Nutrient Concentration Levels Research Articles

Application of Internet of Things (IoT) on Monitoring EC and pH Values for Fertigation System

This paper introduces a novel Internet of Things (IoT) based fertigation control system designed to enhance traditional agricultural practices in Malaysia, particularly in rural areas. The system integrates a fertigation approach, combining fertilization and irrigation, with smart devices and a NodeMCU ESP32 microcontroller to automate the tracking of data from liquid fertilizer mixtures. By utilizing EC and pH sensors, the system accurately monitors the nutrient concentration and pH levels of the fertilizer mix, with data displayed on an IoT platform for real-time observation and control. This approach mitigates common issues such as overfertilization and inefficient nutrient use, offering significant improvements over manual data collection methods. The system's performance was validated, showing successful monitoring and control of the fertilization process, leading to enhanced plant health and crop quality. Key findings indicate that the system's integration with IoT technology provides a more efficient, automated solution for managing fertilizer applications, reducing labor and time while ensuring optimal plant nutrient levels. The study also highlights the potential for future development, including the integration of additional sensors and advanced data analytics to optimize fertigation practices further. The implementation of this IoT-based system represents a significant advancement towards sustainable agriculture, offering practical benefits for Malaysian farmers and setting a foundation for further innovation in fertigation technology.

Foliar applications of zinc oxide nanoparticles and boric acid affect leaf oxidative metabolism and productivity in young pecan trees

Zinc and boron are nutrients that often suffer low bioavailability to pecan trees grown in calcareous soils whereas adequate supplies of these two elements is essential for commercial pecan production. Working with young pecan trees, we evaluated changes in oxidative metabolism, levels of bioactive compounds, yield components and foliar nutrient concentrations in response to foliar sprays (50 or 100 mg L−1) of zinc oxide nanoparticles (ZnO NPs) and boron (H3BO3). Four different treatment solutions were applied in a completely randomised design with six replications per treatment (24 trees in total). Zinc and B treatments were applied before pistil receptivity (3 weeks before anthesis) and at stem elongation stage 31, 39/60; flowering stage 69; fruit stages 7–75 and continued for a total of five applications at 14-day intervals. We evaluated enzyme activities (SOD, H2O2, CAT and GPx), AC, phenols, flavonoids, leaf area, chlorophyll, total anthocyanins and nut yield and quality (nut weight and % kernel). The mineral concentrations in the leaflets were also determined. The mineral concentrations (N, P, K, Ca, Mg, Fe, Cu, Mn, Ni, Zn and B) in the leaflets were also determined. Spraying ZnO NPs and B increased SOD activity, CA, chlorophyll concentration, mineral nutrients (N, K, Ca, Zn and B) and yield. However, reductions were observed for CAT activity, nut quality and concentrations of phenol, flavonoid, anthocyanin and Fe. Boron increased GPx activity and P concentration. These results demonstrate that spraying low doses (50 mg L−1) of ZnO NPs and B can help reduce oxidative stress and increase yield, nut quality and leaf concentrations of Zn and B in young cv. Wichita pecan trees established on a calcareous soil.

