Plant Growth Medium Research Articles

Soil as a Basic Nexus Tool: Soils at the Center of the Food–Energy–Water Nexus

Soil is the medium for plant growth and the substrate for all biogeochemical and biogeophysical processes. Soil’s unique natural organization forms the foundation of any food–water–energy nexus system. It forms a habitat for billions of diverse micro, meso, and macrofauna and flora and is the basis of numerous ecosystem services essential to human well-being and nature conservancy. It moderates soil hydrological processes within the entire vadose zone: which is part of the earth between the soil surface and the phreatic zone. Soil structure also supports numerous ecosystem services including nutrient transformation and availability, water quality and renewability, denaturing and transport of pollutants, and groundwater table fluctuations. It also moderates the soil–water–plant-energy nexus with the replenishement of green-water supply (from precipitation) for plants and soil biota, which in turn enables the production of biomass as a source of food, feed, fiber, and biofuel feedstock. Indeed, soil is a very large reservoir for water and carbon with strong influences on local, regional, and global climate. Also, the energy factor is connected with the climate change through soil–water–food–energy nexus because of numerous interlinked pathways including gaseous emissions, energy and food production, and recycling of nutrients and water at regional, national, and global scales. Through provisioning of numerous ecosystem services, the soil–water–food–energy–climate nexus is interwoven with the ecosystem security and functioning of planet’s four ecospheres (i.e., atmosphere, hydrosphere, lithosphere, and the biosphere). Therefore, the health of soil, plants, animals, people, and ecosystems is one and indivisible. This interconnectivity is also the basis of the “4 per Thousand” initiative adopted by the COP21, the Climate Summit of 2015 in Paris, and “Adapting African Agriculture” (AAA) by COP22 in Morocco. Consequently, soil is not only a foundation for securing the natural resources: food, water and energy, but it is under desperate need to be integrated and appreciated in understanding the complex interconnectedness of any food, energy, water and soil system. Concentration and stock of soil organic carbon are the key soil properties that determine the physical, chemical, biological, and ecological properties and processes, and are major control of all nexuses described herein. This chapter presents a conceptual model and the role of soil as a naturally organized medium to protect global food, water, energy securities. Moreover, it elaborates on using soil as a basic nexus tool and proposes a paradigm shift in integrating soil and creating the food–energy–water–soil nexus.

Detection of nickel in maize roots: A novel nondestructive approach by reflectance spectroscopy and colorimetric models

In this paper, a novel method capable of assessing nickel (Ni) uptake in intact plant roots is proposed and validated. Dimethylglyoxime (DMG) was used to stain roots of seven-day-old maize (Zea mays L.) seedlings grown in solutions containing 0, 0.025, 0.1, 0.2, and 0.5mM Ni2+. A nondestructive approach by using reflectance spectroscopy and CIE XYZ and CIE L*a*b* color systems was used to investigate their optical properties. The maximum intensity in reflectance spectra at 545nm (A545) was used to monitor the development of DMG–Ni complexes. The values of A545 were polynomially related to the concentration of Ni2+ in the growing solution (R2=0.98), and significant correlations were also observed between A545 and the two indicators of phytotoxicity, namely, root growth inhibition (I) and variations in the shoot-to-root ratio (S/R). The variation of dominant wavelength (λd) and excitation purity (Pe) graphically derived from the x, y color gamut in the CIE XYZ system paralleled the two highest Ni concentrations. Most of the color parameters in the CIE L*a*b* system were closely related to both Ni2+ concentrations in plant growing medium and the values of (I) and (S/R) used here as markers of Ni toxicity. The revealed dependences confirm that the prelaminar method proposed here is capable of nondestructive estimating of Ni concentrations in intact root tissue. The values of A545 in the reflectance spectra of stained roots and color parameters, namely, opponent redness–greenness (a*), integral color difference (ΔE)*, lightness color difference (ΔL)*, and hue angle difference (ΔH)*, showed the highest potential for diagnostic purposes.

