heavily rely on irrigation. This study designs a framework based on the AquaCrop model to optimize the irrigation schedule of winter wheat under dry, normal and wet hydrologic scenarios over a large region in China. The model parameters were calibrated for one cultivar using observed data from three locations in the Fenwei Plain, northern China, and were shown to slightly vary spatially across this region. Regional weather data at high spatio-temporal resolution were generated by interpolation and were combined with regional soil data on a 2×2km grid to drive the model. The irrigation schedule for the study area was optimized by combining a multi-objective algorithm with the exponential efficacy coefficient method. The optimization objectives included crop yield, water use efficiency (WUE), irrigation WUE and economic irrigation benefit. The results showed that the optimized irrigation schedule performed better than the current irrigation schedule applied by the farmers under studied hydrologic scenarios, resulting in increased crop yield, WUE, irrigation WUE and irrigation economic benefit by 1.1–9.7% and decreased irrigation amount by 4.2–5.7%, depending on regions within the study area. The framework developed in this study reallocated irrigation water amounts between regions, thereby improving water allocation to achieve optimal crop yield, water use and economic benefit for the Fenwei Plain. The results can also serve as a guide for local farmers and irrigation district managers.

    • Research article

      Hydroponic production of ‘Biquinho’ pepper with brackish water

      Agricultural Water Management, Volume 245, 2021, Article 106607

      In order to generate information about the potential of ‘Biquinho’ pepper as an alternative crop for regions with limited supply of freshwater but with availability of brackish water, such as the semiarid region, a study was carried out with this crop grown in NFT (Nutrient Film Technique) hydroponic system for 120 days after transplanting (DAT). The experiment used nutrient solution prepared in water from the local municipal supply system (electrical conductivity of water –ECw=0.34 dS m−1) and six other brackish waters prepared artificially by the addition of NaCl, with electrical conductivity of the nutrient solution -ECsol: 2.70 (control), 3.64, 4.58, 5.28, 6.09, 6.90 and 7.77 dS m−1, composing seven treatments repeated six times in randomized blocks. Fruit yield, salt tolerance and yield earliness index were evaluated. The yield of ‘Biquinho’ pepper cultivated in NFT hydroponic system, without restriction of salinity, was 2.87kg per plant, corresponding to 46.1 Mg ha−1, considering an estimated area of 0.62m2 per plant. A plateau followed by exponential decay model was fitted to determine the threshold salinity of ‘Biquinho’ pepper, which was 5.22 dS m−1 in the nutrient solution, corresponding to the relative potential yield. Salinity reduced the yield earliness index of ‘Biquinho’ pepper.

    • Research article

      Effect of different root lengths for retaining freshness of hydroponic lettuce

      Journal of Agriculture and Food Research, Volume 4, 2021, Article 100151

      Harvesting with roots can help retain the freshness of hydroponic lettuce. And different root lengths may have different effects for freshness. To determine the optimal root length of hydroponic lettuce for retaining freshness, a root cutting and storage experiment was carried out to study some influenced factors of freshness such as changes in weight loss rate, color, and chlorophyll contents. Root lengths of samples were selected as five groups, i.e., 0 cm, 3 cm, 6 cm, 9 cm, and whole root length. Balance, chroma meter, and chlorophyll meter were used to measure the influenced indicators of different root lengths every other day for 15 days. Results showed that the relationship between the loss rate of chlorophyll content and the root length of hydroponic lettuce was not apparent. The chromatic aberration and the root length of hydroponic lettuce maintained a linear relationship. In the group of 0 cm, the chromatic aberration was 8.70 NBS that was maximum in the five groups. In the group of 9 cm, the chromatic aberration was 6.00 NBS that was minimal in the five groups. The relationship between the weight loss rate of hydroponic lettuce and the root length was linear. In the group of the whole root length, the weight loss rate of lettuces was 1.23% that was minimal in the five groups. It can be known that retaining the primary root or whole root of the hydroponic lettuce was beneficial for reducing the change in chromatic aberration, and increasing root length could reduce the weight loss rate of the lettuce. Therefore, considering the influence of the root length on the changes in weight loss rate, color, chlorophyll contents, and the hydroponic characteristics of lettuce, the optimal length of root retention for hydroponic lettuce was selected as 9 cm.

