Reduction of Nitrate Content in Baby-Leaf Lettuce and Cichorium endivia Through the Soilless Cultivation System, Electrical Conductivity and Management of Nutrient Solution

Soilless cultivation systems are efficient tools to control nitrates by managing nutrient solution (NS) salinity and nitrogen availability, however, these nitrate-lowering strategies require appropriate calibration based on species/genotype-specific responses interacting with climate and growing conditions. Three experiments were carried out on lettuce and Cichorium endivia grown in ebb-and-flow (EF) and floating (FL) systems at two levels of NS salinity (EC = 2.5 and 3.5 dS m−1) (EC2.5, EC3.5, respectively) under autumn and early-spring (lettuce) and winter and late-spring conditions (C. endivia). Nitrogen deprivation (NS withdrawal a few days before the harvest) was tested at EC2.5, in the autumn and winter cycles. The EF-system caused an increase in salinity in the substrate where roots mainly develop so it mimicked the effect of the EC3.5 treatment. In the winter-grown lettuce, the EF-system or EC3.5 treatment was effective in reducing the nitrate level without effects on yield, with the EF baby-leaf showing an improved quality (color, dry matter, chlorophylls, carotenoid, vitamin C, phenol). In both seasons, the EF/EC3.5 treatment resulted in a decline in productivity, despite a further reduction in nitrate content and a rise in product quality occurring. This response was strictly linked to the increasing salt-stress loaded by the EC3.5/EF as highlighted by the concurrent Cl− accumulation. In early-spring, the FL/EC3.5 combination may represent a trade-off between yield, nitrate content and product quality. In contrast, in winter-grown endive/escarole the EC3.5, EF and EC3.5/EF reduced the nitrate level with no effect on yield, product quality or Cl− uptake, thus proving them to be more salt-tolerant than lettuce. High temperatures during the late-spring cycle promoted nitrate and Cl− uptake, overcoming the nitrate-controlling effect of salinity charged by the EF system or EC3.5. The nitrate level decreased after 3 day-long (lettuce) or 6 day-long (C. endivia) NS withdrawal. In C. endivia and EF-grown lettuce, it provoked a decrease in yield, but a concurrent improvement in baby-leaf appearance and nutritional quality. More insights are needed to fine-tune the duration of the NS removal taking into account the soilless system used and species-specific characteristics.

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Soilless Cultivation System, Electrical Conductivity of Nutrient Solution and Growing Season on Yield and Quality of Baby-Leaf Oak-Leaf Lettuce

Agronomy ◽

10.3390/agronomy11061220 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1220

Author(s):

Giulia Conversa ◽

Anna Bonasia ◽

Corrado Lazzizera ◽

Antonio Elia

Keyword(s):

Electrical Conductivity ◽

Product Quality ◽

Nutrient Solution ◽

Late Spring ◽

Growth And Yield ◽

Nitrate Content ◽

Saline Stress ◽

Leaf Production ◽

Leaf Lettuce ◽

Oak Leaf Lettuce

The floating system (FL) is a common soilless method for baby-leaf production, whereas the ebb and flow system (EF) has been proposed as an alternative. Both of them allow managing plant saline stress while preventing reduction in plant growth and yield and increasing product quality. The oak-leaf lettuce response to the growing conditions (hydroponics, salinity) in interaction with climate and genotype has been little studied. Two experiments were carried out with two oak-leaf cultivars (green- and red-colored type) grown in FL and EF systems at two levels of nutrient solution (NS) electrical conductivity (EC) (EC = 2.5 and 3.5 dS m−1; EC2.5, EC3.5, respectively) under autumn and late-spring conditions. The EF system caused an increase in salinity in the substrate where roots mainly develop, so it overcomes the effect of the EC3.5 treatment. In the autumn cycle, irrespective of the EC, EF-grown plants had improved leaf thickness (specific leaf area), color, and antioxidative (total phenol and carotenoid contents) properties; however, a reduction in yield was observed in the most productive cultivar (green type). In late spring, higher yield and product quality (processability, nitrate content) were obtained at the expense of color, with the FL showing the best productivity in the green type cultivar. The red type cultivar had higher dry mass, phenol, and carotenoid concentrations.