Residual loads from tilapia farming on the sediment of a Brazilian reservoir

This study investigated the sediment geochemistry of a fish farming area in net cage tanks in the Rosário reservoir, Brazil. Three areas were investigated: reference (RA), fish farming (FFA), and dispersion (DA). The results were analyzed through correlation, similarity, principal component analysis, comparison with legislation, sediment quality guidelines, and sediment pollution indices. The mean concentrations for RA, FFA, and DA areas were respectively: Cu (mg.kg−1) 37.74, 62.23, and 71.83; Mn (mg.kg−1) 22.55, 66.48, and 55.90; Zn (mg.kg−1) 9.13, 114.83, and 94.27; Fe (%) 0.28, 0.40, and 0.43; OM (%) 15.84, 21.95, and 18.45; TOC (%) 1.86, 3.69, and 6.05; TN (mg.kg−1) 2365.00, 5015.00, and 3447.51; TP (mg.kg−1) 780.00, 6896.00, and 2585.50; ORP (mV) −95.50, −135.20, and −127.10; pH 6.60, 6.58, and 6.05; <63 μm 90.59, 78.68, and 87.30. Statistically, the influence of fish farming on sediment, organic matter, and pollutant sedimentation was demonstrated. Cu and Zn concentrations were below sediment quality guidelines. Regarding legal limits (resolution 454/2012/CONAMA), nutrients in the FFA area exceeded by 60% (TN) and 100% (TP), while in DA and RA areas they were 100% lower. TOC was 100% lower in all areas. Organic matter exceeded the limit by 100% in all areas. Pollution indices resulted in: low contamination factor 78%; unpolluted for 87% of pollution load and 83% of combined pollution; moderately polluted for 75% of the Nemerow index. The greatest impacts and influence of farming on pollutant sedimentation were more concentrated in the fish farming area. In terms of legal aspects and pollution indices, fish farming produced low levels of trace metal pollution and nutrient concentrations exceeded legal limits.

A Study of the Influence of the Type of Land Use on the Enzymatic Activity of Soils in Southwestern China

Although soil enzyme activity can act as an effective indicator of soil nutrient status, there is some uncertainty about its accuracy within soil depth across different land uses. To assess the effects of different land uses on the interactions between soil enzyme activity and nutrient status within different soil horizons, in this study we examined soil total carbon (C), nitrogen (N), and phosphorus (P) concentrations, pH, and the activities of five hydrolytic (i.e., amylase, invertase, cellulase, acid phosphatase, and urease) and three oxidative enzymes (i.e., catalase, dehydrogenase, and phenol oxidase) involved in C, N, and P acquisition and evaluated their interactions within the topsoil (0–10 cm), subsoil (10–20 cm), and deeper soil layer (20–30 cm) under various land uses (i.e., rice field, cultivated land, bamboo plantation, forest land, and barren land). We found that the levels of hydrolytic enzyme activities and nutrient concentrations were higher in the topsoil than the deeper layer. The hydrolytic enzyme activities were positive correlated with soil C, N, and P concentrations, while the activities of oxidative enzymes showed strong associations with soil pH. Furthermore, the results of fuzzy comprehensive evaluation models suggest that the overall enzyme activity can serve as an indicator of soil nutrient status in the topsoil and subsoil, but not in the deeper layer. The depth-specific nature of soil enzyme–nutrient relationships may be attributed to different land-use management practices. Our study highlights the complex interactions between soil nutrients, pH, and enzyme activities within soil profiles, and soil enzyme activity as an indicator of soil nutrient status is depth-dependent across the different land uses. The specific functional groups of enzymes and the gradients of resources and environmental conditions within the soil profile that is partly mediated by land use play crucial roles in shaping these relationships. Our results can also provide some new insights into sustainable soil management practices under the background of intense anthropogenic activities and global change.

The exometabolome of microbial communities inhabiting bare ice surfaces on the southern Greenland Ice Sheet.

Microbial blooms colonize the Greenland Ice Sheet bare ice surface during the ablation season and significantly reduce its albedo. On the ice surface, microbes are exposed to high levels of irradiance, freeze-thaw cycles, and low nutrient concentrations. It is well known that microorganisms secrete metabolites to maintain homeostasis, communicate with other microorganisms, and defend themselves. Yet, the exometabolome of supraglacial microbial blooms, dominated by the pigmented glacier ice algae Ancylonema alaskanum and Ancylonema nordenskiöldii, remains thus far unstudied. Here, we use a high-resolution mass spectrometry-based untargeted metabolomics workflow to identify metabolites in the exometabolome of microbial blooms on the surface of the southern tip of the Greenland Ice Sheet. Samples were collected every 6 h across two diurnal cycles at 5 replicate sampling sites with high similarity in community composition, in terms of orders and phyla present. Time of sampling explained 46% (permutational multivariate analysis of variance [PERMANOVA], pseudo-F = 3.7771, p = 0.001) and 27% (PERMANOVA, pseudo-F = 1.8705, p = 0.001) of variance in the exometabolome across the two diurnal cycles. Annotated metabolites included riboflavin, lumichrome, tryptophan, and azelaic acid, all of which have demonstrated roles in microbe-microbe interactions in other ecosystems and should be tested for potential roles in the development of microbial blooms on bare ice surfaces.