An improved formula for evaluating electrical capacitance using the dissipation factor

The measurement of electrical capacitance in root–soil system (CR) is a useful method for estimating the root system size (RSS) in situ; however, CR–RSS regressions are often poor. It was hypothesized that this weak relationships could be partly due to the variable energy-loss rate, indicated by the dissipation factor (DF). The values of CR and the associated DF were measured in six plant species grown in quasi-hydroponic pumice medium, arenosol and chernozem soil. The dielectric properties of the plant growth media were also recorded. A modified root–soil capacitance, CDF, was calculated from each CR/DF pair according to the formula CDF = CR·(DF/DFmean)α by estimating α with a standard nonlinear minimization of the sum of squared residuals for CDF–RSS regressions. The capacitive behavior of the medium improved (mean DF decreased) but fluctuated increasingly as the substrate became more complex. The mean DF values in plant–substrate systems were chiefly determined by the plant and were the most variable in chernozem soil. This strengthening substrate effect on CR measurements appeared as a decreasing trend in the R2 values obtained for the CR–RSS regressions. The regression slope was influenced by plant species and medium, while the y-intercept differed only between substrate types. The proposed use of CDF in place of CR could significantly improve the R2 of CDF–RSS regressions, particularly in chernozem soil (R2 increased by 0.07–0.31). The application of CDF will provide more reliable and accurate RSS estimations and more efficient statistical comparisons. The findings are worth considering in future investigations using the root capacitance method.

Nutrient Leaching When Soil Is Part of Plant Growth Media

Soils can serve as sorbents for phosphorus (P), negating the need for artificial sorbents. The purpose of this study was to compare soils with different properties for their effect on nutrient levels in effluent. Four soils were mixed with sand and packed into columns 0.5 m long, with or without compost on the surface. Infiltration and effluent concentrations were measured before and after growing plants [Buffalograss (Buchloe dactyloides (Nutt.) Engelm.) and bluegrama grasses (Bouteloua gracilis H.B.K.) and red clover (Trifolium pratense L.)]. The growth media with compost at the surface had higher nutrient levels than the media without the compost, but the final effluent nitrate concentrations post-harvest were significantly lower for columns with the compost blanket (59 vs. 86 mg L−1). All of the nitrate concentrations were high (many >100 mg L−1) due to mineralization and nitrogen fixation. The final effluent P concentrations before planting were significantly higher in the soil with the most sand (0.71 mg L−1), and after harvest in the mixture that contained the high soil P levels (0.58 mg L−1). Some soils (high in aluminum or calcium) were adequate sorbents for P without additions of other sorbents, but soils often generated too much nitrate in effluent.

Physiological and antioxidant response of wheat (Triticum aestivum) seedlings to fluoroquinolone antibiotics

Combinations of antibiotics occur in terrestrial environments due to excessive prescription, consumption, and disposal and have adverse effects, including crop toxicity. We examined short-term (20-d) toxicity of the fluoroquinolone antibiotics ciprofloxacin, enrofloxacin, levofloxacin, and their mixture in a germination and a greenhouse sand culture study with wheat. We tested the hypothesis that oxidative stress plays a role in toxicity by examining stress products and antioxidants involved in detoxifying reactive oxygen species (ROS) during stress. Germination was unaffected by any antibiotic concentration or mixture used. The highest antibiotic concentrations, 100 and 300 mg L−1, significantly decreased wheat growth. In 20 days exposure the maximum malondialdehyde production (2.45 μmol g−1 fresh weight), total phenols (16.40 mg g−1 of extract), and total antioxidant capacity (17.74 mg of Vitamin C g−1 of extract) and maximum activities of superoxide dismutase (7.99 units mg−1 protein min−1) and ascorbate peroxidase (0.69 μmol ascorbate mg−1 protein min−1) significantly increased compared to the control. In contrast, catalase (0.45 mmol H2O2 mg−1 protein min−1) and peroxidase (0.0005 units mg−1 protein min−1) activity significantly decreased compared to the control. We conclude that high antibiotic concentrations in the plant growth medium reduced wheat growth by causing oxidative stress. The capacity to respond to oxidative stress was compromised by increasingly higher antibiotic concentrations in some enzyme systems. This stress damaged the physiological structure of the young plants and could reduce crop productivity in the long term. Consequently, fluoroquinolone-contaminated water challenges developing countries with constraints on available water for irrigation.

