Root Irrigation Research Articles

Biocontrol fungi induced stem-base rot disease resistance of Morinda officinalis How revealed by transcriptome analysis.

Morinda officinalis How (MO) is a Rubiaceae plant, and its medicinal part is dried root, which is one of the "Four Southern Medicines" in China. At present, the plant MO breed seedlings mainly by cutting methods. Long-term asexual propagation makes pathogenic fungi accumulate in MO, leading to stem-base rot, which is caused by Fusarium oxysporum (Fon). In this study, we used Trichoderma harzianum and Pestalotiopsis sp. as biocontrol fungi to investigate their antagonistic ability to Fon through in vitro antagonism and pot experiments, and combined with transcriptome sequencing to explore the mechanism of biocontrol. The results showed that both Trichoderma harzianum and Pestalotiopsis sp. could inhibit the growth of Fon. In addition, Trichoderma harzianum and Pestalotiopsis sp. could also enhance the basic immunity to Fon by increasing the activities of defensive enzymes such as POD and SOD, chlorophyll content, soluble sugar content, and oligosaccharide content of MO. The mechanism of biological control of stem-base rot of MO was discussed by transcriptome technology. MO was treated with two treatments, root irrigation with biocontrol fungi or inoculation with Fon after root irrigation with biocontrol fungi. Transcriptome sequencing revealed that nearly 11,188 differentially expressed genes (DEGs) were involved in the process of inducing MO systemic resistance to Fon by biocontrol fungi. Meanwhile, Gene Ontology (GO) classification and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, as well as transcription factor (TFs) prediction showed that there were significant differences in the expression levels of MO roots under different treatments. Also, the genes of the "MAPK signaling pathway" and "plant hormone signaling pathway" were analyzed, in which the ERFs gene of the ethylene signal transduction pathway participated in the metabolism of glycosyl compounds. It is speculated that the ethylene signal may participate in the immune response of the sugar signal to the infection of Fon. After qRT-PCR verification of 10 DEGs related to the ethylene signal transduction pathway, the expression trend is consistent with the results of transcriptome sequencing, which proves the reliability of transcriptome sequencing. In conclusion, this study preliminarily identified the molecular mechanism of the biological control of MO stem-base rot and provided a scientific basis for further research on the prevention and control mechanism of MO stem-base rot.

Improving evapotranspiration computation with electrical resistivity tomography in a maize field

AbstractHydrogeophysical methods have been increasingly used to study subsurface soil–water dynamics, yet their application beyond the soil compartment or the quantitative link to soil hydraulic properties remains limited. To examine how these methods can inform model‐based evapotranspiration (ET) calculation under varying soil water conditions, we conducted a pilot‐scale field study at an experimental maize plot with manipulated irrigation treatments. Our goal was to develop a workflow for (1) acquiring and inverting field electrical resistivity tomography (ERT) data, (2) correlating ERT to soil hydraulic properties, (3) spatially characterizing soil water stress that feeds into ET modeling (the FAO‐56 model), and (4) evaluating the performance of ERT‐based ET computation. Our results showed that ERT was able to capture decimeter‐scale soil water content (SWC) dynamics from root water uptake and irrigation manipulation and the contrast of soil water stress between deficiently and fully irrigated maize. We also demonstrated the flexibility of using ERT to spatially integrate soil water stress in the soil volume of interest, which could be adjusted based on different crops and plot layouts. The integration of the ERT datasets into ET modeling provided insights into the spatial heterogeneity of the subsurface that has been challenging for point‐based sensing, which can further our understanding of the hydraulic dynamics in the soil‐plant‐atmosphere continuum.

