Levels Of Electrical Conductivity Research Articles

A water acquisition strategy may regulate the biomass and distribution of winter forage species in cold Asian rangeland

AbstractAboveground biomass is often restricted by water availability; therefore, water acquisition strategies have important roles in determining biomass volume and distribution under arid conditions. In cold Asian rangelands, the large tussock grass Achnatherum splendens is the most important forage for maintaining livestock under severe winter conditions. However, A. splendens distribution is restricted to the middle of the slopes of ephemeral streams, making it difficult to manage winter foraging. To understand the mechanisms behind the specific distribution and maintenance of a large A. splendens biomass under arid conditions, we established four typical vegetative plots along a riverside slope with different A. splendens density levels and elevations: river bottom with no A. splendens, riverbank with a large A. splendens community, upper slope with an isolated A. splendens community, and flat plain with no A. splendens. We measured the soil pH and electric conductivity (EC) of the plots and investigated the vertical biomass and root distribution of A. splendens. We also investigated the water source for the A. splendens communities using isotope techniques. The soil pH was not different among plots, while the soil EC was significantly higher in the river bottom because of salt accumulation. However, low soil EC levels were found under the A. splendens communities. In the ground below the A. splendens communities, plant stems were buried deeply. The belowground biomass and buried stem depths decreased at the sites of the isolated A. splendens communities in the upper slope. The aboveground biomass of A. splendens increased as the stem burial depths and, therefore, the adventitious roots depths increased. The water source of A. splendens was estimated to be at a depth of more than 30 cm. Thus, A. splendens prefers a habitat with a low level of soil salinity and a high level of water availability, which may increase with the sand burial depth because of the increasing accessibility of a substantial water source in the deeper soil layer. Sand burial may affect the water acquisition strategy and maintenance of large biomasses of tussock grass species that act as important winter forage in cold Asian rangelands.

Development and evaluation of novel salt-tolerant Eucalyptus trees by molecular breeding using an RNA-Binding-Protein gene derived from common ice plant (Mesembryanthemum crystallinum L.).

SummaryThe breeding of plantation forestry trees for the possible afforestation of marginal land would be one approach to addressing global warming issues. Here, we developed novel transgenic Eucalyptus trees (Eucalyptus camaldulensis Dehnh.) harbouring an RNA‐Binding‐Protein (McRBP) gene derived from a halophyte plant, common ice plant (Mesembryanthemum crystallinum L.). We conducted screened‐house trials of the transgenic Eucalyptus using two different stringency salinity stress conditions to evaluate the plants’ acute and chronic salt stress tolerances. Treatment with 400 mM NaCl, as the high‐stringency salinity stress, resulted in soil electrical conductivity (EC) levels >20 mS/cm within 4 weeks. With the 400 mM NaCl treatment, >70% of the transgenic plants were intact, whereas >40% of the non‐transgenic plants were withered. Treatment with 70 mM NaCl, as the moderate‐stringency salinity stress, resulted in soil EC levels of approx. 9 mS/cm after 2 months, and these salinity levels were maintained for the next 4 months. All plants regardless of transgenic or non‐transgenic status survived the 70 mM NaCl treatment, but after 6‐month treatment the transgenic plants showed significantly higher growth and quantum yield of photosynthesis levels compared to the non‐transgenic plants. In addition, the salt accumulation in the leaves of the transgenic plants was 30% lower than that of non‐transgenic plants after 15‐week moderate salt stress treatment. There results suggest that McRBP expression in the transgenic Eucalyptus enhances their salt tolerance both acutely and chronically.

