Tolerance to Iron-Deficiency Stress of Three Apple Rootstock Species in Hydroponic System

[Objective] Iron deficiency is one of the most important crop element deficiencies in the Loess Plateau of northwestern China. The selection for crop cultivars that are tolerant to low iron levels could be one of the approaches to solving the problem and improving crop production. [Method] Three major apple root stock species （Malus prunifolia, Malus sieversii and Malus baccata） were selected to evaluate their tolerance to iron defciency in hydroponic system. A 3×2 factorial pot experiment was conducted with three replicates in a greenhouse at Gansu Agricultural University, Lanzhou, China. [Result] The SOD, POD and CAT activities in roots and stems of the 3 root stock species in Fe-defcient Hoagland solution decreased, however Malus sieversii got the less reduction and had better root architecture and growth than the other species. The aboveground biomass, plant height, chlorophyll content, total root length and lateral root number were correlated positively with iron-defciency stress tolerance. The species’ tolerance to iron-defciency from high to low was M. sieversii’s〉M. baccata’s〉M. prunifolia’s. Moreover, the improvement of some morphological features such as root length, above-ground biomass, plant height and lateral root number in apple could be conducive to breeding cultivars with tolerance to iron-defciency stress. [Conclusion] Malus sieversii had better tolerance to iron-defciency stress than the others in this study.

Vertical Farming Using Hydroponic System: Toward a Sustainable Onion Production in Nueva Ecija, Philippines

The development of new technology for food production is essential to sustain man’s needs for survival. The use of farmlands for food production and industrial purposes goes beyond the carrying capacity of the environment. The study determined the applicability of Vertical Farming using Hydroponic Technology to onion production in Nueva Ecija, Philippines. The country is known as the onion capital of Southeast Asia. The study measured the technology’s sustainability and acceptability to onion farmers. By using experimental method, interview, and Focused Group Discussions (FGD), the study established its viability. Three phases of field experiments were conducted in August 2016, May 2017 and July 2017 using the Vertical Farming and Hydroponics Technology and Single Factor Analysis of Variance. The results showed that there is significant difference in the growth of onion bulb per week and the suitability and comparability of the technology to conventional farming. The study concluded that the VFH technology is acceptable to most onion farmers except the aspect of the cost of initial investment which requires government subsidy for the ordinary onion grower to avail of this new and sustainable technology in onion production.

Effect of Electric Field on the Kinetics of Growth of Lettuce (Lactuca sativa) in a Hydroponic System

The implementation of alternative harvest systems which are able to accelerate the kinetics of growth of plants, is extremely important to decrease the time of crop. In this sense, Electro-Hydroponic culture, i.e., the application of an electric field in the nutrient solution of the hydroponic culture emerges as an alternative and interesting harvest system. The objective of the present study was to investigate the effect of the electric field applying different intensities of direct current (DC) at the galvanostatic regime (50, 37.5, 25 and 12.5 mA) on the growth of lettuce (Lactuca sativa) plants in hydroponic culture. Fifty lettuce plants were used in a nutrient solution, from which 4 groups composed of ten lettuces each one, were subjected at 12.5, 25, 37.5 and 50 mA, respectively. A fifth group of ten lettuces was used as a reference test, i.e., without application of DC. The experiments were carried out during 16 days. The results reveal that the kinetics of growth of the lettuce is dependent on the applied current;actually it is observed an increase in the foliate area of the plants cultivated in the presence of DC than that obtained in the reference test. Furthermore, the plants subjected at 12.5 mA, revealed an increase in the foliate area of 65.3% and 73.2% in comparison with the reference test.

