Fresh-cut lettuce is widely used in ready-to-eat salads sold in modified atmosphere packages (MAP).Even in MAP,fresh-cut lettuce has short shelf life that results in loss of nutrients.Lettuce cultivars exhibit genetic...Fresh-cut lettuce is widely used in ready-to-eat salads sold in modified atmosphere packages (MAP).Even in MAP,fresh-cut lettuce has short shelf life that results in loss of nutrients.Lettuce cultivars exhibit genetic variation for shelf life in MAP,but their variation for nutrient retention is not known.Fifty accessions were evaluated for initial content of ascorbic acid (AsA),carotenoids,and sugars and their retention in storage.Accessions with high content and/or good retention of one or more nutrients were identified.The romaine accession ‘Floricos’ had high levels of all the three nutrients.Accessions with relatively high retention of all the three nutrients were ‘Salinas 88’,‘Siskiyou’,‘Solar’,SM09A,‘Romance’,and ‘Green Towers’.Romaine cultivars,‘Balady Barrage’,‘Green Towers’,and ‘Darkland’ had relatively high initial levels of all tested nutrients and good rate of their retention.There was no clear correlation between initial AsA/carotene concentrations and their retention rates,suggesting that besides content,retention of nutrients should also be a breeding target in a lettuce nutritional improvement program.Statistical analyses with the Pearson's correlation coefficient determined a negative relationship between tissue deterioration(AUDePS) and retention of all tested nutrients[r of-0.52 (P<0.0001) for AsA,-0.27 (P<0.01) for total carotene,and-0.59 (P<0.0001) for total sugars],suggesting that an increase in tissue deterioration intensifies nutrient decay.Broad-sense heritability (H^(2)) across the experiments was0.15 for AsA,0.23 for total carotene,and 0.50 for total sugars.Identification of germplasm with high nutrient content,extended shelf life and good nutrient retention provides valuable information for the lettuce industry and associated breeding programs.展开更多
[Objectives]This study was conducted to investigate the effects of lignin-based fully biodegradable plastic film on the growth and quality of lettuce under open-field cultivation conditions.[Methods]In this experiment...[Objectives]This study was conducted to investigate the effects of lignin-based fully biodegradable plastic film on the growth and quality of lettuce under open-field cultivation conditions.[Methods]In this experiment,compared with bare soil,a polyethylene plastic film(PE)treatment and two lignin-based fully biodegradable plastic film treatments(LBF-0.01 and LBF-0.008)with different thicknesses were set to study the effects on the growth and quality of lettuce.[Results]During autumn cultivation in Shanghai,the thermal insulation performance and yield-increasing effect of the two degradable plastic films were consistent with those of PE film,and effectively met lettuce growth requirements,but treatment LBF-0.01was better than treatment LBF-0.008.Moreover,lignin-based fully biodegradable plastic film could significantly increase the contents of Vc,soluble sugar and carotenoids in lettuce,and treatment LBF-0.008 showed the best effect.It could be seen that under the experimental conditions,the two kinds of lignin-based biodegradable plastic films with different thicknesses could be applied to the cultivation of lettuce in the open field in Shanghai in autumn,and LBF-0.01 had the best effect of increasing temperature and increasing yield,while LBF-0.008 had the best effect of improving quality.[Conclusions]This study provides theoretical basis and technical support for the further application of lignin-based fully biodegradable plastic film.展开更多
Reclaimed water for irrigation or hydroponic cultivation provides exposure pathways for per-and polyfluoroalkyl substances(PFAS)to enter the human food chain.This study employed hydroponic methods to investigate the b...Reclaimed water for irrigation or hydroponic cultivation provides exposure pathways for per-and polyfluoroalkyl substances(PFAS)to enter the human food chain.This study employed hydroponic methods to investigate the behavior of legacy PFAS and emerging chlorinated polyfluoroalkyl ether sulfonic acids(Cl-PFESAs)in lettuce grown under environment-related exposure levels and assessed the human exposure risks from consuming contaminated lettuce.Overall,PFAS in lettuce were concentration-dependent,with long-chain PFAS tending to accumulate in roots and short-chain PFAS accumulating more in shoots.The enrichment of PFAS in lettuce was jointly influenced by their chain length and polar functional groups.Specifically,the root concentration factors(RCFs)of PFAS generally increased with increasing chain length,and RCF values of most perfluoroalkanesulfonic acids(PFSAs)were significantly higher than those of perfluoroalkyl carboxylic acids(PFCAs)with the same chain length(p<0.01),while the translocation factors(TFs)exhibited opposite trends.RCF values of perfluorooctane sulfonate(PFOS)and its alternatives,Cl-PFESAs,were ranked as follows:8:2 Cl-PFESA(mean:139)>6:2 Cl-PFESA(28.6)>PFOS(25.7),which was attributed to the increased molecular size and hydrophobicity resulting from the insertion of ether bonds and additional CF2 in 8:2 Cl-PFESA.Notably,TF value of 8:2 Cl-PFESA(mean:0.007)was the smallest among all PFAS,indicating 8:2 Cl-PFESA was difficult to transfer to nutritional compartments.Adults and children would exceed the most conservative health-based reference dose(RfD)by consuming approximately 15.9–148 g and 7.92–74.0 g of contaminated lettuce per day,implying high health risks.展开更多