The benefit of top soil and fertilizer mixture to improve the ex-coal mining land

Sopialena, Rosfiansyah, Sila S. 2017. The benefit of top soil and fertilizer mixture to improve the ex-coal mining land. Nusantara Bioscience 9: 36-43. The mining activities have led severe impacts on some environmental issues including a decrease in soil fertility, which affects the ability of soil to supply soil nutrients to growing plants, a destruction in soil structure, and the loss of microorganisms, which are important for reforming process to treat organic materials. In this regards, reclamation of mined degraded land has been continually used to improve soil structure and its microorganisms. In practice, for large scale reclamation, fertilizer use can primarily enhance soil qualities in improving plant’s growth and yield. It is suggested that healthy soil should contain millions of microorganisms at the aggregation which leads to the improvement of soil nutrients and its structure, as the medium for plant growth. For this purpose, therefore, this study aimed to determine the impact of organic fertilizer (Ostindo) and top soil mixture on microbial diversity, soil fertility and the growth of sengon (Paraserianthes falcataria L. Nielsen). This study made use of a randomized block design, using four treatments and five replications including P0: without top soil and fertilizer, P1: with top soil but without fertilizer, P2: without top soil but with fertilizer, P3: mixture of top soil and fertilizer. The results showed that a mixture of top soil and fertilizer has successfully increased in the number of fungal genus, starting from two genus (Phytium and Penicillium) turning into five genus (Phytium, Fusarium, Penicillium, Aspergillus, and Rhizoctonia), as well as in the number of nematode genus, from two (Dorylaimus and Rhabditis) turning into five genus (Dorylaimus, Steinernema, Dorylaimus, Hoplolaimus, and Mononchus). This study indicated that the mixture has significantly improved soil health in ex-coal mining land, which was viable through the pH level (almost neutral), the significant increase of C, N and P2O5 , and also the growth of Sengon. In conclusion, this study succeeds in demonstrating that the mixture of top soil and fertilizer has enhanced the microbial diversity, soil fertility, and sengon growth.

Salicylic Acid-Dependent Plant Stress Signaling via Mitochondrial Succinate Dehydrogenase.

Mitochondria are known for their role in ATP production and generation of reactive oxygen species, but little is known about the mechanism of their early involvement in plant stress signaling. The role of mitochondrial succinate dehydrogenase (SDH) in salicylic acid (SA) signaling was analyzed using two mutants: disrupted in stress response1 (dsr1), which is a point mutation in SDH1 identified in a loss of SA signaling screen, and a knockdown mutant (sdhaf2) for SDH assembly factor 2 that is required for FAD insertion into SDH1. Both mutants showed strongly decreased SA-inducible stress promoter responses and low SDH maximum capacity compared to wild type, while dsr1 also showed low succinate affinity, low catalytic efficiency, and increased resistance to SDH competitive inhibitors. The SA-induced promoter responses could be partially rescued in sdhaf2, but not in dsr1, by supplementing the plant growth media with succinate. Kinetic characterization showed that low concentrations of either SA or ubiquinone binding site inhibitors increased SDH activity and induced mitochondrial H2O2 production. Both dsr1 and sdhaf2 showed lower rates of SA-dependent H2O2 production in vitro in line with their low SA-dependent stress signaling responses in vivo. This provides quantitative and kinetic evidence that SA acts at or near the ubiquinone binding site of SDH to stimulate activity and contributes to plant stress signaling by increased rates of mitochondrial H2O2 production, leading to part of the SA-dependent transcriptional response in plant cells.

