Low Nutrient Levels Research Articles

A coherent status of summer monsoon phytoplankton communities (2017–2018) along the Western Indian continental shelf: Implications for fisheries

The western Indian continental shelf is characterized by contrasting biogeochemical features from south to north mostly governed by monsoon wind forcing. Here we present the first detailed study on the phytoplankton community (analyzed by marker pigments and microscopy) during the summer monsoon addressing the interannual variability (Aug 2017 and 2018) along the Western Indian Continental Shelf waters (8° N-21° N, at 200 m isobaths). A distinct interannual variability in monsoon impacted the hydrography and nutrient stoichiometry that was further cascaded to the phytoplankton community structure. The timing of the monsoon onset, wind speeds, and the strength of the alongshore wind component were the major factors that governed the interannual variability in the development and progression of the upwelling as well as phytoplankton bloom. The upwelling-dominated southwestern shelf was characterized by cold, nutrient-rich waters dominated by the marker pigment of diatoms, fucoxanthin, and microscopy also revealed the presence of large, chain-forming diatoms (Chaetoceros sp.; Dactyliosolen fragilissimus). In contrast, low nutrient warm waters in the northern shelf housed nanophytoplankton and picophytoplankton along with small diatoms (Thalassiosira sp.) and dinoflagellates (Gymnodinium sp.). Interestingly, in a few stations in the southern shelf, the surface waters were low saline that was intensified in 2018 compared to 2017 inhibiting upwelled water from reaching the surface. Consequently, due to low nutrient levels caused by reduced upwelling and low salinity, picoplanktonic cyanobacteria dominated replacing the larger diatoms that were found plenty in 2017. Likely, such a niche shift adversely impacted the planktivorous fish catch (Indian Oil Sardine) that was seen to be less in 2018 relative to 2017. Any further changes in monsoon variability and freshwater flow to this region may have direct consequences on the phytoplankton community as well as fisheries.

Physiological Response of Nutrient-Stressed Lemna gibba to Pulse Colloidal Silver Treatment.

Wastewater is a source of many environmental pollutants and potentially high concentrations of essential plant nutrients. Site-specific nutrient levels may influence the response of exposed plants to a chemical stressor. In the present study, we focused on the responses of model aquatic macrophyte swollen duckweed (Lemna gibba L.) to a short pulse exposure and a commercially available colloidal silver product as a potential environmental chemical stressor, combined with two levels of total nitrogen and phosphorus nutrition. Treatment with the commercially available colloidal silver product caused oxidative stress in L. gibba plants under both high and low nutrient levels. Plants grown and treated under high nutrient levels showed lower levels of lipid peroxidation and hydrogen peroxide accumulation, as well as higher levels of photosynthetic pigment content in comparison to treated plants under low nutrient levels. Higher free radical scavenging activity for plants treated with silver in combination with high nutrient levels resulted in better overall protection from silver-induced oxidative stress. The results showed that external nutrient levels significantly affected the L. gibba plant's response to the colloidal silver presence in the environment and that nutrient levels should be considered in the assessment of potential environmental impact for contaminants.

Antioxidant and photo-physiological acclimatisation in tropical macroalgae at sites with distinct nutrient levels

Abstract. Gopeechund A, Bhagooli R, Neergheen VS, Bahorun T. 2023. Antioxidant and photo-physiological acclimatisation in tropical macroalgae at sites with distinct nutrient levels. Indo Pac J Ocean Life 7: 79-90. The antioxidant efficacy, Total Phenolic Contents (TPC) and Total Flavonoid Contents (TFC) were investigated at Gis Gris with Lower Nutrient levels (LN site) and Bain boeuf with Higher Nutrient levels (HN site) around Mauritius Island. A field-based 7-days transplantation manipulation of Turbinaria ornata, Gracilaria salicornia and Sargassum obovatum between HN and LN sites was conducted to test the impact of different nutrient conditions on their physiology. All the species had lower antioxidant efficacies, TPC and TFC at LN compared to HN site. The glutathione peroxidase and catalase were more sensitive at reflecting the lower oxidative stress at LN site and acclimatisation to oxidative stress occurring at the HN site. ETRmax and ? were significantly higher in all species at HN site. The quantum yield Fv/Fm increased in S. obovatum only, after 7 days of transplantation at HN site, while, T. ornata and G. salicornia had similar adaptability to photo-physiological stress at both sites. NPQmax decreased in S. obovatum but increased in T. ornata transplanted to HN site, indicating increased photo-protection at HN site. Lagoons with higher nutrient levels may enhance macroalgal capacity to deal with oxidative stress, thus lowering the need for further photo-protection.

