•It was evaluated different light qualities and intensities in lettuce plants regards to (de)etiolation processes.•White, blue, green, red and far-red light, as well as combinations, totaling 18 ...treatments were tested.•Blue light is capable of inhibiting or reducing etiolation-related responses, but the effects are not only dependent on the quality alone, but also on the light intensity.•The presence of red light and mostly far-red light limits the effect of blue light on de-etiolation process.•Negative action of PHYA on CRY is considered more intense than that of PHYB on CRY.
The role of photoreceptors (phytochromes and cryptochromes) was evaluated in lettuce regarding (de)etiolation processes. The manipulation of light quality and intensity can modulate their activity and response and, consequently, promote morphophysiological changes in plants. To this end, lettuce plants were grown under controlled conditions at two photosynthetically active radiation levels (300 and 600 µmol m−2 s−1) and at different qualities, including white, blue, green, red and far-red light, as well as combinations, totaling 18 treatments. Biomass gain, internode length, light interception, pigment content, morpho-anatomical changes in the leaves and ultrastructural changes in the chloroplast and cell wall were evaluated. It was verified that in green, there was the highest degree of etiolation; however, the supplementation of blue promotes a strong de-etiolation process. In pure red (R), the plants were slightly less etiolated, but with limited action of blue in stimulating de-etiolation, and in R plus far-red (FR) (R:FR ratio was 0.33 in R + FR treatment), there was a strong degree of etiolation and weak action of blue on those set of treatments. In general, the plants submitted to the highest intensities of blue light, alone or in combination, approach the control phenotype (white light at total 300 µmol m−2 s−1; 18 % blue = 54 µmol m−2 s−1). The morpho-anatomical phenotype supports the hypothesis that blue light is capable of inhibiting or reducing etiolation-related responses, but the effects are dependent not only on the quality alone but also on the light intensity. Based on the known light-dependent response of phytochromes and cryptochromes, we suggest a weak interference of PHYB on CRY and a strong negative action of PHYA on CRY proteins.
•The most intensive browning in stems appears in the vascular bundle area.•The browning of stems is highly correlated with the browning of leaf ribs.•Both stem and rib browning have high broad-sense ...heritability.
Enzymatic browning is a major postharvest quality defect of romaine lettuce (Lactuca sativa L.). This study provides the first analysis of the relationship between the browning of leaf ribs and stems across twelve lettuce genotypes (ten cultivars, a breeding line, and a plant introduction). While all samples showed a progressive increase in browning index (BI) and decline in lightness (L*) and hue (h°) during 5 °C storage, differences in the rate of browning development were observed among genotypes. The most intensive browning was observed mainly around the vascular bundles dispersed along the rim area of the stems. Browning on the cut surfaces of the stems was correlated with browning on the cut leaf ribs, with Pearson correlation coefficients of 0.886 for BI, 0.891 for L* and 0.866 for h°. These results showed that the degree of browning in leaf ribs can be predicted by the browning degree of the stems. High genetic similarity was found among four cultivars with limited browning (Darkland, Parris Island Cos, Green Towers, and Hearts Delight) and also between cultivars with severe browning (King Henry and Tall Guzmaine). The highest broad-sense heritability (H2) in both trials (July and November 2018) was 0.88 and 0.92 for stem and rib browning, respectively. The method based on stem browning can be used to simplify postharvest phenotypic evaluation of lettuce and to decipher the genetics of browning to accelerate the breeding of browning-resistant cultivars.
