Hydroponic Conditions Research Articles

The Effects of Brassinosteroids on Nitrogen Utilization in Rice

Nitrogen and brassinosteroids (BRs) play a vital role in modulating the growth, development, and yield of rice. However, the influences of BRs on nitrogen assimilation and metabolism in rice are not fully understood. In this study, we analyzed the impact of BRs on nitrogen utilization in rice using the indica variety ‘Zhongjiazao 17’ and the japonica variety ‘Nipponbare’ in hydroponic conditions. The results showed that BR treatment could efficiently elevate nitrate and ammonium nitrogen accumulation in both shoots and roots. Furthermore, some genes involved in the uptake of nitrate and ammonium in roots were stimulated by BRs, though we noted subtle variances between the two rice cultivars. Moreover, BRs augmented the activity of nitrate reductase (NR) and glutamine synthetase (GS) in roots, along with NR in shoots. Interestingly, BRs also spiked the total free amino acid content in both the shoots and roots. Gene expression analysis uncovered a robust induction by BRs of NR genes and GS-related genes in the roots of both ‘Nipponbare’ and ‘Zhongjiazao 17’. Collectively, our data suggest that BRs significantly enhance the accumulation of both nitrate and ammonium in rice and trigger a series of reactions related to nitrogen utilization.

Cyanobacteria Based Nanoformulation of Biogenic CuO Nanoparticles for Plant Growth Promotion of Rice Under Hydroponics Conditions.

Synthesizing nanoparticles through a green synthesis approach is common nowadays. Cyanobacteria have attained great importance in the field of biosynthesis of nanoparticles as there is no use of toxic chemicals as reducing or capping agents for the synthesis of metal oxide nanoparticles. Micronutrient-based nano-formulations have become a topic of great interest in recent times due to their various advantageous properties and applications in agriculture. The current study aims to exploit the potential cyanobacterial strains isolated from different locations such as freshwater and soil ecosystems. The potential cyanobacterial isolates were screened based on their multiple plant growth promoting (PGP) attributes such as Indol acetic acid (IAA) production, siderophores, and phosphate solubilization. After the screening of cyanobacteria based on multiple PGP activities, the cyanobacterial strain was identified at the species level as Pseudanabaena foetida RJ1, based on microscopy and molecular characterization using 16S rRNA gene sequencing. The cyanobacterial biomass extract and cell-free extracts are utilized for the synthesis of CuO micronutrient Nanoparticles (NPs). The cyanobacterial strain Pseudanabaena foetida RJ1 possesses plant growth-promoting (PGP) attributes that provide reduction and capping for CuO NPs. The synthesized NPs were characterized and subjected to make a nano-formulation, utilizing the cyanobacteria-mediated CuO NPs along with low-cost zeolite as an adsorbent. The application of cyanobacterial biomass extract and cell-free extract provided an excellent comparative aspect in terms of micronutrient NP synthesis. The NPs in the form of formulations were applied to germinated paddy seeds (Pusa Basmati -1509) with varying concentrations (5, 10, 15mg/l). Effects of cyanobacteria based CuO NPs on hydroponically grown paddy crops were analyzed. The application of nano-formulations has shown a significant increase in plant growth promotion in rice plants under hydroponics conditions. There is no such type of comparative investigation reported earlier, and NPs of micronutrients can be utilized as a new economic nanofertilizer and can be applied to plants for their growth promotion.

Comparative uptake, translocation and metabolism of phenamacril in crops under hydroponic and soil cultivation conditions

Many studies investigate the plant uptake and metabolism of xenobiotics by hydroponic experiments, however, plants grown in different conditions (hydroponic vs. soil) may result in different behaviors. To explore the potential differences, a comparative study on the uptake, translocation and metabolism of the fungicide phenamacril in crops (wheat/rice) under hydroponic and soil cultivation conditions was conducted. During 7–14 days of exposure, the translocation factors (TFs) of phenamacril were greatly overestimated in hydroponic-wheat (3.6–5.2) than those in soil-wheat systems (1.1–2.0), with up to 3.3 times of difference between the two cultivation systems, implying it should be cautious to extrapolate the results obtained from hydroponic to field conditions. M-144 was formed in soil pore water (19.1–29.9 μg/L) in soil-wheat systems but not in the hydroponic solution in hydroponics; M-232 was only formed in wheat shoots (89.7–103.0 μg/kg) under soil cultivation conditions, however, it was detected in hydroponic solution (20.1–21.2 μg/L), wheat roots (146.8–166.0 μg/kg), and shoots (239.2–348.1 μg/kg) under hydroponic conditions. The root concentration factors (RCFs) and TFs of phenamacril in rice were up to 2.4 and 3.6 times higher than that in wheat for 28 days of the hydroponic exposure, respectively. These results highlighted that cultivation conditions and plant species could influence the fate of pesticides in crops, which should be considered to better assess the potential accumulation and transformation of pesticides in crops.

