Root Biomass Accumulation Research Articles

Enhancing wheat crop production with eco-friendly chitosan encapsulated nickel oxide nanocomposites: A safe and sustainable solution for higher yield

In this work, we looked at using nickel oxide (NiO) nanocomposites with chitosan encapsulation as a nano-primer to improve wheat crop output. A straightforward green precipitation procedure was used to create the nanocomposites, and they were then characterized using several methods. According to the findings, the chitosan-encapsulated NiO nanocomposites possessed a large surface area and were resilient to changes in pH. Following this, wheat seeds were primed with the nanocomposites, and under greenhouse circumstances, the impact on crop growth was assessed. The findings demonstrated that, in comparison to the control group, nanocomposites priming considerably enhanced wheat growth and germination rate up to 99 %. In comparison to untreated plants, the wheat plants treated with the nanocomposites primer had greater plant height i.e. shoot length (11.4 cm) and root length (10.3 cm), leaf area, and biomass accumulation. Further research into the mechanism underlying the priming effect of nanocomposites on wheat growth revealed that the nanocomposites enhanced nutrient absorption, photosynthesis, and stress tolerance in wheat plants. In conclusion, our research shows that chitosan-encapsulated NiO nanocomposites have the potential to improve wheat crop productivity in an environmentally benign and long-term manner, offering a viable strategy for sustainable farming.

Strategies for reducing the impact of clubroot on broccoli cultivation in tropical mountain regions

Brassica spp. production can be negatively affected by clubroot, which is caused by the protozoan Plasmodiophora brassicae Woronin. Most of the information on clubroot control is derived from studies in temperate regions. Here, management strategies were evaluated to reduce broccoli (Brassica oleracea L. var. italica Plenck) crop losses owing to clubroot in tropical mountain regions. The first experiment revealed the effect of green manure from coriander (Coriandrum sativum L.), sunn hemp (Crotalaria juncea L.), sweet corn (Zea mays L.), and spontaneous vegetation (control) associated with broccoli seedlings of 4 different sizes. In the second experiment, the effect of soil amendments (limestone and steel slag) in conjunction with poultry litter (fresh or composted for 45 days) and without poultry litter (control), was assessed. Both field experiments sought to evaluate the disease intensity, plant development (root growth, biomass, and nutrient accumulation), and yield. Sunn hemp and coriander biomass resulted in higher healthy root volumes and dry weights of broccoli. However, such benefits were not derived from corn treatment. Compared to smaller seedlings (10 mL cell and 20 days of age, and 16 mL cell and 24 days of age), the use of larger seedlings (35 mL cell and 28 days of age, and 50 mL cell and 32 days of age) resulted in lower intensity of clubroot and increased the average yield by 143% in summer crops. Steel slag, like limestone, corrected soil acidity and resulted in plant growth; however, clubroot intensity was not significantly affected. Fresh and composted poultry litter increased the percentage of diseased roots compared with the control; however, broccoli yield was not affected by the treatments. Using green manure (sunn hemp or coriander) and well-developed seedlings is recommended as a strategy to reduce losses induced by clubroot during broccoli cultivation.

Nitrogen fertilization and arbuscular mycorrhizal fungi do not mitigate the adverse effects of soil contamination with polypropylene microfibers on maize growth

Soil contamination with microplastics may adversely affect soil properties and functions and consequently crop productivity. In this study, we wanted to verify whether the adverse effects of microplastics in the soil on maize plants (Zea mays L.) are due to a reduction in nitrogen (N) availability and a reduced capacity to establish symbiotic relationships with arbuscular mycorrhizal (AM) fungi. To do this, we performed a pot experiment in which a clayey soil was exposed to two environmentally relevant concentrations of polypropylene (PP; one of the most used plastic materials) microfibers (0.4% and 0.8% w/w) with or without the addition of N fertilizer and with or without inoculation with AM fungi. The experiment began after the soil had been incubated at 23 °C for 5 months. Soil contamination with PP considerably reduced maize root and shoot biomass, leaf area, N uptake, and N content in tissue. The adverse effects increased with the concentration of PP in the soil. Adding N to the soil did not alleviate the detrimental effects of PP on plant growth, which suggests that other factors besides N availability played a major role. Similarly, although the presence of PP did not inhibit root colonization by AM fungi (no differences were observed for this trait between the uncontaminated and PP-contaminated soils), the addition of the fungal inoculum to the soil failed to mitigate the negative impact of PP on maize growth. Quite the opposite: mycorrhization further reduced maize root biomass accumulation. Undoubtedly, much research remains to be done to shed light on the mechanisms involved in determining plant behavior in microplastic-contaminated soils, which are most likely complex. This research is a priority given the magnitude of this contamination and its potential implications for human and environmental health.