Reduction of nitrogen application in crop production is desirable for ecological and health-related reasons. Interestingly, nitrogen deficiency can lead to enhanced concentrations of polyphenols in ...plants. The reason for this is still under discussion. The plants' response to low nitrogen concentration can interact with other factors, for example radiation intensity. We cultivated red and green leaf lettuce hydroponically in a Mediterranean greenhouse, supplying three different levels of nitrogen (12 mM, 3 mM, 0.75 mM), either in full or reduced (-50%) radiation intensity. In both red and green lettuce, we found clear effects of the nitrogen treatments on growth characteristics, phenolic and photosynthetic compounds, nitrogen, nitrate and carbon concentration of the plants. Interestingly, the concentrations of all main flavonoid glycosides, caffeic acid derivatives, and sucrose increased with decreasing nitrogen concentration, whereas those of chlorophylls, beta-carotene, neoxanthin, lactucaxanthin, all trans- and cis-violaxanthin decreased. The constitutive concentrations of polyphenols were lower in the green cultivar, but their relative increase was more pronounced than in the red cultivar. The constitutive concentrations of chlorophylls, beta-carotene, neoxanthin, all trans- and cis-violaxanthin were similar in red and green lettuce and with decreasing nitrogen concentration they declined to a similar extent in both cultivars. We only detected little influence of the radiation treatments, e.g. on anthocyanin concentration, and hardly any interaction between radiation and nitrogen concentration. Our results imply a greater physiological plasticity of green compared to the red lettuce regarding its phenolic compounds. They support the photoprotection theory regarding anthocyanins as well as the theory that the deamination activity of phenylalanine ammonia-lyase drives phenylpropanoid synthesis.
High temperature (HT) is an environmental factor that considerably affects plant physiology, development, crop yield, and economic value. HT can cause diseases and early bolting of leaf lettuce, ...thereby reducing the yield and quality of leaf lettuce. Herein, we used two leaf lettuce (Lactuca sativa L.) cultivars (bolting-resistant ‘S24’ and bolting-sensitive ‘S39’) to investigate the key factors and molecular mechanism impacting bolting. We found that 14 MADS-box genes implicated in bolting and flowering, LsMADS54 (also referred to as L. sativa FRUITFULL, LsFUL), was significantly up-regulated 1,000 times after 5-d HT treatment and that HT-induced up-regulation of LsFUL was higher in bolting-sensitive than in resistant cultivars. The overexpression lines of LsFUL exhibited an earlier bolting time than that in the non-transformed ‘S39’(CK). However, the RNA interference, and CRISPR-Cas9-mediated knockout lines of LsFUL exhibited a later bolting time than that in CK. In addition, we found that L. sativa SUPPRESSORS OF MEC-8 AND UNC-52 PROTEIN 2 (LsSMU2) and L. sativa CONSTANS-LIKE PROTEIN 5 (LsCOL5) interact with LsFUL, and these interactions could stimulate or prevent bolting. We observed that elevated temperature stimulated the abundance of LsSMU2 in the stem, which collaborated with LsFUL to accelerate bolting. Conversely, room temperature (RT) condition led to relatively more stable LsCOL5, which worked with LsFUL to postpone bolting. In summary, our findings demonstrate a molecular regulatory module of LsSMU2–LsFUL associated with HT-induced premature bolting, which serves as a reference for understanding HT-induced premature bolting phenomenon in leaf lettuce.
•LsFUL is differentially expressed in bolting-resistant cultivar and high temperature•LsFUL is a positive regulator in leaf lettuce bolting•LsSMU2 confers high temperature induced bolting process via interact with LsFUL in leaf lettuce•LsFUL interacts with LsCOL5 to inhibit early bolting and flowering under normal conditions
Interest in aquaponics (AP) is increasing due to its ability to minimize sewage and maximize feed efficiency in fish farming. However, owing to limitations of intensive cultures and a lack of ...nutrients such as NOsub.3 for growing crops, AP requires the use of artificial nutrients. Therefore, novel approaches are required to develop AP-intensive culturing methods. An AP system based on biofloc technology (BFT) called FLOCponics (FP) has been recommended. Here, the productivity of the weather loach (Misgurnus anguillicaudatus ) in the FP system, BFT system, and flow-through systems (FTSs), as well as these systems’ effect on Caipira lettuce (Lactuca sativa ) growth, was analyzed. To compare crop productivity, a hydroponic (HP) bed was installed. The growth rate of M. anguillicaudatus showed significant differences, at 51.1 ± 3.69% in the FP system, followed by 24.0 ± 4.16% in the BFT system and −14.3 ± 1.4% in the FTS. Its survival rates were better in the FP system (91.1 ± 2.64%) than in the BFT system (82.1 ± 10.98%) or the FTS (66.8 ± 2.75%) (p < 0.05). Total ammonia nitrogen and NOsub.2 sup.− -N concentrations were stabilized in every plot during the experimental period. However, the NOsub.3 sup.− -N concentration continuously increased in the BFT system but decreased in the FP system and was maintained. The shoot weight of the Caipira lettuce was 163.6 ± 8.65 g in the FP system and 149.6 ± 9.05 g in the HP system. In conclusion, FP system can provide a large amount of nutrients and improve the growth performance of both fish and crops in the FP system.