Towards a comprehensive understanding of zinc tolerance in Limonium brasiliense as a useful tool for environmental remediation and monitoring.

Heavy metal pollution is a serious environmental problem worldwide, creating the necessity to find eco-friendly strategies for monitoring and remediating environments. This study aimed to evaluate morphological, physiological, and biochemical responses as indicative of Zn tolerance in Limonium brasiliense and to determine the ability of this halophyte to accumulate different concentrations of Zn (0, 100, and 200 μM) in hydroponic conditions. The leaf shape at high Zn concentration showed enlarged petioles and lanceolate blades, whereas the leaf size was reduced. Water content, chlorophyll fluorescence parameters, and pigment content decreased with Zn addition. Of the antioxidant activities, only APx increased 75% compared to the control by Zn stress. Zn concentration was higher in aerial structures than in roots (BAC>1 and TF>1), suggesting that L. brasiliense could function as an accumulator of Zn. Its great ability to resist metal stress and its strong capacity to protect itself against high Zn concentration postulate it as a good phytoremediation of environments enriched with Zn. The study emphasizes using leaf morphology as an early biomonitoring tool for detecting Zn pollution, providing more evidence of their potential use as a biomarker for evaluating and assessing ecosystem health in biomonitoring programs.

Unveiling the absorption, translocation, and metabolism of penthiopyrad in pakchoi under hydroponic and soil-cultivated conditions

The efficient use of pesticides has long been a topic of public concern, necessitating a thorough understanding of their movement in plants. This study investigates the translocation and distribution of penthiopyrad in pakchoi plants cultivated both in hydroponic and soil-cultivated conditions. Results indicate that penthiopyrad predominantly accumulates in the roots, with concentrations of 11.3–53.9 mg/kg following root application, and in the leaves, with concentrations of 2.0–17.1 mg/kg following foliar application. The bioconcentration factor exceeded 1, with values ranging from 1.2 to 23.9 for root application and 6.4 to 164.0 for foliar application, indicating a significant role in the absorption and accumulation processes. The translocation factor data, which were <1, suggest limited the translocations within pakchoi plants. The limitation may be attributed to the hydrophobic properties of penthiopyrad (log Kow = 3.86), as evidenced by its predominant distribution in the subcellular solid fractions of pakchoi tissues, accounting for 93.1% to 99.5% of the total proportion. Six metabolites (753-A-OH, M12, 754-T-DO, M11, PCA, and PAM) were identified in this study as being formed during this process. These findings provide valuable insights into the absorption, translocation, and metabolism of penthiopyrad in pakchoi.

Assessment of sulfamethoxazole removal by three wetland plant species under hydroponic conditions: uptake, accumulation, and physiological responses

Plants play a crucial role as a removal pathway in constructed wetlands, demonstrating the ability to absorb and tolerate antibiotics from wastewater. However, the specific contribution of plants in this regard has not yet to be sufficiently established. To gain a more comprehensive insight into the associated processes, we selected three common wetland plant species, Canna indica L. (C. indica), Cyperus alternifolius L. (C. alternifolius), and Thalia dealbata Fraser (T. dealbata), to evaluate their capacity for uptake, accumulation, and physiological response in the removal of sulfamethoxazole (SMX) at varying initial concentrations (10, 30, 100, and 300 µg/L) under hydroponic conditions. The results showed that SMX removal was more efficient at lower concentrations (10 and 30 µg/L) than at higher concentrations (100 and 300 µg/L). Moreover, plant systems were found to consistently outperform unplanted systems in SMX removal. Among the assessed species, C. indica was identified as being relatively effective in the removal of SMX, whereas the performance of C. alternifolius was notably less pronounced. A positive correlation was observed between the concentration of SMX in the plant tissues and that in the external aqueous medium. However, plant tissue residues contributed only a minor fraction to the overall removal of SMX. Wetland plants absorb SMX through their roots, and we accordingly detected significantly higher concentrations in submerged plant tissues. Furthermore, we also detected reductions in net photosynthetic rates indicative of potential phytotoxicity, which is associated with the accumulation of antibiotic in the shoot tissues. Accumulation of SMX in the roots and rhizomes was also found to be associated with the development of shorter roots, with this effect becoming more pronounced with an increase in the concentration of exogenous SMX. However, despite these adverse effects, plants can detoxify antibiotics via the glutathione pathway. Of the assessed plant species, C. indica was identified as the most SMX tolerant, as indicated by K m and V max values, with C. alternifolius being the least tolerant. Our findings in this study reveal the potential value of wetland plants in the sequestration of antibiotics and provide evidence for the underlying mechanisms of action. These findings could make an important contribution to the implementation of phytoremediation in antibiotic-contaminated water.