Multiple controls on carbon dioxide sequestration in the beagle channel (Southern Patagonia) in early fall

Subpolar coastal waters are key hotspots in the global carbon cycle. However, the small-scale distribution of partial pressure of carbon dioxide (pCO2) in these environments and the physical and biological controls underlying this variability are still poorly understood. Here, we examine simultaneous high-resolution spatial measurements of wind speed and pCO2, temperature, salinity, and in-vivo chlorophyll-a fluorescence (chl-a fluo, a proxy of phytoplankton biomass) in surface waters that were obtained during an oceanographic survey in the Argentinian Beagle Channel (subantarctic Atlantic Patagonian) in early fall 2017. The 240 km study transect (centered at 55°S - 67°W) was divided into two zones: (A1) The Beagle Channel innermost portion, semi-enclosed and subject to strong continental influence and (A2) its eastern outlet towards the open Southwest Atlantic. Discrete seawater samples were also collected for apparent oxygen utilization (AOU), nutrients and pH measurements. High-resolution spatial measurements revealed the persistence of pCO2 below atmospheric equilibrium, increasing in median (interquartile range 25–75%) from 314 μatm in the inner Beagle Channel (A1) to 348 μatm towards the adjacent open sea (A2). A decrease in atmospheric CO2 sequestration was associated with an increase in water temperature from 9.5 °C to 10.7 °C, salinity from 30.8 to 32.5, and chl-a fluo from 2.24 to 2.91 mg m−3 along the coastal-offshore gradient. Low AOU and nutrient levels were found in regions inside the channel. Indeed, the relationships between CO2 and temperature or salinity were significantly different from those expected from the theoretical solubility effect, indicating a dominance of metabolic over physicochemical controls on this gas. Moreover, physical factors such as vertical stratification contributed to the variable surface pCO2 values. These findings reveal the existence of short-scale spatial variability of CO2 in the Beagle Channel, improving our understanding of the multiple controls on atmospheric carbon sequestration in extensive subpolar continental shelves.

Soil quality and fertility dynamics under a continuous cassava-maize rotation in the semi-deciduous forest agro-ecological zone of Ghana

The practice of crop rotation is known to significantly influence soil nutrient dynamics, depending on the type of rotation and the crops involved. As such, a field study was conducted to find out the effect of continuous cassava-maize rotation, where mineral fertilizer was only applied to the maize crop, on soil nutrients dynamics and soil quality thereof under varying rotation periods. The study revealed that Soil Organic Matter (SOM) and levels of soil nutrients, such as total nitrogen, available phosphorus and exchangeable cations (potassium, calcium, magnesium, and sodium) significantly declined with rotation period. Long term maize–cassava rotation led to subsoil (20–50cm) acidification. Soil quality as measured by Carbon Management Index (CMI) on the different aged rotations decreased with age, with the longest rotation period giving the least quality. These results and observations imply that long term cassava-maize rotation reduced soil quality and the resilience of the cropping system for continuous sustainable crops production. A regression analysis of soil nutrients with CMI under the continuous cassava-maize rotation identified the crucial role of soil total N (r2 = 0.56) and exchangeable K (r2 = 0.44) in sustaining productive cassava-maize rotation system and improved soil quality within the semi-deciduous forest agro-ecological zone. It is thus, recommended that enhanced and targeted organic and inorganic fertilization regime could be deployed on the cassava-maize rotation system to improve the inherently low levels of nutrients and increase crop yields.