Combination of intercropping maize and soybean with root exudate additions reduces metal mobility in soil-plant system under wastewater irrigation

The effects of root exudates and irrigation with treated wastewater on heavy metal mobility and soil bacterial composition under intercropping remain poorly understood. We conducted a pot experiment with maize and soybean grown in monocultures or intercultures, irrigated with either groundwater or treated wastewater. In addition, the pre-collected root exudates from hydroponic culture with mono- or inter-cropped maize and soybean were applied to the soil at four levels (0 %, 16 %, 32 % and 64 %). The results showed that application of root exudates increased plant growth and soil nutrient content. The analysis of “Technique for Order of Preference by Similarity to Ideal Solution” for higher plant biomass and lower soil Cd and Pb concentrations indicated that the best performance of soybean under treated wastewater irrigation was recorded under intercropping applied with 64 % of exudates, with a performance score of 0.926 and 0.953 for Cd and Pb, respectively. The second-best performance of maize under treated wastewater irrigation was also observed under intercropping applied with 64 % of exudates. Root exudate application reduced heavy metals migration in the soil-plant system, with a greater impact in intercropping than in monocropping. In addition, certain soil microorganisms were also increased with root exudate application, regardless of irrigation water. This study suggests that appropriate application of root exudates could potentially improve plant growth and soil health, and reduce toxic heavy metal concentrations in soils and plants irrigated with treated wastewater.

Absorption, translocation, and accumulation of the fungicide triadimefon in Pak choi (Brassica rapa var chinensis), pepper (Capsicum annuum), and cucumber (Cucumis sativus).

Triadimefon is a typical systemic fungicide that is widely used in the management of powdery mildew, rust disease, and southern blight. In this study, we measured fungicide residue to profile its absorption, translocation, and accumulation in three representative vegetable crops (Pak choi, cucumber, and pepper) after over-application. The fungicides were applied through entire-plant spraying (EPS), root-irrigation (RI), and middle-leaf-daubing (MLD). The half-life of triadimefon depends on the application method and plant species. In EPS, the half-life was 5.42 days (Pak choi), 6.86 days (cucumber), and 6.73 days (pepper), while in RI it was 4.39 days (Pak choi), 6.30 days (cucumber), and 5.98 days (pepper). In the EPS treatment, triadimefon is translocated both upward/outside and downward/inner-side from the daubed leaves in all the three vegetable crops. The transfer amount to each organ reached a peak on the 2nd day after fungicide application. The mesophyll of Pak choi exhibited a higher fungicide deposition compared to the petiole. In cucumber and pepper, the leaves demonstrated the highest accumulation of triadimefon (approximately 0.3-0.5 mg·kg-1), followed by stems. Roots and fruits displayed the lowest levels of triadimefon accumulation. Furthermore, triadimefon was found to have an impact on chlorophyll content, root activity, as well as the activity of superoxide dismutase and catalase in Pak choi, indicating its potential as a plant growth regulator. These aforementioned studies provide novel insights for the safe and efficient application of triadimefon in the production of Pak choi, cucumber, and pepper.

Favorable physiological and morphological effects of molybdenum nanoparticles on tobacco (Nicotiana tabacum L.): root irrigation is superior to foliar spraying.

Nano fertilizers can provide efficient solutions to the increasing problem of nutrient deficiency caused by low availability. However, the most important prerequisite is to fully understand whether nanomaterials induce phytotoxicity in plants under a variety of different conditions. The mechanisms underlying interactions between molybdenum nanoparticles (Mo NPs) and plants with respect to their uptake and biological effects on crops are still not fully understood. In this study, the impacts of Mo NPs over a range of concentrations (0, 25, and 100 μg/mL) on tobacco (Nicotiana tabacum L.) seedling growth were comparatively evaluated under foliar applications and root irrigation. The results indicated that more significant active biological effects were observed with root irrigation application of Mo NPs than with foliar spraying. The agronomic attributes, water content and sugar content of Mo NPs-exposed seedlings were positively affected, and morphologically, Mo NPs induced root cell lignification and more vascular bundles and vessels in tobacco tissues, especially when applied by means of root irrigation. Moreover, the photosynthetic rate was improved by 131.4% for root exposure to 100 μg/mL Mo NPs, mainly due to the increased chlorophyll content and stomatal conductance. A significant concentration-dependent increase in malonaldehyde (MDA) and defensive enzyme activity for the Mo NPs-treated tobacco seedlings were detected compared to the controls. Significantly improved absorption of Mo by exposed tobacco seedlings was confirmed with inductively coupled plasma mass spectrometry (ICP-MS) in tobacco tissues, regardless of application method. However, the accumulation of Mo in roots increased by 13.94 times, when roots were exposed to 100 mg/L Mo NPs, higher than that under treatment with foliar spray. Additionally, Mo NPs activated the expression of several genes related to photosynthesis and aquaporin processes. The present investigations offer a better understanding of Mo NPs-plant interactions in terrestrial ecosystems and provide a new strategy for the application of Mo NPs as nano fertilizers in crop production.