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Protein Hydrolysates Supplement in the Nutrient Solution of Soilless Grown Fresh Peppermint and Spearmint as a Tool for Improving Product Quality

Agronomy ◽

10.3390/agronomy11020317 ◽

2021 ◽

Vol 11 (2) ◽

pp. 317

Author(s):

Danai-Christina Aktsoglou ◽

Dimitrios S. Kasampalis ◽

Eirini Sarrou ◽

Pavlos Tsouvaltzis ◽

Paschalina Chatzopoulou ◽

...

Keyword(s):

Essential Oil ◽

Product Quality ◽

Nutrient Solution ◽

Protein Hydrolysate ◽

Dry Weight ◽

Protein Hydrolysates ◽

Mentha Piperita ◽

Nitrate Content ◽

Fresh Tissue ◽

Polyphenolic Composition

The present study investigated the potential of fresh peppermint (Mentha × piperita L.) and spearmint (Menthaspicata L.) production on a floating raft system combined with a commercial protein hydrolysate supplement (Amino16®) in a nutrient solution aiming to improve plant product quality. Three levels of the protein hydrolysate solution (0, 0.25 and 0.50%) were added in the nutrient solution, and the plants were harvested after twenty-four days. Plant growth characteristics were recorded, and nutritional, essential oil and polyphenolic composition were determined in fresh tissue. The addition of protein hydrolysates did not affect the fresh or dry weight but reduced plant height. Nitrate content significantly decreased, while total chlorophyll and essential oil content increased in both species. Moreover, the protein hydrolysate solution further increased total antioxidant capacity, total soluble phenol and carotenoid contents in spearmint plants, while it did not affect the essential oil and polyphenolic composition in both species. In conclusion, protein hydrolysates solution may be added in the nutrient solution, to improve the quality of peppermint and spearmint grown in a floating system, without adverse effects on crop yield or the essential oil and polyphenolic profile.

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EC Sensitivity of Hydroponically-Grown Lettuce (Lactuca sativa L.) Types in Terms of Nitrate Accumulation

Agriculture ◽

10.3390/agriculture11040315 ◽

2021 ◽

Vol 11 (4) ◽

pp. 315

Author(s):

Noémi Kappel ◽

Ildikó Fruzsina Boros ◽

Francia Seconde Ravelombola ◽

László Sipos

Keyword(s):

Lactuca Sativa ◽

Nitrate Content ◽

Saline Condition ◽

Fresh Weight ◽

Nitrate Level ◽

Nitrate Accumulation ◽

Strong Negative Correlation ◽

Lactuca Sativa L ◽

Hydroponically Grown ◽

European Markets

The goal of this research was to investigate the effect of electrical conductivity (EC) levels of the nutrient solution on the fresh weight, chlorophyll, and nitrate content of hydroponic-system-grown lettuce. The selected cultivars are the most representative commercial varieties grown for European markets. Seven cultivars (‘Sintia,’ ‘Limeira,’ ‘Corentine,’ ‘Cencibel,’ ‘Kiber,’ ‘Attiraï,’ and ‘Rouxaï’) of three Lactuca sativa L. types’ (butterhead, loose leaf, and oak leaf) were grown in a phytotron in rockwool, meanwhile the EC level of the nutrient solutions were different: normal (<1.3 dS/m) and high (10 dS/m). The plants in the saline condition had a lower yield but elevated chlorophyll content and nitrate level, although the ‘Limeira’ and ‘Cencibel’ cultivars had reduced nitrate levels. The results and the special characteristic of the lollo-type cultivars showed that the nitrate level could be very different due to salinity (‘Limeira’ had the lowest (684 µg/g fresh weight (FW)) and ‘Cencibel’ had the highest (4396 µg/g FW)). There was a moderately strong negative correlation (−0.542) in the reverse ratio among the chlorophyll and nitrate contents in plants treated with a normal EC value, while this relationship was not shown in the saline condition. Under the saline condition, cultivars acted differently, and all examined cultivars stayed under the permitted total nitrate level (5000 µg/g FW).