Effect of Combination of Poultry Manure and Rice Husk Biochar on Soil Fertility and Rice Plants

<p><em>Rice plants occupy a strategic position as a staple food producer for the people of Indonesia. Faced with limited suboptimal soil fertility, especially low levels of nutrients and soil pH, the use of organic fertilizers combined with local ameliorants is one solution to increase soil fertility. The purpose of this study was to obtain a combination of chicken or quail manure with rice husk biochar, which can reduce the use of inorganic fertilizers (urea, SP-36, and KCl). This study used a completely randomized design (CRD) consisting of 7 treatments (A, B, C, D, E, F, and G) which was a combination of 100% to 25% inorganic fertilizer of the recommendations, chicken manure or bird manure quail 5 tons/ha, and rice husk biochar 5 tons/ha. The parameters observed were plant height, total chlorophyll, seed dry weight, soil pH, soil NPK content, and Al-dd content. Observational data were analyzed with the F test at the 5% level then further tests were carried out using the Honest Significant Difference (HSD) test. The results showed that the treatments had a very significant effect, namely C, D, and E treatments resulted in a decrease in Al-dd, and an increase in K and had a significant effect on rice plant height. It was concluded that a combination of 5 tons/ha of chicken manure or quail manure with 5 tons/ha of biochar could increase soil fertility and rice plant height during the vegetative period and could substitute inorganic fertilizers up to 50% of the recommended dose.</em></p>

Tumor lactic acid: a potential target for cancer therapy

Tumor development is influenced by circulating metabolites and most tumors are exposed to substantially elevated levels of lactic acid and low levels of nutrients, such as glucose and glutamine. Tumor-derived lactic acid, the major circulating carbon metabolite, regulates energy metabolism and cancer cell signaling pathways, while also acting as an energy source and signaling molecule. Recent studies have yielded new insights into the pro-tumorigenic action of lactic acid and its metabolism. These insights suggest an anti-tumor therapeutic strategy targeting the oncometabolite lactic acid, with the aim of improving the efficacy and clinical safety of tumor metabolism inhibitors. This review describes the current understanding of the multifunctional roles of tumor lactic acid, as well as therapeutic approaches targeting lactic acid metabolism, including lactate dehydrogenase and monocarboxylate transporters, for anti-cancer therapy.

Effects of arbuscular mycorrhizal fungi on plant growth and herbivore infestation depend on availability of soil water and nutrients.

Fitness of plants is affected by their symbiotic interactions with arbuscular mycorrhizal fungi (AMF), and such effects are highly dependent on the environmental context. In the current study, we inoculated the nursery shrub species Artemisia ordosica with AMF species Funneliformis mosseae under contrasting levels of soil water and nutrients (diammonium phosphate fertilization), to assess their effects on plant growth, physiology and natural infestation by herbivores. Overall, plant biomass was synergistically enhanced by increasing soil water and soil nutrient levels. However, plant height was surprisingly repressed by AMF inoculation, but only under low water conditions. Similarly, plant biomass was also reduced by AMF but only under low water and nutrient conditions. Furthermore, AMF significantly reduced leaf phosphorus levels, that were strongly enhanced under high nutrient conditions, but had only minor effects on leaf chlorophyll and proline levels. Under low water and nutrient conditions, specific root length was enhanced, but average root diameter was decreased by AMF inoculation. The negative effects of AMF on plant growth at low water and nutrient levels may indicate that under these conditions AMF inoculation does not strongly contribute to nutrient and water acquisition. On the contrary, the AMF might have suppressed the direct pathway of water and nutrient absorption by the plant roots themselves despite low levels of mycorrhizal colonization. AMF inoculation reduced the abundance of the foliar herbivore Chrysolina aeruginosa on plants that had been grown on the low nutrient soil, but not on high nutrient soil. Fertilization enhanced the abundance of this herbivore but only in plants that had received the high water treatment. The lower abundance of the herbivore on AMF plants could be related to their decreased leaf P content. In conclusion, our results indicate that AMF negatively affect the growth of Artemisia ordosica but makes them less attractive to a dominant herbivore. Our study highlights that plant responses to AMF depend not only on the environmental context, but that the direction of the responses can differ for different components of plant performance (growth vs. defense).