Measuring Bacterial Colonization on Arabidopsis thaliana Roots in Hydroponic Condition.

Measuring bacterial colonization on Arabidopsis thaliana root is one of the most frequent experiments in plant-microbe interaction studies. A standardized method for measuring bacterial colonization in the rhizosphere is necessary to improve reproducibility. We first cultured sterile A.thaliana in hydroponic conditions and then inoculated the bacterial cells in the rhizosphere at a final concentration of OD600 of 0.01. At 2 days post-inoculation, the root tissue was harvested and washed three times in sterile water to remove the uncolonized bacterial cells. The roots were then weighed, and the bacterial cells colonized on the root were collected by vortex. The cell suspension was diluted in a gradient with a phosphate-buffered saline (PBS) buffer, followed by plating onto a Luria-Bertani (LB) agar medium. The plates were incubated at 37 °C for 10 h, and then, the single colonies on LB plates were counted and normalized to indicate the bacterial cells colonized on roots. This method is used to detect bacterial colonization in the rhizosphere in mono-interaction conditions, with good reproducibility.

Optimization of an efficient hydroponic cultivation method for high yield of strawberry plants

The widely grown octoploid strawberry (2n = 8x = 56) (Fragaria × Ananassa Duch.), cherished for its delectable flavour, rich nutritional content, and pleasing aroma has consistently held a significant position in global fruit market. Despite of rising demand, strawberry plants are not grown universally, likely due to variations in weather conditions across regions, available of infectious soil pathogen and insufficient knowledge of soilless hydroponic cultivation. The current research aims to establish an efficient nutrient medium that enhances the growth and yield of strawberry (Fragaria × Ananassa Duch.) Cv. Winter Dawn, using soilless hydroponic and semi-hydroponic cultivation methods. The fruit fresh weight and total fruit yield of formulation 2 treated plants (EC 2.41 mScm−1) in hydroponic condition exhibited a 1.73-fold and 2.18-fold higher respectively as compared to soil control plants. Among the five different growing medium treatments in semi-hydroponic condition, the fresh weight and total strawberry fruit yield was found to be maximum in treatment 3 and observed 2.04-fold and 3.03-fold increase respectively as compared to plants grown in soil control condition. The high yield may be due to higher uptake of macronutrients (NPK) by the plants supplemented with F2 formulation and T3 substrate medium the plants. As a result, the strawberry fruits of these plants accumulated higher amount of anthocyanin, which ultimately enhanced the fruit quality. The studies concluded that formulation 2 in hydroponic and treatment 3 in semi-hydroponic were most effective in terms of growth, nutrient uptake, physiology, fruit yield and anthocyanin content. The result of this study gives an alternative to the farmers for cultivation of strawberry plants in soilless hydroponic and semi-hydroponic conditions.

The yield of various varieties of lettuce grown in hydroponic conditions

The study is aimed at evaluating the effectiveness of growing various varieties of lettuce using flow hydroponics in protected soil. The following varieties of lettuce were studied: cabbage with an oily leaf (Gauguin, Fairlie, Santoro, Aquino, Casey), semi-rolled with a crispy leaf (Dunstar, Frillis, Extemp, Exact, Skilton), leafy (Lalique, Jokari, Litska, Rosaline, Alzevir, Xerafin). The experiments were conducted in the conditions of the Yelets district of the Lipetsk region in the conditions of the greenhouse of I.A. Bunin YSU. The assessment of product quality helped to identify the main productive varieties recommended for cultivation in protected soil by the method of flow hydroponics. For all-season cultivation: Casey, Gauguin, Dunstar, Alzevir, Jokari, Litska, for the autumn–winter period - Exact, for the spring-summer period – Extemp. Keywords: LETTUCE, VARIETY, YIELD, HYDROPONICS

Biocontrol potential of endophytic Pseudomonas strain IALR1619 against two Pythium species in cucumber and hydroponic lettuce.