The storm runoff management strategy based on agricultural ditch nutrient loss characteristics in Erhai Lake, China

Initial flush management is an effective measure to control non-point source pollution (NPSP) in storm runoff. However, determining the parameter of the initial flush in different areas may pose challenges in storm runoff management strategies. To address this issue, Erhai Lake in China, Yunnan-Guizhou Plateau, was selected as an example for the study. Erhai Lake is a typical mesotrophic lake with the profound influence of NPSP. The NPSP control strategy in this area will provide a valuable reference for other lakes. In 2021, 289 storm events and 190 ditchwater samples were detected around Erhai Lake. The average flow in the ditches ranged from 0.004 to 0.147 m3/s, the instant total nitrogen (TN) concentration ranged from 0.28 to 91.43 mg/L, and the instant total phosphorus (TP) concentration ranged from 0.26 to 7.35 mg/L in the storm events. It was found that the concentration of pollutants was lower than expected in the initial flush period. Instead, the event mean concentrations of TN and TP were 9.3 and 2.1 times higher than in the wet seasons, showing high nutrient concentration levels throughout the entire rainfall period. To manage storm runoff effectively, a flow-processes-division method was proposed to analyze the inflow condition and pollutant removal rate in different runoff periods. The peak flow interception strategy was recommended as the optimal stormwater management plan, as it showed the highest inflow conditions and 50% pollutant removal rate.Considering the need to reduce the constant flush of stormwater runoff, it is essential to establish a healthy water cycle system to alleviate NPSP and raise the Erhai water level. The storm runoff management method can serve as a practical tool for lake areas that do not exhibit initial flush characteristics.

Volatile-Mediated Signalling Between Potato Plants in Response to Insect Herbivory is not Contingent on Soil Nutrients

Plant-plant signalling via volatile organic compounds (VOCs) has been studied intensively, but its contingency on abiotic conditions (e.g., soil nutrients, drought, warming) is poorly understood. To address this gap, we carried out a greenhouse experiment testing whether soil nutrients influenced signalling between potato (Solanum tuberosum) plants in response to insect leaf herbivory by the generalist caterpillar Spodoptera exigua. We placed pairs of plants in plastic cages, where one plant acted as a VOC emitter and the other as a receiver. We factorially manipulated soil nutrients for both emitter and receiver plants, namely: unfertilized (baseline soil nutrients) vs. fertilized (augmented nutrients). Then, to test for signalling effects, half of the emitters within each fertilization level were damaged by S. exigua larvae and the other half remained undamaged. Three days after placing larvae, we collected VOCs from emitter plants to test for herbivory and fertilization effects on VOC emissions and placed S. exigua larvae on receivers to test for signalling effects on leaf consumption and larval mass gain as proxies of induced resistance. We found that herbivory increased total VOC emissions and altered VOC composition by emitter plants, but these effects were not contingent on fertilization. In addition, bioassay results showed that receivers exposed to VOCs from herbivore-damaged emitters had lower levels of herbivory compared to receivers exposed to undamaged emitters. However, and consistent with VOC results, fertilization did not influence herbivore-induced signalling effects on receiver resistance to herbivory. In sum, we found evidence of S. exigua-induced signalling effects on resistance to herbivory in potato plants but such effects were not affected by increased soil nutrients. These results call for further work testing signalling effects under broader range of nutrient concentration levels (including nutrient limitation), teasing apart the effects of specific nutrients, and incorporating other abiotic factors likely to interact or covary with soil nutrients.

