Plant Growth Stages Research Articles

Identification of field resistance to HPPD-inhibiting herbicides in wild radish (Raphanus raphanistrum)

AbstractThe control of multiple-resistant wild radish (Raphanus raphanistrum L.) populations in no-till Australian wheat (Triticum aestivum L.) crops has relied upon 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting herbicides over the last decade. Two R. raphanistrum populations identified as putatively resistant to pyrasulfotole + bromoxynil in an initial large-scale screening trial were characterized and confirmed to be 5- to 8-fold (comparison of LD50 values) less sensitive than the susceptible control population to the HPPD inhibitor pyrasulfotole when plants were treated at the 4-leaf stage. The two pyrasulfotole-resistant populations exhibited up to 4-fold resistance to the coformulated herbicide mixture pyrasulfotole + bromoxynil and up to 9- and 11-fold cross-resistance to mesotrione and topramezone postemergence, respectively. A small-plot trial was conducted in the field from which of one of the populations suspected of resistance was originally collected. Pyrasulfotole + bromoxynil or topramezone + bromoxynil applied postemergence delivered reduced R. raphanistrum control (79% to 87%), whereas mesotrione applied preemergence was >99% effective. We report here the first case of field resistance to HPPD-inhibiting herbicides in R. raphanistrum, caused by 12 yr of continuous reliance on that mode of action. The mitigation of herbicide resistance in continuous no-till cropping requires a constant optimization of the herbicide technology via alternation and mixtures of multiple sites of action, use of preemergence herbicides, and ensuring postemergence herbicides are applied at the most sensitive plant growth stages.

The bacterial world inside the plant

Sustainable agriculture requires the recruitment of bacterial agents to reduce the demand for mineral fertilizers and pesticides such as bacterial endophytes. Bacterial endophytes represent a potential alternative to the widespread use of synthetic fertilizers and pesticides in conventional agriculture practices. Endophytes are formed by complex microbial communities and microorganisms that colonize the plant interior for at least part of their life. Their functions range from mutualism to pathogenicity. Bacterial endophytes colonize plant tissues, and their composition and diversity depend on many factors, including the plant organ, physiological conditions, plant growth stage, and environmental conditions. The presence of endophytes influences several vital activities of the host plant. They can promote plant growth, elicit a defense response against pathogen attack, and lessen abiotic stress. Despite their potential, especially with regard to crop production and environmental sustainability, research remains sparse. This review provides an overview of the current research, including the concept of endophytes, endophytes in plant organs, endophyte colonization, nutrient efficiency use, endophytes and crop nutrition, inoculation with synergistic bacteria, the effect of inoculum concentration on plant root microbiota and synthetic communities. It also examines the practical opportunities and challenges when utilizing endophytes in the field of sustainable agriculture. Finally, it explores the importance of these associations with regard to the future of agriculture and the environment.

A pH-responsive/sustained release nitrogen fertilizer hydrogel based on aminated cellulose nanofiber/cationic copolymer for application in irrigated neutral soils

Stimuli-responsive release nitrogen (N)-fertilizer hydrogels are new materials recently introduced to improve control and sustained release N-fertilizer hydrogels efficacy by adding additional functionality for greater N use efficiency. However, the stimuli-responsive behavior and release mechanisms of these fertilizer hydrogels in response to irrigated-soil stimulus fluctuations during different plant growth stages are still facing limitations and have not been considered. Herein, a novel N-fertilizer nanocomposite hydrogel with the function of N pH-responsive/sustained release (pHRSRNFH) was prepared based on wheat straw aminated-cellulose nanofibers (A-CNFs) and cationic poly(acrylamide-co-2-aminoethyl methacrylate hydrochloride) (PAM-PAEM) by direct ammonium nitrate (AN) fertilizer encapsulation. The fertilizer hydrogel structure, properties, and effects on N use efficiency and N metabolism process were characterized by FTIR, zeta potential, SEM, porosity, swelling-release behaviors, TEM, flowcytometric analysis, and N use efficiency indicators. The hydrogel nanocomposite with 3 wt% A-CNFs and 4 wt% AEM (pHRSRNFH4) exhibited desirable enhancement of characterizations, pH-responsive/sustained behaviors, and biodegradability. The soil and buffers release kinetic studies in-vitro revealed the best pH-dependent/sustained AN release of 3.00 and 2.69 mg.day−1 at pH 5.5 and 0.92 and 0.55 mg.day−1 at pH 7.4 from 1g pHRSRNFH4 for 58 and 65 days, respectively, desirably synchronizing with the pH fluctuations of irrigated-neutral soil. The whole lifetime of AN release data revealed that the three sustained delivery stages were governed by the First-order mechanism, followed by Zeroth-order, and finally via the Higuchi mechanism, covering the N crop requirements during different plant growth phases. Application of pHRSRNFH4 at 1 g kg−1 irrigated-neutral soil successfully improved water-holding capacity and N recovery efficiency by 15.7% and 38.6%, respectively, compared with free AN treated soil with over 90-days sustained AN release. Furthermore, positive impacts on rice growth indicators, N-nutrition status, and cell progression were achieved with a feasible-compatible application, demonstrating its further significant potential to be a viable alternative fertilizer formulation for N/water management of cropping systems in the irrigated-neutral soils.