[Objective]The aim of this study was to understand the role of polyamine oxidative degradation in the process of lettuce seed germination. [Method]After lettuce seed soaking treatments with aminoguanidine （AG,a speci...[Objective]The aim of this study was to understand the role of polyamine oxidative degradation in the process of lettuce seed germination. [Method]After lettuce seed soaking treatments with aminoguanidine （AG,a specific inhibitor of polyamine oxidases）,seed germination rate,activities of polyamine oxidase （PAO） and diamine oxidase （DAO）,change of endogenous polyamine and H2O2 content were determined. [Result]Compared with the control,AG treatment strongly inhibited the seed germination,which also had an extremely significant difference in seed germination rate after incubation for 12 h. During the seed germination,activities of PAO and DAO significantly changed,while their activities firstly increased and then decreased,then DAO and PAO reached peaks at 24 h and 48 h respectively. AG treatment was strongly inhibitory for activities of DAO and PAO,whose activities even disappeared after incubation with AG for 24 h and 36 h. During the seed germination,endogenous Put reduced sharply in the first 24 h,then reduced slowly in 24-60 h,while Spd decreased slowly in the early stage of germination,and then sharply declined after 48 h. However,Spm content was low but slightly increased,and the total polyamine gradually decreased. AG treatment could significantly increase endogenous polyamines,especially Put and Spd contents. During the seed germination,H2O2 content gradually increased,and had a peak from 36 to 48 h,then kept a high level at last. AG treatment could significantly reduce H2O2 content. [Conclusion]During the seed germination,the changes of endogenous polyamine and H2O2 content correspond with the changes of PAO and DAO activities,which indicate that there is an active polyamine metabolism of oxidative degradation during the lettuce seed germination.展开更多
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 nu...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.展开更多
High nitrate(NO3-) in vegetables, especially in leaf vegetables poses threaten to human health. Selenium(Se) is an important element for maintaining human health, and exogenous Se application during vegetable and crop...High nitrate(NO3-) in vegetables, especially in leaf vegetables poses threaten to human health. Selenium(Se) is an important element for maintaining human health, and exogenous Se application during vegetable and crop production is an effective way to prevent Se deficiency in human bodies. Exogenous Se shows positive function on plant growth and nutrition uptake under abiotic and/or biotic stresses. However, the influence of exogenous Se on NO3-accumulation in hydroponic vegetables is still not clear. In the present study, hydroponic lettuce plants were subjected to six different concentrations(0, 0.1, 0.5, 5, 10 and 50 μmol L–1) of Se as Na2 Se O3. The effects of Se on NO3-content, plant growth, and photosynthetic capacity of lettuce(Lactuca sativa L.) were investigated. The results showed that exogenous Se positively decreased NO3-content and this effect was concentration-dependent. The lowest NO3-content was obtained under 0.5 μmol L–1 Se treatment. The application of Se enhanced photosynthetic capacity by increasing the photosynthesis rate(Pn), stomatal conductance(Cs) and the transpiration efficiency(Tr) of lettuce. The transportation and assimilation of NO3-and activities of nitrogen metabolism enzymes in lettuce were also analysed. The NO3-efflux in the lettuce roots was markedly increased, but the efflux of NO3-from the root to the shoot was decreased after treated with exogenous Se. Moreover, Se application stimulated NO3-assimilation by enhancing nitrate reductase(NR), nitrite reductase(Ni R), glutamine synthetase(GS) and glutamate synthase enzyme(GOGAT) activities. These results provide direct evidence that exogenous Se shows positive function on decreasing NO3-accumulation via regulating the transport and enhancing activities of nitrogen metabolism enzyme in lettuce. We suggested that 0.5 μmol L–1 Se can be used to reduce NO3-content and increase hydroponic lettuce yield.展开更多
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 qualit...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.展开更多
High temperature stress on different varieties of lettuce seedlings in MDA, proline and soluble sugar content were studied. The results were as follows : With the stress temperature, varieties of leaf lettuce seedling...High temperature stress on different varieties of lettuce seedlings in MDA, proline and soluble sugar content were studied. The results were as follows : With the stress temperature, varieties of leaf lettuce seedlings in the MDA, proline and soluble sugar content gradually increased;Different varieties had the most significant difference in 38/33℃(d/n). The increase of heat-resistant varieties on proline and soluble sugar content was quick and high, while its increase in MDA content was slow and small.展开更多
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 te...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°C. 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.展开更多
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 nut...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.展开更多
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 whethe...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.展开更多
Spectral quality of radiation has a major impact on the growth, development and nutritional quality of crops. The effect of supplemental radiation (blue, red and far-red) on the growth and nutritional quality with reg...Spectral quality of radiation has a major impact on the growth, development and nutritional quality of crops. The effect of supplemental radiation (blue, red and far-red) on the growth and nutritional quality with regard to health-promoting phytochemical and micronutrient composition of two lettuce (Lactuca sativa) varieties (red leaf “New Red Fire” and green leaf “Two Star”) was studied. Supplemental radiation was provided by blue (450 nm), red (660 nm) or far-red (730 nm) LEDs against a background of white light (fluorescent lighting, PAR;270 μmol/m2/s) in a growth chamber study. All the supplemental radiation treatments increased dry shoot biomass in both varieties. However, supplemental far-red radiation increased both fresh and dry shoot biomass in both varieties. In addition, supplemental far-red radiation produced distinct morphological characteristics in lettuce plants. It produced the largest shoot biomass, bigger and taller plants, fewer leaves but with larger leaf area compared to the control, similar to the shade avoidance response. With regard to the accumulation of phytochemicals, supplemental blue radiation enhanced the total phenolic compound concentration in both varieties. In addition, supplemental blue radiation sharply increased the accumulation of several phenolic compounds in green leaf lettuce including chlorogenic acid, chicoric acid, rutin, kaempferol, luteolin and apigenin. For example, the leaf concentration of rutin in green leaf lettuce increased by 20-fold under supplemental blue radiation. Similarly, supplemental red radiation increased the concentration of many of these phenolic compounds in red leaf lettuce. However, supplemental far-red radiation had an inhibitory effect on the accumulation of chlorogenic acid, chicoric acid, rutin and kaempferol in red leaf lettuce. While supplemental radiation did not affect the accumulation of most of the micronutrients, it had a negative impact on the accumulation of some micronutrients, the response being variety dependent. The results show that supplementing white light with specific spectral quality has a major impact on the biomass accumulation, morphology and on the accumulation of many health-promoting phytochemicals and micronutrients in lettuce. While it had a large positive effect in enhancing the accumulation of several phytochemicals, it also suppressed the accumulation of some micronutrients.展开更多
