Lettuce Cultivars Research Articles

Fluorine in 20 vegetable species and 25 lettuce cultivars grown on a contaminated field adjacent to a brick kiln.

Crops grown in areas contaminated by industrial and agricultural fluorine (F) have gained increasing attention, however F levels in different vegetables and lettuce cultivars are rarely reported. In situ-field experiment was designed to investigate the concentration, translocation, and health risks of F in 20 vegetable species and 25 lettuce cultivars. After the growth of 150 d for vegetables and 60 d for lettuce, F concentration (12.83-138.07mgkg-1), translocation factor (0.16-6.32), and bio-concentration factor (1.90-13.73) varied significantly between vegetable species and lettuce cultivars. According to the hazard quotient values (based on the reference dose of F), all the vegetable species appears to pose no risk to human health, while 60% of the lettuce cultivars present potential health risks to children. Therefore, the limit value of F in vegetables for adults and children should be enacted in the future. Moreover, cabbage, green radish, spinach, leaf mustard, and Frisee lettuce (Huayu) were considered as a safe dietary product. These findings contributed to the safe cultivation of vegetables and the control of fluorosis in the areas contaminated by industrial and agricultural activities.

Growth, Physicochemical, Nutritional, and Postharvest Qualities of Leaf Lettuce (Lactuca sativa L.) as Affected by Cultivar and Amount of Applied Nutrient Solution

The effects of different nutrient solution quantities on growth, physicochemical, nutritional, and postharvest qualities of lettuce were investigated. Two differently pigmented Korean leaf lettuce cultivars “Geockchima” and “Cheongchima” were grown in soilless perlite culture supplied with 250, 500, 1000, and 2000 mL·d−1·plant−1 nutrient solutions. Several growth parameters (plant height, leaf number, fresh weight, dry matter) were evaluated. The highest lettuce growth was observed when plants were supplied with 1000 mL·d−1·plant−1. Cultivating lettuces in the lowest nutrient solution quantity showed higher dry matter, crude fiber, osmolality, chlorophyll, and anthocyanin contents. Upon increasing the nutrient solution, the crispiness, greenness, and levels of ascorbic acid, nitrogen, and potassium, increased, while phosphorus and magnesium were unaffected, and calcium content declined. Postharvest qualities were better maintained in lettuces irrigated with the least amount of nutrient solution, extending their shelf life. We conclude that lettuce can be grown with 1000 mL·d−1·plant−1 for higher yield, and short-term storage and/or transportation. However, when lettuces need to be stored for a certain period, such as long-distance shipment, they should be cultivated with a limited nutrient solution, which requires further detailed investigation. The results of this study can be applied for distributing, storing, transporting, and marketing lettuce.

Performance of Vanda lettuce in relation to the use of chemical fertilizer and organic compost

Horticulture is a widespread activity in family farming in the Transamazonian region—Pará, with emphasis on production aimed at the family’s own consumption. The lettuce cultivar Vanda (Lactuca sativa L.) represents a significant part of this production, which prioritizes the use of internal labor. The main objective of this work was to evaluate the development of lettuce CV Vanda grown in beds using organic compost and chemical fertilization (NPK). The criteria considered to evaluate this performance were: Root system development, plant height and total fresh mass production. The best averages in relation to root development occurred in the plots cultivated with organic compost in the proportion of 5 kg/m2, due to its characteristics as a fertilizer and soil conditioner. The cultivation with the use of NPK provided the best averages in relation to the production of total fresh mass and plant height, results that were mainly attributed to the extra supply of nitrogen in the covering fertilization, which consisted in the addition of 10 g urea per square meter via soil. Statistical analysis showed no statistically significant difference regarding plant height for both treatments. And in relation to root development, the difference was statistically significant.