Assessing the effectiveness of imidacloprid and thiamethoxam via root irrigation against Megalurothrips usitatus (Thysanoptera: Thripidae) and its residual effects on cowpea.

Systemic neonicotinoid insecticides (NEOs) applied by seed-treatment or root application have emerged as a prevalent strategy for early-season insect pest management. This research investigated the effectiveness of imidacloprid and thiamethoxam, administered through root irrigation, in managing thrips in cowpea [Vigna unguiculata (Linn.) Walp.], and the residual properties of both insecticides in cowpea and soil. The results show that thrips density depends on the application rate of insecticides. At the maximum application rate (1,500 µg/ml, active ingredient), imidacloprid and thiamethoxam controlled thrips densities below the economic injury level (EIL, the EIL of thrips on cowpea was 7/flower) for 20 days and 25 days with the density of 6.90 and 6.93/flower at the end of the periods, respectively. Imidacloprid and thiamethoxam residues decreased gradually over time and decreased sharply after 15 days after treatment (DAT), the 2 insecticides were not detected (<0.001 mg/kg) at 45 DAT. According to our findings, the application of imidacloprid and thiamethoxam via root irrigation proved residual control lasting up to 20-25 days for controlling thrips damage at experimental rates, with a strong association to their residual presence in cowpea (0.6223 < R2 < 0.9545). Considering the persistence of the imidacloprid and thiamethoxam, the maximum tested application rate (1,500 µg/ml) was recommended. As the residues of imidacloprid and thiamethoxam were undetectable in cowpea pods at all tested rates, it may be suggested that the use of each insecticide is safe for consumers and effective against thrips, and could be considered for integrated thrips management in the cowpea ecosystem.

Endophytic Beauveria bassiana of Tomato Resisted the Damage from Whitefly Bemisia tabaci by Mediating the Accumulation of Plant-Specialized Metabolites.

Beauveria bassiana acts as an endophytic fungus that controls herbivorous pests by stimulating plant defenses and inducing systemic resistance. Through multiomics analysis, 325 differential metabolites and 1739 differential expressed genes were observed in tomatoes treated with B. bassiana by root irrigation; meanwhile, 152 differential metabolites and 1002 differential genes were observed in tomatoes treated by local leaf spraying. Among the upregulated metabolites were α-solanine, 5-O-caffeoylshikimic acid, clerodendrin A, and peucedanin, which demonstrated anti-insect activity. These differential metabolites were primarily associated with alkaloid biosynthesis, flavonoid biosynthesis, and tryptophan metabolism pathways. Furthermore, the gene silencing of UDP-glucose:sterol glucosyltransferase, a gene involved in α-solanine synthesis, indicated that B. bassiana could inhibit the reproduction of whiteflies by regulating α-solanine. This study highlighted the ability of B. bassiana to modulate plant secondary metabolites and emphasized the significance of understanding and harnessing multitrophic interactions of endophytic B. bassiana for sustainable agriculture.

The intrinsic resistance of Fusarium solani to the Fusarium-specific fungicide phenamacril is attributed to the natural variation of both T218S and K376M in myosin5

Fusarium solani is responsible for causing root rot in various crops, resulting in wilting and eventual demise. Phenamacril, a specific inhibitor of myosin5 protein, has gained recognition as an effective fungicide against a broad spectrum of Fusarium species. It has been officially registered for controlling Fusarium diseases through spray application, root irrigation, and seed dipping. In this study, phenamacril was observed to exhibit negligible inhibitory effects on F. solani causing crop root rot, despite the absence of prior exposure to phenamacril. Considering the high selectivity of phenamacril, this phenomenon was attributed to intrinsic resistance and further investigated for its underlying mechanism. Sequence alignment analysis of myosin5 proteins across different Fusarium species revealed significant differences at positions 218 and 376. Subsequent homology modeling and molecular docking results indicated that substitutions T218S, K376M, and T218S&K376M impaired the binding affinity between phenamacril and myosin5 in F. solani. Mutants carrying these substitutions were generated via site-directed mutagenesis. A phenamacril-sensitivity test showed that the EC50 values of mutants carrying T218S, K376M, and T218S&K376M were reduced by at least 6.13-fold, 9.66-fold, and 761.90-fold respectively compared to the wild-type strain. Fitness testing indicated that mutants carrying K376M or T218S&K376M had reduced sporulation compared to the wild-type strain. Additionally, mutants carrying T218S exhibited an enhanced virulence compared to the wild-type strain. However, there were no significant differences observed in mycelial growth rates between the mutants and the wild-type strain. Thus, the intrinsic differences observed at positions 218 and 376 in myosin5 between F. solani and other Fusarium species are specifically associated with phenamacril resistance. The identification of these resistance-associated positions in myosin5 of F. solani has significantly contributed to the understanding of phenamacril resistance mechanisms, thereby discouraging the use of phenamacril for controlling F. solani.