Reduced chemodiversity suppresses rhizosphere microbiome functioning in the mono-cropped agroecosystems

BackgroundRhizodeposits regulate rhizosphere interactions, processes, nutrient and energy flow, and plant-microbe communication and thus play a vital role in maintaining soil and plant health. However, it remains unclear whether and how alteration in belowground carbon allocation and chemodiversity of rhizodeposits influences microbiome functioning in the rhizosphere ecosystems. To address this research gap, we investigated the relationship of rhizosphere carbon allocation and chemodiversity with microbiome biodiversity and functioning during peanut (Arachis hypogaea) continuous mono-cropping. After continuously labeling plants with 13CO2, we studied the chemodiversity and composition of rhizodeposits, along with the composition and diversity of active rhizosphere microbiome using metabolomic, amplicon, and shotgun metagenomic sequencing approaches based on DNA stable-isotope probing (DNA-SIP).ResultsOur results indicated that enrichment and depletion of rhizodeposits and active microbial taxa varied across plant growth stages and cropping durations. Specifically, a gradual decrease in the rhizosphere carbon allocation, chemodiversity, biodiversity and abundance of plant-beneficial taxa (such as Gemmatimonas, Streptomyces, Ramlibacter, and Lysobacter), and functional gene pathways (such as quorum sensing and biosynthesis of antibiotics) was observed with years of mono-cropping. We detected significant and strong correlations between rhizodeposits and rhizosphere microbiome biodiversity and functioning, though these were regulated by different ecological processes. For instance, rhizodeposits and active bacterial communities were mainly governed by deterministic and stochastic processes, respectively. Overall, the reduction in carbon deposition and chemodiversity during peanut continuous mono-cropping tended to suppress microbial biodiversity and its functions in the rhizosphere ecosystem.ConclusionsOur results, for the first time, provide the evidence underlying the mechanism of rhizosphere microbiome malfunctioning in mono-cropped systems. Our study opens new avenues to deeply disentangle the complex plant-microbe interactions from the perspective of rhizodeposits chemodiversity and composition and will serve to guide future microbiome research for improving the functioning and services of soil ecosystems.2t8oyWpyXt9Xr4Hhf-zbjPVideo abstract

Metagenomic analysis of the dynamical conversion of photosynthetic bacterial communities in different crop fields over different growth periods.

Photosynthetic bacteria are beneficial to plants, but knowledge of photosynthetic bacterial community dynamics in field crops during different growth stages is scarce. The factors controlling the changes in the photosynthetic bacterial community during plant growth require further investigation. In this study, 35 microbial community samples were collected from the seedling, flowering, and mature stages of tomato, cucumber, and soybean plants. 35 microbial community samples were assessed using Illumina sequencing of the photosynthetic reaction center subunit M (pufM) gene. The results revealed significant alpha diversity and community structure differences among the three crops at the different growth stages. Proteobacteria was the dominant bacterial phylum, and Methylobacterium, Roseateles, and Thiorhodococcus were the dominant genera at all growth stages. PCoA revealed clear differences in the structure of the microbial populations isolated from leaf samples collected from different crops at different growth stages. In addition, a dissimilarity test revealed significant differences in the photosynthetic bacterial community among crops and growth stages (P<0.05). The photosynthetic bacterial communities changed during crop growth. OTUs assigned to Methylobacterium were present in varying abundances among different sample types, which we speculated was related to the function of different Methylobacterium species in promoting plant growth development and enhancing plant photosynthetic efficiency. In conclusion, the dynamics observed in this study provide new research ideas for the detailed assessments of the relationship between photosynthetic bacteria and different growth stages of plants.