Si Supply Could Alter N Uptake and Assimilation of Saplings—A 15N Tracer Study of Four Subtropical Species

Si availability may be altered by bamboo expansion when other trees are replaced by bamboo due to the influence of plant communities on the quantity of phytoliths and Si accumulation. It has been shown that Si availability can modify nutrient-use efficiency (e.g., N and P) of some Si-accumulating plants. However, it is unclear how Si availability might alter N uptake and assimilation between Si-accumulating plants such as bamboo compared to other species, particularly for different chemical forms such as ammonium (NH4+) and nitrate (NO3−). To explore the influences of Si availability on uptake and assimilation rates for different forms of inorganic N between bamboo and other trees, we selected one-year-old seedlings of bamboo (Phyllostachys pubescens) and three other native subtropical species, namely Phoebe bournei, Schima superba, and Cunninghamia lanceolata. We applied three levels of Si and 15N tracers in a pot experiment and then measured the concentrations of Si (total Si, soluble Si, and exchangeable Si), C, N (total N, NH4+-N, and NO3−-N), and N uptake and assimilation rates for both roots and leaves. We found that there were higher inorganic N root uptake and assimilation rates for bamboo compared to other species, likely due to higher biomass accumulation and quicker turnover of fine roots. Moreover, Si supply did not change the uptake preference for N forms or overall uptake and assimilation rates in most species; however, a high concentration of the Si supply slightly increased NO3−-N uptake and assimilation rates in fine roots and leaves of P. bournei, particularly immediately following the addition of Si. These results have implications for predicting the coexistence and competition between bamboo and other trees through the uptake and assimilation of different forms of inorganic N (i.e., high Si-accumulating plants compared to other plants), particularly when Si availability is altered in ecosystems.

Plant diversity drives soil carbon sequestration: evidence from 150 years of vegetation restoration in the temperate zone.

Large-scale afforestation is considered a natural way to address climate challenges (e.g., the greenhouse effect). However, there is a paucity of evidence linking plant diversity to soil carbon sequestration pathways during long-term natural restoration of temperate vegetation. In particular, the carbon sequestration mechanisms and functions of woody plants require further study. Therefore, we conducted a comparative study of plant diversity and soil carbon sequestration characteristics during 150 years of natural vegetation restoration in the temperate zone to provide a comprehensive assessment of the effects of long-term natural vegetation restoration processes on soil organic carbon stocks. The results suggested positive effects of woody plant diversity on carbon sequestration. In addition, fine root biomass and deadfall accumulation were significantly positively correlated with soil organic carbon stocks, and carbon was stored in large grain size aggregates (1-5 mm). Meanwhile, the diversity of Fabaceae and Rosaceae was observed to be important for soil organic carbon accumulation, and the carbon sequestration function of shrubs should not be neglected during vegetation restoration. Finally, we identified three plants that showed high potential for carbon sequestration: Lespedeza bicolor, Sophora davidii, and Cotoneaster multiflorus, which should be considered for inclusion in the construction of local artificial vegetation. Among them, L. bicolor is probably the best choice.