The increase in electrical conductivity of nutrient solution enhances compositional and sensory properties of tomato fruit cv. Patrón

The intensity of tomato taste is affected by the increase of total soluble solids (TSS). Tomato fruit is characterized by its high TSS content that could be modified by different metabolic and physiological pathways. These pathways can be affected by pre and postharvest factors having a marked effect in the quality of tomato fruit at consumer ripeness. In this study, an increase of the electrical conductivity (EC) of the nutrient solution (2.2 dS m−1 and 4.5 dS m−1) in two crop cycles of soilless tomate: fall-winter and spring-summer were evaluated. The evolution of physico-chemical and physiological parameters associated to fruit quality at different developmental stages and differences in compounds associated to the primary metabolism and taste (sugars, organic acids and aminoacids) and with a sensory panel at the red stage for both EC treatments and crop cycles were evaluated. The fall-winter cycle with the highest 4.5 dS m−1 EC level presented not only higher content of TSS associated to a higher concentration of aminoacids (l-serine, threonine, l-aspartic and glutamate) that possibly affected the taste and were positively perceived by the sensory panel. However, the spring-summer cycle with the highest level of EC (4.5 dS m−1) presented a higher concentration of TSS and organic acids during early stages of fruit development and were not perceived positively by the sensory panel. The present study provides interesting and useful results with direct commercial application to obtain better taste tomatoes.

Growth and nutrients content of Atriplex canescens across a soil electric conductivity gradient

Atriplex canescens canopy cover, biomass production, and nutrient content were evaluated after four years of livestock grazing exclusion and mechanical shrub removal, except A. canescensin an arid rangeland with a slightly saline soil and with a long history of heavy livestock grazing in the southern Chihuahuan Desert, Mexico (24° N). Twenty 3 × 3 m paddocks were established in terrains with three levels of electric conductivity (EC): <1.4 dS/m (n=7), 1.4–1.6 dS/m (n=7) and >1.6 dS/m. Atriplex canescens canopy cover was higher (49.5%; p<0.01) on paddocks with soil EC >1.6 dS/m than paddocks with soil EC <1.4 and 1.4–1.6 dS/m (32.1 and 22.9%, respectively). Above-ground biomass did not differ between paddocks with soils with EC of <1.4 and 1.4–1.6 dS/m (1309 ± 535 and 1372 ± 180 kg DM/ha), but biomass increased 2.7 times (p<0.01) when soil EC was greater than 1.6 dS/m. The soil EC had no effect on the levels of crude protein (range 13.6 to 14.3%), neutral detergent fiber (range 56.5 to 57.7%) and ash (range 14.5 to 16.4%). In vitro dry matter digestibility (IVDMD) of the foliage of A. canescens was not affected by of soil EC level (range 60.4 to 62.2%). It was concluded that in an arid rangeland with slight saline soil, the increase in salinity favors canopy cover and biomass production of A. canescens without altering nutrient content and IVDMD of this fodder shrub.

Development of Automatic Mixing Process for Fertigation System in Rock Melon Cultivation

This work proposed an automatic mixing system of nutrient solution for rock melon fertigation according to the required electrical conductivity (EC) level. Compared to the manual practice, this automatic system will ensure continuous supply of mixed nutrient solution without the need to daily check and mix new nutrient. Thus, this easy to use and low cost automatic system will reduce the burden of the farmers. This system uses an EC sensor to automatically check the concentration level of the mixed nutrient solution. Other than that, the system only consists of electronic pumps for mixing process and an Arduino board as the controller. The controller will monitor the EC level and run the mixing process when the EC level is below the required level. By calibrating the EC sensors, the test shows that the automatic mixing system is able to accurately keep the mixed nutrient solution concentration in a 400 L mixing reservoir at several required levels.

Response of photosynthetic performance, water relations and osmotic adjustment to salinity acclimation in two wheat cultivars