Successive lettuce cultivation on organic substrates

The purpose of the present work was to evaluate i the influence of organic compost and soil proportions on lettuce growth in greenhouse and ii - the residual effect of organic fertilization in successive lettuce crops. Six compost:soil proportions were evaluated (100:0, 80:20, 60:40, 40:60, 20:80 and 0:100) in three successive lettuce (cultivar “Monica”) crops under randomized blocks design. Stem and crown diameter, plant height, number of leaves, volume of roots, fresh weight of leaves and the aerial portion, dry weight of leaves, stem, aerial portion, roots and the total dry weight; chlorophyll A, B and total chlorophyll were evaluated. There was a significant interaction between the organic compost dosages and the successive cultivation. The effect of the cultivation periods according to the proportions showed, in a general manner, a tendency to produce higher values of CLB, ALP and DMC in the first cultivation period for the majority of proportions. The best proportion of organic compost:soil was of 60:40, in the first crop. For all successive crops, although a residual effect of the compost was detected, the proportion of 60:40 was not enough to sustain the productivity level of the first crop and therefore requiring supplementing fertilization.

Evaluation of the Existence of a New Race of Bremia lactucae on Lettuce

Lettuce is one of the most consumed leafy vegetables in Turkey. The production of lettuce has been to get difficult due to infestation of cultivation areas with Bremia lactucae. This pathogen is genetically very variable. Pathogenic variation of B. lactucae has not been studied yet in Turkey. The objective of this study was to monitore the races of B. lactucae in the two geographic regions of Turkey. During the lettuce growing season in May and October 2018, totally 72 diseased leaf samples containing B. lactucae sporangia were collected from the fields of Bartın and Ankara provinces. From these samples 6 isolates were obtained. After a multiplication procedure, in which the susceptible lettuce cultivar 'Green Towers' was used, the B. lactucae sporangia were inoculated in differentiating lettuce cultivars. The response of the lettuce seedlings to pathogen was evaluated on the 7, 11 and 14 days after inoculation. The qualitative method was used for the assessment of infected seedlings. Sextet codes of Ankara and Bartın isolates were found as 44-00-01 and 13-03-04 respectively. The sextet codes of Turkish isolates did not match any of the present 37 races of B. lactucae. This result suggests that our isolates may be new races or pathotypes.

Accumulation of anthocyanins and phenolic acids and antioxidant activity of lettuce cultivars grown hydroponically and in the open ground

We assess the level of anthocyanins and phenolic acids accumulated in the leaves of lettuce cultivars grown hydroponically and in the open ground. In addition, the antioxidant activity of the cultivars under study was determined. The plant material was macerated overnight using a selected extractant. The anthocyanin concentration was determined by spectrophotometry, while the composition of anthocyanins and phenolic compounds was determined by reverse-phase high performance liquid chromatography. In general, anthocyanins in the extracts of all red-leaved lettuce cultivars were represented by cyanidin-3-(6″- malonylglucoside) with a small amount of its isomer – cyanidin-3-(3″-malonylglucoside). The highest level of anthocyanins was detected in the leaves of c.v. Thurinus, amounting up to 0.200 g per 100 g of fresh product for the intensively painted leaf areas. The cultivation of lettuce under the green-house conditions (hydroponically) leads to a significant reduction in the anthocyanin concentration in its leaves. The loss of anthocyanins during leaf drying was established to exceed 50%. Along with anthocyanins, the derivatives of caffeic acid, including chlorogenic (5-caffeoylquinic) acid, 5CQA, chicoric (3,4-caffeoyltartaric) acid, and 3,5- dicaffeoylquinic acid are important water-soluble compounds with antioxidant effects. The 5CQA accumulation was the highest, comprising 140 mg per 100 g of fresh weight (Red Thurinus). Antioxidant properties correlating with the level of anthocyanin accumulation were determined using the Folin-Ciocalteu method. In comparison with green-leaved cultivars, red-leaved lettuce was found to exhibit a greater antioxidant activity, thus representing a more valuable and functional food product. According to the obtained results, a system of additional illumination is required for intensification of the anthocyan biosynthesis aimed at obtaining highquality products cultivated hydroponically in green-house facilities.