Pot experiments were conducted in a glasshouse to determine the growth pattern of lettuce, true potato seedlings （TPS） and single node cuttings of TPS in response to biochar. The treatments were arranged in a random...Pot experiments were conducted in a glasshouse to determine the growth pattern of lettuce, true potato seedlings （TPS） and single node cuttings of TPS in response to biochar. The treatments were arranged in a randomized complete block design with 5 treatments （0, 10, 30, 50 and 100 t ha^-1） ofbiochar from greenwaste with 5 replications in lettuce, 10 in TPS and 5 in single node cuttings of TPS. The observations recorded on growth parameters showed that biochar had significant effect on growth of lettuce but no consistent effect on growth of TPS and single node cuttings. Among the biochar rates, 30 t ha^-1 had the greatest influence on overall growth of lettuce. The pH and electrical conductivity increased as the biochar rates increased in all experiments. These results provide an avenue for soil management system by using biochar as an amendment in horticultural crops. However, their verification in the field is important for specific recommendations.展开更多
Rare earth elements(REEs)as nonessential trace elements are enriched in living organisms and threaten their health.To early detect and reduce REE enrichment in living organisms,scientists are focused on clarifying the...Rare earth elements(REEs)as nonessential trace elements are enriched in living organisms and threaten their health.To early detect and reduce REE enrichment in living organisms,scientists are focused on clarifying the enrichment process of REEs in living organisms and its risks.However,the enrichment process of REEs in edible plant cells has remained unclear.Herein,by using interdisciplinary methods and techniques,the enrichment process of lanthanum(La(Ⅲ))in the leaf cells of lettuce(Lactuca sativa L.)was investigated.(1)When La(Ⅲ)exposure dose is 0.5-5μmol/L,La(Ⅲ)is enriched outside the plasma membrane(PM).In this zone,La(Ⅲ)is bound to vitronectin-like protein(VN)to form La-VN complexes;(2)When La(Ⅲ)exposure dose is 5-20μmol/L,besides the zone outside the PM,La(Ⅲ)is also enriched on the PM and bound to arabinogalactan proteins(AGPs)to form La-AGPs complexes;(3)When La(Ⅲ)exposure dose is 20-140μmol/L,besides the zone outside and on the PM,La(Ⅲ)is enriched inside the PM;(4)When La(Ⅲ)exposure dose is 60-140μmol/L,malondialdehyde content(an important indicator of invisible damage)significantly increases.Thus,as La(Ⅲ)exposure dose increases,La(Ⅲ)gradually migrates from outside the PM to the PM and inside the PM,enriching in these zones in turn.The enriched La(Ⅲ)will cause invisible damage to lettuce leaf cells and even enter human bodies along food chains.These results provide references for investigating the enrichment process of REEs in plants and its environmental risks,and finding strategies to early detect and reduce REE enrichment in plants.展开更多
We investigated the possibility of producing chicken alpha interferon （ChlFN-α） in transgenic plants. The cDNA encoding ChlFN-α was introduced into lettuce （Lactuca sativa L.） plants by using an agro-infiltratio...We investigated the possibility of producing chicken alpha interferon （ChlFN-α） in transgenic plants. The cDNA encoding ChlFN-α was introduced into lettuce （Lactuca sativa L.） plants by using an agro-infiltration transient expression system. The ChlFN-a gene was correctly transcribed and translated in the lettuce plants according to RT-PCR and ELISA assays. Recombinant protein exhibited antiviral activity in vitro by inhibition of vesicular stomatitis virus （VSV） replication on chicken embryonic fibroblast （CEF）. The results demonstrate that biologically active avian cytokine with potential pharmaceutical applications could be expressed in transgenic lettuce plants and that it is possible to generate interferon protein in forage plants for preventing infectious diseases of poultry.展开更多
Rising global CO<sub>2</sub> levels are a major factor that impacts not only the environment but also many plant functions including growth, productivity and nutritional quality. The study examined the imp...Rising global CO<sub>2</sub> levels are a major factor that impacts not only the environment but also many plant functions including growth, productivity and nutritional quality. The study examined the impact of elevated [CO<sub>2</sub>] on nutritional quality and growth characteristics of lettuce (Lactuca sativa) and spinach (Spinacia oleracea). Elevated [CO<sub>2</sub>] decreased the concentration of many important nutrients including nitrogen (protein), potassium and phosphorus in the edible parts of both lettuce and spinach. The nitrogen concentration in lettuce shoots was reduced by more than 30% at elevated [CO<sub>2</sub>] compared to the plants grown at ambient level of CO<sub>2</sub>. Similarly the concentration of a number of micronutrients including sulfur, zinc, copper and magnesium, was depressed in lettuce shoots. Although the total phenolic content and antioxidant capacity were higher in lettuce at elevated CO<sub>2</sub>, they were not affected in spinach. The photosynthetic activity was variable among the plant species while there was no increase in the carbon accumulation in these plants at elevated [CO<sub>2</sub>]. However, there was significant reduction in the leaf stomatal conductance in both lettuce and spinach in response to higher [CO<sub>2</sub>], which is likely affect both water loss from the leaves and their photosynthetic activity. The results indicate a broad adverse impact of rising [CO<sub>2</sub>] on the nutritional quality of commonly consumed leafy vegetables namely, lettuce and spinach.展开更多