Endophytic Beauveria bassiana promotes plant biomass growth and suppresses pathogen damage by directional recruitment.

Entomopathogenic fungi (EPF) can colonize and establish symbiotic relationships with plants as endophytes. Recently, EPF have been reported to suppress plant pathogens and induce plant resistance to diseases. However, the potential mechanisms via which EPF as endophytes control major plant diseases in situ remain largely unknown. Pot and field experiments were conducted to investigate the mechanisms via which an EPF, Beauveria bassiana, colonizes tomato, under Botrytis cinerea infection stress. B. bassiana blastospores were inoculated into tomato plants by root irrigation. Tomato resistance to tomato gray mold caused by B. cinerea was evaluated by artificial inoculation, and B. bassiana colonization in plants and rhizosphere soil under B. cinerea infection stress was evaluated by colony counting and quantitative PCR. Furthermore, the expression levels of three disease resistance-related genes (OXO, CHI, and atpA) in tomato leaves were determined to explore the effect of B. bassiana colonization on plant disease resistance performance in pot experiments. B. bassiana colonization could improve resistance of tomato plants to gray mold caused by B. cinerea. The incidence rate, lesion diameter, and disease index of gray mold decreased in both the pot and field experiments following B. bassiana colonization. B. bassiana was more likely to accumulate in the pathogen infected leaves, while decreasing in the rhizosphere soil, and induced the expression of plant resistance genes, which were up-regulated in leaves. The results indicated that plants could "recruit" B. bassiana from rhizosphere soil to diseased plants as directional effects, which then enhanced plant growth and resistance against pathogens, consequently inhibiting pathogen infection and multiplication in plants. Our findings provide novel insights that enhance our understanding of the roles of EPF during pathogen challenge.

Translocation and dissipation of thiamethoxam applied by root irrigation in tomato plant-soil system.

Thiamethoxam (TMX) has been registered for use on a wide range of crops due to its versatile application methods, however, there is limited literature evaluating the residue behaviors of TMX applied through root irrigation. In this study, the uptake and translocation of TMX, its degradation to clothianidin (CLO), and dissipation in the tomato plant-soil system were conducted. TMX applied by root irrigation was transferable within the tomato plant, including stems, leaves, and fruits at different heights. TMX concentrations in the four sections of stems were ordered as Clower > Cmid > Cupper > Ctop, while in the leaves were ordered as Ctop > Cupper > Cmid > Clower. The degradation product CLO was detected in the tomato plant, and concentrations of CLO were even higher than those of TMX in the leaves. The translocation factor (TF) of TMX in the same section generally followed the order of TFleaf > TFstem > TFfruit. Residues of TMX and CLO in tomato on 7 days after application were below maximum residue limits (MRLs) in China and Codex Alimentarius Commission(CAC). This study promotes the evaluation of TMX applied through root irrigation for use in the tomato system from a dietary safety perspective.

Improving the Efficiency of the Indoor Air Purification from Formaldehyde by Plants Colonized by Endophytic Bacteria Ochrobactrum sp.