Alfalfa stand age at termination influences soil properties, root characteristics, and subsequent maize yield

Alfalfa (Medicago sativa L.)–maize (Zea mays L.) rotation is an important cropping practice to improve crop production and soil fertility, but the effects of the alfalfa stand age on the performances of the following maize remain unexplored. It is not clear how different alfalfa stand ages at termination influence soil properties, root characteristics, and yield of subsequent maize. The aim of this study was to evaluate how alfalfa influences soil characteristics, which in turn influence the root and aboveground growth and grain yield of the following maize crop. A field experiment from 2014 to 2019 was conducted at the Lishu Experimental Station, Jilin Province, China. The field treatments included six years of continuous maize (CM), six years of continuous alfalfa (CA), three years of alfalfa followed by two years of maize (3A2M), four years of alfalfa followed by two years of maize (4A2M), and five years of alfalfa followed by one year of maize (5A1M). Only the yield for the first-year maize after alfalfa in the 3A2M, 4A2M, and 5A1M treatments significantly increased by 8 %, 23 %, and 13 %, respectively. Root biomass (RB) of CA treatment gradually increased from 2014, reaching its maximum value of 5866 kg ha−1 in 2019, which was 35 % greater than the RB accumulation under CM in the 0–60 cm soil layer. Compared with the CM treatment, 3A2M and 4A2M treatments increased RB, while 3A2M, 4A2M, and 5A2M increased root length density (RLD), root surface area density (RSAD), and root volume density (RVD) of first-year maize after alfalfa. The 4A2M treatment also increased RLD, RSAD, and RVD in the 0–60 cm soil layer of second-year maize and reduced the soil bulk density (BD) in the 0–20 cm soil layer of first-year maize after alfalfa. Only 4A2M and 5A1M treatments significantly increased soil Olsen-P and soil organic carbon by first-year maize after alfalfa. The redundancy analysis results showed that the soil water content in the critical period and soil Olsen-P were the primary factors, which explained 33.8 % and 13.0 % of variation in maize root characteristics (P < 0.01), respectively. Structural equation modeling indicated that sowing alfalfa influenced the subsequent maize yield by influencing the soil Olsen-P, soil mineral nitrogen before sowing, and root characteristics. Therefore, keeping alfalfa for at least four years should be the recommended practice owing to its ability to improve the soil properties, root growth, and subsequent maize yield.

ASSESSING THE IMPACT OF INDOLE-3-BUTYRIC ACID (IBA) ON ROOTING EFFICIENCY IN CARNATION (DIANTHUS CARYOPHYLLUS L.) PROPAGATION UNDER PROTECTED CONDITIONS

The study aimed to assess the impact of varying Indole-3-Butyric Acid (IBA) concentrations on the rooting efficacy of Carnation (Dianthus Caryophyllus L.) cuttings within a controlled greenhouse setting. Different concentrations of IBA were applied to selected Carnation cultivars to stimulate root development. The greenhouse environment maintained controlled conditions, regulating temperature, humidity, and light to mimic optimal growth settings. The study focused on observing and analyzing rooting responses, particularly concerning root initiation, elongation, and biomass accumulation. Results indicated a distinct relationship between IBA concentrations and the rooting efficiency of Carnation cuttings. Lower concentrations displayed negligible effects on root development, while moderate concentrations significantly stimulated root initiation and elongation. Surprisingly, excessively high IBA concentrations led to reduced rooting responses, suggesting a hormetic effect on root growth. Morphological assessments highlighted that optimal IBA concentrations fostered vigorous root systems characterized by increased length, number, and mass of roots. This research underscores the pivotal role of precise IBA application in promoting successful rooting of Carnation cuttings, especially in controlled environments. The findings provide crucial insights for refining propagation techniques tailored specifically for Carnations, offering guidance to growers in optimizing IBA concentrations for efficient and sustainable cultivation practices in the floriculture industry. Further investigations delving into the prolonged impacts of IBA on overall plant growth and development would deepen the understanding derived from these findings.

Divergent responses of plant functional traits and biomass allocation to slope aspects in four perennial herbs of the alpine meadow ecosystem.