This paper investigated the effects of root-zone (RZ) CO<sub>2</sub> concentration ([CO<sub>2</sub>]) on root morphology and growth, nitrate (NO<sub>3</sub>-</sup>) uptake and...This paper investigated the effects of root-zone (RZ) CO<sub>2</sub> concentration ([CO<sub>2</sub>]) on root morphology and growth, nitrate (NO<sub>3</sub>-</sup>) uptake and assimilation of lettuce plants at different root-zone temperatures (RZT). Elevated RZ [CO<sub>2</sub>] stimulated root development, root and shoot growth compared to ambient RZ [CO<sub>2</sub>]. The greatest increase in root growth was observed in plants grown under elevated RZ [CO<sub>2</sub>] of 50,000 ppm. However, RZ [CO<sub>2</sub>] of 10,000 ppm was sufficient to achieve the maximal leaf area and shoot productivity. Lettuce plants exhibited faster shoot and root growth at 20°C-RZT than at ambient (A)-RZT. However, under elevated RZ [CO<sub>2</sub>], the magnitude of increased growth was greater at A-RZT than at 20°C-RZT. Compared to RZ [CO<sub>2</sub>] of 360 ppm, elevated RZ [CO<sub>2</sub>] of 10,000 ppm increased NO<sub>3</sub>-</sup> accumulation and nitrate reductase activity (NRA) in both leaves and roots. NO<sub>3</sub>-</sup> concentrations of leaf and root were higher at 20°C-RZT than at A-RZT in all plants. NRA was higher in root than in leaf especially under A-RZT. The total reduced nitrogen (TRN) concentration was significantly higher in plants grown under elevated RZ [CO<sub>2</sub>] of 10,000 ppm than under ambient RZ [CO<sub>2</sub>] of 360 ppm with greater concentration in 20°C-RZT plants than in A-RZT plants. These results imply that elevated RZ [CO<sub>2</sub>] significantly affected root morphology, root and shoot growth and N metabolism of temperate lettuce with greater impacts at A-RZT than at 20°C-RZT. These findings have practical significance to vegetable production by growing the vegetable crops at cool-RZT with elevated RZ [CO<sub>2</sub>] to enhance its productivity.展开更多
Lettuce(Lactuca sativa L.),which belongs to the large Asteraceae(Compositae)family,breeds by sexual reproduction and produces seeds.Actually,lettuce seeds are achenes,which are defined as fruits.However,few studies ha...Lettuce(Lactuca sativa L.),which belongs to the large Asteraceae(Compositae)family,breeds by sexual reproduction and produces seeds.Actually,lettuce seeds are achenes,which are defined as fruits.However,few studies have described the morphological characteristics of the lettuce achenes,and genes essential for achene development are largely unknown in lettuce.To investigate the gene activity during achene development and determine the possible mechanisms that influence achene development in lettuce,we performed a time-course transcriptome analysis of lettuce achenes.A total of 27,390 expressed genes were detected at the five achene development stages.We investigated the gene expression patterns during achene development and identified the enriched biological processes at the corresponding stages.Kyoto Encyclopedia of Genes and Genomes and Gene Ontology analyses revealed a variety of transcriptomic similarities and differences at different achene development stages.Further,transcription factors and phytohormones were found to play important roles during achene development.Finally,we proposed a working model to illustrate the gene expression modules and possible molecular mechanisms underlying achene development.Our time-course transcriptome data also provide a foundation for future functional studies to reveal the genetic control of achene development in lettuce.展开更多
Light-emitting diodes(LEDs)have been widely applied in the controlled environment agriculture,which are characterized by relatively narrow-band spectra and energetical efficiency.Most recently,the spectrum of Sunlike ...Light-emitting diodes(LEDs)have been widely applied in the controlled environment agriculture,which are characterized by relatively narrow-band spectra and energetical efficiency.Most recently,the spectrum of Sunlike LEDs has been engineered and it closely resembles solar spectrum in the range of photosynthetic active radiation(PAR,400–700 nm).To investigate how plant growth responses to the spectrum of Sunlike LEDs,cucumber and lettuce plants were cultivated and their responses were compared with the conventional white LEDs as well as composite of red and blue LEDs(RB,R/B ratio was 9:1).We observed that although Sunlike LEDs resulted in a longer stem in cucumber,dry weight and leaf area were similar as those under RB LEDs,and significantly higher than those under white LEDs.Moreover,cucumber leaves grown under Sunlike and white LEDs showed higher photosynthetic capacity than those grown under RB LEDs.For lettuce,plants grown under Sunlike LEDs showed larger leaf area and higher dry weight than the other two treatments.However,the leaf photosynthetic capacity of lettuce grown under Sunlike LEDs was the lowest.In this context,the spectrum induced plant functions are species-dependent.Furthermore,the three types of LEDs show distinct light spectra and they are different in many aspects.Therefore,it is difficult to attribute the different plant responses to certain specific light spectra.We conclude that plants grown under Sunlike LEDs exhibit larger leaf area,which may be due to some specific spectrum distributions(such as more far-red radiation),and consequently are favorable for light interception and therefore result in greater production.展开更多