The present study was focused on lettuce, a widely consumed leafy vegetable for the large number of healthy phenolic compounds. Two differently-pigmented lettuce cultivars, i.e. an acyanic-green leaf ...cv. and an anthocyanic-red one, were grown under high light intensity or elevated CO2 or both in order to evaluate how environmental conditions may affect the production of secondary phenolic metabolites and, thus, lettuce quality. Mild light stress imposed for a short time under ambient or elevated CO2 concentration increased phenolics compounds as well as antioxidant capacity in both lettuce cvs, indicating how the cultivation practice could enhance the health-promoting benefits of lettuce. The phenolic profile depended on pigmentation and the anthocyanic-red cv. always maintained a higher phenolic amount as well as antioxidant capacity than the acyanic-green one. In particular, quercetin, quercetin-3-O-glucuronide, kaempferol, quercitrin and rutin accumulated under high light or high CO2 in the anthocyanic-red cv., whereas cyanidin derivatives were responsive to mild light stress, both at ambient and elevated CO2. In both cvs total free and conjugated phenolic acids maintained higher values under all altered environmental conditions, whereas luteolin reached significant amounts when both stresses were administered together, indicating, in this last case, that the enzymatic regulation of the flavonoid synthesis could be differently affected, the synthesis of flavones being favored.
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•Green and anthocyanic leaf cultivars of lettuce were exposed to high CO2 and high light intensity.•High light intensity increased different phenolic compounds.•Under elevated CO2, carbohydrates and phenolic compounds accumulated.•Elevated CO2 and high light, alone or in combination, change phenolic composition of lettuce.
•Plants grown under a LED-SUN spectrum had stem length 2.1–4.4 times longer than all treatments, indicating bolting.•Plants grown under a LED sun simulated spectrum have higher fresh mass per dry ...mass ratio.•Plants grown under a LED sun simulated and 100B spectra had greater leaf area than common B:R treatments.•Phytochemical content was lower in plants under SUN and 100B LED spectra.•The impact of light spectrum on plant growth was differed by plant growth stage (transplant, baby-leaf, head lettuce).