Notes on the distribution, ecology and open sea mariculture trials of the Philippine blue sponge, Xestospongia sp. (Porifera)

AbstractThe Philippine blue sponge, Xestospongia sp., is a potential source of natural products for pharmaceutical use. However, knowledge on different aspects of its biology and ecology is still lacking, and improvement on biomass production through mariculture is still needed. In this study, we conducted ecological surveys and open sea mariculture trials of the Philippine blue sponge. The ecological surveys conducted were abundance and size–frequency surveys, as well as monitoring of wild blue sponge colonies. Mariculture trials were done by monitoring explant health and survival using different farming methods and consistent observation of various factors (i.e., predation, biofouling, maintenance effort, presence of disease). We also compared growth rates of explants and wild colonies. Colonies were highly abundant, and all size classes were wellrepresented in stations characterised by previous studies to have low water movement and high nutrient levels. These pieces of information were critical in selecting the sites for establishing mariculture setups. We additionally demonstrated the survival and growth of explants using artificial substrates made of polyvinyl chloride pipes. Several factors affecting sponge survival and health included predation, biofouling, habitat, and maintenance effort. We observed a higher growth rate of sponge explants compared with wild colonies. This study provides novel information on the ecology of the Philippine blue sponge and highlights the process of establishing an open sea mariculture setup for biomass production, which can potentially lead to increased production of biomedically important chemicals.

Cadmium stress interacts with nutrient availability and light condition to affect the growth of Hydrocotyle vulgaris.

Heavy metal pollution is becoming a serious problem in wetland and often co-occurs with nutrient availability and light conditions variation. We hypothesized that nutrient availability and light condition can affect the growth of wetland plants under heavy metal stress. To test this hypothesis, single ramets of a common, clonal wetland plant Hydrocotyle vulgaris were grown for four weeks at three levels of cadmium with three levels of nutrient availability under 30% or 100% light conditions. High level of nutrient availability and high light condition overall promoted growth of H. vulgaris under Cd stress. Under the two light conditions, responses of H. vulgaris to Cd treatments differed among three nutrient levels. Under 30% light condition, 2 mg L-1 Cd2+ treatment decreased total mass at the low nutrient level and decreased ramet number at the medium nutrient level; 0.5 and 2 mg L-1 Cd2+ treatments decreased leaf mass ratio at the low and the medium nutrient levels. Under 100% light condition, 2 mg L-1 Cd2+ treatments significantly decreased total mass at the high level of nutrients; 2 mg L-1 Cd2+ treatment decreased ramet number at the medium and the high nutrient levels and decreased leaf mass ratio at the medium nutrient levels. Our results suggested that Cd stress can interact with nutrient availability and light condition to affect the performance of wetland plants such as H. vulgaris.

Relationship of Physiographic Position to Physicochemical Characteristics of Soils of the Flooded-Savannah Agroecosystem, Colombia

Savannah floodplains are a natural agroecosystem located in the eastern plains of Colombia, with soils considered to be of low fertility. This assumption has not been rigorously validated by direct experimental studies. The aim of the study was to analyze the soils’ physicochemical characteristics of the “banks” and “lows”, which are physiographic positions, from the floodplain savannah in Arauca, Colombia. Soil samples were collected in “low” (n = 14) and “bank” (n = 15) physiographic positions. For each soil sample, the following chemical variables were determined: pH, organic carbon (OC), total nitrogen (TN), P, K, Ca, Mg, Na, exchange acidity, cation-exchange capacity (CEC), Fe, Cu, Mn, Zn and B, and physical variable (texture). The Wilcoxon non-parametric test (Mann–Whitney) was applied for the comparison of the soil’s physicochemical variables in each physiographic position (p < 0.05). The highest values for each variable analyzed correspond to the physiographic position of “low” (p < 0.05). The pH, T.N., Na, K and B were not statistically significant (p > 0.05). The physiographic positions of “bank” and “low” of floodplain savannah presented low levels of most nutrients, with slightly higher values in the “low” physiographic position. Corrective measures must be applied to improve the nutritional values of savannah soils and, consequently, the productivity of native forages. Despite these deficiencies, the vegetation cover is given by very well-adapted native grasses, reflecting the conditions of said agroecosystem.

Coral Reef Arks: An In Situ Mesocosm and Toolkit for Assembling Reef Communities.