Plasma nitrogen fixation(PNF)has been emerging as a promising technology for greenhouse gasfree and renewable energy-based agriculture.Yet,most PNF studies seldom address practical application-specific issues.In this ...Plasma nitrogen fixation(PNF)has been emerging as a promising technology for greenhouse gasfree and renewable energy-based agriculture.Yet,most PNF studies seldom address practical application-specific issues.In this work,we present the development of a compact and automatic PNF system for on-site agricultural applications.The system utilized a gliding-arc discharge as the plasma source and employed a dual-loop design to generate NO_(x)from air and water under atmospheric conditions.Experimental results showed that the system with a dualloop design performs well in terms of energy costs and production rates.Optimal operational parameters for the system were determined through experimentation,resulting in an energy cost of 13.9 MJ mol^(-1)and an energy efficiency of 16 g kWh^(-1)for NO_(3)^(-)production,respectively.Moreover,the concentration of exhausted NO_(x)was below the emission standards.Soilless lettuce cultivation experiments demonstrated that NO_(x)^(-)produced by the PNF system could serve as liquid nitrate nitrogen fertilizer.Overall,our work demonstrates the potential of the developed PNF system for on-site application in the production of green-leaf vegetables.展开更多
基金supported by the Specialty Crop Block Grant Program of the U.S. Department of Agriculture's (USDA), Agricultural Marketing Service (AMS) through the California Department of Food and Agriculture (SCB15015)partly also by funding from the California Leafy Greens Research Board and by Oak Ridge Institute for Science and Education (ORISE) Research Participation Program。
文摘Fresh-cut lettuce is widely used in ready-to-eat salads sold in modified atmosphere packages (MAP).Even in MAP,fresh-cut lettuce has short shelf life that results in loss of nutrients.Lettuce cultivars exhibit genetic variation for shelf life in MAP,but their variation for nutrient retention is not known.Fifty accessions were evaluated for initial content of ascorbic acid (AsA),carotenoids,and sugars and their retention in storage.Accessions with high content and/or good retention of one or more nutrients were identified.The romaine accession ‘Floricos’ had high levels of all the three nutrients.Accessions with relatively high retention of all the three nutrients were ‘Salinas 88’,‘Siskiyou’,‘Solar’,SM09A,‘Romance’,and ‘Green Towers’.Romaine cultivars,‘Balady Barrage’,‘Green Towers’,and ‘Darkland’ had relatively high initial levels of all tested nutrients and good rate of their retention.There was no clear correlation between initial AsA/carotene concentrations and their retention rates,suggesting that besides content,retention of nutrients should also be a breeding target in a lettuce nutritional improvement program.Statistical analyses with the Pearson's correlation coefficient determined a negative relationship between tissue deterioration(AUDePS) and retention of all tested nutrients[r of-0.52 (P<0.0001) for AsA,-0.27 (P<0.01) for total carotene,and-0.59 (P<0.0001) for total sugars],suggesting that an increase in tissue deterioration intensifies nutrient decay.Broad-sense heritability (H^(2)) across the experiments was0.15 for AsA,0.23 for total carotene,and 0.50 for total sugars.Identification of germplasm with high nutrient content,extended shelf life and good nutrient retention provides valuable information for the lettuce industry and associated breeding programs.
基金Supported by Shanghai Science and Technology Innovation Action Plan,China(22N51900900).
文摘[Objectives]This study was conducted to investigate the effects of lignin-based fully biodegradable plastic film on the growth and quality of lettuce under open-field cultivation conditions.[Methods]In this experiment,compared with bare soil,a polyethylene plastic film(PE)treatment and two lignin-based fully biodegradable plastic film treatments(LBF-0.01 and LBF-0.008)with different thicknesses were set to study the effects on the growth and quality of lettuce.[Results]During autumn cultivation in Shanghai,the thermal insulation performance and yield-increasing effect of the two degradable plastic films were consistent with those of PE film,and effectively met lettuce growth requirements,but treatment LBF-0.01was better than treatment LBF-0.008.Moreover,lignin-based fully biodegradable plastic film could significantly increase the contents of Vc,soluble sugar and carotenoids in lettuce,and treatment LBF-0.008 showed the best effect.It could be seen that under the experimental conditions,the two kinds of lignin-based biodegradable plastic films with different thicknesses could be applied to the cultivation of lettuce in the open field in Shanghai in autumn,and LBF-0.01 had the best effect of increasing temperature and increasing yield,while LBF-0.008 had the best effect of improving quality.[Conclusions]This study provides theoretical basis and technical support for the further application of lignin-based fully biodegradable plastic film.
基金supported by the Fundamental Research Funds for Central Non-profit Scientific Institution(No.1610132022015)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB0750200)the National Natural Science Foundation of China(No.22176198).
文摘Reclaimed water for irrigation or hydroponic cultivation provides exposure pathways for per-and polyfluoroalkyl substances(PFAS)to enter the human food chain.This study employed hydroponic methods to investigate the behavior of legacy PFAS and emerging chlorinated polyfluoroalkyl ether sulfonic acids(Cl-PFESAs)in lettuce grown under environment-related exposure levels and assessed the human exposure risks from consuming contaminated lettuce.Overall,PFAS in lettuce were concentration-dependent,with long-chain PFAS tending to accumulate in roots and short-chain PFAS accumulating more in shoots.The enrichment of PFAS in lettuce was jointly influenced by their chain length and polar functional groups.Specifically,the root concentration factors(RCFs)of PFAS generally increased with increasing chain length,and RCF values of most perfluoroalkanesulfonic acids(PFSAs)were significantly higher than those of perfluoroalkyl carboxylic acids(PFCAs)with the same chain length(p<0.01),while the translocation factors(TFs)exhibited opposite trends.RCF values of perfluorooctane sulfonate(PFOS)and its alternatives,Cl-PFESAs,were ranked as follows:8:2 Cl-PFESA(mean:139)>6:2 Cl-PFESA(28.6)>PFOS(25.7),which was attributed to the increased molecular size and hydrophobicity resulting from the insertion of ether bonds and additional CF2 in 8:2 Cl-PFESA.Notably,TF value of 8:2 Cl-PFESA(mean:0.007)was the smallest among all PFAS,indicating 8:2 Cl-PFESA was difficult to transfer to nutritional compartments.Adults and children would exceed the most conservative health-based reference dose(RfD)by consuming approximately 15.9–148 g and 7.92–74.0 g of contaminated lettuce per day,implying high health risks.