Regulation of accumulation and metabolism circadian rhythms of starch and sucrose in two leaf-color lettuces by red:blue ratios of LED continuous light

There are interspecies differences in lettuce CL tolerance to LED red and blue light. It is important to clarify the response mechanism of tolerant and sensitive lettuce to CL to achieve efficient application of CL in artificial light plant factories. In the experiment, red-blue LEDs were used to provide a conventional light (360μmol·m−2·s−1, red:blue ratio 4:1 and 18/6 h photoperiod) and three continuous light (CL) treatments with various red:blue ratios (270μmol·m−2·s−1, red:blue ratio 4:1, 2:1 and 1:1) for CL-sensitive and tolerant lettuce cultivars (Yidali and Zishan) with the same daily light integral. The effects of CL quality on the growth, diurnal starch and sucrose accumulation and metabolism of two lettuces were studied by sampling at 6:00, 12:00, 18:00 and 24:00 on the 12 days after light treatment. The results showed that red-blue CL up-regulated shoot biomass of two cultivars, which might be attributed to root and leafy morphology, and chlorophyll content responses. CL with the 80% red light produced the greatest yield, but minor and medium leafy injury was found only on Yidali. CL improved starch and sucrose contents diurnally in two lettuce cultivars, and they totally decreased with blue light proportion. Sucrose synthase (SS), sucrose phosphate synthase (SPS), acid invertase (AI), neutral invertase (NI), adenosine diphosphate glucose pyrophosphorylas (AGP), α-amylase and β-amylase activities under CL were improved in two lettuces compared with the conventional light. Starch and sucrose contents and SS, SPS and AGP activities basically decreased with blue light proportion for two cultivars, while AI, NI, α-amylase and β-amylase activities increased inversely totally. CL irrespectively of its quality disordered the circadian rhythms of carbohydrate accumulation and metabolic enzyme activities in two lettuces. Starch content related closely positively with AGP, α-amylase and β-amylase activities for Zishan, but positively AGP and β-amylase activities for Yidali. Sucrose content correlated negatively with AI and NI activities for Zishan, while positively SS and SPS activities for Yidali. To sum up, red-blue CL with low-dose blue light could improve Yidali and Zishan lettuce yield, starch and sucrose accumulation, and metabolic enzyme activity, but CL disordered the circadian rhythms of carbohydrate accumulation and metabolic enzyme activity irrespectively of spectral quality. Yidali and Zishan lettuces are sensitive and tolerant cultivars to red-blue CL, which is not up to their abilities to maintain circadian rhythms of carbohydrate accumulation and metabolism. Furthermore, starch accumulation in two cultivars was controlled jointly by synthesis and decomposition enzymes, but sucrose accumulation in Yidali lettuce depended on decomposition enzymes rather than synthesis enzyme for purple lettuce.

CARBENDAZIM RESIDUES QUANTIFICATION IN GREEN LETTUCE BY ENZYME-LINKED IMMUNOSORBENT ASSAY

Carbendazim is a fungicide that is not approved for use in the European Union, but is used in some other countries to preserve agricultural crops. Enzyme-linked immunosorbent assay (ELISA) become a viable alternative to traditional instrumental methods in pesticides analysis, for screening purpose. Carbendazim residues were determined in two green lettuce cultivars, from the experimental lots, harvested at different times after the treatment with 0.1 % carbendazim solution, by an ELISA carbendazim commercial kit and the values were compared with those obtained by high performance liquid chromatography (HPLC). The results of ELISA and HPLC analysis of carbendazim residues in the two green lettuce cultivars were well correlated (Pearson correlation coefficient r=0.8925). Carbendazim residues in green lettuce/vegetables can be determined with high reliability by commercial ELISAs with results well correlated with those obtained by HPLC, with an additional sample preparation step involving solid phase extraction, in order to reduce matrix effects; the assay can be used for carbendazim screening of many vegetable/fruit samples in shorter time and with inexpensive/cheaper equipment.

Response of Lettuce Cultivars to Inoculation with Trichoderma spp.