Slope aspect can cause environmental heterogeneity over relatively short distances, which in turn affects plant distribution, community structure, and ecosystem function. However, the response and adaptation strategies of plants to slope aspects via regulating their physiological and morphological properties still remain poorly understood, especially in alpine ecosystems. Here, we selected four common species, including Bistorta macrophylla, Bistorta vivipara, Cremanthodium discoideum, and Deschampsia littoralis, to test how biomass allocation and functional traits of height, individual leaf area, individual leaf mass, and specific leaf area (SLA) respond to variation in slope aspect in the Minshan Mountain, eastern Tibetan Plateau. We found that the slope aspect affected SLA and stem, flower mass fraction with higher values at southwest slope aspect, which is potentially related to light environment. The low-temperature environment caused by the slope aspect facilitates the accumulation of root biomass especially at the northeast slope aspect. Cremanthodium discoideum and D. littoralis invested more in belowground biomass in southeast and southwest slope aspects, although a large number of significant isometric allocations were found in B. macrophylla and B. vivipara. Finally, we found that both biotic and abiotic factors are responsible for the variation in total biomass with contrasting effects across different species. These results suggest that slope aspect, as an important topographic variable, strongly influences plant survival, growth, and propagation. Therefore, habitat heterogeneity stemming from topographic factors (slope aspect) can prevent biotic homogenization and thus contribute to the improvement of diverse ecosystem functioning.

RELACIÓN BRADYRIZOBIUM-CAUPÍ EN CONDICIONES DE SALINIDAD: SU INFLUENCIA EN LA TOLERANCIA AL ESTRÉS SALINO

&lt;p&gt;&lt;strong&gt;Background:&lt;/strong&gt; The introduction of species with tolerance to salinity is one of the strategies to reduce the harmful effect of salts in the eastern region of Cuba. The species &lt;em&gt;Vigna unguiculata&lt;/em&gt; L., shows rusticity and capability of adaptation, however, it is necessary to search for cultivars with greater tolerance and symbiotic nitrogen fixation possibilities to increase yields. &lt;strong&gt;Objective: &lt;/strong&gt;To determine the behavior of the &lt;em&gt;bradyrizobium&lt;/em&gt;-cowpea bean relationship under salinity conditions, based on variables related to symbiotic nitrogen fixation, growth and development. &lt;strong&gt;Methodology:&lt;/strong&gt; An experiment was carried out under controlled glass house conditions at the CSIC, Madrid, Spain. Two cultivars were used; IITA-Precoz and IT 86 D-715, which were inoculated with Strain VIBA-1 of &lt;em&gt;Bradyrhizobum liaoningense.&lt;/em&gt; Treatments were Hoagland nutrient solution (control) and nutrient solution with 150 mM NaCl (saline). A completely randomized design with eight replications was used. At 40 days after germination, variables related to symbiotic nitrogen fixation, growth and development, protein concentration of the cytosolic soluble fraction of leaves and nodules were evaluated.&lt;strong&gt; Results: &lt;/strong&gt;Although salinity negatively affected both cultivars, the damage did not manifest with the same intensity. IT 86 D-715 was less affected by showing less damage on the variables number of nodules, ARA, protein concentration in nodules and leaves, accumulation of leaf and root biomass, so its tolerance was greater. The IITA-Precoz cultivar was more susceptible, all the variables were notably affected under stress conditions, therefore, its tolerance level is lower. &lt;strong&gt;Implications:&lt;/strong&gt; The cultivar IT 86 D-715 can be used in salinized soils due to its high tolerance, which is evidenced in variables of growth development and atmospheric nitrogen fixation. &lt;strong&gt;Conclusions: &lt;/strong&gt;The cultivar IT 86 D-715 presents a greater capacity for symbiotic nitrogen fixation under salinity conditions and the tolerance index in all the growth and development variables evaluated was higher than IITA-Precoz, for which it presents a high susceptibility level.&lt;/p&gt;

High nitrogen inhibits biomass and saponins accumulation in a medicinal plant Panax notoginseng.