基金Supported by Doctorate Fund of Suzhou University (13120740)~~
文摘[Objective]The aim of this study was to understand the role of polyamine oxidative degradation in the process of lettuce seed germination. [Method]After lettuce seed soaking treatments with aminoguanidine （AG,a specific inhibitor of polyamine oxidases）,seed germination rate,activities of polyamine oxidase （PAO） and diamine oxidase （DAO）,change of endogenous polyamine and H2O2 content were determined. [Result]Compared with the control,AG treatment strongly inhibited the seed germination,which also had an extremely significant difference in seed germination rate after incubation for 12 h. During the seed germination,activities of PAO and DAO significantly changed,while their activities firstly increased and then decreased,then DAO and PAO reached peaks at 24 h and 48 h respectively. AG treatment was strongly inhibitory for activities of DAO and PAO,whose activities even disappeared after incubation with AG for 24 h and 36 h. During the seed germination,endogenous Put reduced sharply in the first 24 h,then reduced slowly in 24-60 h,while Spd decreased slowly in the early stage of germination,and then sharply declined after 48 h. However,Spm content was low but slightly increased,and the total polyamine gradually decreased. AG treatment could significantly increase endogenous polyamines,especially Put and Spd contents. During the seed germination,H2O2 content gradually increased,and had a peak from 36 to 48 h,then kept a high level at last. AG treatment could significantly reduce H2O2 content. [Conclusion]During the seed germination,the changes of endogenous polyamine and H2O2 content correspond with the changes of PAO and DAO activities,which indicate that there is an active polyamine metabolism of oxidative degradation during the lettuce seed germination.
基金Supported by Science and Technology Innovative Leading Fund of Ningxia Academy of Agriculture and Forestry Sciences(NKYZ-16-1101)~~
文摘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.
基金supported by the National High-Tech R&D Program of China(863 Program,2013AA103004)the International S&T Cooperation Program of China(2014DFG32110)the National Key Research and Development Program of China(2014BAD08B020106)
文摘High nitrate(NO3-) in vegetables, especially in leaf vegetables poses threaten to human health. Selenium(Se) is an important element for maintaining human health, and exogenous Se application during vegetable and crop production is an effective way to prevent Se deficiency in human bodies. Exogenous Se shows positive function on plant growth and nutrition uptake under abiotic and/or biotic stresses. However, the influence of exogenous Se on NO3-accumulation in hydroponic vegetables is still not clear. In the present study, hydroponic lettuce plants were subjected to six different concentrations(0, 0.1, 0.5, 5, 10 and 50 μmol L–1) of Se as Na2 Se O3. The effects of Se on NO3-content, plant growth, and photosynthetic capacity of lettuce(Lactuca sativa L.) were investigated. The results showed that exogenous Se positively decreased NO3-content and this effect was concentration-dependent. The lowest NO3-content was obtained under 0.5 μmol L–1 Se treatment. The application of Se enhanced photosynthetic capacity by increasing the photosynthesis rate(Pn), stomatal conductance(Cs) and the transpiration efficiency(Tr) of lettuce. The transportation and assimilation of NO3-and activities of nitrogen metabolism enzymes in lettuce were also analysed. The NO3-efflux in the lettuce roots was markedly increased, but the efflux of NO3-from the root to the shoot was decreased after treated with exogenous Se. Moreover, Se application stimulated NO3-assimilation by enhancing nitrate reductase(NR), nitrite reductase(Ni R), glutamine synthetase(GS) and glutamate synthase enzyme(GOGAT) activities. These results provide direct evidence that exogenous Se shows positive function on decreasing NO3-accumulation via regulating the transport and enhancing activities of nitrogen metabolism enzyme in lettuce. We suggested that 0.5 μmol L–1 Se can be used to reduce NO3-content and increase hydroponic lettuce yield.
文摘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.
文摘High temperature stress on different varieties of lettuce seedlings in MDA, proline and soluble sugar content were studied. The results were as follows : With the stress temperature, varieties of leaf lettuce seedlings in the MDA, proline and soluble sugar content gradually increased;Different varieties had the most significant difference in 38/33℃(d/n). The increase of heat-resistant varieties on proline and soluble sugar content was quick and high, while its increase in MDA content was slow and small.
文摘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°C. 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.
基金supported by the Special Fund for Agro-scientific Research in the Public Interest, China (20130310104)the Key Technology R&D Program of Tianjin, China (12ZCZDNC09600)
文摘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.
文摘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.
文摘Spectral quality of radiation has a major impact on the growth, development and nutritional quality of crops. The effect of supplemental radiation (blue, red and far-red) on the growth and nutritional quality with regard to health-promoting phytochemical and micronutrient composition of two lettuce (Lactuca sativa) varieties (red leaf “New Red Fire” and green leaf “Two Star”) was studied. Supplemental radiation was provided by blue (450 nm), red (660 nm) or far-red (730 nm) LEDs against a background of white light (fluorescent lighting, PAR;270 μmol/m2/s) in a growth chamber study. All the supplemental radiation treatments increased dry shoot biomass in both varieties. However, supplemental far-red radiation increased both fresh and dry shoot biomass in both varieties. In addition, supplemental far-red radiation produced distinct morphological characteristics in lettuce plants. It produced the largest shoot biomass, bigger and taller plants, fewer leaves but with larger leaf area compared to the control, similar to the shade avoidance response. With regard to the accumulation of phytochemicals, supplemental blue radiation enhanced the total phenolic compound concentration in both varieties. In addition, supplemental blue radiation sharply increased the accumulation of several phenolic compounds in green leaf lettuce including chlorogenic acid, chicoric acid, rutin, kaempferol, luteolin and apigenin. For example, the leaf concentration of rutin in green leaf lettuce increased by 20-fold under supplemental blue radiation. Similarly, supplemental red radiation increased the concentration of many of these phenolic compounds in red leaf lettuce. However, supplemental far-red radiation had an inhibitory effect on the accumulation of chlorogenic acid, chicoric acid, rutin and kaempferol in red leaf lettuce. While supplemental radiation did not affect the accumulation of most of the micronutrients, it had a negative impact on the accumulation of some micronutrients, the response being variety dependent. The results show that supplementing white light with specific spectral quality has a major impact on the biomass accumulation, morphology and on the accumulation of many health-promoting phytochemicals and micronutrients in lettuce. While it had a large positive effect in enhancing the accumulation of several phytochemicals, it also suppressed the accumulation of some micronutrients.
