Weight Of Lettuce Research Articles

CO2 Utilization Strategy for Sustainable Cultivation of Mushrooms and Lettuces

Mushroom cultivation generates a large amount of CO2 that can be used sustainably. The objective of this study was to use actual cultivation and simulation to find a sustainable cultivation method that uses the CO2 generated by king oyster mushrooms for the production of romaine lettuces. A closed cultivation system consisting of one mushroom chamber, three lettuce chambers, and one gas-mixing chamber was used. Two cultivation conditions, non-continuous and continuous, were analyzed. The non-continuous system cultivated 15 lettuces and 12 mushroom bottles at a time every 25 and 16 days, respectively. The continuous system cultivated three lettuces and mushroom bottles every five and four days, respectively, so that each chamber contained mushrooms or lettuces at each growth stage. The CO2 concentrations in the lettuce and mushroom chambers were stably maintained above 1000 μmol∙mol−1 and below 2000 μmol∙mol−1 in the continuous system. Mathematical models were developed to analyze the CO2 concentration in each chamber. The shoot dry weight of lettuces grown in the mixed cultivation were 48.0%, 21.9%, 19.7%, and 18.1% at 10, 15, 20, and 25 days after transplanting, respectively, higher than those in the lettuce-only cultivation. Compared to mushroom-only cultivation, mixed cultivation reduced the accumulated CO2 emissions into the air by 80.6%. Thus, using CO2 from mushrooms to cultivate lettuce in a continuous cultivation system could reduce CO2 emissions into the air and enable mixed cultivation of mushrooms and lettuces, achieving sustainable agriculture.

Red and blue wavelengths affect the morphology, energy use efficiency and nutritional content of lettuce (Lactuca sativa L.)

Since red (R) and blue (B) LED light has different quantum efficiency and photoelectric conversion efficiency, mixed RB with different proportions of R and B results in varied energy consumption. In order to improve the energy use efficiency of the closed-type plant production systems, the effects of R and B proportions on the electric use efficiency (EUE), light use efficiency (LUE) as well as the quality of butter leaf lettuce were evaluated in this study. Lettuce seedlings were cultivated in a plant factory with artificial lighting (PFAL) and subjected to eleven combinations of R and B (100%R, 90%R, 80%R, 70%R, 60%R, 50%R, 40%R, 30%R, 20%R, 10%R, 0%R; the rest of the photons in each treatment were B) with the same total photosynthetic photon flux density (PPFD) and photoperiod (200 ± 3 μmol·m−2·s−1, 16 h) for 35 days. The results showed that palpable petiole distortion appeared when R proportion was more than 70% and the distortion was aggravated with the increase of R proportion. The highest EUE and LUE were both detected in lettuce under 90%R treatment, which were respectively 3.64% and 1.20%. The least number of photons and the least electricity amount required to produce 1 g dry weight of lettuce was respectively 2.92 mol and 1.67 MJ, which were both detected in lettuce treated with 90%R. The sucrose content in lettuce treated with more than 50%R was significantly higher than those treated with less than 50%R (50%R included). Lettuce treated with 80%R possessed the highest soluble sugar content as well as the lowest crude fiber and nitrate content (not significantly different with the minimum values). R proportion exceeding 50% in mixed RB light was beneficial to the accumulation of hexose and sucrose, as well as the decomposition of nitrate in lettuce. The vitamin C content in lettuce treated with 100%R was significantly higher than that in lettuce under other treatments in the study. On the whole, the study indicated that the proportions of R and B affected the energy use efficiency and quality of lettuce in closed plant factory, however the responses of plants to the proportions of R and B varied according to different indexes. Thus, some indexes of top priority should be determined before choosing the optimal proportions of R and B.