Nitrogen (N) is an important macronutrient and is comprehensively involved in the synthesis of secondary metabolites. However, the interaction between N supply and crop yield and the accumulation of effective constituents in an N-sensitive medicinal plant Panax notoginseng (Burkill) F. H. Chen is not completely known. Morphological traits, N use and allocation, photosynthetic capacity and saponins accumulation were evaluated in two- and three-year-old P. notoginseng grown under different N regimes. The number and length of fibrous root, total root length and root volume were reduced with the increase of N supply. The accumulation of leaf and stem biomass (above-ground) were enhanced with increasing N supply, and LN-grown plants had the lowest root biomass. Above-ground biomass was closely correlated with N content, and the relationship between root biomass and N content was negatives in P. notoginseng (r = -0.92). N use efficiency-related parameters, NUE (N use efficiency, etc.), NC (N content in carboxylation system component) and P n (the net photosynthetic rate) were reduced in HN-grown P. notoginseng. SLN (specific leaf N), Chl (chlorophyll), NL (N content in light capture component) increased with an increase in N application. Interestingly, root biomass was positively correlated with NUE, yield and P n. Above-ground biomass was close negatively correlated with photosynthetic N use efficiency (PNUE). Saponins content was positively correlated with NUE and P n. Additionally, HN improved the root yield of per plant compared with LN, but reduced the accumulation of saponins, and the lowest yield of saponins per unit area (35.71 kg·hm-2) was recorded in HN-grown plants. HN-grown medicinal plants could inhibit the accumulation of root biomass by reducing N use and photosynthetic capacity, and HN-induced decrease in the accumulation of saponins (C-containing metabolites) might be closely related to the decline in N efficiency and photosynthetic capacity. Overall, N excess reduces the yield of root and C-containing secondary metabolites (active ingredient) in N-sensitive medicinal species such as P. notoginseng.

Response of photomorphogenesis and photosynthetic properties of sweet pepper seedlings exposed to mixed red and blue light.

Various light spectra, especially red (RL) and blue light (BL), have great effects on physiological processes and growth of plants. Previously, we revealed that the plant photomorphogenesis and photosynthesis of sweet pepper was significantly altered under BL or mixed RL and BL. The present study aimed to elucidate how mixed RL and BL influences plant photosynthesis during photomorphogenesis. We examined the growth, plant morphology, photosynthetic response of sweet pepper seedlings under monochromatic RL, BL, different ratios of mixed RL and BL (9R1B, 6R1B, 3R1B, 1R1B, 1R3B) with the same photosynthetic photon flux density of 300 μmol·m-2·s-1. White light (WL) were used as a control. The findings showed that the elongation of hypocotyl and first internode as well as leaf expansion were all stimulated by RL, while significantly restrained by BL compared with WL. Conversely, the leaf development, biomass accumulation and photosynthetic properties were inhibited by RL but promoted by BL. Additionally, compared with WL and other treatments, 3R1B could significantly improve the net photosynthetic rate, gas exchange, photosynthetic electron transport capacity, photochemical efficiency, shoot and root biomass accumulation. Furthermore, seedlings grew robustly and exhibited the greatest value of seedling index when exposed to this treatment. Overall, these results suggested that pepper seedlings grown under 3R1B performed better, possibly due to the more balanced light spectrum. It was more conducive to improve the plant photomorphogenesis and photosynthesis of sweet pepper, and a higher biomass accumulation and energy utilization efficiency could be achieved simultaneously under this mixed light spectrum.

Functional Analysis of Bna-miR399c-PHO2 Regulatory Module Involved in Phosphorus Stress in Brassica napus

Phosphorus stress is one of the important factors restricting plant growth and development, and the microRNA (miRNA) family is involved in the regulation of the response to plant nutrient stress by repressing the expression of target genes at the post-transcriptional or translational level. miR399 is involved in the transportation of phosphate in multiple plants by improving tolerance to low Pi conditions. However, the effect of miR399 on the response of low Pi stress in rapeseed (Brassica napus L.) is unclear. The present study showed a significant increase in taproot length and lateral root number of plants overexpressing Bna-miR399c, while the biomass and Pi accumulation in shoots and roots increased, and the anthocyanin content decreased and chlorophyll content improved under low Pi stress. The results illustrate that Bna-miR399c could enhance the uptake and transportation of Pi in soil, thus making B. napus more tolerant to low Pi stress. Furthermore, we confirmed that BnPHO2 is one of the targets of Bna-miR399c, and the rejection of Pi in rapeseed seedlings increased due to the overexpression of BnPHO2. Hence, we suggest that miR399c-PHO2 module can effectively regulate the homeostasis of Pi in B. napus. Our study can also provide the theoretical basis for germplasm innovation and the design of intelligent crops with low nutrient input and high yield to achieve the dual objectives of income and yield increase and environmental protection in B. napus.