Experiment was conducted to identify the impacts of the salinity acclimation process on the photosynthetic efficiency, osmotic adjustment, membrane integrity, and yield components in two wheat cultivars differing in their salinity tolerance. The design of the experiment was factorial randomized block, where genotype is factor 1 and acclimation treatments represent factor 2. Genotypes were grown from emergence to 30 days after sowing (DAS) by irrigating with tap water [electrical conductivity (EC) of 0.776 dS m−1]. Thereafter, both the genotypes were divided into two groups and exposed to either irrigation with sublethal level of salinity EC of 2.09 or 3.76 dS m−1 for 21 days. At booting stage (65 DAS), both groups were subjected to lethal level of salinity stress EC of 12 dS m−1 for 21 days, followed by irrigation with tap water till maturity. Non-acclimated plants were irrigated with tap water from emergence to 65 days, then directly irrigated with lethal level of salinity for 21 days, followed by irrigation with tap water till maturity. The control plants were continuously irrigated with tap water from emergence until maturity. The non-acclimated plants had decreased electron transport rates at the donor and acceptor side of PSII and PSI in Giza 168, and decreased electron transport rates at PSII acceptor side in Sakha 8 compared to control plants. In both genotypes, the non-acclimated plants had decreased chlorophyll a, b, carotenoid, proline and total soluble sugar concentration, relative water content, membrane stability index, yield and yield components compared with acclimated plants. While, osmotic potential and lipid peroxidation showed an opposite trend. Overall, acclimation treatment (EC of 2.09 dS m−1) during vegetative stage alleviated the inhibitory effects of lethal level of salinity stress at booting stage through enhanced photosynthetic efficiency and osmotic adjustment, resulting in increased membrane integrity, biomass production and grain yield than in non-acclimated plants.

Response of Weeping Lantana (Lantana montevidensis) to Compost-Based Growing Media and Electrical Conductivity Level in Soilless Culture: First Evidence.

The most common substrate for potted ornamental plants is prepared with Sphagnum peat; however, the cost and declining availability of high-quality peat, due to environmental constraints, make it necessary to investigate for alternative organic materials. The present study aimed to determine the effects of partial compost replacement with peat and the optimum electrical conductivity (EC) level of the nutrient solution in potted weeping lantana [L. montevidensis (Spreng.) Briq.] under a recirculating soilless system. Three compost-based substrates were prepared by mixing peat (Pe) with sewage sludge-based compost (Co.) at a rate of 0% (Pe90Co0Pu10, control), 30% (Pe60Co30Pu10), or 60% (Pe30Co60Pu10), respectively. The soilless recirculated closed system was equipped with two different EC levels (high and low) of nutrient solution. Growing media main characteristics and plant bio-morphometric parameters were evaluated. Our first evidence clearly demonstrates that the replacement of peat with compost at doses of 30% and 60% gave the poorest results for plant diameter, shoots, leaves, flowers, and fresh and dry mass, probably indicating that the physical characteristics of the compost based substrates may be the major factor governing plant growth rate. Compost media pH and EC values, too, showed negative effects on plant growth. Considering the effect of EC level, all morphological traits were significantly improved by high EC compared to low EC in weeping lantana. Thus, based on first evidence, further research is needed on organic materials for the establishment of ecological substrates with optimal physicochemical characteristics for the growth of weeping lantana.

Water potential in soil and Atriplex nummularia (phytoremediator halophyte) under drought and salt stresses

ABSTRACTAtriplex nummularia is a halophyte widely employed to recover saline soils and was used as a model to evaluate the water potentials in the soil-plant system under drought and salt stresses. Potted plants grown under 70 and 37% of field capacity irrigated with solutions of NaCl and of a mixture of NaCl, KCl, MgCl2 and CaCl2 reproducing six electrical conductivity (EC): 0, 5, 10, 20, 30, and 40 dS m−1. After 100 days, total water (Ψw, plant) and osmotic (Ψo, plant) potentials at predawn and midday and Ψo, soil, matric potential (Ψm, soil) and Ψw, soil were determined. The type of ion in the irrigation water did not influence the soil potential, but was altered by EC. The soil Ψo component was the largest contributor to Ψw, soil. Atriplex is surviving ECs close to 40 dS m−1 due to the decrease in the Ψw. The plants reached a Ψw of approximately −8 MPa. The water potentials determined for different moisture levels, EC levels and salt types showed huge importance for the management of this species in semiarid regions and can be used to recover salt affected soils.