PENGARUH VARIASI DOSIS PUPUK ORGANIK LIMBAH CAIR NANAS (LCN) TERHADAP PERTUMBUHAN DAN PRODUKSI TANAMAN SELADA

Abstract: This research is an experimental research, which aims to determine the effect of variation dosage in of organic pineapple liquid waste fertilizer, on the growth and productivity of red lettuce (Lactuca Sativa L) and its potential as learning resources of biology learning. This research uses a Completely Randomized Design with 1 control and 3 treatment combinations and 5 repetitions. This research was conducted for 30 days. The parameters which is used in this research include plant height and wet weight of lettuce (Lactuca sativa L), with supporting data in the form of number of leaves and stem diameter. The main data is tabulated and analysed using the SPSS 25.0 application which includes Multivariate Analysis of Variance. The results of this research can be concluded that the application of organic fertillizer from pineaplle liquid waste has a significant influence on the growth and product of lettuce (Lactuca sativa L). The results of the research be used as a practical guide on plant growth and development materials.

Dynamic Responses of Ascorbate Pool and Metabolism in Lettuce to Light Intensity at Night Time under Continuous Light Provided by Red and Blue LEDs.

To understand the dynamic changes of hydroponic lettuce growth, ascorbate (AsA) pool and metabolism under two different dark period light intensities (LL, 20 μmol·m−2·s−1; CL, 200 μmol·m−2·s−1) of continuous light and normal light (NL, 0 μmol·m−2·s−1) provided by red (R) and blue (B) LEDs, the chlorophyll fluorescence parameters, ascorbate pool size, AsA metabolism-related enzyme activities, and H2O2 contents of lettuce were measured at 0, 8, 16, 24, 32, 40, 48, 56, 64, and 72 h after light treatment and the lettuce growth parameters were measured on the 9th day after light treatment. The results showed that compared with the NL, CL treatment for 9 days significantly increased the biomass, dry matter content, and specific leaf weight of lettuce, but had no significant effect on the leaf area and root-to-shoot ratio; LL had no significant effect on lettuce biomass, but it would reduce the root-shoot ratio. Compared with the NL, the AsA content of CL increased significantly within 8 h after light treatment (at the end of first dark period), and then maintained at a relatively stable level with a slight increase; there was no significant difference in AsA contents between NL and LL showing the same circadian rhythm characteristics. Overall, the activities of L-galactono-1,4-lactone dehydrogenase (GalLDH), ascorbate peroxidase(APX), monodehydroascorbate reductase (MDHAR), and glutathione reductase (GR) under CL were the highest among the three treatments, and the differences with the other two treatments reached significant levels at several time points; there was almost no significant difference in the activities of GalLDH, APX, MDHAR, and GR between NL and LL; there was no significant difference in the activities of dehydroascorbate reductase (DHAR) under different treatments. Compared with the NL, CL caused a sharp decrease of PSⅡ maximal photochemical efficiency (Fv/Fm) in lettuce within 0–8 h after treatment, which then stabilized at a relatively stable level; the Fv/Fm value under the LL was almost the same as the NL. Except for 32 h, the H2O2 content of lettuce under CL was the highest among the three treatments during the entire experimental period, and was significantly higher than that of NL at several time points; the H2O2 content of LL was almost the same as NL. In summary, lettuce biomass, AsA contents, AsA metabolism-related enzyme activities, chlorophyll fluorescence parameters, and H2O2 contents were regulated by the dark period light intensities of continuous light rather than continuous light signals.

LED Light Quality of Continuous Light before Harvest Affects Growth and AsA Metabolism of Hydroponic Lettuce Grown under Increasing Doses of Nitrogen.

To study the effects of light quality of continuous light before harvest on the growth and ascorbic acid (AsA) metabolism of lettuce (Lactuca sativa L.) grown under relative high nitrogen level, lettuce plants grown under different nitrogen levels (8, 10 and 12 mmol·L−1) were subjected to continuous light with different red: blue light ratios (2R:1B and 4R:1B) before harvest. The results showed that the shoot fresh weight of lettuce under 12 mmol·L−1 nitrogen level was significantly higher than that under other treatments. There were no significant differences in shoot dry weight, root fresh weight, root dry weight, soluble sugar content, nitrate content and AsA content in leaves among the treatments at different nitrogen levels. The content of AsA in leaves was significantly higher than that in petioles before and after continuous light. Under the same nitrogen level, the fresh weight of lettuce under continuous light quality 4R:1B was significantly higher than that under other treatments. The content of AsA in lettuce leaves increased in different degrees after continuous light before harvest. High yield and AsA content could be obtained by 72 h continuous light with red and blue light 4R:1B at 12 mmol·L−1 nitrogen level. After continuous light, the content of AsA increased significantly due to the increase of the ratio of red light and nitrogen level, which increased the activities of L-galactono-1,4-lactone dehydrogenase (GalLDH) and dehydroascorbic acid reductase (DHAR) involved in AsA synthesis and in the recycling of DHAR to AsA respectively.