Trace metals and nutrients in tropical volcanic island rivers: Insights on chemical weathering and anthropogenic influences of Pohnpei, Micronesia

River systems in tropical islands play a vital role in maintaining the ecosystem function of surrounding oceans by delivering land-derived materials. Researches on tropical river systems frequently focused on continents and peninsulas, while little research has been conducted in tropical islands. In the present study, we conducted field surveys in a Pacific volcanic island, Pohnpei, Micronesia, and determined the substance composition of river waters (major ions, trace metals, nutrients, etc.) to quantify terrestrial material loading and biogeochemical influence on the surrounding oceans. In Pohnpei, total dissolved solutes were observed to be 71.4 mg/L; the NH4+, NO3−, PO4−, and SiO32- concentrations were 0.46, 3.9, 0.52, 221.7 μmol/L, respectively; and NO2− was lower than the detection limit (0.14 μmol/L). The trace metals concentrations of rivers in Pohnpei Island were much lower than records in tropical rivers of the world. The variation in concentration levels of major ions and nutrients among rivers was relatively limited. A similar pattern was observed in the distribution of Al and V. Trace elements, including As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Se, Sr, U and Zn in rivers were most enriched in Urban Area (human activity dominated region), compared with the Mixing Area (Multiple effect region) to Natural Area (natural weathering region). Exchangeable trace metals concentrations from suspended particulate matter (SPM) were lower than in dissolved state in river waters, while water-soluble, while acid-soluble metals concentrations in the sediment were much higher than in dissolved state in rivers. In our results, trace metals in Pohnpei rivers may mainly be influenced by domestic sewage and agricultural activity—these data can be used in biogeochemical models to estimate the contribution of domestic sewage. Furthermore, we have quantified the land-derived input of trace metals from tropical volcanic islands in Pacific (TVIP) into the surrounding oceans. Though the land area of TVIP only accounts for 0.1 % of global land area, the terrigenous inputs of some trace metals from TVIP account for approximately 1 %—and even more than 2 % of those in global riverine flux. Therefore, the nutrients and trace metals inputs from TVIP would be significant for the cycle of biogenic elements in the receiving ocean.

Seedling nanopriming with selenium-chitosan nanoparticles mitigates the adverse effects of salt stress by inducing multiple defence pathways in bitter melon plants

Advances in the nanotechnology fields provided crucial applications in plant sciences, contributing to the plant performance and health under stress and stress-free conditions. Amid the applications, selenium (Se), chitosan and their conjugated forms as nanoparticles (Se-CS NPs) have been revealed to have potential of alleviating the harmful effects of the stress on several crops and subsequently enhancing the growth and productivity. The present study was addressed to assay the potential effects of Se-CS NPs in reversing or buffering the harmful effects of salt stress on growth, photosynthesis, nutrient concentration, antioxidant system and defence transcript levels in bitter melon )Momordica charantia(. In addition, some secondary metabolite-related genes were explicitly examined. In this regard, the transcriptional levels of WRKY1, SOS1, PM H+-ATPase, SKOR, Mc5PTase7, SOAR1, MAP30, α-MMC, polypeptide-P and PAL were quantified. Our results demonstrated that Se-CS NPs increased growth parameters, photosynthesis parameters (SPAD, Fv/Fm, Y(II)), antioxidant enzymatic activity (POD, SOD, CAT) and nutrient homeostasis (Na+/K+, Ca2+, and Cl−) and induced the expression of genes in bitter melon plants under salt stress (p ≤ 0.05). Therefore, applying Se-CS NPs might be a simple and effective way of improving crop plants' overall health and yield under salt stress conditions.