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Do applications of systemic herbicides when green fruit are present prevent seed production or viability of Alliaria petiolata (garlic mustard)?

Invasive Plant Science and Management ◽

10.1017/inp.2021.8 ◽

2021 ◽

pp. 1-17

Author(s):

Leo Roth ◽

José Luiz C. S. Dias ◽

Christopher Evans ◽

Kevin Rohling ◽

Mark Renz

Keyword(s):

Seed Production ◽

Seed Viability ◽

Early Spring ◽

Alliaria Petiolata ◽

Late Spring ◽

Garlic Mustard ◽

Viable Seed ◽

Application Timing ◽

Control Seed ◽

Second Year

Garlic mustard [Alliaria petiolata (M. Bieb.) Cavara & Grande] is a biennial invasive plant commonly found in the northeastern and midwestern United States. Although it is not recommended to apply herbicides after flowering, land managers frequently desire to conduct management during this timing. We applied glyphosate and triclopyr (3% v/v and 1% v/v using 31.8% and 39.8% acid equivalent formulations, respectively) postemergence to established, second-year A. petiolata populations at three locations when petals were dehiscing, and evaluated control, seed production and seed viability. Postemergence glyphosate applications at this timing provided 100% control of A. petiolata by 4 weeks after treatment at all locations whereas triclopyr efficacy was variable, providing 38-62% control. Seed production was only reduced at one location, with similar results regardless of treatment. Percent seed viability was also reduced, and when combined with reductions in seed production, we found a 71-99% reduction in number of viable seed produced plant-1 regardless of treatment. While applications did not eliminate viable seed production, our findings indicate that glyphosate and triclopyr applied while petals were dehiscing is a viable alternative to cutting or hand-pulling at this timing as it substantially decreased viable A. petiolata seed production. Management Implications Postemergence glyphosate and triclopyr applications in the early spring to rosettes are standard treatments used to manage A. petiolata. However, weather and other priorities limit the window for management, forcing field practitioners to utilize more labor-intensive methods such as hand-pulling. It is not known how late in the development of A. petiolata these herbicides can be applied to prevent viable seed production. Since prevention of soil seedbank replenishment is a key management factor for effective long-term control of biennial invasive species, we hypothesized late spring foliar herbicide applications to second year A. petiolata plants when flower petals were dehiscing could be an effective management tool if seed production or viability is eliminated. Our study indicated that glyphosate applications at this timing provided 100% control of A. petiolata plants by 4 weeks after treatment at all locations, whereas triclopyr efficacy was inconsistent. Although both glyphosate and triclopyr decreased viable seed production to nearly zero at one of our three study locations, the same treatments produced significant amounts of viable seed at the other two locations. Our findings suggest late spring glyphosate and triclopyr applications should not be recommended over early spring applications to rosettes for A. petiolata management, as our late spring application timing did not prevent viable seed production, and may require multiple years of implementation to eradicate populations. Nonetheless, this application timing holds value in areas devoid of desirable understory vegetation compared to no management practices or mechanical management options including hand-pulling when fruit are present, as overall viable seed production was reduced to similar levels as these treatments.

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Nutrient Solution Deprivation as a Tool to Improve Hydroponics Sustainability: Yield, Physiological, and Qualitative Response of Lettuce

Agronomy ◽

10.3390/agronomy11081469 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1469

Author(s):

Michele Ciriello ◽

Luigi Formisano ◽

Antonio Pannico ◽

Christophe El-Nakhel ◽

Giancarlo Fascella ◽

...