Hierarchical pattern recognition in milking parameters predicts mastitis prevalence

The aim of this study was to develop a predictive model for mastitis incidence, independent from Somatic Cell Count (SCC), to provide an alternative, simple, and cost-effective approach for mastitis risk management based on available milking parameters. The test-day Somatic Cell Count (SCC) is the most common indicator for Sub-Clinical Mastitis (SCM) surveillance in dairy industries worldwide. However, SCC is highly variable between days, raising major concerns for its reliability. This caveat highlights the need for longitudinal/frequent monitoring of SCC and/or developing alternative approaches for SCM surveillance. A considerable proportion of available milking data such as Milk Volume, Protein, Lactose, Electrical Conductivity (EC), Milking Time, and Peak Flow provide the possibility of pattern recognition and model discovery towards mastitis occurrence. Developing a predictive model involves: (1) finding the threshold (cutoff) of different predictive milking parameters and (2) finding the best combination of features that lead to mastitis and their hierarchical pattern/order. Here, in a large-scale study on 346,248 milking records, for the first time, we evaluated four different decision tree algorithms (Decision Tree, Stump Decision Tree, Parallel Decision Tree and Random Forest Decision Tree) with four different criteria (Accuracy, Info Gain, Gini Index and Gain Ratio) run on 11 datasets (original dataset and 10 created datasets by attribute weighting selection algorithms). Therefore, 572 models were evaluated and compared by 10-fold cross validation. The performance of each decision tree in drawing an inverted tree; with the most important feature at the root and less important variables as the leaf; was calculated by 10-fold cross validation. Random Forest Decision Tree with Gini Index criterion was the best model for predicting mastitis from milking parameters with a high accuracy of 90%. Decision Tree models identified a strong pattern for SCM in milking data where all (100%) of cows with low levels of lactose (Lactose ≤ 4.5 g/L) and low milk volume (Volume ≤ 21.7 L) had mastitis. In addition, a significant pattern was found for identifying healthy cows by high levels of lactose (Lactose ≥ 4.5 g/L) and low levels of EC (EC ≤ 5.2). This study doccuments that milking parameters mined by the Decision Tree Random Forest model can be utilised to accurately predict SCM. The findings can be employed to increase the reliability of test-day SCC or as SCC-independent and cost-effective predictors of SCM.

Extensive reclamation of saline-sodic soils with flue gas desulfurization gypsum on the Songnen Plain, Northeast China

Previous studies have reported that flue gas desulfurization (FGD) gypsum can be used as an amendment for saline-alkali soils. However, little information is available regarding the effects of FGD gypsum on soil quality and crop production at large scales. Thus, we evaluated the changes in the soil salinity, sodicity, soluble ion levels, paddy rice (Oryza sativa L.) yield and heavy metal levels in soil and rice after reclamation with FGD gypsum and paddy planting over three years. Data (90 samples) were also collected from three neighbouring saline-sodic fields (1780 ha). As expected, soil salinity and sodicity decreased significantly after two years of reclamation. The levels of electrical conductivity (EC) and the sodium absorption ratio (SAR) decreased rapidly in the first year, and the pH and exchangeable sodium percentage (ESP) decreased substantially in the second year. Averaged across the experimental sites, the mean EC, pH, ESP and SAR levels of the soils two years after reclamation decreased by 38.6%, 14.6%, 61.2% and 87.8%, respectively, compared to those of the initial soils. In addition, the concentrations of water-soluble Na+ and CO32− + HCO3− were 97.5% and 96.8% lower, respectively, two years after reclamation than the concentrations before reclamation. The paddy rice yield increased over time with reclamation; the mean level in the second year was 7.4 t ha−1 or 80% of the yield harvested from the managed fields of neighbouring farmers. Moreover, the heavy metal (Cd, Cr, Hg, Pb and As) contents of both soils and rice were lower than the established standards and below detectable limits after FGD gypsum application. These results confirm that FGD gypsum is a safe and effective way to reclaim saline-sodic soils and worthy of widespread application on the Songnen Plain in Northeast China and in similar ecological areas.