Thermo-Chemical Treatment for Carcass Disposal and the Application of Treated Carcass as Compost

A mechanized thermo-chemical treatment system was developed to treat the undecomposed carcass and remediate livestock burial sites. Animal carcasses were thus processed via crushing, mixing, and treatment with quicklime treatment, heat treatment (200–500 °C), and mixing with sawdust. The machinery was applied to two sites where 16,000 chickens and 418 pigs had previously been buried in fiber-reinforced plastic storage bins. No dioxins were detected in the gas discharged during processing, and the concentration of total volatile organic compound, toluene, ethylbenzene, xylene, and styrene were 430.3, 139.0, 18.3, 21.4, and 10.4 μg/m3, respectively, which were below the air pollutant emission standards issued by the Korean Ministry of Environment. Korean standards stipulating the use of treated carcasses as compost (C, N, and P content, heavy metal concentration, Escherichia coli, and Salmonella) were met, but the germination index value was less than 70, not satisfying the criteria. Plant height, leaf length, leaf width, and dry weight of lettuce grown in soil amended with treated carcass product were significantly lower than those grown in low nutrient soil due to the poor germination index of the treated carcass. These results indicate that a composting process is required before the use of the treated carcass as a fertilizer. The addition of zeolite retarded the elution of ammonia from the carcasses and its efficiency was about 87.9%. It is expected that the mechanized thermo-chemical treatment process developed in this study could replace other technologies for the remediation of livestock burial sites.

Altering light–dark cycle at pre-harvest stage regulated growth, nutritional quality, and photosynthetic pigment content of hydroponic lettuce

Lettuce exposed to red (R) and blue (B) LEDs (4R:1B, 200 μmol·m−2·s−1) were cultivated hydroponically in an environmentally controlled plant factory to examine the effects of light–dark cycle (LDC) conversion at pre-harvest stage on the growth, phytochemical, and photosynthetic pigment accumulation of lettuce. Lettuce plants of four groups were firstly cultivated with the same LDC of 16/8 h (light/dark) for fourteen days. Six days before harvest, the LDC of three groups were altered to 8/4 h (T12), 24/12 h (T36), and 32/16 h (T48), respectively. The last group had invariable photoperiod and was concerned as control (CK, 16/8 h). The results showed that T12 and T36 significantly improved while T48 reduced leaf area and shoot fresh and dry weight of lettuce compared with the CK. The plants treated with altered LDC had higher phytochemicals (soluble sugar, soluble protein, and ascorbate) and photosynthetic pigments (chlorophyll and carotenoids) contents than the CK, but the starch and nitrate contents of the CK were higher. These results suggested that the yield and nutritional quality of lettuce can be increased by changing the LDC properly in the later growth stage. But if the light–dark period was too long, it would have negative effects on the growth of lettuce. In addition, shorten the LDC at pre-harvest stage promoted better production yield and nutritional quality based on the same electricity consumption.

The Effect of NPK Doses and Plant Spacing on Lettuce (Lactuca sativa L.) Growth and Production

The aim of this study was to determine the impact of NPK doses and proper plant spacing in lettuce growth and production. The experiment was conducted in Wirimpalennae Village, Tempe Subdistrict, Wajo Regency from January to March 2017. The experiment employed randomized block design with 2 factor factorial namely NPK doses (300 kg/ha, 350 kg/ha, 400 kg/ha and plant spacing (20 x 25 cm, 25 x 25 cm, 25 x 40 cm). The result showed that the interaction between NPK doses and plant spacing were significantly influenced the fresh weight of lettuce. The highest yield of lettuce was 2,16 kg/Ha (12 t/Ha) produced by the combination of NPK dose (350 kg/ha) and plant spacing (25 x 25). The interaction of NPK dose and plant spacing treatments were not significantly influenced others parameters

Recycling Nutrient Solution Can Reduce Growth Due to Nutrient Deficiencies in Hydroponic Production.