The use of fungicides to manage disease has led to multiple environmental externalities, including resistance development, pollution, and non-target mortality. Growers have limited options as legacy chemistry is withdrawn from the market. Moreover, fungicides are generally labeled for traditional soil-based production, and not for liquid culture systems. Biocontrol agents for disease management are a more sustainable and environmentally friendly alternative to conventional agroprotectants. Pythium ultimum is a soil borne oomycete plant pathogen with a broad taxonomic host range exceeding 300 plants. Cucumber seedlings exposed to P. ultimum 1 day after a protective inoculation with bacterial endophyte accession IALR1619 (Pseudomonas sp.) recorded 59% survival; with the control assessed at 18%. When the pathogen was added 5 days post endophyte inoculation, 74% of the seedlings treated survived, compared to 36% of the control, indicating a longer-term effect of IALR1619. Under hydroponic conditions, IALR1619 treated leaf type lettuce cv. 'Cristabel' and Romaine cv. 'Red Rosie' showed 29% and 42% higher shoot fresh weight compared to their controls, respectively. Similar results with less growth decline were observed for a repeat experiment with IALR1619. Additionally, an experiment on hydroponic lettuce in pots with perlite was carried out with a mixture of P. ultimum and P. dissotocum after IALR1619 inoculation. The endophyte treated 'Cristabel' showed fresh weight gain, but the second cultivar 'Pensacola' yielded no increase. In summary, the endophyte IALR1619 provided short term as well as medium-term protection against Pythium blight in cucumber seedlings and may be used as an alternative to conventional fungicides in a greenhouse setting. This study also demonstrated the potential of ALR1619 as a biocontrol agent against Pythium blight in hydroponic lettuce.

Strigolactone roles in maize tolerance to low nitrogen involve shifts in acquisition and partitioning of protein, sulfur, and iron

Abstract Background and Aims Nitrogen (N) is an essential macronutrient that can limit plant development and crop yield through widespread physiological and molecular impacts. In maize, N-starvation enhances biosynthesis and exudation of strigolactones (SLs) in a process reversible by nitrate addition and consequent repression of genes for SL biosynthesis. Methods In the present study, a maize mutant deficient in SL biosynthesis (zmccd8) allowed an in-depth analysis of SL contributions under low N. Both hydroponic and field conditions were used to better characterize the response of the mutant to N availability. Results The severity of responses to N-limitation by the SL-deficient zmccd8 mutant extended from growth parameters to content of iron, sulfur, protein, and photosynthetic pigments, as well as pronounced impacts on expression of key genes, which could be crucial molecular target for the SL-mediated acclimatation to N shortage. Conclusions Our results demonstrate that SLs are critical for physiological acclimation to N deficiency by maize and identify central players in this action. Further contributions by iron and sulfur are implicated in the complex pathway underlying SL modulation of responses to N-deprivation, thus widening our knowledge on SL functioning and providing new hints on their potential use in agriculture.

Phytoextraction potential of Canna indica (L.) for Cd removal from a hydroponic system

ABSTRACT The research explored Canna indica's ability to extract Cd in hydroponic conditions, determining its upper tolerance threshold and assessing Cd's impact on growth and biochemical properties. Plants were grown in 5L tanks containing nutrient solutions with varying Cd concentrations (0, 100, 200, 300, and 400 mg/L) for 18 days. Each treatment was performed in triplicate. Analysis of Cd content across roots, shoot, and leaves revealed high absorption rates of 89.5% to 96.8% efficiency for Cd treatments of 100–400 mg/L. Metrics like bioaccumulation coefficient (BAC), translocation factor (TF), and bio-concentration factor (BCF) were determined, indicating BAC > 1 across treatments, while TF was <1 for 100 mg/L and >1 for higher Cd treatments. Bio-concentration patterns varied with Cd concentration. Optimal Cd uptake occurred at 200–300 mg/L, declining notably at 400 mg/L. The study suggests C. indica's potential for phytoextraction up to 400 mg/L Cd contamination, but adverse effects emerged at ≥300 mg/L: reduced chlorophyll pigments, ascorbic acid, fresh/dry weights, and elevated leaf pH, indicating a Cd tolerance threshold of 300 mg/L for C. indica.

