Modified Hoagland Nutrient Solution Research Articles

Transcriptomics and metabolomics reveal the primary and secondary metabolism changes in Glycyrrhiza uralensis with different forms of nitrogen utilization.

The roots and rhizomes of Glycyrrhiza uralensis Fisch. represent the oldest and most frequently used herbal medicines in Eastern and Western countries. However, the quality of cultivated G. uralensis has not been adequate to meet the market demand, thereby exerting increased pressure on wild G. uralensis populations. Nitrogen, vital for plant growth, potentially influences the bioactive constituents of plants. Yet, more information is needed regarding the effect of different forms of nitrogen on G. uralensis. G. uralensis seedlings were exposed to a modified Hoagland nutrient solution (HNS), varying concentrations of nitrate (KNO3), or ammonium (NH4)2SO4. We subsequently obtained the roots of G. uralensis for physiology, transcriptomics, and metabolomics analyses. Our results indicated that medium-level ammonium nitrogen was more effective in promoting G. uralensis growth compared to nitrate nitrogen. However, low-level nitrate nitrogen distinctly accelerated the accumulation of flavonoid ingredients. Illumina sequencing of cDNA libraries prepared from four groups-treated independently with low/medium NH4 + or NO3 - identified 364, 96, 103, and 64 differentially expressed genes (DEGs) in each group. Our investigation revealed a general molecular and physiological metabolism stimulation under exclusive NH4 + or NO3 - conditions. This included nitrogen absorption and assimilation, glycolysis, Tricarboxylic acid (TCA) cycle, flavonoid, and triterpenoid metabolism. By creating and combining putative biosynthesis networks of nitrogen metabolism, flavonoids, and triterpenoids with related structural DEGs, we observed a positive correlation between the expression trend of DEGs and flavonoid accumulation. Notably, treatments with low-level NH4 + or medium-level NO3 - positively improved primary metabolism, including amino acids, TCA cycle, and glycolysis metabolism. Meanwhile, low-level NH4 + and NO3 - treatment positively regulated secondary metabolism, especially the biosynthesis of flavonoids in G. uralensis. Our study lays the foundation for a comprehensive analysis of molecular responses to varied nitrogen forms in G. uralensis, which should help understand the relationships between responsive genes and subsequent metabolic reactions. Furthermore, our results provide new insights into the fundamental mechanisms underlying the treatment of G. uralensis and other Glycyrrhiza plants with different nitrogen forms.

Saline-Alkaline Stress Resistance of Cabernet Sauvignon Grapes Grafted on Different Rootstocks and Rootstock Combinations.

Grafting the wine grape variety Cabernet Sauvignon onto salinity-tolerant rootstocks can improve salinity tolerance and grape yields in regions with high salinity soils. In this experiment, the effects of different rootstocks and rootstock combinations on the saline-alkaline stress (modified Hoagland nutrient solution + 50 mmol L-1 (NaCl + NaHCO3)) of Cabernet Sauvignon were studied. Correlation and principal component analyses were conducted on several physiological indicators of saline-alkaline stress. Salinity limited biomass accumulation, induced damage to the plant membrane, reduced the chlorophyll content and photosynthetic capacity of plants, and increased the content of malondialdehyde, sodium (Na+)/potassium (K+) ratio, and antioxidant enzyme activities (superoxide dismutase, peroxidase, and catalase). Significant differences in several indicators were observed among the experimental groups. The results indicate that the saline-alkaline tolerance of Cabernet Sauvignon after grafting was the same as that of the rootstock, indicating that the increased resistance of Cabernet Sauvignon grapes to saline-alkaline stress stems from the transferability of the saline-alkaline stress resistance of the rootstock to the scion.