Response of Japanese Privet to Plastic Mulch Applied over Nonspaced Containers

Mulches have many positive benefits for the production of plants, ranging from weed suppression to water conservation. In this study, a novel method of using plastic film mulch for container-grown plants was evaluated. Plots of 25 japanese privet (Ligustrum japonicum) in #1 (2.5 qt) nonspaced containers were wrapped with 1.25-mil white or black plastic mulch over the top and sides of containers. Small plants were planted through the plastic and grown for 22 weeks with overhead irrigation. Water application amount was determined by moisture sensors placed in the substrate of each treatment. Plant growth, dry weights (DWs), weed fresh weights, weeding time, substrate electrical conductivity (EC), substrate temperature, total water applied, and mulch costs were determined. Black plastic (BP) and white plastic (WP) mulch reduced water applied by 82% and 91%, respectively, compared with the nontreated control (NT). Nontreated control plants grew faster and had greater DW at the end of the experiment. Mulched containers had fewer weeds and required less labor to remove weeds than the NT treatment. Substrate EC level was greater in BP and WP treatments than for the NT after 20 weeks, and plastic mulch did not result in different substrate temperatures. Plastic mulch added $4.94/1000 containers ($2.24 input cost and $2.70 removal cost) to production costs, not including disposal costs. This novel method of mulching nonspaced plants reduced irrigation water, herbicide applications, and weeding labor, but probably added 2–3 weeks to finish time.

Processing methods of organic liquid fertilizers affect nutrient availability and yield of greenhouse grown parsley

AbstractThe demand for organic foods is increasing globally, but a key limiting factor to the production of organic greenhouse produce is the lack of certified liquid fertilizers. In this experiment, four organic fertilizers were produced using either acidic extraction, anaerobic digestion or both of ensiled biomass of organic red clover and white mustard. The resulting fertilizers were applied to greenhouse-grown parsley either alone, or in combination with nitrogen (N)-enriched water produced by flushing acidic water with ammonia, to determine their effect on plant growth and the nutrient concentrations of parsley. Six combinations of fertilizer treatments were included in the greenhouse experiment. Three treatments received either fertilizers derived from acidic extraction, anaerobic digestion or both and three treatments received fertilizers derived from acidic extraction combined with N-enriched water. Conventional inorganic liquid fertilizer, chicken manure extract and no liquid fertilizer (only water) were added as control treatments. A higher N-min (ammonium and nitrate) to potassium (K) ratio was found in fertilizers after anaerobic digestion compared to acidic extraction. All organic fertigation treatments resulted in high pH, high K and chloride concentrations and high NH4/NO3 ratios in the root zone. In addition, high electrical conductivity (EC), P, K and Mg concentrations were found when only acidic extracted fertilizers were applied. Application of plant-based organic fertilizers without amending with N-enriched water resulted in biomass yields that were 21–26% lower than the inorganic fertigation control. However, fertigation with chicken manure extract, or a combination of fertilizer derived from acidic extraction and N-enriched water, resulted in similar plant growth as inorganic fertilizer. The lower yield from fertilizer derived from acidic extraction was due to elevated EC levels in the growing medium. Our results suggest that yield of greenhouse-grown parsley using either organic fertilizers combined with N-enriched water or chicken manure extract is similar to conventional fertilizer.

Differential Tolerance of Glyphosate-Susceptible and Glyphosate-Resistant Biotypes of Junglerice (Echinochloa colona) to Environments during Germination, Growth, and Intraspecific Competition

AbstractMuch of the agricultural area in California’s southwestern San Joaquin Valley (SJV) is prone to moisture stress and high soil-salinity conditions. Increased prevalence of glyphosate-resistant (GR) biotypes of junglerice [Echinochloa colona (L.) Link] in these environments and their ecological implications need to be further explored. Studies were conducted on GR and glyphosate-susceptible (GS) biotypes of E. colona to compare the effects of moisture and salinity stress on seed germination and salinity stress alone on growth and seed production. Intraspecific competition between the GR and GS plants was also assessed in a replacement series design experiment. With respect to germination, both biotypes were tolerant to moisture and salinity stress at germination; however, the GR biotype was more tolerant than the GS biotype. Water potential and electrical conductivity (EC) levels that reduced germination by 50% were estimated as −1.5 and −2.3 MPa and 8.5 and 12 dS m−1 for the GS and GR biotypes, respectively. The EC levels that reduced aboveground biomass by 50% were estimated as 9 and 11.5 dS m−1 for the GS and GR biotypes, respectively. Seed production was generally greater in the GR than the GS plants below 10 dS m−1. All plants produced up to 140 seeds plant−1, even at 20 dS m−1. The GR plants were more competitive and produced more aboveground dry biomass and seeds than the GS plants when grown together or alone. In conclusion, differences between these particular GR and GS biotypes to environmental stresses and intraspecific competition were noted that could have ecological implications for their prevalence in the southwestern SJV. The results also suggested that there could be high genetic variability and phenotypic plasticity in E. colona populations in the SJV and further population shifts could occur due to selection pressure from glyphosate.