Formation of a model of lettuce (&lt;i&gt;Lactuca sativa&lt;/i&gt; L.) variety of the Batavia type for hydroponic cultivation

Relevance. Currently, there is a tendency to increase the volume of lettuce cultivation in hydroponics. Such specific conditions for growing lettuce hydroponically as high humidity in the root zone, different levels of illumination throughout the year and specific mineral nutrition, dictate a number of necessary characteristics that varieties should possess. In addition, the lettuce variety for hydroponics should consistently give high yield and have good consumer qualities. Accordingly, it is necessary to carry out selection separately for specific hydroponic conditions. And for theoretical justification of the selection of lettuce varieties for this technology and increasing the efficiency of the breeding process, it is necessary to form a model of the variety, which was the goal of this research.Methods. The 13 most common lettuce varieties were research: 8 light green and 5 dark green Batavia. The morphological characteristics of plants in the phase of industrial ripeness were described and the biometric traits of plants were determined.Results. Based on research in 2021-2023 the 13 most commonly hydroponically grown lettuce varieties of the Batavia variety have been defined as the variety model criteria for hydroponics. The characteristics of a leaf rosette, leaf blade, indicators of early ripening and productivity inherent in these varieties were identified, and a model of the variety was formed on their basis.

Response of leaf photosynthesis, chlorophyll content and yield of hydroponic tomatoes to different water salinity levels.

Tomato (Solanum lycopersicum L.) is an important vegetable crop that grows easily under controlled conditions, such as in greenhouses and hydroponics. To overcome freshwater scarcity, researchers are searching for alternatives to groundwater sources such as desalinated water (saline water) for irrigation. High salinity in irrigation water alters physiological functions and crop development, thereby reducing the yield. Best management practices and the use of grafted tomato plants on salt-tolerant rootstocks can alleviate salinity stress. The present study was conducted to address the impact of salinity stress on leaf transpiration (Tr), stomatal conductance (gs), photosynthesis (Pn), leaf chlorophyll content, proline content, and yield of hydroponically cultivated tomato plants. Saline (NaCl) water was used for the preparation of nutrient solution with three salinity levels, electrical conductivity (EC, dS m-1) of 2.5 (control), 6.0, and 9.5. Three commercial tomato cultivars (Valouro-RZ, Ghandora-F1, and Feisty-Red) were used. Both self-rooted plants and plants grafted onto Maxifort rootstocks were transplanted onto a perlite substrate. The recorded data revealed that all studied cultivars were critically affected by higher salinity (≈ 9.5 dS m-1) compared to low (≈ 2.5 dS m-1) and medium (≈ 6.0 dS m-1) salinity levels. The Variations in Tr, Pn, gs, chlorophyll content of leaf, and yield between medium and high salinity trials were reported at 3%, 5%, 9%, 5%, and 7.1%, respectively, whereas no significant differences were observed between low and medium salinities. However, at medium salinity levels, grafted plants performed better in photosynthesis than non-grafted plants. This is due to the accumulation of leaf proline, which maintains osmotic regulation and photosynthetic activity by preventing cell damage at medium salinities. Hence, this study confirmed the use of saline water for growing tomatoes under hydroponic conditions up to an EC of 6.0 dS m-1 including the EC of nutrient fertilizers.

Efficacy of Plant Growth Promoting Rhizobacteria to Improve the Biochemical Properties and Development of Wheat Seedlings under Drought Stress Control

The most significant cereal crop is wheat, which ranks third among the world's most demanding staple crops after rice and maize. Temperate climates with moderate rainfall are ideal for growing it. Under the current changing climate, abiotic stress conditions, particularly drought conditions, have a significant impact on wheat crop productivity. Plants under drought stress have less water accessible to them, which slows down germination, growth, and yield. In this study, plant growth promoting rhizobacteria (PGPR) is used to boost the drought tolerance capability of the wheat plant. PGPR isolate KD-3B strain is used to investigate the plant growth characteristic such as, mineral solubilization (zinc, phosphate, and potassium), ammonia production, indole acetic acid (IAA), and the enzyme 1-carboxylic acid (ACC). Moreover, the plant showed drought tolerance at polyethylene glycol (PEG 6000) concentrations of 0%, 5%, 10%, 15%, 20%, and 25% (w/v). Wheat seedlings were exposed to both normal and drought conditions when they interacted with the KD-3B bacterial strain, which possesses many features that promote plant development. In comparison to growth in a non-PEG condition, this strain is tested for relative growth up to 41.05% in a 25% PEG concentration. When inoculum of KD-3B bacterial strain used under normal and drought conditions, the relationship between microbes and plants was examine in wheat seedlings grown under hydroponic condition. Under drought stress condition significant changes were observed in the morphological and biochemical conditions of seedlings. This research concluded that, in drought stress condition, PGPR KD-3B strain inoculated seedlings showed increased chlorophyll content, TSS content, malondialdehyde concentration and decreased proline, H2O2 content, SOD and POD activities, as compared to the negative control seedlings. The PGPR stain KD-3B improved their biochemical and physiological parameters and plant microbe interaction decreased the deleterious effect of drought on wheat seedlings.