Application of Peanut Shells Composts in Replacement with Peat on Growth Indices and Physical and Chemical Properties of Violet Growth Media (<i>Viola</i> spp) in Outdoor

Peanut Shells as the waste left from peanut planting, which considerable amount of compost can be used as available resources to replace with peat in cultivation of Ornamental plant growth media. So, in this experiment, five treatments in a completely randomized design with three replications were conducted in outdoor in Lahijan ornamental plants Research Station. Treatments were included: 2 peat + 1 perlite + 0 Shells Peanut composts (control), 1.5 Peat + 1 perlite + 0.5 Shells peanut compost, 1 Peat + 1 perlite + 1 Shells Peanut composts, 0.5 Peat + 1 perlite + 1.5 peanut shells compost, 0 peat + 1 perlite + 2 peanut shells compost. In this experiment growth index of violets are included, number of flower, plant height, fresh and dry weight of canopy, root length, root fresh and dry weight, and physical and chemical properties of substrates were measured. The results showed that replacement of Shells Peanut compost has a significant effect on, number of flowers, plant height, Dry weight of canopy, root fresh and dry weight in comparison to control. Increasing levels of Peanut Shells compost caused to reduce in bulk density and an increase in total porosity, Water capacity and air fill porosity.

CHARACTERISTICS OF COMPOSTED BIO-TOILET RESIDUE AND ITS POTENTIAL USE AS A SOIL CONDITIONER

Bio-toilet is a dry toilet where human excreta is trapped in a lignocelluloses soil matrix such as wood sawdust, then it is decomposed by aerobic bacteria to organic compost rich in minerals such as N, P, and K. The study aimed to characterize the bio-toilet residue and its potential use as a soil conditioner for Jatropha curcas. The study was conducted in a private school of Daarut Tauhid in Bandung West Java. A bio-toilet S-50 type of Japan was constructed consisting of a composting chamber, mixer, heater, exhaust fan, and closet. The composting chamber was filled with 63 kg of Albizzia sawdust. Feces and urine was loaded daily by 54 students for 122-day observation. At the end of observation, the decomposed bio-toilet residue was evaluated for its physical properties such as bulk density (rb), porosity (%), and water retention (WR). Chemical properties such as pH, C/N ratio, N, P, and K, as well as microbiological properties such as numbers of bacteria, fungi, and worm eggs were evaluated at 14 and 122 days of decomposition process. Effect of the composted bio-toilet residue as plant growth media was evaluated using J. curcass as a plant indicator. Before it was used as a growth media, the composted bio-toilet residue was dried in a room temperature for 30 days. The experiment was designed in a completely randomized design 2 x 4 factorial with three replications. The first factor was the rate of composted biotoilet residue, i.e., 0, 20, 40, and 60% based on weight of the growth media mixture (1500 g pot-1), and the second was NPK fertilizer addition at 0 and 2 g pot-1. Each pot was planted with 2-month old of J. curcas seedlings. Parameters evaluated were leaf number, leaf area, stem height, and stem diameter measured at 12 weeks after planting. The results showed that the biotoilet residue was suitable as soil conditioner because it had high porosity (76%), low bulk density (0.19 g cm-3), high water retention (2.6 ml g-1 DM), neutral pH (6.9), C/N ratio 27, and contained N, P, K, and Na of 1.73, 1.15, 1.03, and 0.88%, respectively. Its microbial count showed only two kinds of bacteria, i.e., Klebsiella pneumonia and Escherichia coli, detected at 14 and 122 days of bio-toilet usage. The composted bio-toilet residue improved vegetative performances of J. curcas as indicated by increasing leaf number, leaf area, stem height, and stem diameter.