Growth of Lettuce in Hydroponics Fed with Aerobic- and Anaerobic–Aerobic-Treated Domestic Wastewater

Reusing water and nutrients from municipal wastewater can conserve resources and reduce wastewater treatment costs. In this study, the suitability of different qualities of treated wastewater for plant production in a hydroponic flow-through system was investigated. Lettuce (Lactuca sativa L.) was grown in hydroponic lines fed with treated wastewater, i.e., conventional effluent from aerobic wastewater treatment by the activated sludge process (CE), ozonised CE (CEO), anaerobically pre-treated and nitrified wastewater (AN) and biological activated carbon filtered AN (ANC) in comparison with a modified Hoagland nutrient solution. In CEO, AN and ANC, the lettuce reached a similar weight and elemental composition as that in HS. The low N and P concentrations in CE and CEO were quickly depleted, resulting in limited plant development at the ends of these lines. The lower water content in the CE shoots was probably related to hypoxia that occurred at higher temperatures. In the CEO line, this condition did not arise due to the constant decay of O3. At lower temperatures, the CEO shoot dry weight was 90% higher than that in CE. This was possibly an effect of residual ozone and/or oxygen supersaturation. AN produced the highest yield, while carbon filtration lowered the content of cations in ANC, inducing deficiency of Fe > Mn > Cu > Zn > K. Coupling wastewater treatment with hydroponics allows for efficient nutrient recovery, and thus could reduce the energy and reactor volume needed for N and P elimination.

Kapacitet izmjene plinova graha (Phaseolus vulgaris L.) u uvjetima nedostatka hranjiva

The lack of plant nutrients is a major problem for agriculture. Because of their essential role in the most important metabolic processes of plants, their deficiency depresses photosynthesis and disrupts the efficient operation of the photosynthetic apparatus. In this study, we investigated the gas exchange of common beans bean under the N, P, K, Mg, and Fe deficiency. The experiment was set up as a hydroponic, fully aerated, floating system in 6 hydroponic tubs. Each hydroponic tub contained 10 plants and was filled with a modified Hoagland nutrient solution. One group of plants was grown in a complete nutrient solution (control), while the other treatments lacked one of the following nutrients: N, P, K, Mg and Fe. During the experiment, gas exchange parameters: net photosynthetic rate (A), transpiration rate (E), stomatal conductance (gs) and intercellular CO2 concentration (Ci) were measured. At the end of the experiment, the nutrient content of the plant tissue was determined. Nutrient deficiency significantly affected all measured photosynthetic parameters and visual symptoms indicated that a lack of different nutrients affected the photosynthetic machinery at different points. Potassium deficiency lower stomatal conductance and increased mesophyll resistance to CO2 diffusion and/or RubisCO activity. Nitrogen and Mg deficiency affected chlorophyll synthesis and accelerated leaf senescence. Phosphorus deficiency caused less damage to gas exchange parameters probably due to protective mechanisms of reduced leaf area. Seed Fe content was surplus to sustain photosynthetic machinery during the early developmental phase.

Optimum Nitrogen Application Promotes Sweetpotato Storage Root Initiation

Storage root formation of sweetpotato (Ipomoea batatas (L.) Lam) is a complex developmental process relating to the activity of cambium. Little information is available on the relationship between nitrogen (N) application levels and the initiation and development of sweetpotato storage roots (SRs). This study aims to examine how N application rates promoted/inhibited the formation and development of storage roots (SRs) for sweetpotato cultivar ‘Orleans’ during the first 8 weeks after planting. Cuttings were grown in coarse river sand culture supplied with modified Hoagland nutrient solution at four different rates (0 (N0), 50 (N50), 100 (N100) or 200 (N200) mg L−1) of N. The results showed that N100 treatment promoted the formation of primary and secondary cambium, resulting in a significant higher rate of SR formation between 21 and 56 days after transplanting (DAT). Due to the higher N demand after formation of SRs, N200 treatment displayed faster growth, higher N acquisition and the highest efficiency of N use after 35 DAT, but the SR formation rate and SR number per plant remained insignificantly lower than N100 when differentiation of adventitious root was mostly completed (49 DAT), suggesting irreversible an effect of N rate during SR initiation, which eventually affects SR number. The results suggested that the optimal substrate N level for sweetpotato SR initiation is lower than that for following SR growth, which should be considered in the fertilisation scheme.

Excess Zinc Supply Reduces Cadmium Uptake and Mitigates Cadmium Toxicity Effects on Chloroplast Structure, Oxidative Stress, and Photosystem II Photochemical Efficiency in Salvia sclarea Plants.