Fungi of the Trichoderma genus are present in practically all types of soil and they have the ability to establish a beneficial relationship with plants. In addition to acting as direct biological control agents, they also act as plant growth promoters, by an indirect biological control mechanism. Because of these, many products containing Trichoderma strains are used to improve seed health, providing better development of roots and aerial parts of plants. In view of this fact, research work was carried out in a greenhouse with the aim of evaluating the effect of five Trichoderma strains, belonging to the species T. virens, T. asperellum, T. asperelloides, in addition to a strain unidentified at the species level T. koningiopsis, in three new crisp lettuce cultivars (BRS Lélia, BRS Leila, and BRS Mediterrânea). A conidial suspension of each of the strains was prepared (1.0 x 107 conidia mL-1) and applied at the time of sowing the lettuce in pots. The experiment was completely randomized in a factorial 5x3 design (Trichoderma spp. x cultivars). Control treatments consisted of pots containing plants without any of the fungi. All Trichoderma strains applied increased fresh mass and length of root, fresh mass of aerial part and lettuce height in comparison to the controls treated just with water. The cultivar BRS Leila showed an increase of 44% in fresh root mass, 45% in fresh mass of aerial part, with T. virens; 15% in plant height with T. koningiopsis, and 23.94% in root length, with Trichoderma sp. For ‘BRS Lélia’ the highest values ​​of fresh root mass, fresh mass of aerial part and root length were 30%, 36.71%, and 13.33% with T. asperellum. Trichoderma asperelloides provided 13.72% increase in height compared to the control. ‘BRS Mediterrânea’ showed increments of 75% of fresh root mass, 78.45% of fresh mass of aerial part, and 44.37% of height with T. virens. With T. asperelloides, 40.61% was observed in root length. The strain T. virens performed better in all the analyzed variables, except for root length.

Comparing Efficacy of Different Biostimulants for Hydroponically Grown Lettuce (Lactuca sativa L.)

Biostimulants can enhance horticultural crop production. However, their application in hydroponically grown lettuce is still limited, and information regarding their relative efficacy is lacking. A greenhouse trial was conducted to address this issue. Five nutrient solution treatments were evaluated on two lettuce cultivars: butterhead and red oak-leaf. The treatments included a half-strength modified Hoagland solution (Hs-H); a full-strength modified Hoagland solution (Fs-H); and Hs-H supplemented with 50 mg L−1 fulvic acid (FA), 334 mg L−1 seaweed extract (SE), or 5 mL L−1 gamma polyglutamic acid (PGA). The results indicated that the shoot biomass observed after biostimulant supplementation was significantly greater than or comparable to that observed with Fs-H. Nutrient solutions supplemented with SE and PGA led to a greater increase in the root biomass than that realized with Hs-H and Fs-H treatments. The Hs-H + FA treatment resulted in the lowest root-to-shoot ratio on a fresh weight basis among all treatments. The nitrate concentration in the shoot was significantly reduced following biostimulant supplementation compared to that realized with Fs-H and Hs-H treatments. Nutrient solutions supplemented with SE and PGA also decreased soluble sugar concentrations compared to that achieved using Hs-H and Fs-H treatments. FA and SE improved nutrient uptake for both cultivars, but PGA had a minimal effect on nutrient uptake. The two cultivars varied in their responses to biostimulant supplementation with regard to biomass, quality traits, and nutrient uptake. This study supports using fulvic acid and seaweed extract, rather than γ-PGA, in hydroponic lettuce production systems.

Influence of cultivar and season on carotenoids and phenolic compounds from red lettuce influence of cultivar and season on lettuce

This paper presents complete HPLC profiles and MS spectrometric data of bioactive compounds from four cultivars of red lettuce produced in winter and summer and their antioxidant capacity. The experiment was carried out in a greenhouse, where red curly lettuce was cultivated: Mila, Maira, Carmin and Scarlet. The cultivar and season have not influenced the qualitative profile of carotenoids (CAR) and phenolic compounds (PC) of red lettuce. Instead, the season influenced the concentration of these components in all cultivars. The levels of phenolic compounds were significantly higher in winter, while the levels of carotenoids were higher in summer. Ten anthocyanins were identified (cyanidins and delphinidins). The main carotenoid found was the all-trans-β-carotene (45–48%), followed by lutein (13–20%) and zeaxanthin (11–15%). Major phenolic compounds include 5-caffeoylquinic acid, rutin and amentoflavone. Red lettuce cultivars have their main bioactive compounds described and compared within the variety and within the growing season. Different season and different lettuce cultivars may differ in the content of their bioactive compounds and in their antioxidant capacity.