The Comparative Performance of Soil-Based Systems with Hydroponics

Conventional soil-based agriculture is resource-intensive, utilizing large amounts of land and water, thereby placing a strain on Earth’s natural resources. Soil-based agricultural techniques create environmental issues such as soil degradation, deforestation, and groundwater pollution from the mass implementation of fertilizers and pesticides. Agricultural crop production using hydroponics has shown promise to be less resource intensive and provide a faster turnaround in crop production. Soilless cultivation using hydroponics promises to relieve some pressure on Earth’s ecosystems and resources by utilizing lesser land and water footprint. The APS Laboratory for Sustainable Food at Florida Gulf Coast University (FGCU) compared the growth of Lettuce Lactuca sativa “Rex Butterhead” crop grown using soil and soilless methods to analyze the growth performance in each setting. Crops grown in the soil-based medium were raised in the FGCU Food Forest, used a mix of soil and potting mix, watered regularly, and followed standard Integrated Pest Management (IPM) practices. Crops grown hydroponically were grown in a thermally insulated grow tent with an artificial lighting source, ventilation, environmental controls, and the Deep-Water Culture (DWC) method. Lettuce plugs were grown for 15 days in controlled environments until two leaves after the cotyledons had developed and were ready for transplant. Plugs were transplanted into a 4 × 6 matrix at the FGCU Food Forest and the DWC growth system. Crops were grown to full bloom and ready for harvest in the soil (60 days) and soilless (30 days) based setups. We collected crop growth data, including wet weight (g), dry weight (g), leaf area (cm2), and chlorophyll concentration (μmol/m2). From the collected data, we derived the Specific Leaf Area (SLA, cm2/g) and biomass productivity (kg/m2). Descriptive statistics were used to describe the collected and derived data. We investigated the slopes of regression lines for each growth curve which derived the differences in biomass and productivity parameters between lettuce grown using soil and hydroponics. Both growing methods can grow lettuce crops to full bloom and to adequate harvest weight. The biomass parameters and productivity differ significantly between the growing methods. The lettuce crops grown using hydroponics increase in wet weight statistically and significantly faster than those grown in soil (p < 0.0001). Therefore, we determined that a hydroponic method of crop production may provide better crop output and biomass indicators measured than soil-based growth.

Evaluation of gradual hydroponic system for decentralized wastewater treatment and reuse in rural areas of Palestine

A pot experiment was conducted to evaluate the performance of a gradual multi-stage vertical flow hydroponic system as an option for decentralized wastewater treatment and reuse.The low cost of such option and the ease of its application make it feasible for rural areas where low cost decentralized options of wastewater treatment and reuse have a great potential in improving environmental and economic conditions in these areas.To evaluate the performance of such option,a five-stage vertical flow gradual hydroponic pot experiment was conducted in a greenhouse in the new campus of An-Najah National University.The experiment included five types of plants:two types of corn,barely,alfalfa,and sunflowers.Wastewater flow was applied through a drip system for the five types of plants.Wastewater was drained by gravity from one pot to the next through a gradual vertical flow hydroponic system.Quality of wastewater entering the first pot and leaving the last pot for each set of plants was monitored throughout the growing season.Results showed an over 90%removal efficiency of soluble organics and suspended solids,and about 60%removal efficiency of nitrogen through the system.The proposed gradual hydroponic treatment system was proved to be a successful alternative method to treat and reuse wastewater.Thus,gradual hydroponic systems could be successfully used as small decentralized wastewater treatment systems.This system could be used in producing crops with economic returns in Palestinian rural areas,where agriculture has a significant contribution in the income and employment of communities.

Development of a Cylindrical Hydroponics System for Vertical Farming

The study aimed to develop a vertical crop cultivation system for leafy plants based on cylindrical hydroponics and light emitting diode （LED） technology. Investigations were conducted on growing lettuce （Lactuca sativa cv. ＂Rex＂, ＂Nanda＂ and ＂Canasta＂） indoors in a rotary system and Chinese cabbage （Brassica chinensis） in a multi-tier cylindrical hydroponics system under red and blue （RB） LED lightings. Light intensity from different light sources have an influence on the yield and growth behaviour of indoor lettuce. Photosynthetically active radiation （PAR） levels at 63 μmol/m2·s produced low fresh weights （FW） and leaf areas of lettuce ＂Rex＂ and ＂Nanda＂ were grown under rotating conditions. The effect was, however, different on the better developed ＂Canasta＂. Stem etiolation was a common occurrence under such influence. Chlorosis was not observed on all plant types grown under the LEDs. Cultivating Chinese cabbage plants （FW： 28 g/plant） in cylindrical units stacked vertically above another, increased planting density by 47% when compared to the rotary system,