Salvia sclarea L. is a Cd2+ tolerant medicinal herb with antifungal and antimicrobial properties cultivated for its pharmacological properties. However, accumulation of high Cd2+ content in its tissues increases the adverse health effects of Cd2+ in humans. Therefore, there is a serious demand to lower human Cd2+ intake. The purpose of our study was to evaluate the mitigative role of excess Zn2+ supply to Cd2+ uptake/translocation and toxicity in clary sage. Salvia plants were treated with excess Cd2+ (100 μM CdSO4) alone, and in combination with Zn2+ (900 μM ZnSO4), in modified Hoagland nutrient solution. The results demonstrate that S. sclarea plants exposed to Cd2+ toxicity accumulated a significant amount of Cd2+ in their tissues, with higher concentrations in roots than in leaves. Cadmium exposure enhanced total Zn2+ uptake but also decreased its translocation to leaves. The accumulated Cd2+ led to a substantial decrease in photosystem II (PSII) photochemistry and disrupted the chloroplast ultrastructure, which coincided with an increased lipid peroxidation. Zinc application decreased Cd2+ uptake and translocation to leaves, while it mitigated oxidative stress, restoring chloroplast ultrastructure. Excess Zn2+ ameliorated the adverse effects of Cd2+ on PSII photochemistry, increasing the fraction of energy used for photochemistry (ΦPSII) and restoring PSII redox state and maximum PSII efficiency (Fv/Fm), while decreasing excess excitation energy at PSII (EXC). We conclude that excess Zn2+ application eliminated the adverse effects of Cd2+ toxicity, reducing Cd2+ uptake and translocation and restoring chloroplast ultrastructure and PSII photochemical efficiency. Thus, excess Zn2+ application can be used as an important method for low Cd2+-accumulating crops, limiting Cd2+ entry into the food chain.

Preferential ammonium: nitrate ratio of blueberry is regulated by nitrogen transport and reduction systems

Blueberry (Vaccinium spp., Vc) is inefficient in uptake and utilizing a single nitrogen (N) form (ammonium or nitrate), and prefers the presence of both N forms; however, its preferential ammonium: nitrate ratios and the underlying molecular mechanism remain elusive. To reveal the mechanism of blueberry preference in the composition of N forms, blueberries had grown over three months in pure coconut bran irrigated with modified Hoagland nutrient solution containing ammonium N (NH4+-N) alone or nitrate N (NO3−-N) alone at two pHs (5.0 and 7.5), and NH4+-N:NO3−-N ratios of 4:1, 2:1 and 1:1 at pH 5.0. After three months, the physiological responses and the expression of key genes involved in N metabolism were analyzed. Afterwards, the genes were then genetically transformed into Arabidopsis thaliana for functional verification. The results showed that (i) plants grew better at pH 5.0 than pH 7.5; (ii) at pH 5.0, when NH4+-N:NO3−-N ratio was applied at 2:1, plant growth was at the best performance (i.e., 11% higher in the crown width compared to the control(nil-N applied). In the presence of both NH4+ and NO3−, the transcriptional levels of VcAMT3, VcNRT1.5, VcNRT2, VcNR and VcNiR were significantly upregulated. The highest value appeared in the 2:1 of NH4+-N:NO3−-N ratio where, VcAMT3 and VcNRT2 were raised by 4 and 5 times, respectively. Hence, the results suggested that the mixed N forms at 2:1 NH4+-N:NO3−-N ratio at pH 5.0 induced the expression of the related gene, which may have increased root absorption and transportation of NH4+-N and NO3−-N, resulting in the better plant growth; and (iii) under NH4+-N alone treatments, the transgenic VcNiR Arabidopsis thaliana plants were the only survival; under NO3−-N alone treatments, compared to the wild-type plants, the transgenic VcAMT3 Arabidopsis thaliana had 11 and 2 times higher in the plant height and leaf disc size. The results showed that VcAMT3, VcNRT2, VcNiR genes could improve the nitrogen absorption ability of Arabidopsis thaliana plants. Our study improved the understanding of the underlying molecular mechanism of N speciation preference of blueberry, and the findings can be a great guidance for better N fertilizer management to promote blueberry productivity.