The endophytic bacteria can be in symbiosis with host plants, owing to the natural stability advantages in degrading pollutants. To explore the technological feasibility of this method for indoor formaldehyde removal, a system combining endophytic bacteria and plants was established. In the present study, highly efficient formaldehyde-degrading bacteria Ochrobactrumintermedium, named strain ZH-1, was successfully induced with antibiotics (rifampicin) to an antibiotic-labeled strain ZH-1R without microbial variation. The strain ZH-1R was then used for colonization in the Epipremnum aureum and Chlorophytum comosumf. variegate plants by three inoculation methods: root irrigation (RI), acupuncture injury to stem (AS), and acupuncture injury to leaves (AL). The results demonstrated that the acupuncture injury to stem (AS) method was the most effective for inoculating ZH-1R strain in Epipremnum aureum plants. Conversely, acupuncture injury to stem (RI) method yielded the best results for the Chlorophytum comosumf. variegate plants, highlighting the importance of usage of optimal plant specific inoculation method ensuring the highest possible performance characteristics of the biological system. The results of 8-day formaldehyde dynamic fumigation experiment demonstrated that the removal efficiency of the formaldehyde by Chlorophytum comosum f. variegata inoculated with ZH-1R was significantly higher than the one demonstrated by non-inoculated plants. The average increase of 20.17% was observed during daytime, while much more significant improvement by 62.88% was achieved at night. This implied that endophytic bacteria could not only effectively improve the removal efficiency of formaldehyde, but also increased the resistance of not-native host plants to formaldehyde toxicity, suggesting its potential in an integrated system which provides a new path of an efficient and economical approach to radically improve indoor air quality, especially at nighttime.

Application Methodology and Physiological Insights of Melatonin Hormone for Water Stress Alleviation in Black Pepper (Piper nigrum L.)

Black pepper is highly sensitive to water deficit stress especially during summer, resulting in significant losses in yield; therefore, strategies aimed at enhancing water stress tolerance are essential. Melatonin improves stress tolerance in plants; however, its method of application and optimum concentration in black pepper under water deficit stress remains unclear. Therefore, we conducted a two pot culture experiment during March and April, 2022 (var. Panniyur-1) to investigate the effects of foliar-sprayed and root-irrigated melatonin (50, 100 and 150 µM L-1) on the recovery per cent and physiological mechanism under water stress. The treatment details were, WW - Well-watered; WS - Water stressed; FM50 - Waterstress+50µM Melatonin (Foliar spray); FRM50 - Water stress + 50µM Melatonin (Foliar spray + Soil drenching @ 50ml/plant); FM100 - Water stress + 100µM Melatonin (Foliar spray); FRM100 - Water stress + 100µM Melatonin (Foliar spray + Soil drenching @ 50ml/plant); FM150 - Water stress + 150µM Melatonin (Foliar spray); FRM150 - Water stress + 150µM Melatonin (Foliar spray + Soil drenching @ 50ml/plant). The melatonin-induced enhanced stress tolerance could be attributed to improved recovery %, leaf relative water content, photosynthetic pigments, activity of antioxidant enzymes (SOD, POD, and CAT), and ultimately significantly relieved the inhibitory effects of water stress on leaves. After rehydration, melatonin-treated plants recovered more quickly than untreated plants. In addition, melatonin counteracted the water stress induced accumulation in proline content. Overall, the results of this study demonstrated that melatonin at 100 µM L-1 (Foliar spray and root irrigation) significantly alleviated the adverse effects of water deficit stress compared untreated plants. In addition, application of exogenous melatonin combined with root and foliar application is superior than foliar spraying alone.

Analysis of Growth and Rhizosphere Soil Changes of Herbaceous Peony Treated with a Compound Microbial Agent under Contrasted Soil Conditions

When used for ornamental purposes, the herbaceous peony is usually propagated by root ramets, but the replanting of divided seedlings in the original planting area results in poor growth and development. No research has reported on a compound microbial agent used for herbaceous peony. The purpose of this experiment is to provide a reference for low–cost soil improvement in production, promote the growth and development of herbaceous peony, and solve the problem of planting back obstacles. In this study, 3–year–old seedlings of herbaceous peony ‘Zifengyu’ were selected and planted into an ordinary garden and replanted soils. Four root irrigation treatments were conducted using the compound microbial agent ‘Junzhongjun’ to determine the physicochemical properties of rhizosphere soil, root physiology, and growth and development of ‘Zifengyu’ under different soil conditions. The growth and development of the aboveground parts of herbaceous peony were promoted by the treatment of the compound microbial agent in the following order: garden soil &gt; sieved–root soil &gt; unsieved–root soil. Root vigour was enhanced in the following sequence: sieved–root soil &gt; unsieved–root soil &gt; garden soil. The organic matter and available potassium in the rhizosphere soil of herbaceous peony increased, and the promotional effect in the sieved–root soil was significantly better than that in the other two soils. The results show that the compound microbial agent is low in cost and has a stimulating effect on the growth and development of herbaceous peony. In the process of production, the residual broken roots in the soil can be sieved and combined with the application of the compound microbial agent to further alleviate the barriers of replanting. The concentration and frequency of agent application should be further optimized at a later stage.

