Use of phytoremediation for pollution removal of hexavalent chromium-contaminated acid agricultural soils

<p>Chromium is a common heavy metal pollutant found in industrial wastewaters which may pollute agricultural soils through groundwater and watering. Phytoremediation is an economical and highly applicable method for removal of pollutants from agricultural soils. This research was carried out for the removal of hexavalent chromium (Cr (VI)) contamination from the soil with the phytoremediation method. For this purpose, only 30 mg kg-1 hexavalent chromium (Cr (VI) as Chromium CrO3, only 10 mL bacteria Rhodobacter capsulatus DSM1710 and chromium plus bacteria applied to the pots and Malabar spinach (Basella alba L.) grown in the pots. At the end of experiment the results showed that side branching, leaf width, plant dry weights were the highest agro-morphological traits when bacteria were applied to chromium polluted soil. Some macro and micro nutrient elements which are essential for plant nutrition were analyzed (N, P, K, Ca, Mg, Fe, Cu, Mn and Zn). Among them, N, P, Fe, Cu, Mn and Zn were found to be statistically significant at the level of 5%. The Cr content of Malabar spinach in control soil was 0.31mgkg-1, but it was 2.33mgkg-1 when the soil was contaminated with Cr at the end of experiment. Moreover, when bacteria were additionally applied the Cr content increased to 4.02 mgkg-1 of Malabar spinach. Chromium pollution antagonistically affected both some nutrient element (P, K, Ca; Mg) and some heavy metals (Fe, Cu, Zn, Mn) in the soil. This study shows that phytoremediation can be used to remove the soil pollution caused by containing high hexavalent chromium. For this reason, the nitrogen fixing bacterium Rhodobacter capsulatus and the hyperaccumulator Malabar spinach plant can be used. It is the first study where Malabar spinach was used a hyperaccumulator plant for chromium pollution in the soils.</p>

Influence of Green Light Added with Red and Blue LEDs on the Growth, Leaf Microstructure and Quality of Spinach (Spinacia oleracea L.)

The aim of this study was to investigate the effects of green light, added with red and blue LEDs, on the growth, leaf microstructure and quality of spinach plants. Plants were transplanted and grown hydroponically for 30 days under different combinations of red:blue with a 4:1 ratio (R4B1), red:blue:green with a 5:2:3 ratio (R5B2G3) and red:blue:green with a 1:1:1 ratio (R1B1G1), at a 190 µmoL m−2·s−1 photosynthetic photon flux density (PPFD). The results showed that green light, added to red and blue LEDs at a reasonable ratio, could reduce the growth, leaf microstructure and quality of spinach plants, but not the organic acid content. The highest values for the growth parameters, photosynthetic pigments, leaf structure characteristics and quality of the spinach plant were observed for the R4B1 treatment, but not for the organic acid content. Therefore, our results suggest that green light added to red and blue LEDs at a reasonable ratio is not suitable for the growth of spinach.

Aerated Buffalo Slurry Improves Spinach Plant Growth and Mitigates CO2 and N2O Emissions from Soil

Manure management is the main strategy for mitigating gas emissions from livestock farming. In this study, a laboratory-scale experiment was set up to identify suitable conditions to be applied in a farm-scale experiment. The liquid fraction (LF) of slurry was aerobically treated and greenhouse gas emissions from soil were evaluated. Furthermore, the value of treated LF as a fertilizer on spinach plants was also tested. The aeration of LF determined an increase in mean alkalinity due to ammonia loss. The mass fraction of heavy metals also decreased, likely due to the reduction in solubility. After being applied on soil, aerated LF determined lower CO2 and N2O emissions compared to untreated LF due to a reduced nitrogen load. Spinach plants fertilized with treated LF showed a lush growth and exhibited a lower heavy metal mass fraction as well as a higher content of antioxidants compared to plants fertilized with untreated slurry. Our results show that aeration might be an effective alternative for slurry management as it is able to produce an eco-friendly final product with a high fertilizing value.