Keyword(s):

Nutrient Solution ◽

Potential Effect ◽

Quality Parameters ◽

Leafy Vegetables ◽

Nitrate Content ◽

Yield Reduction ◽

Quality Performance ◽

Floating Raft ◽

Amino Acids Profile ◽

Excessive Nutrients

Hydroponics growing systems often contain excessive nutrients (especially nitrates), which could lead to a quality loss in ready-to-eat leafy vegetables and posing a health risk to consumers, if managed inadequately. A floating raft system was adopted to assay the production and quality performance of lettuce (Lactuca sativa L. cv ‘Maravilla De Verano Canasta’) deprived of the nutrient solution by replacement with only water, three and six days before harvest. Yield and quality parameters, mineral composition, pigments, organic acids, amino acids profile, soluble proteins, and carbohydrate content were determined. Nutrient solution deprivation six days before harvest resulted in a significant reduction in leaf nitrate (−53.3%) concomitant with 13.8% of yield loss, while plants deprived of nutrient solution three days before harvest increased total phenols content (32.5%) and total ascorbic acid (102.1%), antioxidant activity (82.7%), anthocyanins (7.9%), sucrose (38.9%), starch (19.5%), and γ-aminobutyric acid (GABA; 28.2%), with a yield reduction of 4.7%, compared to the control. Our results suggest that nutrient solution deprivation three days before harvest is a successful strategy to reduce nitrate content and increase the nutritional quality of lettuce grown in floating raft systems with negligible impact on yield. These promising results warrant further investigation of the potential effect of nutrient solution deprivation on the quality attributes of other leafy vegetables cultivated in floating raft systems and in a “cascade” growing system.

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Fall and Spring Preplant Herbicide Applications Influence Spring Emergence of Glyphosate-Resistant Horseweed (Conyza canadensis)

Weed Technology ◽

10.1614/wt-09-064.1 ◽

2010 ◽

Vol 24 (1) ◽

pp. 11-19 ◽

Cited By ~ 23

Author(s):

Vince M. Davis ◽

Greg R. Kruger ◽

Bryan G. Young ◽

William G. Johnson

Keyword(s):

Early Spring ◽

Late Spring ◽

Conyza Canadensis ◽

No Till ◽

Early Fall ◽

Winter Annual ◽

Winter Annual Weeds ◽

Annual Weeds ◽

Spring Emergence ◽

Residual Control

Horseweed (Conyza canadensis) is a common weed in no-till crop production systems. It is problematic because of the frequent occurrence of biotypes resistant to glyphosate and acetolactate synthase (ALS)-inhibiting herbicides and its ability to complete its life cycle as a winter or summer annual weed. Tactics to control horseweed while controlling other winter annual weeds routinely fail; herbicide application timing and spring emergence patterns of horseweed may be responsible. The objectives of this experiment were to (1) determine the influence of fall and spring herbicides with and without soil residual horseweed activity on spring-emerging glyphosate-resistant (GR) horseweed density and (2) evaluate the efficacy and persistence of saflufenacil on GR horseweed. Field studies were conducted in southern Indiana and Illinois from fall 2006 to summer 2007 and repeated in 2007 to 2008. Six preplant herbicide treatments were applied at four application timings: early fall, late fall, early spring, and late spring. Horseweed plants were counted every 2 wk following the first spring application until the first week of July. Horseweed almost exclusively emerged in the spring at both locations. Spring horseweed emergence was higher when 2,4-D + glyphosate was fall-applied and controlled other winter annual weeds. With fall-applied 2,4-D + glyphosate, over 90% of the peak horseweed density was observed before April 25. In contrast, only 25% of the peak horseweed density was observed in the untreated check by April 25. Starting from the initiation of horseweed emergence in late March, chlorimuron + tribenuron applied early fall or early spring, and spring-applied saflufenacil at 100 g ai/ha provided greater than 90% horseweed control for 12 wk. Early spring–applied saflufenacil at 50 g ai/ha provided 8 wk of greater than 90% residual control, and early spring–applied simazine provided 6 wk of greater than 90% control. When applied in late spring, saflufenacil was the only herbicide treatment that reduced horseweed densities by greater than 90% compared to 2,4-D + glyphosate. We concluded from this research that fall applications of nonresidual herbicides can increase the rate and density of spring emerging horseweed. In addition, spring-applied saflufenacil provides no-till producers with a new preplant herbicide for foliar and residual control of glyphosate- and ALS-resistant horseweed.