Effects of plastic-derived carbon dots on germination and growth of pea (Pisum sativum) via seed nano-priming

Seed nano-priming is a promising technology employed in the agronomic field to promote seed germination and plant growth. However, the effects of carbon dots (CDs) on plant development via seed nano-priming remain unclear. In the present study, CDs synthesized from non-biodegradable plastic wastes were adopted as a nano-priming agent for pea (Pisum sativum) seed treatment. The results demonstrated positive effects of seed priming at all CD concentrations (0.25–2 mg/mL), including accelerated seed germination rate, increased shoot and root elongation, biomass accumulation, and root moisture level compared to the control groups. Surface erosion of seed coat was observed after CD priming, which effectively promoted seed imbibition capability. CD penetration, internalization, and translocation were confirmed using transmission electron microscopy. Furthermore, the CD-plant interaction significantly enhanced seed antioxidant enzyme activity, as well as augmented root vigor, chlorophyll content, and carbohydrate content. These findings exhibit great potential of waste-derived CDs as nano-priming agents for seed germination and seedling development in a cost-effective and sustainable manner.

Effect of Glomus intraradices on root morphology, biomass production and phosphorous use efficiency of Chinese fir seedlings under low phosphorus stress.

Available phosphorus (P) scarcity in the highly weathered soils of the subtropical forests in southern China is a serious concern. To ensure whether inoculation of arbuscular mycorrhizal fungi (AMF) with Chinese fir (Cunninghamia lanceolata) under low P stress conditions could promote its growth and P utilization capacity, an indoor pot simulation experiment was carried out with the different P supply treatments and Chinese fir seedlings as the tested material. The experiment had two P supply treatments, no P supply (P0, 0 mmol·L-1 KH2PO4) and normal P supply (P1, 1.0 mmol·L-1 KH2PO4). The seedling in each P supply treatment was inoculated with Glomus intraradices (Gi), a widespread species of AMF in the natural environment, and with no AMF inoculation as a control treatment (CK). The Gi infection rate in the root system, root cortex tissue dissolution rate, root morphological indexes and biomass, whole plant P use efficiency, and root P use efficiency of Chinese fir were determined under different treatment conditions. The results showed that P0 treatment significantly increased the Gi infection rate (p< 0.05). After inoculating AMF with different P supply treatments, the root cortex tissue dissolution rate was considerably enhanced. In contrast, the Chinese fir's root length and surface area were reduced; however, the root volume did not change significantly. The average root diameter in the P0 treatment and inoculated with AMF was significantly more prominent than in the uninoculated treatment (p< 0.05). The root biomass and root-to-shoot ratio at different P supply treatments were significantly higher in the Gi infection treatment than in the CK group. Under different P supply treatments, root inoculation with Gi promoted root P use efficiency and whole plant P use efficiency. In conclusion, low P stress condition promoted the colonization of AMF in the root system, increased the dissolution of root cortex tissue, root volume, and the average diameter, and promoted root biomass accumulation and P use efficiency.