Changes in nutrient concentration and water level affect the microbial loop: a 6-month mesocosm experiment

Changes in nutrient concentration and water level affect the microbial loop: a 6-month mesocosm experiment

The amino acid and carnitine concentration changes in bronchoalveolar lavage fluid from lung cancer patients

ObjectiveTo screen out potential biomarkers by analyzing fundamental nutrients in the bronchoalveolar lavage fluid (BALF) before confirming the lung cancer.MethodsIn this study, 44 patients were enrolled with clinical information. The concentrations of 23 amino acids and 35 carnitines in their BALF were detected with the high-performance liquid chromatography–mass spectrometry (HPLC–MS). Combined with clinicopathological diagnosis, the patients were divided into the lung cancer group (grades I & II and III & IV) and the non-cancer group for standard statistical analysis.ResultsThe partial least squares-discriminant analysis (PLS-DA), the Shapiro–Wilk test, and the Bonferroni correction results showed that the serine concentration was higher and the butane-diacyl-carnitine (C4DC) concentration was lower in the lung cancer group, further showing the same changing trend continuously through the non-cancer stage, grades I & II stage and grades III & IV stage. Those two potential biomarkers have been identified.ConclusionThe HPLC–MS target detection in clinic for nutrient concentration levels is a promising technique to find the changing concentration of serine and C4DC in BALF, which provides an economical and practical way for early warning of lung cancer.

Assessment of seasonal and spatial water quality variation in a cascading lake system in Chennai, India

Water quality and scarcity are among the most severe problems humans have been facing in the last decades. India, as a fast-developing country, is not an exception. The surface water quality has deteriorated due to anthropogenic activities. Another factor which impacts the water quality is the heavy rainfall during monsoon season. To maintain the quality and the sustainability of water resources, there is the need to study how human activities impact water quality. We hypothesized that the water quality can be impacted by the spatial land use types and by the seasonality. In the present study, seasonal and spatial water quality regarding physical, chemical, and biological parameters from a lake cascading system was assessed monthly from July to December 2019. Land use/cover data was produced by Impact Observatory, Microsoft, and Esri based on the 10-m Sentinel-2 images. Redundancy analysis was applied to investigate the relationship between land use/cover data and water quality in the riparian of 500 and 1000 m to the lakes. Our results showed clear temporal and spatial variation of water quality in 2019, with better water quality in rainy season (Oct.-Dec.) and downstream lakes while relatively worse water quality was recorded in dry season (Jul.-Sep.) and upstream lakes. The water quality variation was explained 27.8 % and 42.7 % by the land use types within 500 m and 1000 m buffer widths, respectively. The outlet of the catchment showed exceptional results due to the impact of a dumpsite. Our findings indicate that the water quality is highly impacted by human-induced land use/cover. The land use/cover types, such as crops, woodland and urban area, show negative impacts and relate to the high level of nutrient concentrations. In opposite, grass land shows positive effects and leads to better water quality. Our study confirms that the lake water quality is distinguished in both spatial and seasonal aspects. Monsoon season improves the water quality.

Effects of Anthropogenic Activities on the Water Quality of River Nyakomisaro, Kisii, Kenya

Access to safe drinking water is a major challenge to urban populations in developing countries. Most of Kisii town residents draw raw water from rivers and springs for domestic use which is highly contaminated. No water quality assessments in these rivers have been conducted. An assessment was therefore conducted on water quality of River Nyakomisaro-Riana flowing through Kisii town, during May 2013 to October 2014. The overall objective was to to assess the spatial and temporal variation of selected physical, chemical and biological parameters of river Nyakomisaro-Riana. Five sampling sites equidistant from one another were selected to establish a sampling transect for this river. Standard methods described in APHA, 1998 were used to determine levels of physico-chemical parameters, nutrient concentrations and biological characteristics. This study was conducted on this river for the first time and forms a basis for comparison with future studies. Spatial and temporal patterns of the parameters were analyzed and presented in tabular and graphical formats using Excel and Sigma Plot software. Descriptive statistics were done. Analysis of variance and Tukey’s pairwise comparisons were used to establish whether there were significant differences in studied parameters. Results indicated that the concentrations of total dissolved solids, Total supsennded soilds, Electrical conductivity, temperature, total suspended solids increased downstream while dissolved oxygen concentration and pH decreased. The increasing trend of the physico-chemical parameters downstream was attributed to observable anthropogenic inputs via raw sewage disposal into this rivers, car wash sites, garbage dumpsites close to riverbanks and surface run-off from the town catchment. Inflow of pollutants into the river was made worse by unplanned settlements along the riverbank with lots waste disposal facilities, car-wash bays and garages along it. This study recommends that oversight organizations like NEMA, GWASCO, Ministry of Environment and other related organizations take necessary action to improve the water quality of this river.