Phosphorus Solubilizing and Mineralizing Bacillus spp. Contribute to Rice Growth Promotion Using Soil Amended with Rice Straw

Rice (Oryza sativa L.) is a staple food for more than two billion people worldwide. Its cultivation demands large amounts of nutrients, particularly nitrogen and phosphorus (P). Consequently, low availability of these nutrients in the soil has led to the use of chemical fertilizers, generating increases in production costs and environmental damage. Soil host microorganisms known as plant growth-promoting rhizobacteria (PGPR) colonize the rhizosphere and facilitate the uptake of nutrients by the plants. In this study, rice seeds inoculated with PGPR were grown for 30days in an inert substrate and fertilized with modified Hoagland nutrient solution with phosphate rock as a source of P. Treatments were repeated over time, obtaining five isolates which significantly increased plant length by up to 56% and dry weight of stems and roots up to 45% and 169% respectively relative to an uninoculated control. Selected strains showed in vitro tri-calcium phosphate solubilizing activity, mineralizing phytate activity, and phosphate release from rice straw (RS). Based on the above criteria, three isolates (IBUN-02755, -02,704 and -02,724) that contained β propeller phytase (BPP) genes, were selected to evaluate their effect as PGPR in rice seedlings. These were planted in a soil amended with RS under greenhouse conditions. The results showed that selected Bacillus spp. strains significantly increased plant length and dry weight or increased plant phosphate uptake up to two times compared to an un-inoculated control. This suggests that selected strains may have a capacity as PGPR using RS as carbon and a P amendment.

Effect of Arsenic Toxicity on Chlorophyll Content and Antioxidative Enzymes Activities in Rice Seedlings

Aims: Arsenic (As) contamination in rice is at alarming level as majority of rice growing regions in India are As contaminated. Present investigation is designed to study the better understanding of the physiological and biochemical mechanisms in the amount of chlorophyll change and antioxidative enzymes activity under arsenic stress on rice variety IET-4786 (Shatabdi).
 Study Design: Completely Randomized Design.
 Place and Duration of Study: The experiment was carried out in the departmental laboratory of Plant Physiology, Bidhan Chandra Krishi Viswavidyalaya (BCKV), Mohanpur, Nadia,West Bengal during the year 2017-18.
 Methodology: Two classes of inorganic arsenic- As(V) in the form of Sodium arsenate (Na2HAsO4.7H2O, M. W. = 321.01) and As(III) in the form of Sodium arsenite (NaAsO2, M.W. =129.91) were added to the modified Hoagland nutrient solution@ 2.5, 5.0, 7.5, 10.0, 12.5,15.0 mg L-1concentration. After 20 days of treatment, rice seedlings under arsenate/arsenite treatments were analyzed for change in total chlorophyll content and antioxidative enzymes activity such as superoxide dismutase (SOD: EC 1.15.1.1), catalase (CAT: EC 1.11.1.6), ascorbate peroxidase (APX: EC1.11.1.11) and peroxidase (POD: EC 1.11.1.7).
 Results: A noticeable decrease in total chlorophyll content was observed with arsenic treatments as compared to control. Various antioxidative enzymes showed significant variable response upon exposure to As(III) and As(V). SOD activities increased at low arsenic exposure up to 7.5 mg L-1 but decreased with further increase in arsenic treatments. APX and POD activities were increased with increase in arsenic concentrations while CAT activity displayed decreasing trend.
 Conclusion: The results are suggestive of differential metabolism of As(III) and As(V) in rice and could exert harmfulness in the early development stage of rice at inappropriate concentrations.