Photobiological Efficiency of Radiation of LED Radiators for Cenoses of Different Age Plants in Relation to Conditions of Closed Ecosystems

The paper presents experimental data on the photo-biological efficiency of the emission of white light LED irradiators and phyto-spectrum with an intensity of 460 μmol/(m2s) and 800 μmol/(m2s) at the intermediate (18 days) and final (27 days) stages of the growing season of growing Chinese cabbage (Brassica rapa), chard (Beta vulgaris), and radish (Raphanus sativus) in relation to the conditions of closed ecosystems (CES). The presence of different specifics of the reaction of plants to the spectral composition of radiation, both at the intermediate and final stages of vegetation, has been established. It has been suggested that in some plant species (Chinese cabbage) it may be physiologically justified at the intermediate stage of vegetation to change the spectral regime of irradiation from the phytospectrum to white light in order to achieve higher productivity values. Using the example of chard, it has been established that the phyto-spectrum can be more effective than white light when growing leaf biomass, regardless of the growing season. Using the example of radishes, it was shown that the phytospectrum stimulates the accumulation of high values of above-ground biomass in comparison with white light, however, for the accumulation of root biomass in relation to the conditions of the CES, it is more expedient to use white light, since with a biomass of root crops comparable to the phytospectrum, plants with an increased coefficient of economic efficiency are formed in white light, which reduces the share of waste in the CES (inedible leafy biomass). On the basis of the data obtained, possible tasks of scientific research on evaluating the spectral efficiency of radiation at certain stages of plant vegetation, as well as the prospects for creating LED irradiators with a physiologically based program for regulating the spectral composition and radiation intensity, are discussed.

Allocation patterns of root biomass and nutrient accumulation in Haloxylon ammodendron seedlings in southern Gurbantunggut Desert

Allocation patterns of root biomass and nutrient accumulation in Haloxylon ammodendron seedlings in southern Gurbantunggut Desert

Exogenous ABA and IAA modulate physiological and hormonal adaptation strategies in Cleistocalyx operculatus and Syzygium jambos under long-term waterlogging conditions

BackgroundThe mechanisms of abscisic acid (ABA) and auxin (IAA) in inducing adventitious root (AR) formation, biomass accumulation, and plant development under long-term waterlogging (LT-WL) conditions are largely unexplored. This study aimed to determine the roles of exogenous application of ABA and IAA in two woody plants (Cleistocalyx operculatus and Syzygium jambos) under LT-WL conditions. A pot experiment was conducted using a complete randomized design with two factors: (i) LT-WL and (ii) application of exogenous phytohormones (ABA and IAA) for 120 d.ResultsResults revealed that exogenous ABA and IAA promoted LT-WL tolerance in both species. In C. operculatus and S. jambos, plant height, the number of blades, leaf area, and fresh shoot weight were increased by exogenous IAA under LT-WL. However, exogenous ABA affected more the adventitious and primary root in C. operculatus compared to S. jambos. LT-WL decreased drastically the photosynthetic activities in both species, but adding moderate amounts of exogenous ABA or IAA protected the photosynthesis apparatus under LT-WL. Exogenous phytohormones at certain levels decreased the superoxide anion level and malondialdehyde accumulation in plants under LT-WL. Also, the increase of the peroxidases and superoxide dismutase activities by exogenous phytohormones was more marked in C. operculatus compared to S. jambos. Meanwhile, the catalase activity was down-regulated in both species by exogenous phytohormones. Exogenous ABA or IAA positively regulated the jasmonic acid content in ARs under LT-WL. Moderate application of exogenous ABA or IAA in plants under LT-WL decreased the ABA content in the leaves. Lower accumulation of IAA and ABA in the leaves of C. operculatus under LT-WL was positively correlated with a decrease in antioxidant activity.ConclusionsLastly, C. operculatus which has greater morphology indexes was more tolerant to waterlogging than S. jambos. Moreover, the adaptive strategies via exogenous ABA were more built around the below-ground biomass indexes particularly in C. operculatus, while exogenous IAA backed the above-ground biomass in both species. Overall, the exogenous hormones applied (spraying or watering) influenced differentially the plant’s responses to LT-WL. The phytohormonal profile of plants exposed to waterlogging stress varied depending on the species’ tolerance level.

Effects of Microplastics on Growth and Physiological Characteristics of Tobacco (Nicotiana tabacum L.)