Evaluation of Methodology for Life Cycle Assessment Applied to Hydroponic Tomato Processes from a System Approach

Analysis of agricultural production systems of hydroponic tomato in Morelos state of Mexico, through a systematic approach, called systems development of life cycle （SDLC） was performed by comparing this with the methodology known as life cycle assessment （LCA）. This permits to analyze the differences in approaches of all these methodologies to propose improvements in the current system, which can allow an improved assessment of the environmental quality of agricultural products, which often is subject to confusion. That due to measurement parameters are not generally accepted by society, producers and consumers, may ensure that the process is fully sustainable and is considered quite as a green technology processes towards an ecological benefit and therefore for the humanity.

Cost Effective Smart Hydroponic Monitoring and Controlling System Using IoT

Hydroponic System is a system in which farmers cultivate different plants without utilizing the soil. The authors have proposed IoT system that monitors and controls all parameters of hydroponic system like water level, pH, humidity and temperature through mobile application. In proposed system, the authors have used an ESP32 micro-controller that is controlled pump. The pump will draw water from a reservoir which is connected to a regular water line. If the water level of the reservoir falls down to a certain level, the system will send an SMS to the Farmer. The farmer can control the water line and make the reservoir full by mobile application. An LDR and DHT11 humidity sensor is used to control the light and temperature of the farm. In system, we also used pH sensor where pH sensor is a scientific instrument that measures the hydrogen-ion activity in water-based solutions and indicating its acidity or alkalinity expressed as pH.

The Comparative Performance of Nutrient-Film Technique and Deep-Water Culture Method of Hydroponics for GREENBOX Technology

With the rising pressures on food security, GREENBOX technology was developed as an avenue for fresh leafy vegetable crop production in urban settings. GREENBOX units were designed to be thermally insulated and climate controlled, with an artificial lighting source that utilized soilless cultivation techniques. Previous studies conducted on GREENBOX technology used the Nutrient Film Technique (NFT);however, various hydroponic methods exist, such as the Deep-Water Culture (DWC) method being the most used. The APS Laboratory for Sustainable Food at Florida Gulf Coast University (FGCU) compared the crop growth performance between DWC and NFT systems using GREENBOX technology. The following study monitored environmental conditions and compared productivity and biomass data of Rex Butterhead Lettuce crops between DWC and NFT systems. We assembled two GREENBOX units using commercially available materials and the standard nutrient solution for fertigation. The crops grown in DWC and NFT were in a 4 × 6 configuration. The DWC and NFT systems were used to grow Lettuce Lactuca sativa “Rex Butterhead” over 30 days to full bloom from prepared plugs grown for 14 days. We collected environmental data including Photosynthetic Photon Flux Density (PPFD, μmol/m2∙s), Daily Light Integral (DLI, mol/ m2∙d), temperature (˚C), relative humidity (%), and Vapor Pressure Deficit (VPD, kPa). We collected lettuce crop growth data, which included wet weight (g), dry weight (g), leaf area (cm2), and chlorophyll concentration (μmol/m2). We derived data, including the Specific Leaf Area (SLA, cm2/g) and biomass productivity (kg/m2), from previously collected data. We used descriptive statistics to present the collected data. A paired t-test was performed to understand the differences in biomass and productivity parameters between the DWC and NFT-grown lettuce crops. Both the DWC and NFT-grown crops could grow lettuce crops to harvest weight at full bloom. Observed data demonstrated that the biomass parameters and productivity did not differ significantly between the two hydroponics techniques. Therefore, we believe both hydroponic methods may be similar in growth performance and may be used in future iterations of GREENBOX design and prove suitable for fresh vegetable crop production in urban settings.