基金financially supported by Horticulture Australia Ltd.,using voluntary contributions from Brisbane City Council and matched funds from the Australian Government (code HG10025)
文摘Pot experiments were conducted in a glasshouse to determine the growth pattern of lettuce, true potato seedlings （TPS） and single node cuttings of TPS in response to biochar. The treatments were arranged in a randomized complete block design with 5 treatments （0, 10, 30, 50 and 100 t ha^-1） ofbiochar from greenwaste with 5 replications in lettuce, 10 in TPS and 5 in single node cuttings of TPS. The observations recorded on growth parameters showed that biochar had significant effect on growth of lettuce but no consistent effect on growth of TPS and single node cuttings. Among the biochar rates, 30 t ha^-1 had the greatest influence on overall growth of lettuce. The pH and electrical conductivity increased as the biochar rates increased in all experiments. These results provide an avenue for soil management system by using biochar as an amendment in horticultural crops. However, their verification in the field is important for specific recommendations.
基金Project supported by the National Natural Science Foundation of China(21977051,21501068,31170477)the Priority Academic Program Development of Jiangsu Higher Education Institutions。
文摘Rare earth elements(REEs)as nonessential trace elements are enriched in living organisms and threaten their health.To early detect and reduce REE enrichment in living organisms,scientists are focused on clarifying the enrichment process of REEs in living organisms and its risks.However,the enrichment process of REEs in edible plant cells has remained unclear.Herein,by using interdisciplinary methods and techniques,the enrichment process of lanthanum(La(Ⅲ))in the leaf cells of lettuce(Lactuca sativa L.)was investigated.(1)When La(Ⅲ)exposure dose is 0.5-5μmol/L,La(Ⅲ)is enriched outside the plasma membrane(PM).In this zone,La(Ⅲ)is bound to vitronectin-like protein(VN)to form La-VN complexes;(2)When La(Ⅲ)exposure dose is 5-20μmol/L,besides the zone outside the PM,La(Ⅲ)is also enriched on the PM and bound to arabinogalactan proteins(AGPs)to form La-AGPs complexes;(3)When La(Ⅲ)exposure dose is 20-140μmol/L,besides the zone outside and on the PM,La(Ⅲ)is enriched inside the PM;(4)When La(Ⅲ)exposure dose is 60-140μmol/L,malondialdehyde content(an important indicator of invisible damage)significantly increases.Thus,as La(Ⅲ)exposure dose increases,La(Ⅲ)gradually migrates from outside the PM to the PM and inside the PM,enriching in these zones in turn.The enriched La(Ⅲ)will cause invisible damage to lettuce leaf cells and even enter human bodies along food chains.These results provide references for investigating the enrichment process of REEs in plants and its environmental risks,and finding strategies to early detect and reduce REE enrichment in plants.
基金Project supported by the National Key Technology Research and Development Program of China (No. 2007BAD59B06)the Interna-tional Science and Technology Cooperation Program of China (No. 2007DFA31260)the Science Foundation for the Excellent Youth Scholars of Guizhou Province, China (No. 20030312)
文摘We investigated the possibility of producing chicken alpha interferon （ChlFN-α） in transgenic plants. The cDNA encoding ChlFN-α was introduced into lettuce （Lactuca sativa L.） plants by using an agro-infiltration transient expression system. The ChlFN-a gene was correctly transcribed and translated in the lettuce plants according to RT-PCR and ELISA assays. Recombinant protein exhibited antiviral activity in vitro by inhibition of vesicular stomatitis virus （VSV） replication on chicken embryonic fibroblast （CEF）. The results demonstrate that biologically active avian cytokine with potential pharmaceutical applications could be expressed in transgenic lettuce plants and that it is possible to generate interferon protein in forage plants for preventing infectious diseases of poultry.
文摘Rising global CO<sub>2</sub> levels are a major factor that impacts not only the environment but also many plant functions including growth, productivity and nutritional quality. The study examined the impact of elevated [CO<sub>2</sub>] on nutritional quality and growth characteristics of lettuce (Lactuca sativa) and spinach (Spinacia oleracea). Elevated [CO<sub>2</sub>] decreased the concentration of many important nutrients including nitrogen (protein), potassium and phosphorus in the edible parts of both lettuce and spinach. The nitrogen concentration in lettuce shoots was reduced by more than 30% at elevated [CO<sub>2</sub>] compared to the plants grown at ambient level of CO<sub>2</sub>. Similarly the concentration of a number of micronutrients including sulfur, zinc, copper and magnesium, was depressed in lettuce shoots. Although the total phenolic content and antioxidant capacity were higher in lettuce at elevated CO<sub>2</sub>, they were not affected in spinach. The photosynthetic activity was variable among the plant species while there was no increase in the carbon accumulation in these plants at elevated [CO<sub>2</sub>]. However, there was significant reduction in the leaf stomatal conductance in both lettuce and spinach in response to higher [CO<sub>2</sub>], which is likely affect both water loss from the leaves and their photosynthetic activity. The results indicate a broad adverse impact of rising [CO<sub>2</sub>] on the nutritional quality of commonly consumed leafy vegetables namely, lettuce and spinach.