It is common in hydroponics to supply nutrients to crops by maintaining electrical conductivity (EC) of the recycling solution at a target level. Levels of individual nutrients in the solution are generally not assessed as their regular measurement and adjustment can be both expensive and technically challenging. However, the approach of growing crops at a target EC can potentially result in nutrient imbalances in the solution and reduced growth. We quantified the effects of recycling on solution EC changes, tissue nutrient concentration, canopy growth rate, plant water status, and shoot and root weight of lettuce (Lactuca sativa) in a greenhouse. The tap water quality was moderately alkaline and similar to that commonly observed in many commercial greenhouses. In our research, recycling solution maintained at a target EC (1.8 dS⋅m–1) significantly reduced shoot fresh (22–36%) and dry weight compared to the control supplied regularly with freshly prepared solution at the target EC. Further, recycling significantly decreased N, P, K, and Fe and increased Na and Cu levels in the tissue, in addition to increasing solution EC between adjustments compared to the control. Using image analysis of groups of plants, we identified that the negative effects of recycling on canopy area started 2 weeks after transplanting. Based on these results, we hypothesized that certain unwanted compounds (e.g., bicarbonates) and slowly consumed elements (e.g., Ca, Mg) were added to the recycling solution through the alkaline tap water with time. Their accumulation “artificially” increased solution EC and “masked” the lower than optimal levels of major nutrients in the solution, leading to the reductions in the concentration of nutrients in the tissue and plant growth. Supporting this, the negative effects of recycling were not observed when the recycling solution was either discarded after 2 weeks of use or made using reverse osmosis water and continuously used. Our findings aid in proper management of recycling solution in hydroponic lettuce production.

Effect of Light Emitting Diode (LED) Spectra on Plant Growth

The effect of lights generated by red, blue and white light emitting diodes (LED) on growth and development of lettuce were investigated and compared with lettuce without supplemental lighting. A vertical multi-tier hydroponic system was used to grow lettuce. Each tier consisted of 60 heads of lettuce with different LED colour and one tier without LED was used as control. The following measurements on plant physiology were taken: number, length and chlorophyll content of leaves, height and weight of plants. Based on number of leaves, red LED shows the highest number of leaves compared to lettuce under blue, white and control treatment. The similar trend also can be found in the lengths of leaves which shows the highest length produce under red LED. Red LED also produce highest weight of lettuce by 28% as compared to white LED. White LED improved lettuce growth development in the height by 13% and amount of chlorophyll content. Lettuce grown under blue LED shows lowest growth and development compared to lettuce grown under red and white LEDs based on parameters above, and lettuce without LED were died within 2 weeks. This result indicated that the red LED was the most effective spectra in growth response of lettuce plants. This study also demonstrates the effectiveness of LED in improving lettuce growth on vertical multi-tier hydroponic system.

Impact of foliar application of some metal nanoparticles on antioxidant system in oakleaf lettuce seedlings