Effect of Salinity Stress on Antioxidative Enzyme Activity in the Leaves of Tolerant and Susceptible Genotypes of Groundnut

Aims: To better understand the physiological and biochemical mechanisms in the light of antioxidative enzymes activity under salinity stress between tolerant and susceptible genotypes of groundnut.
 Study Design: Completely Randomized Design.
 Place and Duration of Study: The laboratory experiment was carried out in the departmental laboratory of Plant Physiology, Bidhan Chandra Krishi Viswavidyalaya (BCKV), Mohanpur, Nadia, and West Bengal during the year 2017-18.
 Methodology: A controlled study was conducted to screen 26 genotypes of groundnut under 200 mM NaCl salinity stress. Fourteen-day old seedlings were subjected to salinity treatment. For this, the modified Hoagland nutrient solution containing 200 mM NaCl (osmotic potential: -0.8 MPa) was applied in each case and the pH was adjusted to 6.3. The treatments were repeated on every third day. Control set without salinity stress was also maintained similarly in each case for comparison of results.
 Results: The salt tolerance index or STI of the genotypes ranged from 47.57% to 96.40%. Out of all the genotypes KDG-197 (STI= 96.40%) was found to be the most tolerant under a salinity stress of 200 mM NaCl and it was closely followed by R 2001-2 (STI=87.92%), VG 315 (STI=84.05%), TCGS 1157 (STI=77.59%) and TG 51 (STI=73.67%). While the genotypes Girnar 3 (STI= 47.57%), OG 52-1 (STI=49.09%), TVG 0856 (STI= 49.28%) and J 86 (STI= 50.66%) were the most susceptible genotypes based on their relative performance under stress in respect of total dry weight. It has been noted further that, out of the nine genotypes, enhancement of antioxidative enzyme like super oxide dismutase (SOD), guaiacol peroxidase (GPOX) and catalase (CAT) activity was recorded maximally in tolerant genotype KDG 197 (64.18%, 71.74% and 52.82% increase over control respectively) and R 2001-2 (53.68 %, 93.48% and 53.96 % increase over control respectively) but the activity of these enzyme in the four susceptible genotypes declined considerably under salinity treatment.
 Conclusion: Tolerant genotypes of groundnut in general registered much higher activities of antioxidative enzymes in their leaves as compared to the susceptible genotype under high salinity stress.

ROS Scavenging and $${\text{NH}}_{4}^{ + }$$ Nitrogen Fertilizer Roles in Alleviation of Cd-Induced Oxidative Stress in Arabidopsis thaliana

Arabidopsis thaliana (L.) Heynh. receiving ammonium, were transferred on modified Hoagland nutrient solution containing Cd (25 µM) alone or supplemented with buthionine sulfoximine (BSO, an inhibitor of glutathione synthesis). In ammonium-fed A. thaliana treated with Cd alone, leaf and root growth was not negatively affected. Carbon metabolism was stimulated through activation of Rubisco and maintain of phosphoenol pyruvate carboxylase (PEP) and NADP(+)-isocitrate dehydrogenase (NADP(+)-ICDH). In another way, superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and peroxidase (GPX), and ascorbate-glutathione-regenerating enzymes (glutathione reductase (GR), dehydroascorbate reductase(DHAR) and monodehydroascorbate reductase (MDHAR) activities were stimulated by Cd. Ascorbate (AsA) and dehydroascorbate (DHA) contents were significantly raised. More that, the high NAD/NADH ratio in Cd-treated A. thaliana fed with ammonium proved the capacity of leaf cells to maintain NAD homeostasis under stressful conditions. The dramatic effect of BSO when added currently with Cd was reflected by the imbalance of all the patterns shown and described previously. Growth was inhibited in parallel to MDA and H2O2 accumulation. Carbon metabolism, ascorbate-glutathione-regenerating and antioxidative enzymes were all reduced. Revealing that alleviation of Cd toxicity by ammonium nitrogen is due to a beneficial relationship between carbon metabolism activation and ROS production minimization also than there may be scavenging enhancement.