Climate Change‐Legacy Phosphorus Synergy Hinders Lake Response to Aggressive Water Policy Targets

AbstractWith mounting scientific evidence demonstrating adverse global climate change (GCC) impacts to water quality, water quality policies, such as the Total Maximum Daily Loads (TMDLs) under the U.S. Clean Water Act, have begun accounting for GCC effects in setting nutrient load‐reduction policy targets. These targets generally require nutrient reductions for attaining prescribed water quality standards (WQS) by setting safe levels of nutrient concentrations that curtail potentially harmful cyanobacteria blooms (CyanoHABs). While some governments require WQS to consider climate change, few tools are available to model the complex interactions between climate change and benthic legacy nutrients. We present a novel process‐based integrated assessment model (IAM) that examines the extent to which synergistic relationships between GCC and legacy Phosphorus release could compromise the ability of water quality policies to attain established WQS. The IAM is calibrated for simulating the eutrophic Missisquoi Bay and watershed in Lake Champlain (2001–2050). Water quality impacts of seven P‐reduction scenarios, including the 64.3% reduction specified under the current TMDL, were examined under 17 GCC scenarios. The TMDL WQS of 0.025 mg/L total phosphorus is unlikely to be met by 2035 under the mandated 64.3% reduction for all GCC scenarios. IAM simulations show that the frequency and severity of summer CyanoHABs increased or minimally decreased under most climate and nutrient reduction scenarios. By harnessing IAMs that couple complex process‐based simulation models, the management of water quality in freshwater lakes can become more adaptive through explicit accounting of GCC effects on both the external and internal sources of nutrients.

Teasing apart the host-related, nutrient-related and temperature-related effects shaping the phenology and microbiome of the tropical seagrass Halophila stipulacea

BackgroundHalophila stipulacea seagrass meadows are an ecologically important and threatened component of the ecosystem in the Gulf of Aqaba. Recent studies have demonstrated correlated geographic patterns for leaf epiphytic community composition and leaf morphology, also coinciding with different levels of water turbidity and nutrient concentrations. Based on these observations, workers have suggested an environmental microbial fingerprint, which may reflect various environmental stress factors seagrasses have experienced, and may add a holobiont level of plasticity to seagrasses, assisting their acclimation to changing environments and through range expansion. However, it is difficult to tease apart environmental effects from host-diversity dependent effects, which have covaried in field studies, although this is required in order to establish that differences in microbial community compositions among sites are driven by environmental conditions rather than by features governed by the host.ResultsIn this study we carried out a mesocosm experiment, in which we studied the effects of warming and nutrient stress on the composition of epiphytic bacterial communities and on some phenological traits. We studied H. stipulacea collected from two different meadows in the Gulf of Aqaba, representing differences in the host and the environment alike. We found that the source site from which seagrasses were collected was the major factor governing seagrass phenology, although heat increased shoot mortality and nutrient loading delayed new shoot emergence. Bacterial diversity, however, mostly depended on the environmental conditions. The most prominent pattern was the increase in Rhodobacteraceae under nutrient stress without heat stress, along with an increase in Microtrichaceae. Together, the two taxa have the potential to maintain nitrate reduction followed by an anammox process, which can together buffer the increase in nutrient concentrations across the leaf surface.ConclusionsOur results thus corroborate the existence of environmental microbial fingerprints, which are independent from the host diversity, and support the notion of a holobiont level plasticity, both important to understand and monitor H. stipulacea ecology under the changing climate.