BackgroundNanoparticles (NPs) serve various industrial and household purposes, and their increasing use creates an environmental hazard because of their uncontrolled release into ecosystems. An important aspect of the risk assessment of NPs is to understand their interactions with plants. The aim of this study was to examine the effect of Au (10 and 20 ppm), Ag, and Pt (20 and 40 ppm) NPs on oakleaf lettuce, with particular emphasis on plant antioxidative mechanisms. Nanoparticles were applied once on the leaves of 2-week-old lettuce seedlings, after next week laboratory analyses were performed.ResultsThe antioxidant potential of oakleaf lettuce seedlings sprayed with metal NPs at different concentrations was investigated. Chlorophylls, fresh and dry weight were also determined. Foliar exposure of the seedlings to metal NPs did not affect ascorbate peroxidase activity, total peroxidase activity increased after Au-NPs treatment, but decreased after applying Ag-NPs and Pt-NPs. Both concentrations of Au-NPs and Pt-NPs tested caused an increase in glutathione (GSH) content, while no NPs affected L-ascorbic acid content in the plants. Ag-NPs and Pt-NPs applied as 40 ppm solution increased total phenolics content by 17 and 15%, respectively, compared to the control. Carotenoids content increased when Ag-NPs and Au-NPs (20 and 40 ppm) and Pt-NPs (20 ppm) were applied. Plants treated with 40 ppm of Ag-NPs and Pt-NPs showed significantly higher total antioxidant capacity and higher concentration of chlorophyll a (only for Ag-NPs) than control. Pt-NPs applied as 40 ppm increased fresh weight and total dry weight of lettuce shoot.ConclusionsResults showed that the concentrations of NPs applied and various types of metal NPs had varying impact on the antioxidant status of oakleaf lettuce. Alteration of POX activity and in biosynthesis of glutathione, total phenolics, and carotenoids due to metal NPs showed that tested nanoparticles can act as stress stimuli. However, judging by the slight changes in chlorophyll concentrations and in the fresh and dry weight of the plants, and even based on the some increases in these traits after M-NPs treatment, the stress intensity was relatively low, and the plants were able to cope with its negative effects.

Lettuce Growth, Nutritional Quality, and Energy Use Efficiency as Affected by Red–Blue Light Combined with Different Monochromatic Wavelengths

Light, as the energy and signal sources for plant growth and development, is one of the most important environment factors in recently developed plant factories with artificial light (PFALs). To find the optimal combination of light wavelengths for lettuce (Lactuca sativa cv. ‘Tiberius’) plant growth in a PFAL, four treatments, each using red (R; 662 nm) and blue light (B; 447 nm) with a ratio of 4:1 and photon flux density (PFD) of 150 μmol·m−2·s−1, and mixing, respectively, with 50 μmol·m−2·s−1 of green light (G; 525 nm; RBG), yellow light (Y; 592 nm; RBY), orange light (O; 605 nm; RBO) and far-red light (FR; 742 nm; RBFR), were set up during this experiment. A combination of R and B with a ratio of 4:1 and PFD of 200 μmol·m−2·s−1 was set as the control (RB). The responses of lettuce growth, morphology, anatomical structure of the lettuce leaf, photosynthetic performance, lettuce nutritional quality, and energy use efficiency were investigated. The results showed that RBG, RBO, and RBFR increased the shoot fresh weight of lettuce by 20.5%, 19.6%, and 40.4%, and they increased the shoot dry weight of lettuce by 24.2%, 13.4%, and 45.2%, respectively, compared with those under RB. The Pn under RBY was significantly lower than that under RB, although no significant differences in chlorophyll or carotenoid content were found between RBY and RB. RBG increased the lettuce leaf area, the thickness of the leaf palisade tissue, Pn, and light use efficiency compared with those under RB. Plants grown under RBO showed better photosynthetic capacity, such as higher Pn, ΦPSII, and other photosynthetic parameters. RBFR caused an increase in lettuce leaf area and energy use efficiency, but a decrease in leaf thickness and Pn of the single leaf. Moreover, tipburn injury was observed under RBFR. Therefore, these results demonstrate that RBG and RBO can be considered optimal combinations of light wavelengths for lettuce growth in a PFAL in this experiment, although plant growth can also be improved by using RBFR.

Study of Quantitative Trait Loci (QTLs) Associated with Allelopathic Trait in Rice.