Differential Growth Responses of Wheat Seedlings to Elevated CO2

Intraspecific variations in wheat growth responses to elevated CO2 was evaluated using 20 Iranian bread wheat (Triticum aestivum L.) cultivars. The plants were grown in the modified Hoagland nutrient solution at a greenhouse until 35 days of age using two levels of CO2 (~380 and 700 µmol mol–1). The shoot and root dry weights of the wheat cultivars exhibited average enhancements of 17% and 36%, respectively, under elevated CO2. This increase was associated with higher levels of chlorophyll a (25%), chlorophyll b (21%), carotenoid (30%), leaf area (54%) and plant height (49.9%). The leaf area (r = 0.69**), shoot N content (r = 0.62**), plant height (r = 0.60**) and root volume (r = 0.53*) were found to have important roles in dry matter accumulation of tested wheat cultivars under elevated CO2 concentration. However, responses to elevated CO2 were considerably cultivar-dependent. Based on the stress susceptibility index (SSI) and stress tolerance index (STI), the wheat cultivars exhibiting the best response to elevated CO2 content were ‘Sistan’, ‘Navid’, ‘Shiraz’, ‘Sepahan’ and ‘Bahar’, while the ones with poor responses were ‘Omid’, ‘Marun’, ‘Sorkhtokhm’ and ‘Tajan’. The findings from the present experiment showed significant variation among the Iranian wheat cultivars in terms of their responses to elevated air CO2, providing the opportunity to select the most efficient ones for breeding purposes.

Effects of ozone-treated domestic sludge on hydroponic lettuce growth and nutrition

Here, the ozone-treated domestic sludge was diluted up to four different multiples and utilized as a nutritional source for hydroponic lettuce growth. Additionally, lettuce was cultured using the modified Hoagland nutrient solution as a control. The effects of ozone-treated domestic sludge on lettuce growth and nutrition were studied. Results showed that the lettuce treated with modified Hoagland inorganic nutrient solution had increased leaf number, plant height, fresh weight and dry weight compared to those treated with the ozone-treated domestic sludge dilution (P<0.05). However, the lettuce cultivated with the 2-fold ozone-treated sludge dilution showed significantly higher (P<0.05) contents of chlorophyll, soluble sugar and ascorbic acid (Vc) compared to that treated with modified Hoagland nutrient solution. And the nitrate concentration in the lettuce cultured with the 2-fold ozone-treated sludge dilution was 53.93% less than that cultured with the modified Hoagland nutrient solution, which was a significant improvement (P<0.05). This study suggested that the 2-fold ozone-treated sludge dilution is optimal for lettuce hydroponic nutrient requirements.

Response of two pomegranate (Punica granatum L.) cultivars to six boron concentrations: Growth performance, nutrient status, gas exchange parameters, chlorophyll fluorescence, and proline and carbohydrate content

ABSTRACTOne-year-old, own-rooted pomegranate cultivars “Ermioni” and “Wonderful” plants were irrigated for 75 days with modified Hoagland nutrient solutions containing 0–10 mg L−1 boron (B). At the end of the experiment, the control plants of “Ermioni” presented better growth performance than those of “Wonderful.” However, there were no differences in the treatments with high B concentration (5.0 or 10 mg L−1). Control “Wonderful” plants had higher fresh and dry matter than control “Ermioni” plants. Moreover, the highest B concentrations in nutrient solution led to a significant increase in chlorophyll and carbohydrate content in the leaves of cultivar “Ermioni.” Furthermore, leaf proline concentration, gas exchange, chlorophyll fluorescence, and micro–macronutrients of both cultivars were not affected by any of the tested B treatments. B concentration in plant parts was linearly correlated to B supply. The highest B concentrations were observed in roots followed by stems and apical and basal leaves.

Root uptake and xylem transport of cadmium in wheat and triticale as affected by exogenous amino acids