Coral reefs thrive and provide maximal ecosystem services when they support a multi-level trophic structure and grow in favorable water quality conditions that include high light levels, rapid water flow, and low nutrient levels. Poor water quality and other anthropogenic stressors have caused coral mortality in recent decades, leading to trophic downgrading and the loss of biological complexity on many reefs. Solutions to reverse the causes of trophic downgrading remain elusive, in part because efforts to restore reefs are often attempted in the same diminished conditions that caused coral mortality in the first place. Coral Arks, positively buoyant, midwater structures, are designed to provide improved water quality conditions and supportive cryptic biodiversity for translocated and naturally recruited corals to assemble healthy reef mesocosms for use as long-term research platforms. Autonomous Reef Monitoring Structures (ARMS), passive settlement devices, are used to translocate the cryptic reef biodiversity to the Coral Arks, thereby providing a "boost" to natural recruitment and contributing ecological support to the coral health. We modeled and experimentally tested two designs of Arks to evaluate the drag characteristics of the structures and assess their long-term stability in the midwater based on their response to hydrodynamic forces. We then installed two designs of Arks structures at two Caribbean reef sites and measured several water quality metrics associated with the Arks environment over time. At deployment and 6 months after, the Coral Arks displayed enhanced metrics of reef function, including higher flow, light, and dissolved oxygen, higher survival of translocated corals, and reduced sedimentation and microbialization relative to nearby seafloor sites at the same depth. This method provides researchers with an adaptable, long-term platform for building reef communities where local water quality conditions can be adjusted by altering deployment parameters such as the depth and site.

Low Bioerosion Rates on Inshore Turbid Reefs of Western Australia

Bioerosion on inshore reefs is expected to increase with global climate change reducing reef stability and accretionary potential. Most studies investigating bioerosion have focused on external grazers, such as parrotfish and urchins, whose biomass is more easily measured. Yet, cryptic endolithic bioeroders such as macroboring (worms, sponges and bivalves) and microboring taxa (fungus and algae) have the potential to be the dominant source of reef erosion, especially among inshore reef systems exposed to increased nutrient supply. We measured bioerosion rates of bioeroder functional groups (microborers, macroborers, and grazers), and their response to environmental parameters (temperature, light, turbidity, chlorophyll a), as well as habitat variables (coral cover, turfing algae, macroalgae) across two inshore turbid reefs of north Western Australia. Total bioerosion rates were low (0.163 ± 0.012 kg m−2 year−1) likely due to low light and nutrient levels. Macroborers were the dominant source of bioerosion and were positively correlated with turfing algae cover, highlighting the role of turf-grazing fish on endolithic bioerosion rates. Overall low bioerosion rates suggest that despite the reduced coral cover and carbonate production, these reefs may still maintain positive reef accretion rates, at least under current environmental conditions. However, an improved understanding of relationships between environmental drivers, habitat and grazing pressure with bioeroding communities is needed to improve predictions of reef carbonate loss with future climate change.

Clonal Transgenerational Effects Transmit for Multiple Generations in a Floating Plant

Environmental conditions of a parent plant can influence the performance of their clonal offspring, and such clonal transgenerational effects may help offspring adapt to different environments. However, it is still unclear how many vegetative generations clonal transgenerational effects can transmit for and whether it depends on the environmental conditions of the offspring. We grew the ancestor ramets of the floating clonal plant Spirodela polyrhiza under a high and a low nutrient level and obtained the so-called 1st-generation offspring ramets of two types (from these two environments). Then we grew the 1st-generation offspring ramets of each type under the high and the low nutrient level and obtained the so-called 2nd-generation offspring ramets of four types. We repeated this procedure for another five times and analyzed clonal transgenerational effects on growth, morphology and biomass allocation of the 1st- to the 6th-generation offspring ramets. We found positive, negative or neutral (no) transgenerational effects of the ancestor nutrient condition on the offspring of S. polyrhiza, depending on the number of vegetative generations, the nutrient condition of the offspring environment and the traits considered. We observed significant clonal transgenerational effects on the 6th-generation offspring; such effects occurred for all three types of traits (growth, morphology and allocation), but varied depending on the nutrient condition of the offspring environment and the traits considered. Our results suggest that clonal transgenerational effects can transmit for multiple vegetative generations and such impacts can vary depending on the environmental conditions of offspring.