Influence of nitrogen source and rate on lettuce yield and quality

AbstractOrganic fertilizers are significantly lower in N content than chemical fertilizers, yet they can offer opportunities for efficient N utilization in lettuce (Lactuca sativa L.) production. A 2‐yr split‐split plot trial was conducted in the growing seasons of 2018 and 2019 at South Deerfield, MA, to evaluate the effect of source and rate of N fertilizers on yield, and quality of two lettuce cultivars. Nitrogen sources including blood meal (BLM), dehulled soybean meal (DSM), dehydrated cow manure (DCM), and urea (URE) were the main plots. Nitrogen application rates of 0, 60, 120, and 180 kg N ha–1 were subplots and two lettuce cultivars with different morphological phenotypes of iceberg (‘Mighty Joe’) and leaf lettuce (‘Bergam's Green’) were sub‐subplots. Quadratic model explained lettuce yield response to N fertilizer rate, regardless of cultivar and N source. Among all N sources, DCM resulted in the least total N, nitrate‐N, ammonium‐N, and the lowest fresh lettuce yield (24.0 Mg ha–1) compared with URE (30.1 Mg ha–1), DSM (30.7 Mg ha–1) and BLM (28.7 Mg ha–1). Lettuce N requirement at maximum yield was 157.7, 171.4, 112.5, and 191.7 kg ha–1 for BLM, DSM, DCM, and URE, respectively. An increase in N application rate increased total N, nitrate‐N, and ammonium‐N but decreased agronomic efficiency and apparent N recovery. Incidence of lettuce tipburn and head decay was cultivar specific and was not influenced by N source. We concluded that DSM could be used as an organic fertilizer source that provides N similar to that of URE for lettuce production.

Germination of green and red lettuce cultivars is influenced by LED light spectrum

Germination of green and red lettuce cultivars is influenced by LED light spectrum

Evaluation of Exogenous Salicylic Acid Application on White Mould Disease (Sclerotinia sclerotiorum) and Photosynthetic Pigments in Lettuce (Lactuca sativa L.)

The aim of this study was to investigate the effectiveness of salicylic acid (SA) treatment against white mould disease (Sclerotinia sclerotiorum) (SS) disease in lettuce (Lactuca sativa L.) plant. In this study, two lettuce cultivars (Melina and Fuzila) were used and four treatments were applied to the plants (control, SS, SA, and +SA+SS treatments). Weight (g), the number of marketable leaf per plant, the number of non-marketable leaf per plant, leaf ratio (%), relative water content (%), chlorophyll parameters (chlorophyll a, b and total chlorophyll (mg 100g-1), colour parameters (L, a and b) and disease severity (%) were determined. According to the results, SA treatment increased the weight (563.65 g plant-1 for cv. Melina and 574.67 g plant-1 for cv. Fuzila) and number of marketable leaves (26.83 leaf per plant for cv. Melina and 31.33 leaf per plant for cv. Fuzila) whereas it decreased the number of non-marketable leaves (8.66 leaf per plant for cv. Melina and 6.67 leaf per plant for cv. Fuzila) in both cultivars. Besides, it was found that SA treatment reduced disease severity by 19% and 14% for cv. Melina and cv. Fuzila, respectively. Total chlorophyll contents ranged from 0.421 mg 100g-1 to 0.484 mg 100g-1 for Melina and 0.467 mg 100g-1 to 0.593 mg 100g-1 for Fuzila cvs. These results demonstrated that there was an increasing tendency due to SA applications for the total chlorophyll content in all cultivars. Consequently, it has been determined that SA treatment is effective and can be used against white mold disease in lettuce plants.