Organic acids exuded from plant roots significantly modify uptake and long-distance translocation of metals. Little is known about the effect of amino acids on metal ion uptake by plant roots. The present study investigated the effects of exogenous amino acids (histidine and glycine) in a nutrient solution on root uptake and xylem sap transport of cadmium (Cd) in triticale (× Triticosecale cv. Elinor) and bread wheat (Triticum aestivum L. cv. Back Cross Rushan). Plant seedlings were grown in a Cd-free modified Hoagland nutrient solution to which 1 µm Cd was added with either 50 µm histidine or 50 µm glycine or without amino acids at 4 weeks after germination. A control treatment consisted of a nutrient solution free of Cd and amino acids. In bread wheat, addition of histidine to the Cd-containing nutrient solution resulted in a higher operationally defined symplastic Cd fraction but a lower apoplastic one in the roots. In triticale, addition of either amino acid decreased the symplastic Cd fraction but increased the apoplastic one. Addition of histidine to the nutrient solution increased Cd concentration in wheat xylem sap but had no significant effect on Cd concentration in triticale xylem sap. Compared with the Cd-only treatment, the glycine-containing treatment led to significantly reduced Cd concentrations in xylem sap of both plant species. Wheat plants supplied with histidine and Cd accumulated greater amounts of Cd in their shoots than those supplied with Cd alone. Glycine had no significant effects on the Cd content of wheat shoots but decreased it in triticale shoots. Results indicate that the effects of amino acids on plant root uptake and xylem sap translocation of Cd depend on the type of amino acid supplemented. This finding is of great importance for selecting and/or breeding cultivars with Cd-toxicity tolerance.

Root growth of cultivated and “wild” olive in response to potassium mineral nutrition

ABSTRACTNutrient availability affects root growth. The effect of potassium (K) level on the root growth, weight, and elongation, as well as on nutrient content of the olive genotypes “Megaritiki,” “wild” olive, “Chondrolia Chalkidikis,” “Biancolilla,” and K utilization efficiency was investigated. For this purpose, a greenhouse experiment was carried out in the farm of the Aristotle University of Thessaloniki. Three treatments were used: T1, that is, 25% modified Hoagland nutrient solution without K in distilled water, T2: 25% modified Hoagland nutrient solution with 0.2 mM K in distilled water, and T3: 25% modified Hoagland nutrient solution with 1.5 mM K in distilled water. K concentration had no significant effect on root growth of olive genotypes. The maximum root elongation was observed in the “wild olive,” in the T3 treatment, and the minimum in “Biancolilla,” in the T1 treatment. K utilization efficiency significantly differed between K treatments for the same genotype, as well as among genotypes for the same K treatment, following the order: Megaritiki > wild olive > Chondrolia Chalkidikis > Biancolilla. Finally, significant differences were found with regard to the effect of K treatment and olive genotype on many macronutrient and micronutrient concentrations in leaves and roots.

Growth Characteristics of Bahiagrass Roots Treated with Micronutrients, Rare Earth Elements, and Plant Hormones

Bahiagrass (Paspalum notatum) is widely used for slope protection and water and soil conservation in southern China. The plants develop an extensive root system that plays a crucial role in the protection of both soil and water. However, little is currently known about the factors that influence early root growth in bahiagrass. Here, the effects of boron (B), calcium (Ca), iron (Fe), lanthanum (La), cerium (Ce), salicylic acid (SA), and melatonin (MLT) on root growth characteristics were examined. Bahiagrass seedlings were grown in 1/25 strength modified Hoagland nutrient solution supplemented with boric acid, calcium chloride, ferric ethylenediaminetetraacetic acid (Fe-EDTA), lanthanum chloride, cerium chloride, SA, or MLT. Root lengths, root surface areas, and the number of root tips were analyzed using a root scanning system after 2, 4, and 6 days of treatment. We found significant effects on root growth after some treatments. Thus, 0.270 or 0.360 mm B for 2 days enhanced root tip number, whereas 0.15 mm Fe for 6 days increased root surface area. Although 3 or 5 mm Ca caused an increase in root tip numbers, the root length was reduced. The addition of La to the nutrient solution significantly increased root length and surface area, and addition of Ce increased root surface area and root tip numbers. Root growth characteristics were optimal after 0.3 μm La for 6 days or 1.0 μm La for 4 days. For Ce treatment, optimal root characteristics were observed at 0.5 μm Ce for 6 days. Root tip numbers increased after 0.1 or 1.0 μm MLT for 6 days, whereas SA treatment reduced the root length, surface area, and root tip numbers. Overall, the analyses indicate that treatment with B, Fe, La, Ce, and MLT benefited root growth in bahiagrass seedlings.

Research Concerning the Influence of Fertilization on Some Physiological Processes and Biochemical Composition of Lavender (Lavandula Angustifolia L.)