The impact of electrocution treatments on weed control and weed seed viability in soybean

AbstractField experiments were conducted in 2020 and 2021 to determine the effectiveness of electrocution on several weeds commonly encountered in Missouri soybean production using an implement known as The Weed Zapper™. In the first study, the effectiveness of electrocution on waterhemp, cocklebur, giant and common ragweed, horseweed, giant and yellow foxtail, and barnyardgrass was determined. Electrocution was applied when plants reached average heights and/or growth stages of 30 cm, 60 cm, flowering, pollination, and seed set. Electrocution was applied once or twice, at two different tractor speeds. Electrocution was more effective at the later plant growth stages. Pearson correlation coefficients indicated that control of weed species was most related to plant height and amount of plant moisture at the time of electrocution. When plants contained seed at the time of electrocution, viability was reduced from 54% to 80% among the species evaluated. A second study determined the effect of electrocution on late-season waterhemp plants, and also soybean injury and yield. Electrocution timings took place throughout reproductive soybean growth stages. The control of waterhemp escapes within the soybean trial ranged from 51% to 97%. Yield of soybean electrocuted at the R4 and R6 growth stages was similar to that of the nontreated control, but soybean yield was reduced by 11% to 26% following electrocution at all other timings. However, the visual injury and yield loss observed in these experiments likely represents a worst-case scenario because growers who maintain a clear height differential between waterhemp and the soybean canopy would not need to maintain contact with the soybean canopy. Overall, results from these experiments indicate that electrocution as part of an integrated weed-management program could eliminate late-season herbicide-resistant weed escapes in soybean, and reduce the number and viability of weed seed that return to the soil seedbank.

Little Evidence of Leaf Damage to Dwarf Palmetto (Sabal minor; Arecaceae) during an Unusual Arctic Outbreak

The dwarf palmetto (Sabal minor) is a widespread understory palm of the southeastern United States. This palm is expected to be one of the species that exhibits a range shift in response to climate change, and the population at the northwestern edge of its distribution in Oklahoma appears to be increasing in both numbers and extent. However, this palm may also be susceptible to cold damage during unusually severe winters, which could potentially limit the spread of this species. An unusually cold arctic outbreak spread across the southern Great Plains during 13–17 February 2021, with minimum temperatures of −11 °C recorded in Houston (Texas), −15 °C in San Antonio (Texas), and −26 °C in Oklahoma City (Oklahoma). In order to evaluate the effects of the arctic outbreak on Sabal minor, I examined individuals in four counties (one site in Brazoria County, TX; one site in Brazos County, TX; two sites in McCurtain County, Oklahoma; and two sites in Oklahoma County, Oklahoma) in the period of 5–16 March 2021. At nearly every site, 30 individuals were examined, and the number of palmate leaves as well as the extent of the green area on the leaf was visually estimated, with percentages rounded to the nearest 5%. There was little evidence of cold damage from southeastern Oklahoma to coastal Texas, with palmate leaves retaining a median of 85% green area. However, some damage was noted in seedlings at the northernmost population in McCurtain County, Oklahoma. In contrast, extensive leaf damage was noted in dwarf palmetto plantings in Oklahoma County, Oklahoma, with plants retaining a median of only 5% green leaf area. The results of this study suggest that arctic outbreaks are unlikely to prohibit the continued spread of this species at the northern edge of its native range but may cause damage to multiple plant growth stages that could reduce the rate at which the species survives and reproduces.

Comparative study between fungicides and some chemical inducers for controlling root rot incidence of green bean (Phaseolus vulgaris L.) under field conditions

Root rot disease caused by Rhizoctonia solani J.G. Kuhn and Fusarium solani (Mart.) Sacc. is a major problem restricting profitable farming of green bean (Phaseolus vulgaris L.). Under field conditions, some chemical inducers compared with chemical fungicides were evaluated for controlling bean root rot disease. Significant effect was observed for all applied treatments against disease incidence compared with control. Applied treatments of seed dressing plus foliar spray showed the highest reduction of root rot incidence followed by seed dressing then foliar spray. Salicylic acid as seed followed by foliar spray showed the highest suppressive effect against disease incidence followed by glutathione treatments. Furthermore, application of calcium silicate revealed higher effect against disease incidence compared with potassium and sodium silicate at both pre-, and post-emergence plant growth stages. Fungicidal treatments showed affect disease incidence in a lower extent compared with Plant Resistance Inducers (PRI). Treatment of Rizolex T50 followed by Topsin M70 was more effectively in controlling root rot than each fungicide alone. Such applied treatments could be useful for controlling root rot disease under field conditions.

Application of extended BBCH scale for studying the development of Phacelia tanacetifolia Benth.