Study on Optimization of Hydroponic Technology of Virus-free Potato Plantlets in Winter in Chengdu Plain

The effects of different heating measures on breeding virus-free potato plantlets with hydroponic technology were studied in this paper. The virus-free tube plantlets of potato （Favorita） were used as test material. A total of 3 treatments were designed, including traditional hydroponics （CK）, installing heaters （T1） and in- stalling heaters and thermal insulation device （T2）. The results showed in the Chengdu Plain in low-temperature winter, the installing of heaters and covering of thermal insulation device could maintain the hydroponic water temperature at 15-22 ~C. The potato seedlings grown in heaters and thermal insulation device-installed seedbed rooted 6.4 d earlier and emerged 13 d earlier compared to that in tradi- tional seedbed. The growth of potato seedlings grown in heaters and thermal insu- lation device-installed seedbed was more robust. Their root length, stem diameter, plant height, leaf number and fresh weight were all higher than that of traditional potato seedlings. The tuber number per plant in T1 group reached 1.7 and in T2 group reached 3.57 42 d after the cutting of hydroponic seedlings, while then the plantlets in CK group just turned into the aeroponics stage. Therefore, heating hy- droponics is conducive to advancing the cutting of virus-free seedlings and breeding robust water-cultured seedlings. Moreover, the fruiting of aeroponics seedlings is al- so advanced. The heating hydroponics plays an important role in actual production.

Response of Over-summer Hydroponic Lettuce to Nutrient Solution Temperature Control

Temperature, as an important feature of hydroponic nutrient solution, is closely related to dissolved oxygen content of nutrient solution and growth status of plant roots. How to precisely adjust the temperature of nutrient solution is the key to obtain high quality and high yield of hydroponic vegetables over summer. With Lactuca sativa vat. crispa ＇Luosheng No.3＇ as the test material, the effect of chiller cooling technology on the temperature of nutrient solution, as well as on the yield and quality of Luosheng No.3, in over-summer hydroponic cultivation was studied. The results showed that the chiller cooling technology controlled the nutrient solution temperature in a reasonable range （（20 ± 1）℃） and promoted the growth and dry matter accumulation of Luosheng No.3, instead of affecting the quality. In short, the chiller cooling technology is applicable to the temperature regulation of nutrient solu- tion in hydroponics over summer.

A Comparative Study on the Leaf Characteristics and Root Vigor of Bowl Lotus under Hydroponics and Soil Culture

[Objective] The experiment aimed to study the growth characteristics of hydroponic bowl lotus. [Method] The lotus variety Hongxia was chosen as the experimental material. Two treatments, hydroponics and soil culture were set to measure their photosynthetic indices, chlorophyll content and root vigor, and to observe their leaf tissue structure and stomatal characteristics. [Result] The findings indicated that there are no differences in the leaf physiological indices between bowl lotus under hydroponics and soil culture, while the leaf stomata of hydroponic bowl lotus is bigger and its amount is larger than that of soil-culture bowl lotus. At the same time, the ratio of the palisade tissue thickness to spongy tissue thickness is small,and its leaf tissue structure is loose. The root vigor of hydroponic bowl lotus reached its summit earlier, then began to drop. Whereas, the root activity of soil-culture lotus sustained increasing, with vigorous growth. [Conclusion] Therefore, it indicated that hydroponic bowl lotus can adapt to the aquatic-culture environment well and quickly, meanwhile, it also enters into its aging period quickly and its growth cycle gets shorter.

Evaluation on Chinese Bread Wheat Landraces for Low pH and Aluminum Tolerance Using Hydroponic Screening

Aluminum （Al） toxicity often takes place in acidic soils with a pH of 5.5 or lower. Breeding and cultivation of Al tolerance wheat can partially protect wheat escaping from Al toxicity. The scarcity of the tolerant sources impedes the wheat breeding. In order to find new Al tolerance sources, we screened 173 bread wheat landraces from Tibet of China using hydroponic screening. It was indicated that： （1） There were diversities on the root regenerate length （RRL）. The RRL of a large of landraces were longer than 7.00 cm in pH 7 （58.38%） and pH 4.5 （66.47%）, but shorter than 5.00 cm in pH 4.5 ＋50μM Al^3＋ （80.93%）. The low pH showed either promotion or restraining effects depend on landraces, but Al toxicity under low pH only showed restraining effects on the root elongation. （2） There were also diversities on root tolerance index of low pH （RTI 1） or root aluminum tolerance index （RTI2） among cultivars. The RTI1 varied from a narrow range but with relatively high value （0.8722-1.2953） in comparison with that of RTI2 （0.3829-1.0058）, and the RTI1 of approximately 60% landraces was higher than 1.0000, the RTI2 of only 19.07% landraces was higher than 0.7000, suggesting that Al toxicity acted as an important factor for the reduction of the root elongation under acidic soils. （3） The RTI 1 of many wheats was higher than 1.0000, and As2256 and As2295 were the most tolerant for low pH, with RTI1 1.2953 and 1.2925, respectively. （4） Based on RTI2, seven wheats showed similar or higher tolerance to Al toxicity than Chinese Spring （CS）, a known tolerance wheat. Much better tolerance existed in landraces of As1543 and As1242, which can be used as the new parents for Al tolerant breeding.