Abstract The aim of the research was to study the influence of phosphorus (P) and potassium (K) fertilization on the main physiological processes in lavender and biochemical characterization of essential oil obtained by steam distillation. Physiological processes studied were the photosynthesis and transpiration intensity. The material used for herbal purposes includes commercial genotype of lavender (Lavandula angustifolia L.). Experiment was carried out under controlled conditions and fertilization was performed with a modified Hoagland nutrient solutions. For biochemical analysis were used average samples of lavender leaf, stem and flowers. Separation and analysis of compounds was performed by gas chromatography analysis coupled with mass spectrometry (GC-MS). Transpiration intensity was performed by successive mass determinations from leaves and resulted values were reported per unit leaf area. The rate of photosynthesis was measured by Qubit Systems CO 2 analysis package. Researches were performed in the laboratory of Plant Physiology within the Faculty of Horticulture and Forestry and Plant extracts laboratory, Faculty of Food Processing Technology, from Banat University of Agricultural Sciences and Veterinary Medicine Timisoara. Following the experiment, it was found that potassium fertilization has a positive effect both on the photosynthesis and transpiration. Linalool (30.398%), lynalil acetate (23.609%), camphor (8.844%), borneol (5.49%) and eucalyptol (3.964%), were determined as the main compounds from over 50 identified through biochemical analysis of the essential oil.

Micropropagation of Achillea millefolium L. on half-strength ms medium and direct rooting and acclimatization of microshoots in hydroponic culture

The aim of this study was to determine the possibility of micropropagation of the medicinal plant A. millefolium on half-strength MS medium and ex vitro rooting and acclimatization of the obtained microshoots in hydroculture in order to establish an efficient production method. Two explant types were used: basal and terminal cuttings, and better results were achieved when terminal cuttings were used. The development of shoots in the multiplication phase was successful with a regeneration percentage of 100%. Ex vitro rooting in a modified Hoagland nutrient solution was successful (83%), but the percentage of in vitro rooting on half-strength MS medium without hormones was higher (95%). However, bearing in mind that mass production of A. millefolium is more efficient when the phase of in vitro rooting is excluded, this method could be recommended for commercial propagation of this medicinal plant. It is necessary to conduct additional research in order to optimize the composition, EC and pH value of the hydroponic nutrient solution.

Effect of Enhanced Zinc Nutrition on Mitigation of Huanglongbing (HLB)-affected Citrus

Author(s): Li, S. L.; Li, Z. G.; He, Z. L. | Abstract: The growth decline of huanglongbing (HLB)-affected citrus trees is considered to be associated with nutritional disorder, as typical symptoms of HLB such as stunted tree growth, chlorosis or blotchy mottle of leaves, resembles zinc (Zn), iron (Fe) and manganese (Mn) deficiencies, while lower Zn concentration has been consistently reported in the HLB affected compared to healthy plants. Hydroponic culture studies were conducted to evaluate the effects of enhanced Zn nutrition on the mitigation of HLB-affected grapefruit seedlings. Modified Hoagland nutrient solutions were used with three Zn2+ levels: 0, 1.0, and 1.5 times that of standard strength. Both HLB-affected and healthy grapefruit seedlings were subjected to the treatments for 49 days. During the growth period, photosynthesis of plant leaves was measured, and at day 49 of the culture, leaf tissues and cells were examined for structural changes using light and scanning electron microscopy. Enhanced Zn nutrition generally improved the growth of HLB plants with less symptom severity. Photosynthesis, in terms of leaf electron transfer rate and photochemical quantum yield, was enhanced. The wax layer and cuticle increased, and the epidermis cells became better organized, with a higher number of normal stomatal openings, compared to the control. In addition, enhanced Zn nutrition resulted in more developed xylem and phloem transport systems, resulting in reduced starch grains and polyphenol substances in the leaf cells. These results indicate thatenhanced Zn nutrition can improve the structure of photosynthetic, transfusion and protective tissue systems, and thus promote photosynthesis, transport of photosynthates, and other related metabolism of HLB-infected citrus.