HBFT-아쿠아포닉 시스템 내 독립 및 종속 미생물의 적용에 따른 시베리아 철갑상어 (Acipenser baerii), 바질 (Ocimum basilicum) 및 엽채류 4종류의 성장과 수질변화

Aquaponics is a cultivation system that combines aquaculture and agricultural hydroponics. This study investigated water quality changes and growth of fish (siberian sturgeon) and leafy vegetables (basil and four leafy vegetables) through the use of nitrifying autotrophic bacteria alone (Auto+CO2)and the mixed use of heterotrophic and autotrophic microorganism (Hetero+HBFT) in operation of aquaponic system. After basil stocking (5-8 weeks) in EXP1, Auto+CO2 experimental groups showed rapid water quality stabilization for about 2 weeks compared to Hetero+HBFT groups, but the lattergroups showed significantly higher growth of both fish and basil (P0.05).. In EXP2 (9-12 weeks), the growth factors of fish and 4 kinds of european lettuce cultivars in Hetero+HBFT experimental groups were higher than Auto+CO₂ groups. In hematological ananlysis [hematocrit (PCV, %), hemoglobin (g/dL), GOT (U/L), GPT (U/L), ALB (g/dL), GLU (mg/dL), plasma Na, K, Cl (mEq/L) and inorganic phosphorus (mg/dL)] between two experimental groups, all items were not significantly different at the end of the experimental period (P0.05). This study shows that for aquaponics water quality management, it is more effective to use it in combination with heterotrophic bacteria rather than autotrophic bacteria alone to stabilize water quality.

Evaluation of moringa (Moringa oleifera Lam.) leaf extract on bioactive compounds of lettuce (Lactuca sativa L.) grown under glasshouse environment

This study aimed to assess the novelty of moringa (Moringa oleifera Lam.) leaf extract (MLE) as a natural biostimulant on bioactive compounds in lettuce. In autumn season of 2019 and 2020, MLE (6%) was foliar sprayed onto lettuce grown under glasshouse conditions. Vitamin C, total polyphenols, total chlorophyll content and nitrate accumulation in three lettuce cultivars (May King, Kobak, and Great Lakes) and some correlations among the bioactive compounds were assessed. The results in 2019 show that there was no significant differences in the total polyphenols (mg GAE 100 g−1 FW) and vitamin C (mg 100 g−1 FW) between treated and untreated plants, while in 2020 significantly higher vitamin C (mg 100 g−1 FW) and total polyphenols (mg GAE 100 g−1 FW) were recorded in the plants treated with 6% MLE. In contrast, in 2019 application of 6% MLE lowered nitrate content (mg kg−1) by 13% in May King, 23% in Kobak, and 44% in Great Lakes. Similarly, in the season of 2020 foliar application of 6% MLE reduced the leaf nitrate content by 16% in May King, 19% in Kobak, and 44% in Great Lakes. In the mean of varieties, the only significant difference in total polyphenol and vitamin C was in the Great Lakes variety grown in 2020 whereas no differences were found for the experiment of 2019. In the mean of years, the only statistical difference was recorded for the nitrate content in control of the Great Lakes variety by 44% lower nitrate in the treated plants with 6%MLE. Positive correlation was found between vitamin C and total polyphenol content, whereas nitrate had a negative regression slop to vitamin C and total polyphenol content in both experiments. The major total chlorophyll differences were found in the experiment of 2019, although no significant differences were found for the SPAD value of the experiment of 2020. In our 2 years study, there was a positive correlation between vitamin C and total polyphenol while negative correlation was found between vitamin C and total polyphenol to nitrate content in all the lettuce cultivars.