Fate of pharmaceuticals and personal care products like metronidazole, naproxen, and methylparaben and their effect on the physiological characteristics of two wetland plants

Plants play a vital role in the phytoremediation process, attenuating various pollutants. However, the dynamic root uptake and fate of emerging pollutants in plants, along with their effects on plant characteristics, have received limited research attention. This study explores the potential of Chrysopogon zizanioides (Vetiver) and Colocasia esculenta (Taro) in mitigating pharmaceutical and personal care products (PPCPs) - metronidazole (MNZ), naproxen (NAP), and methylparaben (MeP), under hydroponic conditions. Both plants demonstrated similar specific uptake potentials for the target pollutants (5.23 to 5.76 mg/g of biomass dry weight), with pollutant accumulation in plants remaining very low (<10 %). Notably, a substantial fraction of pollutants (66.27 % to 78.42 %) underwent metabolism. Qualitative analysis identified five MNZ and NAP metabolites and six MeP metabolites in plant tissues. Over a 28-day PPCPs exposure, accumulation of reactive oxygen species (ROS) resulted in reduced chlorophyll content, root activity, protein, and carbohydrates, alongside increased oxidative stress levels. The study highlighted distinct accumulation patterns, with NAP (anion) primarily in roots and MeP (cation) and MNZ (neutral) predominantly in aerial parts. Phloroglucinol staining confirmed the intact endodermis (Casparian Strips) in Vetiver roots, indicating symplastic transport of PPCPs to aerial parts. Moreover, significant morphological alterations were observed in plant roots exposed to target pollutants. During recuperation, a decrease in accumulated ROS indicates partial self-recovery from oxidative damage. In conclusion, both Vetiver and Taro emerge as promising candidates for removing specified PPCPs, emphasizing the critical role of addressing emerging contaminants for sustainable development and preserving the environment and human wellbeing.

Superior glucose metabolism supports NH4+ assimilation in wheat to improve ammonium tolerance.

The use of slow-release fertilizers and seed-fertilizers cause localized high-ammonium (NH4 +) environments in agricultural fields, adversely affecting wheat growth and development and delaying its yield. Thus, it is important to investigate the physiological responses of wheat and its tolerance to NH4 + stress to improve the adaptation of wheat to high NH4 + environments. In this study, the physiological mechanisms of ammonium tolerance in wheat (Triticum aestivum) were investigated in depth by comparative analysis of two cultivars: NH4 +-tolerant Xumai25 and NH4 +-sensitive Yangmai20. Cultivation under hydroponic conditions with high NH4 + (5 mM NH4 +, AN) and nitrate (5 mM NO3 -, NN), as control, provided insights into the nuanced responses of both cultivars. Compared to Yangmai20, Xumai25 displayed a comparatively lesser sensitivity to NH4 + stress, as evident by a less pronounced reduction in dry plant biomass and a milder adverse impact on root morphology. Despite similarities in NH4 + efflux and the expression levels of TaAMT1.1 and TaAMT1.2 between the two cultivars, Xumai25 exhibited higher NH4 + influx, while maintaining a lower free NH4 + concentration in the roots. Furthermore, Xumai25 showed a more pronounced increase in the levels of free amino acids, including asparagine, glutamine, and aspartate, suggesting a superior NH4 + assimilation capacity under NH4 + stress compared to Yangmai20. Additionally, the enhanced transcriptional regulation of vacuolar glucose transporter and glucose metabolism under NH4 + stress in Xumai25 contributed to an enhanced carbon skeleton supply, particularly of 2-oxoglutarate and pyruvate. Taken together, our results demonstrate that the NH4 + tolerance of Xumai25 is intricately linked to enhanced glucose metabolism and optimized glucose transport, which contributes to the robust NH4 + assimilation capacity.