AbstractPhacelia tanacetifolia is a fast‐growing crop from the family of Hydrophyllaceae that can be grown as an intercrop or also as a main crop, especially for the production of seed. It is grown both for fodder and for green manure and it is also an excellent melliferous plant. As it has no relation to other cultivated crops, it is suitable as a break crop in rotation. Despite its agrotechnological significance, no detailed study of its phenological development and detailed characterisation of growth stages have been published so far. The precise description of growth stages is a tool very useful not only for farmers but also for researchers. This paper presents a detailed characterisation of the development of P. tanacetifolia from germination to senescence. Based on research results, a characterisation of phenological growth stages is proposed using the extended BBCH scale. Individual methods of the evaluation of growth stages in plants are discussed and possibilities are assessed for using these methods in evaluating the development of P. tanacetifolia. The individual phenological growth stages of P. tanacetifolia are described using both the two‐ and three‐digit BBCH coding system. Schematic drawings illustrating the most representative growth stages are presented, too.

Seed Quality Parameters as Influenced by Plant Growth Regulators and Fresh Fruit Harvesting in Okra

The research work was conducted to find out the most suitable level of plant growth regulator (PGR) and stage of plant for spray as well as fresh fruit pickings to increase the seed yield of okra. The experiment was laid out in randomized block design (factorial) with three replications to at the Vegetable seed production area BAU, Sabour, Bhagalpur. Present investigation was framed with Sixty (60) treatments consisting of 10 PGR’s level, P0 (distilled water), GA3 (100 ppm, 150 ppm and 200 ppm), NAA (100 ppm, 150 ppm and 200 ppm), IAA (30 ppm, 60 ppm and 90 ppm), 2 Stage of plant for spraying of PGRs, S1 (4 leaf stage), S2 (4 leaf stage + Flower initiation) and 3 pickings of fruits, H1 (3 Pickings of fresh fruits + rest fruits left for seed production), H2 (6 Pickings of fresh fruits + rest fruits left for seed production), H3 (No pickings of fresh fruits + all fruits left for seed production. It was observed that the different levels of treatments affected the seed quality attributes of the crops. Among the treatments, P2S1H1 treatment was recorded maximum Germination % (86.36), Seedling length (31.04 cm), Vigour index-I (2787.73), Vigour index-II (5.27) and seed viability test (88.00). Thus, P2S1H1 was superior among all treatments.

Urea-Hydroxyapatite-Polymer Nanohybrids as Seed Coatings for Enhanced Germination

Modern agriculture practices play a vital role in fulfilling the doubling food demands of the increasing population. In particular, several attempts have been made to enhance the nutrient supply and plant uptake process in different growth stages of plants, but little effort has been made to enhance the nutrient status of the seeds at the seedling stage. At this stage of growth, phosphorus is the most essential nutrient, and the requirement is high, while nitrogen requirement is very low. This study focuses on developing a seed coating containing urea-modified hydroxyapatite nanocomposite to supply N and P to the seedlings in a controlled manner throughout the early growth stage. A nanohybrid based on urea-modified hydroxyapatite was synthesized using an in-situ sol-gel method and further combined with an alginate/cellulose polymer to develop the coating. Seed coating was realized using a dip coating method containing calcium chloride as the cross-linking agent. Seed germination experiments were conducted under laboratory conditions according to a randomized complete block design under constant light conditions, controlled humidity, and temperature. The structural features of the nanocomposite were studied using powder X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopic data was used to analyze the morphology. The formation of HA nanoparticles was confirmed by powder x-ray diffraction patterns that revealed the characteristic peaks for (002), (211), (300), and (202) planes of HA. Furthermore, the successful insertion of urea into the HA lattice was corroborated by both the powder X-ray diffraction and Fourier transform infrared spectroscopic techniques. Nanocomposite coatings of 50 -100 μm demonstrated excellent compatibility with the surfaces of the seeds. Seed coating composed of hydroxyapatite-urea (1:0.3) treatment revealed an increase of 124.6%, 147.6%, 100%, and 166.7% in average biomass, root length, number of roots, and maximum plant width, respectively, compared to the control, after 21 days of planting.Keywords: Urea Modified Hydroxyapatite, Nanocomposite, Alginate, Carboxymethyl Cellulose, Seed Coating, Germination.

Leaf bacterial microbiota response to flooding is controlled by plant phenology in wheat (Triticum aestivum L.)