The effect of abamectin application in combination with agronomic measures on the control efficacy of cucumber root-knot nematodes and the cucumber yield.

As a registered non-fumigant nematicide, abamectin has been widely used as a soil treatment against many cash crop nematode diseases. In a previous study, we found that soil adsorption hindered the stable performance of abamectin against root-knot nematodes in the field. In this study, an efficient and labor-saving application method of soil blending abamectin combined with rotary tillage, a common agronomic measure, was developed to improve the efficacy of abamectin against root-knot nematode disease. We revealed the role of four parameters in this application method. At an abamectin dose of 750 g a.i. ha-1 , spray water volume of 675 L ha-1 and rotation depth of 20 cm, abamectin was well distributed in the 0-20 cm soil layer at a concentration of 0.41-0.46 mg kg-1 , the efficacy against root-knot nematode disease was 72.12%, and the cucumber yield was 51.93 t ha-1 . At the same dosage, root irrigation and flood irrigation measures resulted in only 29.28% and 33.43% control, with cucumber yields of 42.96 and 44.73 t ha-1 , respectively. To control root-knot nematode disease with abamectin, a soil blending application combined with rotary tilling is superior to leaching application combined with the agronomic measure of irrigation. The former application method can improve the dispersion of abamectin in the soil, enhance the efficacy of abamectin against root-knot nematodes and maintain a stable cucumber yield. In addition, the increased labor required for application combined with agronomic measures is negligible and has excellent application prospects. © 2023 Society of Chemical Industry.

A cysteine-rich secretory protein involves in phytohormone melatonin mediated plant resistance to CGMMV

BackgroundMelatonin is considered to be a polyfunctional master regulator in animals and higher plants. Exogenous melatonin inhibits plant infection by multiple diseases; however, the role of melatonin in Cucumber green mottle mosaic virus (CGMMV) infection remains unknown.ResultsIn this study, we demonstrated that exogenous melatonin treatment can effectively control CGMMV infection. The greatest control effect was achieved by 3 days of root irrigation at a melatonin concentration of 50 μM. Exogenous melatonin showed preventive and therapeutic effects against CGMMV infection at early stage in tobacco and cucumber. We utilized RNA sequencing technology to compare the expression profiles of mock-inoculated, CGMMV-infected, and melatonin+CGMMV-infected tobacco leaves. Defense-related gene CRISP1 was specifically upregulated in response to melatonin, but not to salicylic acid (SA). Silencing CRISP1 enhanced the preventive effects of melatonin on CGMMV infection, but had no effect on CGMMV infection. We also found exogenous melatonin has preventive effects against another Tobamovirus, Pepper mild mottle virus (PMMoV) infection.ConclusionsTogether, these results indicate that exogenous melatonin controls two Tobamovirus infections and inhibition of CRISP1 enhanced melatonin control effects against CGMMV infection, which may lead to the development of a novel melatonin treatment for Tobamovirus control.

Positive effects of Cordyceps cateniannulata colonization in tobacco: Growth promotion and resistance to abiotic stress.