Moderate salinity and high ammonium/nitrate ratio enhance early growth in “summer wonder” lettuce cultivar

Because its impact in plant development and growth and its interaction with Na+ and Cl−, the supply of different N-forms to crops can be an easy-to-use tool with effective results on salinity tolerance. Here the effect of four N–NO3-/N–NH4+ ratios (mM; 2/0, 1.6/0.4, 0.4/1.6, 0/2) on adaptation to salt conditions (15 mM NaCl in a first experiment and 40 mM NaCl in a second experiment) was studied in young lettuce (cv “Summer wonder”) plants. The experiments were carried out in greenhouse and under hydroponics conditions. The results show that this cultivar tolerates and adapts to moderate salinity by deploying several structural and physiological mechanisms; (i) increasing allocation of biomass to the root, (ii) increasing root Na+ uptake and storing it in the shoot and root tissues, (iii) increasing intrinsic water use efficiency and (iv) increasing root N and P uptake. The beneficial effect of salt exposure on growth was greater when the predominant N-form was N–NO3-. These plants with higher tissue N–NO3- concentration, decreased Cl− uptake and shoot and root Cl− concentration. Regardless of salt conditions, plants with a high proportion of N–NH4+ (1.6 mM) and a low proportion of N–NO3- (0.4 mM) had a greater growth and nitrogen use efficiency, that was associated with the improved uptake of nutrients, and the maintenance of water status.

Effect of light intensity on celery growth and flavonoid synthesis.

Light is one of the important environmental factors affecting the growth and development of facility vegetables. In this experiment, we investigated the effects of different light intensities on the growth, nutritional quality and flavonoid accumulation of celery under hydroponic and full LED light conditions. Four light intensities of 40, 100, 200, or 300 µmol·m-2·s-1 were set up in the experiment, and three harvest periods were set up on the basis of different light intensities, which were 15, 30, and 45 d after treatment (labeled as S1, S2, and S3, respectively). The results showed that the plant height and aboveground biomass of celery increased with the increase of light intensity, and the light intensity of 200 μmol·m-2·s-1 was beneficial to increase the contents of chlorophyll, carotenoids, total phenols, vitamin C, cellulose, total flavones and apigenin in celery. During the S1-S3 period, the activities of PAL, CHS, CHI and ANS increased gradually under 200 and 300 μmol·m-2·s-1 light intensity treatments, and the activities of FNS and CHS enzymes were the highest under 200 μmol·m-2·s-1 light intensity treatment. The expression and ANS activity of Ag3GT, a key gene for anthocyanin synthesis, reached the maximum value at 300 μmol·m-2·s-1, and the expression level and FNS activity of AgFNS, a key gene for apigenin synthesis, reached a maximum value at 200 μmol·m-2·s-1. In general, the anthocyanin content was the highest at 300 μmol·m-2·s-1, and the apigenin content was the highest at 200 μmol·m-2·s-1. In conclusion, light intensity of 200 µmol·m-2·s-1 treatment was more favorable for celery growth and nutrient synthesis.

Effects of Excessive Application of P and Zn Fertilizer on Growth and Yield of Maize under Hydroponic Conditions

Background: Phosphate is an essential nutrient but can be toxic to plants when phosphate accumulates in plants at high levels. The objective of the study was to find effects of excessive application of P and Zn fertilizer on growth and yield of maize under hydroponic conditions. Methods: Research of Experiment studied from August to December 2019 at the greenhouse of the Agriculture and Aquaculture School at Tra Vinh University. The study aimed to determine the effect of high phosphate application on growth, biomass, symptoms of poisoning, phosphate and zinc absorption in maize and vegetables grown in hydroponic solution. Result: Experimental results showed the symptoms of phosphate poisoning on maize when grown in Hoagland nutrient solution (2.0 mM P) with an additional phosphorus content of 0.1 mM P, 1.0 mM P, 3.0 mM P in the treatment with or without the addition of Zn. However, the poisoning symptoms have been yet clearly expressed when Zn was not added. Therefore, plants may exhibit phosphorus toxicity, reducing Zn absorption when the phosphorus concentration in solution was increased by more than 1%P2O5. It is necessary to continue investigating plants’ responses to phosphate fertilizers.