THE EFFECT OF AB MIX NUTRIENT SOLUTION ON THE HEIGHT, NUMBER OF LEAVES AND FRESH WEIGHT OF LETTUCE (Lactuca sativa L.) IN HYDROPHONICS CULTIVATION SYSTEM

This study focuses on the effects of AB mix nutrient solution to the height, number of leaves, and fresh weight of lettuce (Lactuca sativa L.) in hydroponics cultivation system. The growth of lettuce was assessed by comparing the plants’ height, number of leaves, and fresh weight of the different levels of AB mix nutrient concentrations (0, 650, 1300, 1950, 2600 ppm) with 2 replications in each treatment. HydroPlus hydroponic nutrients by Green Garages an AB mix nutrient solution were used in this study. The duration of the research investigation started from September 2022 until November 2022. Data obtained from observations were analyzed by using Analysis of Variance (ANOVA) at the accuracy level of 1% and 5%. Data revealed that during the first and second weeks after planting, the AB mix nutrient solution showed positive results on the plant’s height in all of the treatments. Moreover, plants began to wilt in the AB mix treatment at 1950 ppm and in the treatment at 2600 ppm during the third and fourth weeks after planting, resulting in significant negative results. The tallest plant’s height was obtained in the fourth week after planting with an AB mix of 650 ppm treatment, and the shortest plant’s height occurred with an AB mix of 2600 ppm treatment. Although in the AB mix 650 ppm treatment there were plants that were shorter than others, the average height in this treatment was higher compared to other treatments. Data analysis showed that AB mix nutrients have a very significant effect on lettuce’s (Lactucasativa L.) number of leaves in the first to the fourth week after planting. The highest number of leaves was obtained from an AB mix concentration of 650 ppm, and the lowest number of leaves was obtained from an AB mix treatment of 2600 ppm. The research investigation revealed that the AB mix nutrient has a very significant effect on the lettuce’s fresh weight 30 days after planting. The highest fresh weight was obtained from an AB mix concentration of 650 ppm, and the lowest fresh weight was recorded from an AB mix concentration of 2600 ppm. Based on the results of this study, having too much or too little of the AB mix nutrient solution has a bad effect on the fresh weight of lettuce.

Respon Pertumbuhan Tiga Varietas Selada (Lactuca sativa L.) terhadap Konsentrasi Nutrisi AB Mix Secara Hidroponik

Alternative ways to meet the needs of vegetables as their daily nutritional intake for the body, one of the leaf vegetables like lettuce are rich in vitamins, minerals, and other nutrients. Public awareness of the importance of eating vegetables is increasing lately, ironically, the availability of agricultural land decreases due to the conversion of agricultural land. One effort that can be done is by vegetable hydroponic farming. The research objective was to determine the best response of varieties of lettuce on levels of nutrient concentrations (AB mix). The research was conducted in the village of Jember Kidul, District Kaliwates Jember in altitude ± 100 m above sea level, in April to June 2016. The study was conducted using a randomized block design (CRD) consisting of two factors: the first factor is the concentration of the nutrient treatments AB mix (K) consisting of 500 ppm (K1), 550 ppm (K2), 600 ppm (K3). The second factor is the treatment of a wide variety of green lettuce is lettuce green Maat (V1), green lettuce green olivia (V2), red lettuce lolo rosa (V3). The results showed matt green lettuce varieties (V1) has the best growth response and significantly different on all parameters except observations observation root length. Treatment nutrient concentrations AB Mix real effect only on the parameter number of leaves and the fresh weight of the total that is best at a concentration of 600 ppm (K3), but no significant effect on observations of plant height, root length and dry weight. Interaction between wide varieties of lettuce and nutrition konstrasi AB Mix all parameters showed no significant observations.