Treatment and utilization of septic tank effluent using vertical-flow constructed wetlands and vegetable hydroponics

Vertical flow constructed wetlands is a typical ecological sanitation system for sewage treatment. The removal rates for COD, BOD 5, SS, TN, and TP were 60%, 80%, 74%, 49% and 79%, respectively, when septic tank effluent was treated by vertical flow filter. So the concentration of COD and BOD\-5 in the treated effluent could meet the quality standard for irrigation water. After that the treated effluent was used for hydroponic cultivation of water spinach and romaine lettuce, the removal efficiencies of the whole system for COD, BOD\-5, SS, TN and TP were 71 4%, 97 5%, 96 9%, 86 3%, and 87 4%, respectively. And it could meet the integrated wastewater discharge standard for secondary biological treatment plant. It was found that using treated effluent for hydroponic cultivation of vegetables could reduce the nitrate content in vegetables. The removal rates for total bacteria and coliform index by using vertical flow bed system with cinder substrate were 80%—90% and 85%—96%, respectively.

Effect of Partial Replacement of Nitrate by Amino Acid and Urea on Nitrate Content of Non-heading Chinese Cabbage and Lettuce in Hydroponic Condition

In this paper, the authors studied the effect of different mixtures of glycine (Gly), isoleucine (Iso), proline (Pro), and urea solutions used as a partial (20%) replacment of nitrate in the nitrate content and quality of non-heading Chinese cabbage and lettuce in hydroponice. Five treatments were done 12 d before harvest. Compared to the control group, Gly had the best effect in reducing the nitrate content of both vegetable leaves and petioles; the mixture of Gly, Iso and Pro ranked second and urea the least. Treatments with amino acid could also increase soluble sugar and protein contents and enhance total-N in leaves significantly. In contrast, amino acid enhanced NRA in non-heading Chinese cabbage, while they decreased it slightly in lettuce. The results showed that amino acids and urea could reduce the nitrate content of both vegetables, but they had almost the same effect on non-heading Chinese cabbage. Moreover, amino acids were more effective than urea in lettuce. As a result, it was concluded that partial replacement of nitrate with amino acids not only reduced the nitrate content but also improved the quality of vegetables.

Effects of Toxic Levels of Aluminium on Seedling Parameters of Rice under Hydroponic Culture

The presence of AI in the rhizosphere of rice in acid soil restricts root growth and significantly reduces crop productivity. In this study, the effects of AI （30, 60 and 90 μg/mL） on seedling root growth, number of primary roots per seedling, seedling shoot length, number of leaves per seedling, seedling fresh weight, and seedling dry weight were studied. Rice genotypes were classified into three different classes, namely, tolerant, moderately tolerant, and susceptible, based on root tolerance index. The method of hydroponic culture was modified, and elaborated in the text. Toxic levels of AI in nutrient solution significantly decreased seedling root growth, number of primary roots, seedling shoot length, number of leaves per seedling, seedling fresh weight, and seedling dry weight. Few genotypes showed longer root length at 30 pg/mL AI in nutrient solutions compared with the control. High levels of AI in nutrient solutions were highly toxic for rice seedlings. Based on root tolerance index, Radhunipagal, Gobindobhog, Badshabhog, Kalobhog, UBKVR-11, UBKVR-16, UBKVR-18, Khasha and IVT4007-B were classified as tolerant genotypes, and these genotypes may be used as donors for breeding of Altoxicity tolerance.