Gluconacetobacter diazotrophicus Inoculation of Two Lettuce Cultivars Affects Leaf and Root Growth under Hydroponic Conditions

The growth-promoting effects of Gluconacetobacter diazotrophicus inoculation on the leaf lettuce (Lactuca sativa L.) cultivars “Black Seeded Simpson” and “Bibb/Limestone” were investigated. Plants of each cultivar were grown hydroponically in Kratky jars in a growth chamber-controlled environment in a completely randomized factorial design with three or four replications. Each experiment was repeated once. Factors were (1) with or without inoculant and (2) seven levels of nitrogen (N) fertilization ranging from deficient (37.5 mg L−1 N) to excessive (172.5 mg L−1 N). The shoot, root, and total biomass accumulation, nitrogen density, and carbon/nitrogen (C/N) ratios were measured for each variety. Black Seeded Simpson demonstrated a shifting of production towards aerial tissues, with significantly greater shoot production and reduced root production. The observed increase in shoot biomass was greatest at the slightly deficient N rate of 105 mg L−1 N where inoculated plants produced 14.8% more than uninoculated plants. Lower N density and higher C/N ratios in inoculated shoot tissues indicate greater N use efficiency. Bibb/Limestone responded to inoculation with an average increase of 10.9% in shoot production and with greater root biomass. Bibb/Limestone also exhibited lower N density in inoculated shoot tissues with a corresponding increase in the C/N ratio. For growers looking to maximize lettuce yields, G. diaz inoculation may present a beneficial additive to the growing system by increasing leaf yields while not increasing N fertilizer requirements.

The effect of plant biostimulants on the macronutrient content and ion ratio of several lettuce (Lactuca sativa L.) cultivars grown in a plastic house

Plant biostimulants have been identified as one of the most important agronomic factors that scientists have been looking for in a range of natural sources over the last few decades. The purpose of these experiments was to see how plant biostimulants (Willow bark extract, Bistep, and the combination of Willow+Bistep (W+B)) affect macronutrient content and ion ratio in three lettuce cultivars (May King, Kobak, and Great Lakes) from 2019 to 2021. Willow bark extract was diluted to 3% and applied to the plants through irrigation with the amount of 50–60 mL plant−1, whereas Bistep was sprayed every two weeks from transplanting in accordance with the manufacturer's recommendations at 0.05% with the amount of 20 mL plant−1.The data demonstrate that over the grown seasons, the treatments W+B and Willow bark extract were the most effective biostimulants impacting macronutrient content and ion ratio, whereas Bistep was the least effective. In comparison to untreated plants, the amount of macronutrients (Ca2+, Mg2+, and P) in lettuce leaves rose by 18%, 13%, and 9%, respectively, in plants treated with W+B over a period of years, while, potassium (K+) significantly reduced by 15%. Sodium level, on the other hand, was significantly improved using plant biostimulants of Bistep, Willow and W+B by 33%, 57% and 72%, respectively. Ca2+ and Mg2+ levels in lettuce cultivars were substantially higher in the season of 2019 when the climate was cooler and the air humidity was higher, but Na+, K+, and P levels were higher in 2020 when the temperature was somewhat warmer and dryer. Among the lettuce cultivars, Great Lakes lettuce has a greater level of macronutrient content (Ca2+, Mg2+, Na+, and K+), however, Kobak contained much higher phosphorus (P) content at 301.41 (mg kg−1 DM).Plant biostimulants enhanced the ion ratios of Na+: Ca2+ and Na+: Mg2+, but the only substantial improvement in Ca2+: P ratio was in plants treated with W+B from 2019 to 2021, particularly in the Kobak variety by 20%. Biostimulants, on the other hand, decreased the mass ratio of (K++Na+): (Ca2++Mg2+) in lettuce cultivars. Among plant biostimulants, Willow and the combination of W+B had the highest influence on nutritional absorption and ion ratio, although Bistep had the least. The macronutrient composition and ionic ratios of lettuce cultivars varied according to the cultivar differences and climate conditions. In our 3-year experiments, we discovered that the Great Lakes variety had a higher macronutrient content in the season of 2020, whereas the Kobak variety had a higher ion ratio.