In rice there are few genetic studies reported for allelopathy traits, which signify the ability of plants to inhibit or stimulate growth of other plants in the environment, by exuding chemicals. QTL analysis for allelopathic traits were conducted with 98 F8 RILs developed from the cross between the high allelopathic parents of ‘Sathi’ and non-allelopathic parents of ‘Nong-an’. The performance of allelopathic traits were evaluated with inhibition rate on root length, shoot length, total length, root weight, shoot weight, and total weight of lettuce as a receiver plant. With 785 polymorphic DNA markers, we constructed a linkage map showing a total of 2489.75 cM genetic length and 3.17 cM of average genetic distance between each adjacent marker. QTL analysis detected on QTL regions on chromosome 8 responsible for the inhibition of shoot length and inhibition of total length. The qISL-8 explained 20.38% of the phenotypic variation for the inhibition on the shoot length. The qITL-8 explained 14.93% of the phenotypic variation for the inhibition on total length. The physical distance of the detected QTL region was 194 Kbp where 31 genes are located.

Using POC Azolla Mycrophylla and Urea Fertilizer: Lettuce Plant (Lactuca Sativa L) Context

The aim of the study was to obtain the best dose of POC Azolla microphylla in urea efficiency against the growth and production of lettuce. The study was conducted experimentally with non-factorial completely randomized design with 5 treatments and 4 replications each treatment consisting of 4 plants and 2 plants used as samples: A0 = Control (without treatment), A1 = POC treatment Azolla microphylla 30 ml l−1 + Urea 2 g plant−1, A2 = Treatment of POC Azolla microphylla 60 ml l−1+ Urea 1.5 g plant−1, A3 = Treatment of POC Azolla microphylla 90 ml l + Urea 1 g plant−1, A4 = POC treatment Azolla microphylla 120 ml l−1 + Urea 0.5 g plant−1. The results of the study were concluded; The combination of POC Azolla microphylla was able to streamline the administration of urea to stem diameter, number of leaves, fresh weight, consumption weight and dry weight of lettuce (Lactuca sativa L) and A4 treatment by giving POC Azolla microphylla 120 ml l−1 which was the best for urea efficiency.

Differential effects of high light duration on growth, nutritional quality, and oxidative stress of hydroponic lettuce under red and blue LED irradiation

In this study, effects of high light irradiation (HLI, 500 μmol m−2·s-1) duration in the middle of light period (16 h, 150 μmol m−2·s-1) provided by red (R) and blue (B) LEDs (4R:1B) on the growth, nutritional quality, and oxidative stress of hydroponic purple leaf lettuce grown in an environmentally controlled plant factory were examined on the 10th and 20th day after treatment. Set up five treatments with 0 h (CK), 0.5 h (HL0.5), 1 h (HL1), 2 h (HL2), and 4 h (HL4) HLI, respectively. We found that the shoot fresh weight of lettuce increased first and then decreased with the prolongation of HLI duration, whether in the early or late growth stage. On the 10th day after treatment, the root fresh weight and specific leaf weight of lettuce increased linearly with the prolongation of HLI duration, while the shoot/root ratio decreased linearly. On the 20th day after treatment, the lettuce of HL1 had the highest shoot fresh weight, leaf area, and shoot dry weight, followed by HL2. Besides, HL4 promoted the accumulation of soluble sugar, anthocyanin, flavonoid, and total phenolic simultaneously decreased the maximum quantum efficiency compared with others on the 10th day after treatment. On the 20th day after treatment, HL0.5 and HL4 stimulated the accumulation anthocyanin, flavonoid, total phenolic, and ascorbic acid compared with other treatments. The results showed that short-term HLI promotes biomass production and secondary metabolite accumulation, but HL4 caused photo-oxidative damage to lettuce. Therefore, lettuce growth and qualities can be purposely adjusted by adopting different duration of HLI provided by red and blue light in the plant factory, also these responses depended on lettuce growth stage closely.