Beneficial Features of Biochar and Arbuscular Mycorrhiza for Improving Spinach Plant Growth, Root Morphological Traits, Physiological Properties, and Soil Enzymatic Activities

Biochar and arbuscular mycorrhizal fungi (AMF) can promote plant growth, improve soil properties, and maintain microbial activity. The effects of biochar and AMF on plant growth, root morphological traits, physiological properties, and soil enzymatic activities were studied in spinach (Spinacia oleracea L.). A pot experiment was conducted to evaluate the effect of biochar and AMF on the growth of spinach. Four treatments, a T1 control (soil without biochar), T2 biochar alone, T3 AMF alone, and T4 biochar and AMF together, were arranged in a randomized complete block design with five replications. The biochar alone had a positive effect on the growth of spinach, root morphological traits, physiological properties, and soil enzymatic activities. It significantly increased the plant growth parameters, such as the shoot length, leaf number, leaf length, leaf width, shoot fresh weight, and shoot dry weight. The root morphological traits, plant physiological attributes, and soil enzymatic activities were significantly enhanced with the biochar alone compared with the control. However, the combination of biochar and AMF had a greater impact on the increase in plant growth, root morphological traits, physiological properties, and soil enzymatic activities compared with the other treatments. The results suggested that the combined biochar and AMF led to the highest levels of spinach plant growth, microbial biomass, and soil enzymatic activity.

THE FOLIAR SPRAY APPLICATION OF SELECTED ORGANIC FERTILIZERS AND THEIR EFFECTS ON SELECTED PLANTS – A REVIEW

The organic fertilizer or manures like banana peel, coconut peat and waste milk tea (TW) are highly rich in nitrogen, potassium and phosphorus etc. (Vu, H. T., et al., 2018; Khan, M.Z., et al., 2019; Sial, T.A., et al., 2019). The sandy soil is one of the most severe conditions which negatively affect the growth of plant. The aim of the study is to report the foliar spray effect of milk tea waste extract, banana peel extract, coconut peat extract, on the growth of coriander and spinach plants. In this analysis different pots for various organic fertilizers were used to check their effect on plant growth and to investigate the improvement of biochemical properties of sandy soil (Vu, H. T., et al., 2018; Khan, M.Z., et al., 2019; Sial, T.A., et al., 2019).According to review, using various fertilizers growth parameters like plant height, numbers of leaves, shoot moisture content, NPK content present selected in plants can be compared. This review describes the best organic fertilizer among banana peel, coconut peat and waste milk tea and their effect on the growth parameters of coriander and spinach plant. KEYWORDS: Banana peel, Coconut peat, Waste milk tea, Fertilizer, Plants growth, Soil analysis.

Potential of Organic and Inorganic Amendments for Stabilizing Nickel in Acidic Soil, and Improving the Nutritional Quality of Spinach

Contamination of soils by nickel (Ni) has become a serious environmental problem throughout the world, and this substance wields dangerous effects on the ecosystem and food chain. A pot experiment was conducted to examine the effect of rice straw (RS), rice straw biochar (BI) and calcite (CC) at 1% and 2% application rates in a Ni contaminated soil. The objective was to potentially stabilize Ni and reduce its bioavailability to spinach (Spinacia Oleracea L.). Spinach plants were grown in a Ni contaminated Ultisol (commonly known as a red clay soil). Physiological results indicated that a BI 2% application rate significantly increased the photosynthetic rate by 4-18.6 µmol m2 S− 1 and transpiration rate by 1.7–8.9 mmol m2 S− 1. Similarly, growth parameters for root and shoots dry biomass increased 1.7- and 6.3-fold, respectively, while essential nutrients were enhanced in the spinach plant compared to those in the untreated soil (CK). Moreover, adding amendments significantly decreased CaCl2 extractable Ni by 62.5% 94.1%, and 87.2%, while the toxicity characteristics leaching procedure (TCLP) fell by 26.7%, 47.8%, and 41.7% when using RS, BI and CC, respectively, at 2% compared to CK. The Ni concentrations in the spinach roots declined by 51.6%, 73.3% and 68.9%, and in the shoots reduced by 54.1%, 76.7% and 70.8% for RS, BI and CC, at a 2% application rate, respectively. Bio-concentration factor (BCF) and translocation factor (TF) dropped significantly by as much as 72.7% and 20%, for BI 2% application rate. Results of the present study clearly indicated that biochar potential soil amendments for Ni stabilization, thereby reducing its bioavailability in the Ni contaminated soil. This process enhanced the safety of food to be consumed and mitigated security risks.