CHARACTERISTICS OF COMPOSTED BIO-TOILET RESIDUE AND ITS POTENTIAL USE AS A SOIL CONDITIONER

Bio-toilet is a dry toilet where human excreta is trapped in a lignocelluloses soil matrix such as wood sawdust, then it is decomposed by aerobic bacteria to organic compost rich in minerals such as N, P, and K. The study aimed to characterize the bio-toilet residue and its potential use as a soil conditioner for Jatropha curcas. The study was conducted in a private school of Daarut Tauhid in Bandung West Java. A bio-toilet S-50 type of Japan was constructed consisting of a composting chamber, mixer, heater, exhaust fan, and closet. The composting chamber was filled with 63 kg of Albizzia sawdust. Feces and urine was loaded daily by 54 students for 122-day observation. At the end of observation, the decomposed bio-toilet residue was evaluated for its physical properties such as bulk density (rb), porosity (%), and water retention (WR). Chemical properties such as pH, C/N ratio, N, P, and K, as well as microbiological properties such as numbers of bacteria, fungi, and worm eggs were evaluated at 14 and 122 days of decomposition process. Effect of the composted bio-toilet residue as plant growth media was evaluated using J. curcass as a plant indicator. Before it was used as a growth media, the composted bio-toilet residue was dried in a room temperature for 30 days. The experiment was designed in a completely randomized design 2 x 4 factorial with three replications. The first factor was the rate of composted biotoilet residue, i.e., 0, 20, 40, and 60% based on weight of the growth media mixture (1500 g pot-1), and the second was NPK fertilizer addition at 0 and 2 g pot-1. Each pot was planted with 2-month old of J. curcas seedlings. Parameters evaluated were leaf number, leaf area, stem height, and stem diameter measured at 12 weeks after planting. The results showed that the biotoilet residue was suitable as soil conditioner because it had high porosity (76%), low bulk density (0.19 g cm-3), high water retention (2.6 ml g-1 DM), neutral pH (6.9), C/N ratio 27, and contained N, P, K, and Na of 1.73, 1.15, 1.03, and 0.88%, respectively. Its microbial count showed only two kinds of bacteria, i.e., Klebsiella pneumonia and Escherichia coli, detected at 14 and 122 days of bio-toilet usage. The composted bio-toilet residue improved vegetative performances of J. curcas as indicated by increasing leaf number, leaf area, stem height, and stem diameter.

Responses of the phenolic compounds of Zea mays under heavy metal stress

Heavy metal toxicity is one of the major abiotic stresses caused by physiological and biochemical changes. Plants have evolved various phytochemical defense mechanisms to cope with this abiotic stress conditions. Phenolic compounds are one of the stress responses and have multiple roles in respect to adaptation of plants to the environment. In the present study, we aimed to evaluate the differential accumulation of various phenolics with HPLC in the leaves of corn exposed to increasing heavy metal doses in the plant growth medium. The application of Cd, Cu, and Pb increased the total phenolics in all treatments compared to control groups. Chlorogenic acid and rutin were the main phenolic compounds in respect to quantifying. However, the contents of caffeic acid, ferulic acid, and vanillic acid were comparatively lower than chlorogenic acid and rutin in all samples. The content of chlorogenic acid significantly increased and rutin slightly increased in the treatment of the heavy metals. The levels of caffeic acid and ferulic acid significantly decreased in all exposures of heavy metals compared to control groups. The content of vanillic acid changed according to heavy metal types and doses in the leaves of corn, and the low doses of Pb and Cd increased the level of vanillic acid. We show that there is a positive correlation with the total phenolic content and chlorogenic acid when the corn is exposed to Pb. Moreover, there are negative correlations between total phenolic compound and caffeic acid, ferulic acid in the application of Cu and Cd.