EFEITOS DA DEGRADAÇÃO NOS ATRIBUTOS DE SOLOS SOB CAATINGA NO SEMIÁRIDO BRASILEIRO

ABSTRACT Anthropic activities in their various aspects have promoted soil degradation in the Brazilian semi-arid region (SAB). As a result, significant losses in productivity and in the ability of soils to fulfill their ecological functions have been reported. The present study investigated the effects of degradation on soil attributes and properties under dense (CAD) and sparse (CAE) shrubby Caatinga in Campina Grande, PB, Brazil. Samples from the 0-20 cm layer of soil were investigated via physical (particle size distribution and soil density), chemical (acidity, electrical conductivity, macronutrients, soil organic matter) and microbiological attributes (microbial biomass carbon (C-BMS), basal respiration of the soil (RBS) and metabolic quotient (qCO2) Data were submitted to the Mann-Whitney Test and Principal Component Analysis (PCA). Anthropic actions on the CAE promoted the exposure of the saprolitic layer on the surface. This layer has imperfect drainage, low levels of nutrients and organic matter and high sodicity, which contributes to the slow regeneration of vegetation. Carbon stock and microbial activity are significantly lower in CAE compared to CAD. Degradation resulted in losses of supporting ecosystem services (nutrient cycling and primary production) and regulation (erosion control and climate regulation). The results can be used to understand the dynamics of landscapes of low complexity (high degradation) in the SAB and serve as a framework to find strategies to restore the productive capacity of extensive degraded and/or desertified areas in the SAB.

Effectiveness of Liquid Organic Fertilizer On N-Total of Soil, N, P, K Uptake, and Yields of Peanut (Arachis hypogaea L.) In Inceptisols Jatinangor

Inceptisols are often used for intensive cultivation and have low levels of essential nutrients. Improvement of this fertility rate can be achieved by the application of organic based fertilizers that can increase soil fertility. Peanut has long been cultivated in Indonesia and is generally grown on dry land. This research was conducted from February to June 2023, at the experimental garden, Padjadjaran University. This research aims to determine the effect of liquid organic fertilizer combined with standard NPK fertilizer on soil N total, plant nutrient uptake, and peanut yields in Inceptisol Jatinangor. This study used a randomized block design experimental method with nine treatments and three replications, and the amount is 27 experimental units. The result shows that the combination of liquid organic fertilizer with NPK fertilizer can enhance yields of peanuts. The combination of 10 liters of liquid organic fertilizer per hectare andb ¾ dose of Urea, TSP and KCl can increase the total-N content of the soil, the absorption of N, P, and K, as well as the weight of dried pods. Therefore, the use of liquid organic fertilizer in peanut cultivation can be reduced by up to 25% and can increase the yield of peanut pods.

English

This study focuses on the impact of physicochemical parameters and heavy metals concentrations in soil on abundance, richness and diversity of plants at Marlu tailings dam located near Bogoso, Ghana. The concentrations of heavy metals (mg/kg) in soil at the study area are as follows: Fe (10,528.9 - 7,873.0), Cu (224.9 - 177.4), Zn (51.6 - 42.7), Cd (3.0 - 2.6), As (2.4 - 1.7) and Mn (78.3 - 57.1). Soil nutrient levels (nitrate, phosphate and sulphates) were relatively low with most sites having acidic soils (6.4 - 5.3). A total of 2,055 plants composed of eighteen (18) different species were observed at the study area. Pennisetum purpureum was the most abundant plant species (46.8%), and Poaceae and Asteraceae were the predominant families with percentage abundance of 37 and 28.8%, respectively. Diversity of plants measured using Simpson and Shannon indices at sampling sites varied significantly between the different sampling sites but are relatively low compared to other similar sites in Ghana. Species richness and diversity of plants correlated positively with the low nutrient levels and soil acidity. Low plant abundance, species richness and diversity correlated with increased Copper (Cu) levels in soil. Cadmium (Cd) levels were correlated with low abundance of plants belonging to families Asteraceae and Fabaceae. The presence of heavy metals at concentrations above regulatory limits negatively impacted on abundance and diversity of plants at the decommissioned mine tailings dam. Increased concentrations of heavy metals and low nutrient levels in soil could account for reduced plant abundance, species richness and diversity at the mine tailings dam.   Key words: Plant diversity, mine tailings dam, heavy metals, physicochemical parameters.