Effects of ozone-treated domestic sludge on hydroponic lettuce growth and nutrition

Here, the ozone-treated domestic sludge was diluted up to four different multiples and utilized as a nutritional source for hydroponic lettuce growth. Additionally, lettuce was cultured using the modified Hoagland nutrient solution as a control. The effects of ozone-treated domestic sludge on lettuce growth and nutrition were studied. Results showed that the lettuce treated with modified Hoagland inorganic nutrient solution had increased leaf number, plant height, fresh weight and dry weight compared to those treated with the ozone-treated domestic sludge dilution （P〈0.05）. However, the lettuce cultivated with the 2-fold ozone-treated sludge dilution showed significantly higher （P〈0.05） contents of chlorophyll, soluble sugar and ascorbic acid （Vc） compared to that treated with modified Hoagland nutrient solution. And the nitrate concentration in the lettuce cultured with the 2-fold ozone-treated sludge dilution was 53.93% less than that cultured with the modified Hoagland nutrient solution, which was a significant improvement （P〈0.05）. This study suggested that the 2-fold ozone-treated sludge dilution is optimal for lettuce hydroponic nutrient requirements.

Comparative Study of Ascorbic Acid and Tocopherol Concentrations in Hydroponic- and Soil-Grown Lettuces

Hydroponically-grown produce may be a way of helping to feed the world a variety of fruits and vegetables, regardless of soil quality, space availability or climate. The objective of this study was to determine whether hydroponicallygrown lettuce contains as much ascorbic acid and tocopherol as soil-grown lettuce. We analyzed four varieties of lettuce, including: Waldmann’s Dark Green, Red Lollo Antago, Red Romaine Annapolis, and Butterleaf. The tocopherol content of hydroponically-grown Waldmann’s Dark Green, Red Lollo Antago, and Red Romaine Annapolis was 229%, 497% and 492% higher, respectively, compared to their soil-grown counterpart. The ascorbic acid content of hydroponically-grown Waldmann’s Dark Green, Red Lollo Antago, and Red Romaine Annapolis was 93%, 171% and 216% higher, respectively, compared to their soil-grown counterparts. Hydroponically grown lettuce varieties are significantly higher in both ascorbic acid and tocopherol content than their soil-grown counterparts, and hydroponic gardening is a viable option for producing nutritious fruits and vegetables.

Growth Responses of Wheat Cultivars to Rock Phosphate in Hydroponics

Screening cultivars to grow under conditions of low phosphorus (P) availability and utilize P efficiently from compounds of low solubility in soils may be beneficial to overcome poor plant growth in P-deficient soils. The growth behavior and P utilization efficiency of seven wheat cultivars grown in hydroponics were studied, using rock phosphate as P source. The wheat cultivars grown for 30 days were significantly different in biomass accumulation, P uptake and P utilization efficiency. The dry matter production of all the cultivars was significantly correlated with P uptake, which in turn correlated to the drop in the root medium pH. The ranking of wheat cultivars on the basis of dry matter yield, P uptake and P utilization efficiency was Zamindar 80 > Yecora > C 271 > WL 711 > Barani 83 > PARI 73 > Rohtas. The cultivar Zamindar 80 appeared to possess the best growth potential in P-deficient soils.

Effect of Root-Zone Temperature on Growth and Quality of Hydroponically Grown Red Leaf Lettuce (Lactuca sativa L. cv. Red Wave)

Soil temperature influences crop growth and quality under field and greenhouse conditions;however, precise investigation using controlled cultivation systems is largely lacking. We investigated effects of root-zone temperatures on growth and components of hydroponically grown red leaf lettuce (Lactuca sativa L. cv. Red Wave) under a controlled cultivation system at 20&degC. Compared with ambient root-zone temperature exposure, a 7-day low temperature exposure reduced leaf area, stem size, fresh weight, and water content of lettuce. However, root-zone heating treatments produced no significant changes in growth parameters compared with ambient conditions. Leaves under low root-zone temperature contained higher anthocyanin, phenols, sugar, and nitrate concentrations than leaves under other temperatures. Root oxygen consumption declined with low temperature root exposure, but not with root heating. Leaves of plants under low rootzone temperature showed hydrogen peroxide production, accompanied by lipid peroxidation. Therefore, low temperature root treatment is suggested to induce oxidative stress responses in leaves, activating antioxidative secondary metabolic pathways.