Entomopathogenic fungi can live in insects to cause disease and death and are the largest group of entomopathogenic microorganisms. Therefore, these fungi are best known for their microbial control potential. Importantly, they also have other beneficial effects, including promoting plant growth and development by colonizing plant. Here, the study sought to identify specific strains of the entomopathogenic fungus, Cordyceps cateniannulata that would form endophytic associations with tobacco, thus benefiting plant growth and resistance to abiotic stresses, thereby highlighting the application of entomopathogenic fungi in tobacco. The C. cateniannulata-tobacco symbiont was constructed by root irrigation. The effects of C. cateniannulata on tobacco growth were evaluated by measuring the maximum leaf length, maximum leaf width, number of leaves, plant height, stem thickness, stem circumference, dry and fresh shoot weight 7, 14, 21, and 28 days after colonization. The peroxidase, catalase, superoxide dismutase, and malondialdehyde were measured to observe the impact of C. cateniannulata on tobacco defense enzyme activity. Finally, high-throughput sequencing was used to access microbial communities in the rhizosphere, with data subsequently linked to growth indicators. After tobacco was inoculated with C. cateniannulata X8, which significantly promoted growth and related enzyme activity, malondialdehyde was decreased. The most significant impact was on peroxidase, with its activity being upregulated by 98.20, 154.42, 180.65, and 170.38% in the four time periods, respectively. The high throughput sequencing results indicated that C. cateniannulata had changed the rhizosphere microbial relative abundances, such as increasing Acidobacteria and Ascomycetes, and decreasing Actinomycetes and Basidiomycetes. The redundancy analysis showed that C. cateniannulata significantly boosted tobacco growth by reducing the abundance of specific dominant genera such as Stachybotrys, Cephalotrichum, Streptomyces, Isoptericola, and Microbacterium. Specific strains of C. cateniannulata can be introduced into host plants as endophytes, resulting in promotion of host plant growth and increased resistance to abiotic stress and microbial pathogens. The study provides a foundation for future studies of C. cateniannulata as an ecological agent.

Optimization of Key Hydraulic Structure Parameters of a New Type of Water–Pesticide Integrated Sprinkler Based on Response Surface Experiment

To meet the requirements of trellis grape crop root irrigation, spraying pesticides on branches and leaves, an integrated sprinkler was designed, which relies on the flow pressure to change the irrigation water and spray pesticide working modes. The structural parameters that affect the hydraulic performance were selected based on the working principle of the sprinkler. The key parameters for the irrigation mode included diversion hole inclination angle, refractive cone angle, refractive cone length, and cone hole distance. The key parameters for the spray pesticide mode included diversion chute width, the number of diversion chutes, the diversion chute inclination angle, the rotary acceleration chamber height, and the nozzle outlet cylindrical section length. The central composite design response surface tests of the water–pesticide integrated sprinkler were carried out; the analysis of variance and regression analysis were selected; the main influence rules and interactions of key structural parameters on irrigation performance and pesticide spraying performance of sprinkler irrigation system were obtained. The optimal parameters of the water–pesticide integrated sprinkler were: the diversion hole inclination angle is 20.8°, the refractive cone angle is 123.7°, the refractive cone length is 8.8 mm, the cone hole distance is 3.6 mm, the diversion chute width is 2.5 mm, the number of diversion chutes is 2, the diversion chute inclination angle is 10°, the rotary acceleration chamber height is 1.3 mm, and the nozzle outlet cylindrical section length is 0.7 mm. The irrigation hydraulic performance of the wetted radius is 3.4 m, the average irrigation application rate is 0.65 mm/h, and the uniformity coefficient is 88%. The spraying pesticide performance of the droplet volume mid-diameter is 200.2 μm, the droplet spectrum width is 2.2, and the droplet coverage is 9.4%.

Effect of methods application of copper nanoparticles in the growth of avocado plants

The aim of this greenhouse study was to evaluate root irrigation, foliar spray, and stem injection in order to find the best method for the nanofertilization of avocado plants with green synthesized CuNPs. One-year-old avocado plants were supplied four times (every 15 days) with 0.25 and 0.50 mg/ml of CuNPs through the three fertilization methods. Stem growth and new leaf formation were evaluated over time and after 60 days of CuNPs exposure, several plant traits (root growth, fresh and dry biomass, plant water content, cytotoxicity, photosynthetic pigments, and total Cu accumulation in plant tissues) were evaluated for CuNPs improvement. Regarding the control treatment, stem growth and new leaf appearance were increased by 25 % and 85 %, respectively, by the CuNPs supply methods of foliar spray>stem injection>root irrigation, with little significant differences among NPs concentrations. Avocado plants supplied with 0.25 and 0.50 mg/ml CuNPs maintained a hydric balance and cell viability ranged from 91 to 96 % through the three NPs application methods. TEM did not reveal any ultrastructural organelle changes induced by CuNPs in leaf tissues. The concentrations of CuNPs tested were not high enough to exert deleterious effects on the photosynthetic machinery of avocado plants, but photosynthetic efficiency was also found to be improved. The foliar spray method showed improved uptake and translocation of CuNPs, with almost no loss of Cu. In general, the improvement in plant traits indicated that the foliar spray method was the best for nanofertilization of avocado plants with CuNPs.