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MANAGEMENT OF LATE SPRING-EARLY SUMMER PASTURE SURPLUSES IN HILL COUNTRY

Proceedings of the New Zealand Grassland Association ◽

10.33584/jnzg.1984.45.1657 ◽

1984 ◽

pp. 199-206 ◽

Cited By ~ 1

Author(s):

G.W. Sheath ◽

R.W. Webby ◽

W.J. Pengelly

Keyword(s):

Early Spring ◽

Early Summer ◽

Late Spring ◽

First Year ◽

Hill Country ◽

Continuous Grazing ◽

Summer Pasture ◽

Animal Performances ◽

Grazing Policy ◽

Made In

Comparisons of controlling late spring to early summer pasture growth on either easy or steep contoured land with either a fast rotation or continuous grazing policy were made in self-contained farmlets for two years. Pasture control was maintained over more land by controlling steep land first and with continuous grazing. Animal performances (ewes, steers) were generally similar for the mid-November to early January treatment period, and subsequently until May shearing. In the first year better animal performances occurred in "steep control" farmlets during winter and early spring, but this was less evident in the second year. Priority control of steep land during late spring-early summer is recommended because of likely longer-term benefits in pasture composition,density and production. Quick rotation grazing through the period provides a better ability to recognise and manage pasture quantities and should be adopted if summer droughts are anticipated. For well fenced properties in summer-wet areas and with integrated stock grazing, continuous grazing during late spring-early summer may be equally suitable. Keywords: hill country, grazing management, pasture control

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Soil biogeochemistry during the early spring in low arctic mesic tundra and the impacts of deepened snow and enhanced nitrogen availability

Biogeochemistry ◽

10.1007/s10533-009-9396-7 ◽

2009 ◽

Vol 99 (1-3) ◽

pp. 127-141 ◽

Cited By ~ 56

Author(s):

Kate M. Buckeridge ◽

Yan-Ping Cen ◽

David B. Layzell ◽

Paul Grogan

Keyword(s):

Nitrogen Availability ◽

Early Spring ◽

Soil Biogeochemistry ◽

Low Arctic

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Salinity tolerance in Scolymus hispanicus L: preliminary findings from a soilless cultivation

10.5194/egusphere-egu21-14357 ◽

2021 ◽

Author(s):

Dimitris Papadimitriou ◽

Ioannis Daliakopoulos ◽

Thrassyvoulos Manios ◽

Dimitrios Savvas

Keyword(s):