Automatic hydroponic nutrient mixing for hydroponic NFT and fertigation

This paper aims to create hydroponic nutrient mixing system automatically for circulation hydroponic system like NFT (Nutrient Film Technique) and for non-circulation hydroponic system such as drip irrigation system. System continuously sense nutrient concentration and pH level with EC (Electrical Conductivity) sensor and pH sensor. This data will process by ESP32 Wi-Fi microcontroller for monitoring and control dosing pump to maintain nutrient solution EC and pH with the predefined target. In non-circulated hydroponic, nutrition and water will flow into the irrigation system, to control humidity level in plant media, system use soil moisture level sensor. System use IoT cloud Blynk for easy user control and monitoring, user can use application in their smartphone. Test result shows system can increase the EC value from current condition 0.7 to target 3 within ±9 minutes and can maintain the EC value.

A Study of the Effectiveness of Hydroponic Growing Variables on Lactuca sativa var. capitata

Hydroponic growing in controlled environment horticulture has been an increasingly used method of produce production around the world. Its many methods integrate sustainability and growth efficiency through the control of climatic and system variables. This study investigated control variables that would produce and market a more effective lettuce (lactuca sativa. var capitata) crop. Three objectives determined: The comparison between the dimensions of deep water culture systems and the lettuce harvesting length, Consumer and ICP spectrometry recognition of different post-harvest hydroponic nutrient concentration, and the preference of lettuce grown in different hydroponic nutrient concentrations. Through growing trials and consumer tests, it was found that the 14 gallon (102 x 50.8 x 66cm) size deep water culture system also produced lettuce with larger harvest-length; spectrometry recognition of lettuce crops grown in different nutrient levels was effective with 7 of the 12 nutrients elements showing sufficient results of concentration in concentrated lettuce. Consumer identification recognition wasn’t successful with 40% of consumers unable to recognize any nutrient concentration level compared to two other varieties. Representing a diverse market audience, of consumers determined that variety 127 (50% regular concentration) was preferred as significant market influence of purchase. This research will impact future studies in effective small scale hydroponic growing and growers looking to expand knowledge of beneficial growth.

Extending the growth rate hypothesis to species development: Can stoichiometric traits help to explain the composition of macroinvertebrate communities?

Ecological stoichiometry seeks to understand the ecological consequences of elemental imbalances between consumers and their resources. Therein, the well‐accepted growth rate hypothesis (GRH) states that organisms exhibiting rapid growth have higher phosphorus (P) demand – and thus lower C:P and N:P ratios – than slow growing ones, due to a higher allocation to P‐rich rRNA. However, GRH has rarely been extended to other biological traits than growth, especially at the community level. In this study, we investigated whether macroinvertebrate stoichiometric traits (e.g. C:P and N:P ratios) can be linked to their development traits, and whether these stoichiometric traits are related to macroinvertebrate community assemblage under different nutrient conditions. We allocated more than 400 European taxa to different groups, defined using available information about three development‐related traits: ‘life span', ‘voltinism' and ‘number of reproductive cycles per individual'. We sampled 18 invertebrate taxa in six streams exhibiting different levels of nutrient concentration and measured their stoichiometric traits. Further, we quantified invertebrate taxon abundances in these streams during an annual survey. Based on these data, we tested whether community composition regarding the developmental groups differs, depending on nutrient concentration. We found significant differences in the proportions of the developmental groups along a gradient of water N:P, in relation to their stoichiometric traits. Taxa with low C:P and N:P ratios were generally associated with faster development groups, and these taxa tended to occur at higher proportions in streams exhibiting low dissolved N:P ratios. In contrast, communities from P‐poor, high dissolved N:P streams, were dominated by slowly developing taxa with high N:P ratios. Our results highlight that extending the GRH to species development rate might give some insights about the mechanisms by which nutrient concentrations in ecosystems influence consumers' community composition.