Light drives photosynthesis and regulates plant morphology, physiology, and phytochemical content. Using light emitting diodes (LEDs), customized spectra can be created, including spectrum that simulates solar light. The aim of this study was to assess the growth, development, and phytochemical content at three marketable stages of lettuce (transplant, baby-leaf, and head-lettuce) under a sun-simulated spectrum and common light spectra used in indoor growing systems. Oakleaf red (Salanova® ‘Red Oakleaf’) and green (Salanova® ‘Green Oakleaf’) lettuce were grown under seven spectra. A sun-simulated light treatment (SUN) was created with 5 % ultraviolet-A (UV-A), 20 % blue (B), 26 % green (G), 26 % red (R), and 23 % far-red (FR) light as percent photon flux density (PFD). In addition, five treatments of differing blue:red (B:R) ratios were evaluated: 0B:100R (100R), 20B:80R, 50B:50R, 80B:20R, and 100B:0R (100B) and fluorescent white light was used as a control (6500 K). Plants were provided with 200 ± 0.7 μmol·m−2·s−1 biologically active radiation (300–800 nm) for 18 h and grown at 20.0 ± 0.2 °C temperature. Fresh mass of lettuce in the SUN treatment was not significantly different when compared to B:R light treatments in all harvest dates despite the 36 % greater photosynthetic photon flux density (PPFD) in B:R treatments. Plant dry mass on day 17 of’ Green Oakleaf’ and ‘Red Oakleaf’ grown under 20B:80R was 15–39 % greater than those grown in 100B and SUN. When calculating total dry mass accumulation to cumulative yield photon flux density (YPFD), plants in SUN treatment accumulated the same dry mass per YPFD input (mg mol−1). Leaf area at day 42 of plants in 100B, SUN, and FL was 39–78 % greater than plants in B:R treatments. At final harvest (day 42), plant stem length in SUN was 2.1–4.4 times longer than in all other treatments, indicating bolting and flowering initiation. Both total phenolic and anthocyanin concentrations were greater in the B:R treatments than in SUN, 100R, and 100B treatments. This study presents baseline information for lettuce responses under LED-simulated SUN spectrum when compared to common B:R treatments and offers insights on lettuce growth and morphology under different spectra at multiple growth stages.
The ZIP protein (ZRT, the IRT-like protein) is an important metal transporter that transports Zn, Fe, and other divalent metal ions in plants. In this study, we identified 20 ZIP genes in lettuce ...(Lactuca sativa L.). We used bioinformatics methods and renamed them according to their E value in hmmsearch. We also analyzed their gene structure, chromosomal location, constructed a phylogenetic tree, conserved motifs, performed synonymous analysis and responses to abiotic stresses. The results show that these LsZIP genes have 3-11 exons and were distributed unequally on 8 of the 9 chromosomes in lettuce. Based on phylogenetic analyses, the LsZIP gene family can be divided into three subfamilies, and the LsZIP genes within the same subfamily shared similar gene structure. The LsZIP genes contain 12 Motifs, of which Motif1 to Motif8 are widely distributed in group â . Furthermore, the LsZIP gene contains numerous hormones and anti-stress response elements. Real-time quantitative PCR demonstrated that most LsZIP genes is up-regulated under the elemental stress in this experiment, indicating that they are positively regulated. But different elemental stressors can induce the expression of LsZIP gene to varying degrees. The LsZIP genes also change in response to different elemental stresses. The present study serves as a basic foundation for future functional studies on the lettuce ZIP family.
Broccoli (Brassica oleracia L.) and lettuce (Lactuca sativa L.) were part of horticultural commodities that can be consumed and contain a lot of vitamins, such as vitamins A, B Complex, C, and ...essential minerals such as calcium and iron for fulfilling human nutrition. Lettuce plants can also be consumed as salad. The demand for horticultural crops, broccoli and lettuce, was increasing because people awareness on nutritional needs arise. Besides, these plants are also delicious. Intercropping pattern used by farmers on Jalan Kayu Ambon, Lembang District, West Bandung Regency was a form of mixed cropping pattern system that involve two or more types of plants in the same area and the same time. This intercropping pattern can maximize production in a limited land, and the risk of loss can be reduced. The objective of this research was to find out cost, revenue and the R/C ratio of the intercropping system of broccoli and lettuce.The method of the research was the survey method. The data consist of the primary and secondary data. The primary collected directly from the farmer. Meanwhile the secondary data collected from literature and any institutions that related to this research. The farmer was Bapak Jajang. The primary data consisted fix cost, variable cost, and revenue. The data were used to calculate Break Even Point and R/C ratio.Result of the research showed that total cost (TC) used in intercropping broccoli and lettuce system was IDR 5,462,142/planting season, with total revenue (TR) was IDR 5,958,000. The R/C ratio was 1.09. So this Intercropping Farming System was feasible because the R/C ratio more than 1.
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