The environmental effects caused by the proliferation of microplastics have received extensive attention. However, at this stage, there is a lack of research on the toxicology of microplastics and their impacts on plants. This study explored the effects of microplastics on the growth and physiological characteristics of tobacco. Using tobacco (Nicotiana tabacum L.) variety Yunyan87 and low-density polyethylene (LDPE, 13 μm particle size), different concentrations, which were 0 mg/L (CK), 10 mg/L (T1), 100 mg/L (T2), and 1000 mg/L (T3), were subjected to hydroponic experiments to study the effects of microplastics on the growth and physiological characteristics of tobacco. The results showed that microplastics had a certain inhibitory effect on the growth of tobacco. Among them, high concentrations of microplastics significantly inhibited the root architecture and growth characteristics. According to the performance observed with different treatments, the content of malondialdehyde (MDA) and the activity of superoxide dismutase (SOD) increased in the medium and high concentrations. In addition, the changes in catalase (CAT) and peroxidase (POD) activity were not obvious. Experiments showed that microplastics could significantly inhibit the growth and development of tobacco and reduce the accumulation of aerial parts and root biomass.

Effect of Aerated Irrigation on the Growth and Rhizosphere Soil Fungal Community Structure of Greenhouse Grape Seedlings

Conventional irrigation methods decrease greenhouse soil aeration, which leads to restricted root growth and reduced soil fungal abundance in greenhouse grapes. In this study, aerated irrigation equipment was used to investigate the effects of aerated irrigation on the biomass accumulation, root growth, and soil fungal community structure of grape seedlings. The results show that aerated irrigation significantly increased the root length, root surface area, root volume, and number of root tips by 38.5%, 32.1%, 62.1%, and 23.4%, respectively, at a soil depth of 20–40 cm (p ≤ 0.05). The chao1 index and ACE index of fungi at different soil depths under aerated irrigation were higher than those without aerated treatment; aerated irrigation changed the relative abundance of dominant fungi in rhizosphere soil. At a soil depth of 20–40 cm, aerated irrigation increased the abundance of Fusarium by 42.2%. Aerated irrigation also contributed to the abundance of the beneficial fungal genera Mortierella, Cladosporium, and Glomus. At a soil depth of 0–20 cm, the abundance of Mortierella in the soil that received aerated treatment was 180.6% higher than in the control treatment. These findings suggest that aerated irrigation is a promising strategy for the promotion of grape root growth and biomass accumulation, and it can also increase the abundance of some beneficial fungi.

Combined physiological and transcriptome analysis revealed the response mechanism of Pogostemon cablin roots to p-hydroxybenzoic acid.

Pogostemon cablin (patchouli) cultivation is challenged by serious soil sickness, of which autotoxins accumulation is a major cause. p-hydroxybenzoic acid (p-HBA) is one of the main autotoxins of patchouli. However, the molecular mechanism underlying the response of patchouli to p-HBA remains unclear. In this study, RNA-sequencing combined with physiological analysis was used to monitor the dynamic transcriptomic and physiological changes in patchouli seedlings 0, 6, 12, 24, 48, and 96 h after p-HBA treatment. p-HBA stress inhibited root biomass accumulation, induced excessive hydrogen peroxide accumulation and lipid peroxidation, and activated most antioxidant enzymes. Compared with that of the control, the osmotic adjustment substance content was elevated with treatment. Subsequently, 15,532, 8,217, 8,946, 2,489, and 5,843 differentially expressed genes (DEGs) at 6, 12, 24, 48, and 96 h after p-HBA treatment, respectively, were identified in patchouli roots. GO functional enrichment analysis showed that the DEGs were enriched mainly in plasma membrane, defense response, response to chitin, DNA-binding transcription factor activity and abscisic acid-activated signaling pathway. The upregulated genes were involved in glycolysis/gluconeogenesis, cysteine and methionine metabolism, starch and sucrose metabolism, biosynthesis of unsaturated fatty acids, and linoleic acid metabolism. Genes associated with MAPK signaling pathway-plant, plant-pathogen interaction, plant hormone signal transduction were downregulated with p-HBA treatment. These pathways are related to root browning and rotting, leading to plant death.