Trichoderma asperellum GD040 upregulates defense-related genes and reduces lesion size in Coffea canephora leaves inoculated with Colletotrichum cairnsense

Coffee anthracnose is an important disease around the world, which has seriously affected the profits of coffee growers. This study firstly reported Colletotrichum cairnsense as a pathogen to cause coffee anthracnose, and screened Trichoderma asperellum GD040 with good antagonistic (inhibition rate was 88.41%) and mycoparasitism ability. Root irrigation with T. asperellum GD040 spore suspension reduces lesion size caused by C. cairnsense on coffee leaves. Transcriptomic analysis showed that the expression of 175 genes in T. asperellum GD040 treated coffee was up-regulated, including 73 disease-resistance genes involved in the plant-pathogen interaction pathway, phenylpropanes biosynthesis pathway and other pathways, respectively. Results from qRT-PCR analysis indicated that the expression levels of 16 key resistance genes (11 disease-resistance genes reported in Coffea canephora, 2 phenylalanine biosynthesis-related genes, ETR, PAL, and OPR3) and 3 growth hormone synthesis-related genes (Pin-1, SUAR, and GAs-30-O) were up-regulated remarkably in coffee leaves treated by T. asperellum GD040, and were significantly higher than those in coffee leaves inoculated with C. cairnsense. Findings of this study revealed the antagonistic mode of T. asperellum GD040 against C. cairnsense and the mechanism of inducing host resistance in coffee against anthracnose at the molecular level, which laid the foundation for the development of multifunctional Trichoderma biological agents and their application in managing coffee anthracnose.

Multi-factor correlation analysis of the effect of root-promoting practices on tobacco rhizosphere microecology in growth stages

Some agronomic practices not only promote the development of crop roots and increase overall plant performance but also affect colonisation by rhizosphere microorganisms. However, the composition and temporal dynamics of the tobacco rhizosphere microbiota under different root-promoting practices are poorly understood. Here, we characterised the tobacco rhizosphere microbiota at the knee-high, vigorous growing, and maturity stages under the application of potassium fulvic acid (PFA), γ-Polyglutamic acid (PGA), soymilk root irrigation (SRI), and conventional fertilization (CK) and its correlation with root characteristics and soil nutrients. The results showed that three root-promoting practices notably improved the dry and fresh root weights. Total nitrogen and phosphorus, available phosphorus and potassium, and organic matter contents in the rhizosphere markedly increased at the vigorous growing stage. The rhizosphere microbiota was changed through root-promoting practices. However, with tobacco growth, the change of rhizosphere microbiota showed a pattern of slow first and then fast and the microbiota of different treatments gradually approached. SRI reduced plant-pathogenic fungi but increased chemoheterotrophic and phototrophic bacteria, and arbuscular mycorrhizal fungi. PFA and PGA markedly increased arbuscular mycorrhizal and ectomycorrhizal fungi at the knee-high stage, which benefitted tobacco nutrient absorption. The correlation between rhizosphere microorganisms and environmental factors varied at different growth stages. Notably, the rhizosphere microbiota was more sensitive to environmental factors at the vigorous growing stage, and the interactions were more complex than in other stages. Furthermore, a variance partitioning analysis showed that the influence of root–soil interaction on the rhizosphere microbiota increased with tobacco growth. Overall, all three root-promoting practices could improve root characteristics, rhizosphere nutrient, and rhizosphere microbiota to varying degrees and increase the tobacco biomass, among which PGA had the most obvious effect and most suitable for tobacco cultivation. Our findings revealed the role of root-promoting practices in shaping the rhizosphere microbiota during plant growth and elucidated the assembly patterns and environmental drivers of crop rhizosphere microbiota driven by the application of root-promoting practices in agricultural production.