    • Research article

      Fertilizer drawn forward osmosis process for sustainable water reuse to grow hydroponic lettuce using commercial nutrient solution

      Separation and Purification Technology, Volume 181, 2017, pp. 18-28

      This study investigated the sustainable reuse of wastewater using fertilizer drawn forward osmosis (FDFO) process through osmotic dilution of commercial nutrient solution for hydroponics, a widely used technique for growing plants without soil. Results from the bench-scale experiments showed that the commercial hydroponic nutrient solution (i.e. solution containing water and essential nutrients) exhibited similar performance (i.e., water flux and reverse salt flux) to other inorganic draw solutions when treating synthetic wastewater. The use of hydroponic solution is highly advantageous since it provides all the required macro- (i.e., N, P and K) and micronutrients (i.e., Ca, Mg, S, Mn, B, Zn and Mo) in a single balanced solution and can therefore be used directly after dilution without the need to add any elements. After long-term operation (i.e. up to 75% water recovery), different physical cleaning methods were tested and results showed that hydraulic flushing can effectively restore up to 75% of the initial water flux while osmotic backwashing was able to restore the initial water flux by more than 95%; illustrating the low-fouling potential of the FDFO process. Pilot-scale studies demonstrated that the FDFO process is able to produce the required nutrient concentration and final water quality (i.e., pH and conductivity) suitable for hydroponic applications. Coupling FDFO with pressure assisted osmosis (PAO) in the later stages could help in saving operational costs (i.e., energy and membrane replacement costs). Finally, the test application of nutrient solution produced by the pilot FDFO process to hydroponic lettuce showed similar growth pattern as the control without any signs of nutrient deficiency.

    • Research article

      Iodine biofortification of sweet basil and lettuce grown in two hydroponic systems

      Scientia Horticulturae, Volume 276, 2021, Article 109783

      Two hydroponic techniques (floating system and aeroponics) were assessed for iodine (I) biofortification of sweet basil (Ocimum basilicum L.) and baby-leaf lettuce (Lactuca sativa L.). Iodine was supplemented by adding KI into the nutrient solution to achieve a final I concentration of 10 μM. Shoot biomass production and leaf concentration of I, nitrates, total phenols and pigments were measured on the occasion of two successive cuts, 14 and 28 days after transplanting. In both the hydroponic systems, the supplementation of KI represented an effective method for the biofortification of basil as it did not affect the plant growth, while it moderately reduced the biomass production in lettuce. Leaf I accumulation occurred to a greater extent in aeroponics than the floating system in both species. In KI-treated basil plants, leaf I content ranged between 9.76 and 23.58 mg kg−1 FW. Consequently, 6 g of fresh basil leaves, which is contained in a portion of Italian pesto sauce (12 g), could satisfy 40%–94% of the Recommended Daily Intake (RDI) of iodine for healthy adults (150 μg day−1). In lettuce, leaf I contents of first-cut leaves were 1.55 and 3.60 mg kg−1 FW, in the floating system and aeroponics, respectively. Therefore, a serving size of 26 g of lettuce containing I from 1.55 (floating culture) to 3.60 (aeroponics) mg kg−1 FW could satisfy 27 % to 62 % of the RDI of iodine.

      Lettuce grew much less in the floating system than aeroponics, probably because of the lower dissolved oxygen level in the nutrient solution as compared to aeroponics. Basil was less sensitive to the oxygen availability in the root zone, since no differences were detected between the two hydroponic systems in terms of fresh and dry biomass.

    • Research article

      Physical and mechanical properties of hydroponic lettuce for automatic harvesting

      Information Processing in Agriculture, Volume 8, Issue 4, 2021, pp. 550-559

      To design an automatic harvesting machine for hydroponic lettuce (Lactuca sativa L.), physical and mechanical properties of hydroponic lettuce were investigated and analyzed. Moisture content of stem, root and leaf, geometric characteristics, pulling force, and root cutting force were studied for harvesting hydroponic lettuce. The pulling force was examined by a tensile experiment, while the root cutting force was investigated by a shear experiment on the electronic universal testing machine. The moisture content of hydroponic lettuce was obtained by direct drying. Experiment data were processed using regression analysis and mathematical statistics method. A regression equation and the law of numerical distribution were obtained. The results showed that the geometric size of different hydroponic lettuce had little difference, and the distribution of physical parameters was concentrated. Moisture content was found statistically similar in stem and root (around 91%), while the highest moisture content was found in the leaf of 95.73%. The root cutting force decrease with the increase of cutting speed and decrease with the cutting position move downward. The minimum average root cutting force in the experiment was 1.41N. The average pulling force was 13N. This study provides adequate theoretical support for the design of the automatic harvesting machine of hydroponic lettuce.

    View full text

    © 2020 Elsevier B.V. All rights reserved.

    You might also like

    Latest Posts

    Article information

    Author: Msgr. Refugio Daniel

    Last Updated: 08/22/2022

    Views: 6544

    Rating: 4.3 / 5 (74 voted)

    Reviews: 89% of readers found this page helpful

    Author information

    Name: Msgr. Refugio Daniel

    Birthday: 1999-09-15

    Address: 8416 Beatty Center, Derekfort, VA 72092-0500

    Phone: +6838967160603

    Job: Mining Executive

    Hobby: Woodworking, Knitting, Fishing, Coffee roasting, Kayaking, Horseback riding, Kite flying

    Introduction: My name is Msgr. Refugio Daniel, I am a fine, precious, encouraging, calm, glamorous, vivacious, friendly person who loves writing and wants to share my knowledge and understanding with you.