CONFIRMATION OF ENDOPHYTIC MICROBES CAUSING CONTAMINATION IN WATER SPINACH (Ipomoea aquatica Forssk.) TISSUE CULTURE

Konfirmasi Mikroba Endofit Penyebab Kontaminasi pada Kultur Jaringan Kangkung (Ipomoea aquatica Forssk.) Tanaman kangkung secara alami bersimbiosis dengan mikroba endofit, yang berpotensi menjadi kontaminan pada kultur jaringan kangkung karena berada di dalam jaringan dan sulit dijangkau saat proses sterilisasi eksplan. Tujuan penelitian ini adalah mengonfirmasi mikroba endofit penyebab kontaminasi pada kultur jaringan kangkung ‘Tetraploid’ sehingga dapat menjadi informasi awal untuk metode sterilisasi yang efektif. Sebanyak 14 sampel kontaminan pada media tanam kultur jaringan kangkung diisolasi dan diidentifikasi secara molekuler berdasarkan gen 16S rDNA untuk bakteri, daerah D1/D2 dari gen LSU rRNA untuk khamir, dan daerah ITS dari gen rDNA untuk jamur. Keragaman jenis mikroba yang teridentifikasi dibandingkan dengan keragaman jenis mikroba endofit dari jaringan tanaman kangkung yang ditanam pada media kultur jaringan tidak terkontaminasi mikroba, media kultur jaringan terkontaminasi mikroba, media tanam campuran tanah steril dan tidak steril, serta kangkung yang didapatkan dari pasar. Hasil penelitian ini mengonfirmasi bahwa khamir endofit dari kelompok Ustilaginaceae (basidiomycetous yeast) yang berasal dari jaringan tanaman kangkung sama dengan jenis kontaminan yang mengontaminasi media kultur jaringan kangkung ‘Tetraploid’. Khamir dari kelompok Ustilaginaceae (basidiomycetous yeast) tersebut juga merupakan mikroba paling dominan yang mengontaminasi media tanam kultur jaringan kangkung ‘Tetraploid’. Keywords: Ipomoea aquatica, kultur jaringan, mikroba endofit, morfologi, pohon filogeni Water spinach in nature lives in symbiosis with endophytic microbes, which have the potential to become contaminants in water spinach tissue culture because they are difficult to eliminate during the explant sterilization process. This study aimed to confirm endophytic microbes that cause contamination in the tissue culture of 'Tetraploid' water spinach so that it can provide initial information for an effective sterilization method. Fourteen contaminant samples in water spinach tissue culture media were isolated and identified molecularly based on the 16S rDNA gene for bacteria, the D1/D2 region of the LSU rRNA gene sequences for yeast, and ITS region of the rDNA gene for mold. The diversity of microbial species identified was compared with the diversity of endophytic microbial types from water spinach plant tissue grown on sterile tissue culture media, microbially contaminated tissue culture media, sterile and non-sterile soil mixed planting media, and water spinach obtained from the market. The results confirmed that endophytic yeast from Ustilaginaceae group (basidiomycetous yeast) derived from water spinach plant tissue was the same type of microbe that contaminated the 'Tetraploid' water spinach tissue culture media. The results gave new information that yeast from the Ustilaginaceae (basidiomycetous yeast) group was the most dominant microbe contaminating water spinach ‘Tetraploid’ tissue culture media. This group is endophytic yeast that lives within Ipomoea aquatica tissues.

The effect of vertical gardens on temperature and CO2 levels in urban housing

The city's thermal environment plays an important role in achieving comfort and quality of life, especially during the current global pandemic. Meanwhile, reduction in the green areas has been observed to be continuously causing climate change in cities and one of the proposed solutions to this is by developing a greening system for buildings. This paper, therefore, assessed the ability of vertical garden to decrease air and surface temperatures as well as CO2 levels. The research involved field measurements of these parameters both inside and outside the building along with the modification of the vertical garden distance at 0.5 m and 1 m as well as the plant type including red spinach or amaranthus hybridus, mustard or brassica juncea, celery or apium graveolens linn, and cat's whiskers or orthosiphon spicatus. The results showed an average decrease of 0.75°C in air temperature, 16.4ºC in surface temperature, and 58.8 ppm in CO2 levels. Moreover, a maximum reduction of 6ºC was achieved in air temperature with red spinach plants at 0.5 m, 26.3ºC in surface temperature by the Rred spinach plant, and 124 ppm in CO2 levels by celery plants. In conclusion, a closer distance and darker color of the leaves as well as the red spinach species were found to be the main consideration in the application of vertical gardens in urban homes due to their ability to reduce the temperature on the limited land. © 2020 Agung Murti Nugroho