Physiological and Biochemical Responses of Merwilla plumbea Cultured In Vitro with Different Cytokinins After 1 Year of Growth Under Ex Vitro Conditions

Since their discovery in the 1950s, cytokinins (CKs) have become integral, almost indispensable, components of plant growth media in in vitro propagation. However, despite the extensive use of exogenous CKs in plant tissue culture systems, there is a paucity of knowledge on the longevity of their physiological effect post in vitro. The objective of this study was to evaluate the long-term physiological effect of CKs (including a novel meta-topolin derivative) applied during in vitro propagation of Merwilla plumbea after 1 year of ex vitro growth. Ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) was used for the quantification of endogenous auxins and phenolic compounds in the 1-year-old M.plumbea plants. Compared to the control, exogenous CKs had a significant carry-over effect on ex vitro growth of M.plumbea plants after 1 year growing under ex vitro conditions. M. plumbea plants treated with the novel CK 6-(3-hydroxybenzylamino)-9-(tetrahydropyran-2-yl)purine (mTTHP, 1.0 µM) had significantly higher leaf area per plant, total leaf fresh weight and bulb diameter. Varying concentrations of free indole-3-acetic acid (IAA), oxindole-3-acetic acid (OxIAA) and indole-3-acetyl-l-aspartic acid (IAA-Asp) were detected in leaves of plants originally treated with exogenous CKs, whereas these compounds were absent in leaves of plants without exogenous CKs. Likewise, a CK-type and concentration-dependent response was observed for hydroxybenzoic acids, hydroxycinnamic acids, flavonoids and antioxidant activity of the extracts. The current study showed the influence of type and concentration of exogenous CKs used in vitro on production of phytochemical compounds during ex vitro growth. Taken together, the study provides significant insights on the residual effect of exogenous CKs on the regulation of auxin homeostasis and phenolic acid and/or flavonoid metabolism in 1-year-old M.plumbea plants growing under ex vitro conditions.

Soil-roots Strength Performance of Extensive Green Roof by Using Axonopus Compressus

Green roof technology has been proven to provide potential environmental benefits including improved building thermal performance, removal of air pollution and reduced storm water runoff. Installation of green roof also involved soil element usage as a plant growth medium which creates several interactions between both strands. This study was carried out to investigate the soil-roots strength performance of green roof at different construction period up to 4 months. Axonopus compressus (pearl grass) was planted in a ExE test plot with a designated suitable soil medium. Direct shear test was conducted for each plot to determine the soil shear strength according to different construction period. In addition, some basic geotechnical testing also been carried out. The results showed that the shear strength of soil sample increased over different construction period of 1st, 2nd, 3rd and 4th month with average result 3.81 kPa, 5.55 kPa, 6.05 kPa and 6.48 kPa respectively. Shear strength of rooted soil samples was higher than the soil samples without roots (control sample). In conclusion, increment of soil-roots shear strength was due to root growth over the time. The soil-roots shear strength development of Axonopus compressus can be expressed in a linear equation as: y = 0.851x + 3.345, where y = shear stress and x = time.

Soil Physical and Hydraulic Properties over Terrace Adjacent Four Major Rivers

The soil does not only serve as a medium for plant growth but also for engineering construction purposes. It is very weak in tension, very strong in compression and fails only by shearing. The behaviour of the soil under any form of loading and the interactions of the earth materials during and after any engineering construction work has a major influence on the success, economy and the safety of the work. Soils and their management have therefore become a broad social concern. A limitless variety of soil materials are encountered in both agronomy and engineering problems, varying from hard, dense, large pieces of rock through gravel, sand, silt and clay to organic deposits of soft compressible peat. All these materials may occur over a range of physical properties, such as water contents, texture, bulk density and strength of soils. Therefore, to deal properly with soils and soil materials in any case requires knowledge and understanding of these physical properties.The desired value of bulk density varies with the degree of stability required in construction. Bulk density is also used as an indicator of problems of root penetration,soil aeration and also water infiltration. This property is also used in foundation engineering problems. While not conforming to standard test procedures, this work attempts to add to the basic information on such important soil parameters as water content, bulk density.

NodD1 and NodD2 Are Not Required for the Symbiotic Interaction of Bradyrhizobium ORS285 with Nod-Factor-Independent Aeschynomene Legumes.