Leaching characteristics of nitrate nitrogen in an apple orchard andosol under significant snow accumulation

The purpose of this study was to clarify nitrogen (N) leaching behavior as affected by snowmelt percolation in an Andosol soil planted with an established apple orchard, with the aim of supporting fertilization management that preserves the soil environment while maximizing apple production. Simultaneous measurements of electrical conductivity (EC), pH, NO3-N, and NH4-N (inorganic-N concentration) of the apple orchard soil pore water were taken. The adsorption nature of NO3-N and NH4-N were also monitored using Langmuir type and Logistic type adsorption isotherms. Numerical analysis relevant to the spatiotemporal dynamics of inorganic-N in soil pore water was also conducted during the growing and non-growing period for apples. The level of soil pore water EC resulting from fertilizer application was characteristically altered by downward leaching over time. Regarding the NO3-N concentration of soil pore water in the investigated area with heavy snow accumulation, the bulk of the fertilizer applied from January to July 2016 was leached down to z=100cm within 5 to 6months. In the apple orchard during and after snowfall, the numerical results revealed that when NO3-N<100mgL−1, NO3-N was leached without being adsorbed by the soil. In addition, since the NO3-N concentration in soil water after the disappearance of snow was very low, it is necessary to apply N fertilizer in early April (initial growth stage of current shoots and anthogenesis) in order to maximize apple tree growth. Extreme N-leaching due to percolated snowmelt in early spring (a 35-cm movement within 0.5months) was observed in the apple orchard planted on Andosol soil. Therefore, it was inferred that concentrations of inorganic-N in the soil during April were reset to zero, and that N supplementation in the apple orchard is necessary for maximizing apple production.

Effects of surface gold mining on surface and groundwater bodies in Bibiani, Ghana

A study of the water sources from Bibiani and its environs was conducted between November, 2009 and April, 2010 to determine whether contamination (of water sources) from (these parameters) physical, chemical and trace metal in Bibiani is as a result of mining or geochemicaland biochemical processes within the environment. This was done by collecting water samples from two streams, two rivers, three boreholes (BHs) and three hand dug wells (HDWs). These were analysed in the laboratory. Levels of Arsenic (As), Iron (Fe), Manganese (Mn), pH, TotalDissolved Solids (TDS), Electrical Conductivity (EC), Temperature, Alkalinity, Hardness, Phosphate (P) and Cyanide (CN) in water sources were determined. Mining related contaminants detected in water samples were As, CN, Mn and Fe. It was observed that surface water pH values were generally higher than that of groundwater samples. As concentrations in surface water samples were higher compared to that of groundwater samples. Also, CN concentration in ground water samples was higher than that of surface water. Ground water contained higher concentration of Mn than surface water; the opposite can be said of Fe concentration in surfacewater which was higher than that of ground water. The study also observed that pH, TDS, EC, total alkalinity, total hardness , Arsenic and total cyanide levels in the HDW and BH samples showed 100% compliance with the WHO and EPA limits while Mn and Fe levels indicated traces of non – compliance. Compared to WHO / EPA guidelines, few water sources had one or moretrace metal (Fe, As and Mn) levels outside acceptable limits for drinking. However, most of the levels were safe for human consumption.Keywords: Surface, gold mining, quality, degradation, Bibiani

The Utilization of Red Mud as a Plant Growing Medium with The Addition of Ultisol Soil Material and Compost