Maximization of Water Productivity and Yield of Two Iceberg Lettuce Cultivars in Hydroponic Farming System Using Magnetically Treated Saline Water

Egypt has limited agricultural land, associated with the scarcity of irrigation water and rapid population growth. Hydroponic farming, seawater desalination and magnetic treatment are among the practical solutions for sustaining rapid population growth. In this regard, the main objective of the present research study was to design and construct a hierarchical engineering unit as a hydroponic farming system (soilless) to produce an iceberg lettuce crop using magnetically treated saline water. The treatments included four types of irrigation water: common irrigation water (IW1) with an electrical conductivity (EC) of 0.96 dS/m as a control treatment, magnetically treated common irrigation water (IW2) with an EC of 0.96 dS/m, saline water (IW3) with an EC of 4.56 dS/m and magnetically treated saline water (IW4) with an EC of 4.56 dS/m; three depletion ratios (DR) of field capacity (DR0 = 50%, DR1 = 60% and DR2 = 70%) and three slopes of hydroponic pipes (S1 = 0.0%, S2 = 0.025% and S3 = 0.075%). The results revealed that seawater contributed 7.15% to produce iceberg lettuce in the hydroponic system. The geometric parameter, the slope of the pipes, influenced the obtained luminous intensity by an average increase of 21% and 71% for S2 and S3, respectively, compared with the zero slope (horizontal pipes). Magnetization of irrigation water increased the total soluble solids (TSS) and enhanced the fresh weight and water productivity of both iceberg lettuce varieties used. The maximum percentages of TSS were 5.20% and 5.10% for lemur and iceberg 077, respectively, for the combination IW4DR2S2. The highest values of fresh weight and water productivity of 3.10 kg/m and 39.15 kg/m3 were recorded with the combinations IW3DR2S3 and IW4DR1S3, respectively, for lemur and iceberg lettuce. The percentages of these increases were 109.46% and 97.78%, respectively, when compared with the combination IW1DR0S1. The highest values of iceberg lettuce 077 fresh weight and water productivity were 2.93 kg/m and 36.15 kg/m3, respectively, which were recorded with the combination IW4DR1S3. The percentages of these increases were 112.32% and 120.56%, respectively, when compared with IW1DR0S1 (the control treatment).

Morphological and Physiological Screening to Predict Lettuce Biomass Production in Controlled Environment Agriculture

Fast growth and rapid turnover is an important crop trait in controlled environment agriculture (CEA) due to its high cost. An ideal screening approach for fast-growing cultivars should detect desirable phenotypes non-invasively at an early growth stage, based on morphological and/or physiological traits. Hence, we established a rapid screening protocol based on a simple chlorophyll fluorescence imaging (CFI) technique to quantify the projected canopy size (PCS) of plants, combined with electron transport rate (ETR) measurements using a chlorophyll fluorometer. Eleven lettuce cultivars (Lactuca sativa), selected based on morphological differences, were grown in a greenhouse and imaged twice a week. Shoot dry weight (DW) of green cultivars at harvest 51 days after germination (DAG) was correlated with PCS at 13 DAG (R2 = 0.74), when the first true leaves had just appeared and the PCS was <8.5 cm2. However, early PCS of high anthocyanin (red) cultivars was not predictive of DW. Because light absorption by anthocyanins reduces the amount of photons available for photosynthesis, anthocyanins lower light use efficiency (LUE; DW/total incident light on canopy over the cropping cycle) and reduce growth. Additionally, the total incident light on the canopy throughout the cropping cycle explained 90% and 55% of variability in DW within green and red cultivars, respectively. Estimated leaf level ETR at a photosynthetic photon flux density (PPFD) of 200 or 1000 µmol m−2 s−1 were not correlated with DW in either green or red cultivars. In conclusion, early PCS quantification is a useful tool for the selection of fast-growing green lettuce phenotypes. However, this approach may not work in cultivars with high anthocyanin content because anthocyanins direct excitation energy away from photosynthesis and growth, weakening the correlation between incident light and growth.