Photosynthetic Bradyrhizobium strain ORS285 forms nitrogen-fixing nodules on the roots and stems of tropical aquatic legumes of the Aeschynomene genus. Depending on the Aeschynomene species, this symbiotic interaction does or does not rely on the synthesis of Nod-factors (NFs). However, whether during the interaction of Bradyrhizobium ORS285 with NF-independent Aeschynomene species the nod genes are expressed and if the general regulator NodD plays a symbiotic role is unknown. Expression studies showed that in contrast to the interaction with the NF-dependent Aeschynomene species, A. afraspera, the Bradyrhizobium ORS285 nod genes are not induced upon contact with the NF-independent host plant A. indica. Mutational analysis of the two nodD genes present in ORS285, showed that deletion of nodD1 and nodD2 did not affect the symbiotic interaction between Bradyrhizobium ORS285 and A. indica whereas the deletions had an effect on the symbiotic interaction with A. afraspera plants. In addition, when the expression of nod genes was artificially induced by adding naringenin to the plant growth medium, the nodulation of A. indica by Bradyrhizobium ORS285 is delayed and resulted in lower nodule numbers.

EFFECT OF TOPOPHYSIS AND CARBON SOURCE ON ANTI-ALZHEIMER MEDICINAL PLANT (BACOPA MONNIERRI ) IN VITRO GROWTH

Bacopa monnieri is used in traditional Ayurvedic medicine in India for centuries to control asthma, epilepsy and mental disorder. Various studies have shown that Bacopa is useful in controlling Alzheimer’s disease, anxiety, and age-related cognitive decline. It is also used to improve mental function and memory, treat respiratory ailments, and heal stomach ulcers. The present study aimed to in vitro investigate the explants position and carbohydrate sources effect on the growth and development of Bacopa monnieri which were cultured in the MS nutrient medium supplemented with different concentrations (20, 30, 40 gL) of the combination between the carbohydrates (sucrose, fructose, glucose) with the solid and the liquid media type and using stem of Bacopa plant containing of one node, two nodes and three nodes then cultured of two positions, horizontally and vertically method in the solid media. The incubation conditions were 25±2°C at 16 h/day photoperiod (2000-2500 lux). Glucose, 20 gL, gave the best shoot number (148.75), shoot length (5.87), Growth value (4.25) and multiplication rate (15.00). Results showed that the best shoot number (17.00), Leaf number (76.00) and Node number (38.00) resulted from two nodes horizontally position. The best Shoot length (4.12) occurred due to one node horizontally position. The best root number (23.00) resulted from three node horizontally method.In vitro plantlets produced from rooting stage were transferred in plastic pots (8 cm diameter) containing peat, perlite and sand for acclimatization. The rooted plants were successfully acclimatized in different potting media and grew naturally in the greenhouse. The best planting medium for plant growth was peat moss +perlite mixture (2: 3).

Biological, physicochemical and plant health responses in lettuce and strawberry in soil or peat amended with biochar

Biochar, a solid coproduct of biomass pyrolysis, has recently been proposed as soil amendment in agriculture. We studied the effect of biochar on soil and substrate physicochemical properties, plant growth, disease susceptibility and rhizosphere microbiology in two contrasting cropping systems, i.e., lettuce grown in field soil and strawberry grown in white peat. For both systems, changes in the physicochemical properties of the plant growth media were observed. In the lettuce bio-assay, biochar addition had no effect on crop growth, crop health (Rhizoctonia solani infection test) and rhizosphere microbiology. In contrast, in the strawberry bioassay, addition of 3% biochar to peat resulted in (i) a higher fresh and dry plant weight, (ii) a lower susceptibility for the fungal pathogen Botrytis cinerea on both leaves and fruits, and (iii) changes in the rhizosphere microbiology, analysed by Phospholipid Fatty Acid (PLFA) profiling and 16S rDNA amplicon sequencing. Biochar addition led to an increase of bacterial diversity and a shift in composition of the rhizosphere microbiota. Extra inorganic plant nutrition and lime added to the peat reduced these effects of biochar on the strawberry plants. We conclude that in certain plant growth media, biochar amendment can result in chemical changes that induce multiple responses in the plant, including shifts in the rhizosphere microbiome. Biochar can be beneficial for plant growth, especially in conditions of limited nutrient availability.