Pratylenchus penetrans, a potential risk in glasshouse-grown lettuce: population dynamics and damage threshold

Summary The root-lesion nematode, Pratylenchus penetrans, causes growth reduction in glasshouse-grown lettuce and is mainly controlled by chemical soil disinfestation. Integrated management strategies require more knowledge about the population dynamics and damage threshold densities. We monitored the population during 2.5 years in a commercial glasshouse by sampling soil in the same four 1 m2 spots at 0-30 cm and 30-60 cm depth. The grower grew lettuce in rotation with leek, applied 1,3-dichloropropene in summer and left the field fallow during winter. Growing leek reduced the nematode population slightly but chemical soil disinfestation lowered the numbers drastically, although 41% of the nematodes in the deeper layer survived. Black fallow resulted in a slight increase of the population, probably due to hatching. Two pot experiments with ten densities of P. penetrans were conducted to estimate the damage threshold for a summer and autumn cultivar (‘Cosmopolia’ and ‘Brighton’, respectively). The thresholds for lettuce weight were 669 and 3834 P. penetrans (100 ml soil)−1 in summer and autumn, respectively, but with considerable variability in estimated parameters. The thresholds for root damage were much lower: 204 and 48 P. penetrans (100 ml soil)−1. Nematode numbers did not increase on lettuce in the pot tests (maximum multiplication rate was 0.40) but increased slightly in the commercial setting. These results show that populations of P. penetrans build up slowly when butterhead lettuce is rotated with leek and fallow, but chemical soil disinfestation is required to avoid numbers resulting in root damage.

Effects of Fe-loaded biochar on the bioavailability of Arsenic and cadmium to lettuce growing in a mining contaminated soil

ABSTRACT Arsenic (As) and cadmium (Cd) are two prominent metal contaminants in mining soil, threatening food and environmental safety. The effects of Fe-loaded biochar on the accumulation and translocation of As and Cd in a soil-lettuce system were investigated to evaluate the efficiency of Fe-loaded biochar in reducing As and Cd bioavailability. Application of Fe-loaded biochar at a rate of 0.5–1.5% decreased the concentrations of porewater As and Cd by 4.2–53.0% and −0.6–21.7%, respectively. The results of sequential extraction showed that Fe-loaded biochar can promote the transfer of As and Cd in soils from the available fraction to a relatively stable fraction, thus reducing the mobility and availability of As and Cd. The concentrations of As and Cd in lettuce shoots in the Fe-loaded biochar treatment were significantly decreased by 11.4–26.0% and 4.4–12.9% compared with those in the untreated soil, respectively. Fe-loaded biochar applied at a rate of 0.5–1.0% had no obvious effect on plant biomass, and the lowest weight of lettuce shoots and roots was observed in the treatment with Fe-loaded biochar applied at a rate of 1.5%, in which they were reduced by 12.9% and 18.0%, respectively. Overall, Fe-loaded biochar as a soil amendment was effective in simultaneously reducing As and Cd bioavailability in As and Cd co-contaminated soils, and an application rate lower than 1.5% is recommended to avoid significant decreases in plant growth.

Remediation of perfluorooctanoic acid (PFOA) polluted soil using pulsed corona discharge plasma

Perfluorooctanoic acid (PFOA) from contaminated soil accumulates in higher organisms, and causes health risks to humans. In this research, 71 % of the PFOA was degraded, of which 51 % was decomposed into short chain by-products, 19 % mineralized, and 1 % volatilized with 30 kV of voltage, 50 Hz of discharge frequency, 1 % of soil moisture, 300 ppm of PFOA concentration and 6.3 of soil pH using pulsed positive discharge plasma. From a series of experiments, electrons were identified as the dominant active means of PFOA degradation. The decomposition by-products were analyzed by LC–MS. The results indicated that PFOA was decomposed into small by-products including perfluoroheptanoic acid (PFHpA), perfluorohexanoic acid (PFHxA), perfluoropentanoic acid (PFPeA), perfluorobutyric acid (PFBA), pentafluoropropionic acid (PFPrA) and trifluoroacetic acid (TFA). Moreover, in plasma treated soil, the concentration of ammonia nitrogen increased from less than 10 ppm–462 ppm, and the average dry weight of lettuce was 1.6 mg higher than that in natural soil. Additionally, Planctomycetes and Nitrospirae increased after treatment, indicating that plasma technology promotes the process of nitrogen cycle. Thus, PFOA polluted soil could be remediated using this pulse corona plasma technology, and simultaneously improve the fertility of soil without chemical injections.