The utilization of red mud, which is a residue from the extraction of aluminum from mined bauxite ore, as a plant growing medium, needs to be studied further. There are some chemical aspects that may hinder the growth of, or even cause mortality in, plants such as very high pH, electrical conductivity (EC) and exchangeable Na (Na exch ), and very low nutrient elements content. The objective of this study was to investigate the effects of adding Ultisol soil material, mixed with compost, both soil ameliorating agents, to red mud for use as a growing medium for Sengon ( Paraserianthes falcataria ) seedlings. This study was conducted in two stages, namely: washing of the red mud, and trial planting in the greenhouse using different combinations of the soil ameliorants. Washing of the red mud with tap water was intended to reduce the levels of Na, EC, and pH. Trial planting in the greenhouse was carried out in 2-factorial Completely Randomized Design (CRD). Factor 1 was the proportion of the mixture of Ultisol soil material (sm-Ultisol) and red mud, viz : (1) 1500 g red mud + 0 g sm-Ultisol, (2) 1000 g red mud + 500 g sm-Ultisol, and (3) 750 g red mud + 750 g sm-Ultisol. Factor 2 was the dosage of compost that was mixed with the red mud and sm-Ultisol, namely: 0, 58.6, and 117.2 g/polybag which corresponded to 0, 2.5 and 5 kg/planting hole, respectively. The results of the trial indicated that washing the red mud could reduce the level of EC from 28.70 dS m -1 to 2.68 dS m -1 ; but it reduced pH and Na exch only from 11.91 and 149.38 cmol (+) kg -1 to become 10.55, and 66.74 cmol (+) kg -1 , respectively. A better outcome was obtained after the red mud was washed and then, mixed with sm-Ultisol up to 1:1 proportion in which resulted in lower rates of pH, EC, and Na exch from 10.28, 2.53 dS m -1 and 62.79 cmol (+) kg -1 to 8.65, 2.07 dS m -1 and 45.01 cmol (+) kg -1 , respectively. The treatment of using a mixture of 750 g red mud + 750 g sm-Ultisol, and adding compost at 117.18 g/polybag gave the best result in improving the chemical property of the red mud growing medium, and producing the best plant growth among all treatment combinations.

Raising healthy seedling rootstocks of mango

The mango orchards of Pakistan are declining continuously in their productivity due to the soil-borne fungal disease “sudden death” and the entophytic fungal disease “mango malformation”. The possible cause of the diseases can be spread from the infected nursery. This can be better managed by producing containerized mango stock, as traditional field plantation is possibly the vector of these diseases. An experiment was undertaken to evaluate five potting mixes using local ingredients for their suability to grow mango seedlings. The experiment was conducted in an insect-proof shadehouse at Sindh Agriculture University, Tandojam, Pakistan, in 2013. Mango seed was planted in five potting mixes: M1, press mud (60%) + bagasse (40%); M2, press mud (40%) + silt (60%); M3, press mud (60%) + bagasse (20%) + coconut fibre (20%); M4, press mud (30%) + silt (30%) + bagasse (20%) + coconut fibre (20%); and M5, press mud (50%) + bagasse (20%) + coconut fibre (30%). Each potting mix and irrigation water was tested for electrical conductivity (EC), pH and chlorine. Seed sprouting was observed at 100% from each potting mix except M1 and M2. M4 was observed the best potting mix for growth-related attributes, and data were recorded after 2 and 4 months of plantation with maximum plant height (19.6 and 31.3 cm), stem diameter (4.4 and 7.2 mm) and number of leaves (6.3 and 21.3). However, necrosis and mortality of seedlings were observed after 4 months of plantation, and this mortality was observed because of increasing levels of EC in potting mixes.

Metal pollution status of Tajan River – Northern Iran

ABSTRACTThe monitoring of surface water quality of rivers is crucial to protect aquatic life and receiving water bodies of economic importance. The aim of the current study was to examine selected physicochemical parameters of River Tajan due to its ecological importance in Iran. Water samples from nine points covering the entire Tajan River and Caspian Sea estuary were collected and analyzed for pH, electrical conductivity (EC), total dissolved solids (TDS), carbonates, chlorides and selected heavy metals including zinc, cadmium, lead and chromium. The pH and levels of EC, TDS, chlorides, carbonates and all metals were within the USEPA reference guidelines for surface water quality standards. Although these water quality parameters are considered safe, continuous monitoring and assessment is recommended in order to protect the coastal receiving waters of Caspian Sea which serves as a tourist attraction in northern Iran.