文摘This paper investigated the effects of root-zone (RZ) CO<sub>2</sub> concentration ([CO<sub>2</sub>]) on root morphology and growth, nitrate (NO<sub>3</sub>-</sup>) uptake and assimilation of lettuce plants at different root-zone temperatures (RZT). Elevated RZ [CO<sub>2</sub>] stimulated root development, root and shoot growth compared to ambient RZ [CO<sub>2</sub>]. The greatest increase in root growth was observed in plants grown under elevated RZ [CO<sub>2</sub>] of 50,000 ppm. However, RZ [CO<sub>2</sub>] of 10,000 ppm was sufficient to achieve the maximal leaf area and shoot productivity. Lettuce plants exhibited faster shoot and root growth at 20°C-RZT than at ambient (A)-RZT. However, under elevated RZ [CO<sub>2</sub>], the magnitude of increased growth was greater at A-RZT than at 20°C-RZT. Compared to RZ [CO<sub>2</sub>] of 360 ppm, elevated RZ [CO<sub>2</sub>] of 10,000 ppm increased NO<sub>3</sub>-</sup> accumulation and nitrate reductase activity (NRA) in both leaves and roots. NO<sub>3</sub>-</sup> concentrations of leaf and root were higher at 20°C-RZT than at A-RZT in all plants. NRA was higher in root than in leaf especially under A-RZT. The total reduced nitrogen (TRN) concentration was significantly higher in plants grown under elevated RZ [CO<sub>2</sub>] of 10,000 ppm than under ambient RZ [CO<sub>2</sub>] of 360 ppm with greater concentration in 20°C-RZT plants than in A-RZT plants. These results imply that elevated RZ [CO<sub>2</sub>] significantly affected root morphology, root and shoot growth and N metabolism of temperate lettuce with greater impacts at A-RZT than at 20°C-RZT. These findings have practical significance to vegetable production by growing the vegetable crops at cool-RZT with elevated RZ [CO<sub>2</sub>] to enhance its productivity.
基金supported by grants from the Beijing Leafy Vegetables Innovation Team of Modern Agro-industry Technology Research System(Grant no.BAIC07-2020)the Construction of Beijing Science and Technology Innovation and Service Capacity in Top Subjects(Grant no.CEFF-PXM2019_014207_000032)。
文摘Lettuce(Lactuca sativa L.),which belongs to the large Asteraceae(Compositae)family,breeds by sexual reproduction and produces seeds.Actually,lettuce seeds are achenes,which are defined as fruits.However,few studies have described the morphological characteristics of the lettuce achenes,and genes essential for achene development are largely unknown in lettuce.To investigate the gene activity during achene development and determine the possible mechanisms that influence achene development in lettuce,we performed a time-course transcriptome analysis of lettuce achenes.A total of 27,390 expressed genes were detected at the five achene development stages.We investigated the gene expression patterns during achene development and identified the enriched biological processes at the corresponding stages.Kyoto Encyclopedia of Genes and Genomes and Gene Ontology analyses revealed a variety of transcriptomic similarities and differences at different achene development stages.Further,transcription factors and phytohormones were found to play important roles during achene development.Finally,we proposed a working model to illustrate the gene expression modules and possible molecular mechanisms underlying achene development.Our time-course transcriptome data also provide a foundation for future functional studies to reveal the genetic control of achene development in lettuce.
基金financially supported by the National Key Research and Development Program of China(2017YFB0403902)the National Natural Science Foundation of China(31872955)the Central Publicinterest Scientific Institution Basal Research Fund,China(BSRF201911)。
文摘Light-emitting diodes(LEDs)have been widely applied in the controlled environment agriculture,which are characterized by relatively narrow-band spectra and energetical efficiency.Most recently,the spectrum of Sunlike LEDs has been engineered and it closely resembles solar spectrum in the range of photosynthetic active radiation(PAR,400–700 nm).To investigate how plant growth responses to the spectrum of Sunlike LEDs,cucumber and lettuce plants were cultivated and their responses were compared with the conventional white LEDs as well as composite of red and blue LEDs(RB,R/B ratio was 9:1).We observed that although Sunlike LEDs resulted in a longer stem in cucumber,dry weight and leaf area were similar as those under RB LEDs,and significantly higher than those under white LEDs.Moreover,cucumber leaves grown under Sunlike and white LEDs showed higher photosynthetic capacity than those grown under RB LEDs.For lettuce,plants grown under Sunlike LEDs showed larger leaf area and higher dry weight than the other two treatments.However,the leaf photosynthetic capacity of lettuce grown under Sunlike LEDs was the lowest.In this context,the spectrum induced plant functions are species-dependent.Furthermore,the three types of LEDs show distinct light spectra and they are different in many aspects.Therefore,it is difficult to attribute the different plant responses to certain specific light spectra.We conclude that plants grown under Sunlike LEDs exhibit larger leaf area,which may be due to some specific spectrum distributions(such as more far-red radiation),and consequently are favorable for light interception and therefore result in greater production.
基金supported by the Science and Technology Project of State Grid Corporation of China(No.5400202133157A-0-0-00)partially supported by the State Grid Gansu Electric Power Company,China。
文摘Plasma nitrogen fixation(PNF)has been emerging as a promising technology for greenhouse gasfree and renewable energy-based agriculture.Yet,most PNF studies seldom address practical application-specific issues.In this work,we present the development of a compact and automatic PNF system for on-site agricultural applications.The system utilized a gliding-arc discharge as the plasma source and employed a dual-loop design to generate NO_(x)from air and water under atmospheric conditions.Experimental results showed that the system with a dualloop design performs well in terms of energy costs and production rates.Optimal operational parameters for the system were determined through experimentation,resulting in an energy cost of 13.9 MJ mol^(-1)and an energy efficiency of 16 g kWh^(-1)for NO_(3)^(-)production,respectively.Moreover,the concentration of exhausted NO_(x)was below the emission standards.Soilless lettuce cultivation experiments demonstrated that NO_(x)^(-)produced by the PNF system could serve as liquid nitrate nitrogen fertilizer.Overall,our work demonstrates the potential of the developed PNF system for on-site application in the production of green-leaf vegetables.