Potential Bioregulators for Rape (Brassica napus L.) Plants

It is known that polyphenols are a single group of phytochemicals which present in all plants. Their biological activity is based upon functional groups capable to participate in the plant metabolism influencing cell division and biosynthesis processes. In our experiments we have evaluated the effect of spruce bark polyphenolic extract and deuterium depleted water (DDW) as rapeseed plant bioregulators. After aqueous extraction of bark and quantification and identification of polyphenolic compounds by HPLC methods, we applied the extracts in the growth medium of rapeseed plants. Assessment the influence of extracts on rapeseed plants was achieved through determination of germination energy and capacity, biomass accumulation, assimilatory pigments accumulation and photosynthesis activity. The results has shown that it possible to establish the highest stimulating effect of polyphenols on germination energy and capacity. These, were registered in the presence of spruce bark polyphenolic extract (SBPE) with an equivalent content of 130 mg GAE/L. Rape plants treated with DDW+SBPE have accumulated the highest amount of biomass compared with other experimental variants. The photosynthesis activity was considerably intensified especially in the presence of SBPE.

Suitability of Fly Ash Vermicompost as a Component of Pine Bark Growing Media: Effects on Media Physicochemical Properties and Ornamental Marigold (Tagetes spp.) Growth and Flowering

ABSTRACTThis study evaluated the possibility of mixing fly ash vermicompost (FA) with pine bark (PB) compost to produce a horticultural growing medium for ornamental plants using ornamental marigolds (Tagetes spp.) as the test crop. Fly ash vermicompost was mixed with pine bark compost at 0, 25, 50, 75, and 100% and marigold seeds were sown with or without fertilizer in the resultant media to test their suitability as seedling growing media. FA substitution up to 50% significantly improved water-holding capacity, total porosity, and air-filled porosity. It also raised pH from 4.52 to a maximum of 8.33 when incorporated up to 75%. Incorporation of FA up to 75% resulted in significantly high germination percentages above 90% compared to only 22.5% for the 100% PB medium. However, after 4 weeks of growth, seedlings in the 25 and 50% FA substituted media had higher plant height and leaf area. The 25% FA treatment resulted in significantly higher number of flowers and buds compared to the 50 and 75%. For effective marigold seedling germination and growth, a 50% FA:50% PB growing medium is recommended while for maturity and flower production, the 25% FA:75% PB combination is preferred.

Effects of Salinity and Plant Growth Media on in Vitro Growth and Development of Taro (Colocasia Esculenta L.) Varieties

Abstract Taro Colocasia esculenta is a staple food in most countries of the South Pacific region. However, the recent changes in the climatic conditions and the associated factors became a threat to growing taro in the region. Rising sea level and frequent dry and wet conditions had led to increased soil salinity which is a limiting factor in producing taro in these atoll islands. The aim of this research was to screen selected taro varieties based on their ability to tolerate salinity conditions in Samoa. Effects of three salinity levels (0.2, 3% and 5%), and growth hormones Benzylaminopurine (BAP) and Thidiazuron (TDZ) were examined on growth and development of in vitro grown taro varieties. Plant height, number of leaves, and number of roots produced were compared in the selected varieties. Results suggest that all varieties had callus induction and regeneration in MSO medium. Addition of BAP induced better growth and the plants produced higher number of leaves, while TDZ improved roots proliferation in C. esculenta. Solomon variety performed best in high salinity conditions. Samoa-1 grew taller and had more leaves and roots compared to Samoa-2 variety. Thus, we suggest Solomon and Samoa-1 could perform better in high-salinity conditions.