Assessment of Heavy Metal Concentrations in Pawpaw (Carica papaya Linn.) around Automobile Workshops in Port Harcourt Metropolis, Rivers State, Nigeria.

Background.Consumption of plants such as Carica papaya grown around automobile workshops is common in big cities in Nigeria. However, little is known about the heavy metals contamination of these consumables due to the influence of automobile emissions during maintenance activities.Objectives.This study aimed to assess heavy metal concentrations in C. papaya and supporting soils around automobile workshops in Port Harcourt Metropolis, Rivers State, Nigeria.Methods.Seven automobile workshops were used for the present study. First, 20 m × 20 m quadrats were laid out for soil and C. papaya tissue sampling. One composite soil sample was collected from the topsoil (0–15 cm depth) around each of the automobile workshops. Three C. papaya stands at least 30 cm apart around each workshop were used for the study and from these stands, tissues (root, stem, leaf, fruit) of C. papaya were collected. Standard laboratory techniques were used to determine the pH, electrical conductivity (EC) and heavy metals (lead (Pb), mercury (Hg), cadmium (Cd), copper (Cu), and zinc (Zn)) in the soil samples and C. papaya tissues. Pairwise t-test was used to determine significant differences (p<0.05) in the heavy metal concentrations in soil and C. papaya tissues between the sample and control sites, while correlation statistics were used to determine the relationship of heavy metal concentrations between soil and C. papaya tissues.Results.C. papaya tissues and supporting soil had significantly higher levels of pH, EC and heavy metals in the sampled plots than the control plot. The heavy metal concentrations in C. papaya and soil occurred in the decreasing order of Pb>Cu>Hg>Zn>Cd. The fruit of C. papaya had the highest mean concentrations of Pb (51.4±14.1 mg/kg) and Zn (26.4±1.9 mg/kg), while the leaf had the highest mean concentration of Hg (32.0±2.3 mg/kg). The pH, Cu and Zn in the supporting soil were significantly correlated with the levels in the C. papaya tissues.Conclusion.Bio-accumulation of heavy metals by C. papaya is evident around automobile workshops, and Pb, Hg, Cd concentrations were found to be above the permissible limits for human consumption according to World Health Organization (WHO) standards. Consumption of food materials grown around automobile workshops could pose health risks.

Growth and Accumulation of Secondary Metabolites in Perilla as Affected by Photosynthetic Photon Flux Density and Electrical Conductivity of the Nutrient Solution.

The global demand for medicinal plants is increasing. The quality of plants grown outdoors, however, is difficult to control. Myriad environmental factors influence plant growth and directly impact biosynthetic pathways, thus affecting the secondary metabolism of bioactive compounds. Plant factories use artificial lighting to increase the quality of medicinal plants and stabilize production. Photosynthetic photon flux density (PPFD) and electrical conductivity (EC) of nutrient solutions are two important factors that substantially influence perilla (Perilla frutescens, Labiatae) plant growth and quality. To identify suitable levels of PPFD and EC for perilla plants grown in a plant factory, the growth, photosynthesis, and accumulation of secondary metabolites in red and green perilla plants were measured at PPFD values of 100, 200, and 300 μmol m-2 s-1 in nutrient solutions with EC values of 1.0, 2.0, and 3.0 dS m-1. The results showed significant interactive effects between PPFD and EC for both the fresh and dry weights of green perilla, but not for red perilla. The fresh and dry weights of shoots and leafy areas were affected more by EC than by PPFD in green perilla, whereas they were affected more by PPFD than by EC in red perilla. Leaf net photosynthetic rates were increased as PPFD increased in both perilla varieties, regardless of EC. The perillaldehyde concentration (mg g-1) in red perilla was unaffected by the treatments, but accumulation in plants (mg per plant) was significantly enhanced as the weight of dry leaves increased. Perillaldehyde concentrations in green perilla showed significant differences between combinations of the highest PPFD with the highest EC and the lowest PPFD with the lowest EC. Rosmarinic acid concentration (mg g-1) was increased in a combination of low EC and high PPFD conditions. Optimal cultivation conditions of red and green perilla in plant factory will be discussed in terms of plant growth and contents of medicinal ingredients.