Assessment of the Effect of Dimethyl Ether (DME) Combustion on Lettuce and Chinese Cabbage Growth in Greenhouse

The experiment was conducted to determine the performance of DME combustion gas when used as a fuel for DME burner for raising temperature and CO2 concentration in greenhouse and also to examine its effects on chlorophyll content, and fresh and dry weight of lettuce and Chinese cabbage. DME-1 and DME-2 treatments consisted of average DME flow quantity in duct were 17.4 m3 min-1 and 10.2 m3 min-1 respectively to greenhouse-1 and greenhouse- 2 and no DME gas was supplied to greenhouse-3 which was left as control (DME-3). DME supply times were 0.5 hr day-1, 1 hr day-1, 1:30 hrs day-1 and 2 hrs day-1 on week 1, 2, 3, and 4 respectively. Chlorophyll content and fresh and dry weight of lettuce and Chinese cabbage were measured for each treatment and analyzed through analysis of variance with a significance level of P<0.05. The result of the study showed that CO2 concentration increased up to 265% and 174% and the level of temperature elevated 4.8oC and 3.1oC in greenhouse-1 and 2, respectively as compared to greenhouse- 3 due to application of DME combustion gas. Although, the same crop management practices were provided in greenhouse-1, 2 and 3 at a same rate, the highest change (p<0.05) of chlorophyll content, fresh weight and dry weight were found from the DME-1 treatment, followed by DME-2. As a result, DME combustion gas that raised the level of temperature and CO2 concentration in the greenhouse-1 and greenhouse-2, might have an effect on growth of lettuce and Chinese cabbage. At end of experiment, the highest fresh and dry weight of lettuce and Chinese cabbage were measured in greenhouse-1 and followed by greenhouse-2. Similarly chlorophyll content of greenhouse-1 and greenhouse-2 were more compared to greenhouse-3. In general, DME was not producing any harmful gas during its combustion period, therefore it can be used as an alternative to conventional fuel such as diesel and liquefied petroleum gas (LPG) for both heating and CO2 supply in winter season. Moreover, endorsed quantify of DME combustion gas for a specified crop can be applied to greenhouse to improve the plant growth and enhance yield.

UTILIZAÇÃO DE DIFERENTES TIPOS E CONCENTRAÇÕES DE CALDAS NUTRICIONAIS EM ATRIBUTOS AGRONÔMICOS DA ALFACE

Objetivou-se avaliar o efeito da utilização de distintos tipos e concentrações de caldas nutricionais em atributos agronômicos da alface. O experimento foi conduzido em canteiros, em uma propriedade rural no município de Ronda Alta, (RS), de agosto a outubro de 2016. O delineamento experimental utilizado foi em blocos ao acaso, com sete tratamentos e cinco repetições. Os tratamentos utilizados foram: calda bordalesa a 0,1 e 0,5%; húmus líquido a 2,5% e 5%; Microgeo® a 0,5% e 1,0%; testemunha. As variáveis analisadas foram: altura da parte aérea, comprimento do sistema radicular, perímetro da parte aérea, matéria seca da parte aérea e do sistema radicular e redução de peso. Para a variável altura da parte aérea, o tratamento com calda bordalesa a 0,5% apresentou resultado superior ao tratamento com o uso de Microgeo® a 0,5 %. Para o comprimento da raiz o tratamento com húmus líquido a 5% igualou-se ao tratamento húmus líquido a 2,5%, sendo aquele superior aos demais. Para a matéria seca do sistema radicular, o uso de húmus líquido e Microgeo®, em ambas as concentrações, apresentaram os melhores resultados. Para a redução de peso da alface, a calda com húmus líquido e calda bordalesa a 0,5% apresentaram os melhores resultados. Assim, diante dos resultados obtidos com a condução deste trabalho, indica-se o uso de caldas nutricionais para o cultivo de alface. Sobre os atributos agronômicos, o uso de húmus líquido (2,5% e 5%) promove maior comprimento de raízes e menor redução do peso da alface.