Effects of clonal integration on characteristics of free-floating and submerged plant communities under different nutrient conditions

Individual-level effects of clonal integration have been extensively studied, but community-level effects remain poorly understood. We grew the free-floating or submerged plant communities with three speices dominated by free-floating Salvinia natans or submerged Vallisneria natans, respectively. The stolons of S. natans and V. natans were periodically severed, with not severed plant communities as control. The effects of clonal integration on the characteristics of different life-form plant communities under low versus high nutrient levels were examined. Results showed that clonal integration significantly increased the number of ramets in submerged plant communities but not in free-floating plant communities under two nutrient conditions. Clonal integration greatly decreased the growth of free-floating plant communities, changed their species composition, and increased their species diversity and evenness under high nutrient conditions but not under low nutrient conditions. In submerged plant communities, clonal integration and nutrient affected species composition independently but did not affect species diversity. The growth of submerged plant communities was only affected by nutrient. Our findings highlight the importance of nutrient and plant life form in the effects of clonal integration on aquatic plant community characteristics. Studies on the effects of clonal integration at the community level could provide references for the effective management of aquatic plant communities with different life forms and contribute to a better understanding of the importance of clonal integration in the field.

Production and characterization of enriched vermicompost from banana leaf biomass waste activated by biochar integration

Vermicomposting uses less energy and requires fewer infrastructures, and it is capable of restoring soil nutrition and carbon. Banana cultivation produces lots of trash in a single crop season, with 30 tonnes of waste generated per acre. The biodegradable fraction of banana leaf waste is thrown out in large quantities from temples, markets place wedding halls, hotels, and residential areas. Vermicomposting can be used for recovering lignin, cellulose, pectin, and hemicellulose from banana leaves. Earthworm digests organic materials with the enzymes produced in gut microflora. Biochar adds bulk to vermicomposting, increases its value as fertilizer. The goal of this study was to amend biochar (0, 2, 4 and 6%) with banana leaf waste (BLW) + cow dung (CD) in three different combinations (1:1, 2:1 and 3:1) using Eisenia fetida to produce enriched vermicompost. In the vermicompost with biochar groups, there were higher levels of physicochemical parameters, as well as macro- and micronutrient contents. The growth and reproduction of earthworms were higher in groups with biochar. A maximum of 1.82, 1.18 and 1.67% of total nitrogen, total phosphorus and total potassium was found in the final vermicompost recovered from BLW + CD (1:1) amended with 4% biochar; while the other treatments showed lower levels of nutrients. A lower C/N ratio of 18.14 was observed in BLW + CD (1:1) + 4% biochar followed by BLW + CD (1:1) + 2% biochar amendment (19.92). The FTIR and humification index studies show that degradation of organic matter has occurred in the final vermicompost and the substrates with 4% biochar in 1:1 combination showed better degradation and this combination can be used for nutrient rich vermicompost production.

Micronutrients and heavy metals in rice farms: the case of Ahvaz and Bawie Counties, Khuzestan Province, Iran.

This study addressed micronutrients (Fe, Zn, Cu, Mn, Co) and heavy metals (As, Pb) in the soil and rice crop in Khuzestan Province, Iran. Twenty-eight composite soil and grain samples from the intended rice farms were garnered during harvest time. Concentrations of the elements in the samples and in the grains were, respectively, determined by inductively coupled plasma optical emission spectrometry and inductively coupled plasma mass spectrometry device. The average concentration of As, Fe, Co, Cu, Mn, Pb, and Zn in soil of crop were 2.71, 20,065.8, 10.43, 22.28, 422.28, 5.85, and 47.07mg/kg, respectively. The physicochemical properties of soil, bioconcentration factor, daily intakes, and health risk assessment of the elements were calculated. The results revealed that the area covered by alkaline saline soils is poor in micronutrients. Bioconcentration factor values of all elements were less than 1. Low levels of bioconcentration factor may be for low levels of nutrients in the soil and physicochemical conditions of the soil. Furthermore, the daily intake of Co (adults' group) and Fe and Zn (children group) was very low. Health risk assessment showed only adults are threatened by non-cancerous diseases due to excessive value of all the elements (HI = 2.53) and cancerous diseases caused by excessive As and Pb (2.86E-04 and 2.01E-05, respectively). Considering that Khuzestan Province is the fourth largest producer of rice in Iran, the lack of micronutrients and the presence of heavy metals in rice produced in the study area can adversely affect consumers. Further investigation is therefore a must in the region.