Chlorophyll Fluorescence ◽

Nutrient Solution ◽

Cropping Systems ◽

Block Design ◽

Research Work ◽

Soil Salinization ◽

Growth And Yield ◽

Salinity Treatment ◽

Fresh Weight ◽

Soilless Cultivation

Introducing edible salt-tolerant plant species to professional cultivation is a concept compatible with the need of improving the resilience of food systems to shocks and stresses, which is &#160;required to tackle eminent global challenges, such as water scarcity and climate change (Cuevas et al., 2019). Hydroponic systems can contribute to substantial savings of water, nutrients, and space, while increasing yield and produce quality (Savvas and Gruda, 2018). In the current study, we examined the feasibility of cultivating the wild edible green Scolymus hispanicus L. under moderate levels of salinity in a soilless cultivation system. The experiment was installed in October 2019, in an unheated saddle roof double-span greenhouse, as a completely randomized block design with 4 treatments and 4 blocks per treatment (Papadimitriou et al., 2020). Treatments were formed by supplying a standard nutrient solution (NS) with four NaCl concentrations (0.5, 5.0, 10.0, and 15.0 mM), resulting in electrical conductivities of 2.2, 2.8, 3.2, and 3.8 dS m-1, respectively. Measurements of chlorophyll fluorescence (Fv/Fm) and relative chlorophyll levels (SPAD), which were performed to assess the photosynthetic capacity of leaves, did not indicate any significant differences between the non-salinized control (0.5 mM NaCl) and the salinity treatments (5.0, 10.0, and 15.0 mM NaCl), until 60 days after seedling transplanting (DAT). However, by 90 DAT, salinity levels of 10.0 and 15.0 mM significantly reduced leaf chlorophyll levels, as indicated by the SPAD indices, compared to 5.0 and 0.5 mM NaCl in the supplied NS. Moreover, by 90 DAT, the chlorophyll fluorescence (Fv/Fm) was significantly reduced at the salinity level of 15.0 mM compared to 0.5 and 5.0 mM. Nevertheless, no salinity treatment had a significant impact on leaf fresh weight, root fresh weight, rosette diameter, number of leaves and post-harvest storability in plants harvested 90 and 120 DAT, compared to the control. Based on these results, S. hispanicus L. exhibits a considerable resilience to moderate salinity and can be considered a promising candidate plant for introduction in hydroponic cropping systems.AcknowledgementsThe research work was supported by the Hellenic Foundation for Research and Innovation (HFRI) under the HFRI PhD Fellowship grant (Fellowship Number: 240).ReferencesCuevas, J., Daliakopoulos, I.N., del Moral, F., Hueso, J.J., Tsanis, I.K., 2019. A Review of Soil-Improving Cropping Systems for Soil Salinization. Agronomy 9, 295. https://doi.org/10.3390/agronomy9060295Papadimitriou, D., Kontaxakis, E., Daliakopoulos, I., Manios, T., Savvas, D., 2020. Effect of N:K Ratio and Electrical Conductivity of Nutrient Solution on Growth and Yield of Hydroponically Grown Golden Thistle (Scolymus hispanicus L.). Proceedings 30, 87.https://doi.org/10.3390/proceedings2019030087Savvas, D., Gruda, N., 2018. Application of soilless culture technologies in the modern greenhouse industry - A review. Europ. J. Hort. Sci. 83, 280-293.

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Physiological and Phytochemical Responses of Spinach Baby Leaves Grown in a PFAL System with LEDs and Saline Nutrient Solution

Agriculture ◽

10.3390/agriculture10110574 ◽

2020 ◽

Vol 10 (11) ◽

pp. 574

Author(s):

Filippos Bantis ◽

Mariangela Fotelli ◽

Zoran S. Ilić ◽

Athanasios Koukounaras

Keyword(s):

Nutrient Solution ◽

Nutritional Quality ◽

Sugar Content ◽

Soluble Sugar ◽

Maximum Yield ◽

Photosynthetic Apparatus ◽

Salinity Level ◽

Carotenoid Content ◽

Nitrate Content ◽

Red Led

Spinach is a leafy vegetable containing a plethora of bioactive compounds. Our study aimed to evaluate the physiological (i.e., JIP-test) and phytochemical response of spinach baby leaves grown with regular or mildly saline (40 mM NaCl) nutrient solution and irradiated by four light-emitting diodes (LEDs) with broad spectra. T1 (highest red and far-red, low blue) and T3 (high red, balanced blue, green and far-red) led to a better developed photosynthetic apparatus compared to T2 (red peak in 631 nm) and T4 (highest blue and green), highlighted by PIABS and its structural components: RC/ABS, φP0, ψE0, and ΔVIP. Elevated salinity only affected the latter parameter. T1 induced the maximum yield production but also the highest nitrate content which was far below the maximum level permitted by European legislation. Regardless of salinity level, T3 enhanced total phenol, chlorophyll, and carotenoid content. T2 and T4 led to inferior nutritional quality. Non-saline nutrient solution promoted the chlorophyll and carotenoid contents and the antioxidant potential, regardless of light treatment. By contrast, soluble sugar content was enhanced by saline nutrient solution. Our study shows that physiology and nutritional quality of spinach baby leaves can be manipulated by small interplays in the light spectra and salinity level.

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