Leaf microbiota mediates foliar functional traits, influences plant fitness, and contributes to various ecosystem functions, including nutrient and water cycling. Plant phenology and harsh environmental conditions have been described as the main determinants of leaf microbiota assembly. How climate change may modulate the leaf microbiota is unresolved and thus, we have a limited understanding on how environmental stresses associated with climate change driven weather events affect composition and functions of the microbes inhabiting the phyllosphere. Thus, we conducted a pot experiment to determine the effects of flooding stress on the wheat leaf microbiota. Since plant phenology might be an important factor in the response to hydrological stress, flooding was induced at different plant growth stages (tillering, booting and flowering). Using a metabarcoding approach, we monitored the response of leaf bacteria to flooding, while key soil and plant traits were measured to correlate physiological plant and edaphic factor changes with shifts in the bacterial leaf microbiota assembly. In our study, plant growth stage represented the main driver in leaf microbiota composition, as early and late plants showed distinct bacterial communities. Overall, flooding had a differential effect on leaf microbiota dynamics depending at which developmental stage it was induced, as a more pronounced disruption in community assembly was observed in younger plants.

INFLUENCE OF PARTIAL ROOT-ZONE DRYING ON WATER USE EFFICIENCY AND PHOSPHORUS UPTAKE OF CORN (ZEA MAYS L.) IN A GYPSIFEREOUS SOIL

Pot experiment was conducted to study the alternate and fixed partial root zone drying on irrigation water use efficiency and phosphorus absorption efficiency of corn (Zea mays L.) in a gypsiferous soil during the spring growing season. The experiment included three irrigation techniques, which were conventional irrigation (C1), alternating partial root-zone drying (APRD) and fixed partial root-zone drying (FPRD), and three levels of phosphate fertilizer application (40, 80, 120 Kg h-1), for three stages of plant growth, jointing stage (40 days from planting), booting stage (60 days from planting) and maturing stage (105 days from planting). The experiment was carried out with a complete randomized design with nine replications. Yellow corn seeds variety DKC6664 were planted on 20/3/2020. During the aforementioned growth stages, the development of the root system and vegetative parts of corn plants were studied and the water use efficiency was calculated for each growth stage. Results showed a decrease in the ratio of root to the vegetative weight under the alternating and fixed root-zone drying for the three fertilization levels and the three-growth stage (jointing, booting, maturing). The conventional irrigation treatment gave a grain yield of 40.53, 51.44 and 57.71 g pot-1 for the fertilization levels of 40, 80 and 120 kg P h-1 with a significant difference compared to alternate and fixed partial root-zone drying treatments. Alternate partial root-zone drying give the highest water use efficiency of 0.90, 0.93 and 0.98 kg m-3. Higher values of phosphorus absorption was recorded with CI treatment. The phosphorus absorption was high in the jointing and booting stages of corn growth. Phosphorous reduced some of the negative effects of water shortage on plant growth and yield and the reason for an increase in water use efficiency.

EFFECT OF SUBMERGENCE STRESS ON AGRO-MORPHOLOGICAL AND PHYSIOLOGICAL TRAITS IN RICE (ORYZA SATIVA L.) GENOTYPES

Submergence stress due to flash flooding is one of the most adverse abiotic factor of plant growthand productivity, considered a severe threat for sustainable crop production in the changing climate. Riceis semi-aquatic crop, able to make several modulations in their adaptive traits to sustain submergence stress,but intense and prolonged flooding is fatal for its sustainability. In this context, a field experiment wasconducted to assess the effect of different submergence regimes (7, 14 and 21 days’ submergence) on agromorphologicaland physiological traits in rice at ICAR-National Rice Research Institute, Cuttack, India. Theexperiment was laid out in a Complete Randomized Design with three replications. Control (nosubmergence) and submergence (7, and 14 days) were imposed on eleven rice genotypes at vegetative stage.Plant height, number of tillers hill-1, spikelets fertility, % survival, chlorophyll content, total soluble sugarcontent showed decreasing trend under submergence, whereas, accumulation of proline content and ADHactivities reported enhanced level under submergence, especially in Sub1 carrying lines. From the currentresearch, it was observed that submergence stress affected plant growth stages substantially, therefore,genotypes showed least vulnerability under seven days’ submergence might be utilized in traitsimprovement program.

Exploring Functional Diversity and Community Structure of Diazotrophic Endophytic Bacteria Associated with Pennisetum glaucum Growing under Field in a Semi-Arid Region

Diazotrophic endophytic bacteria (DEB) are the key drivers of nitrogen fixation in rainfed soil ecosystems and, hence, can influence the growth and yield of crop plants. Therefore, the present work investigated the structure and composition of the DEB community at different growth stages of field-grown pearl millet plants, employing the cultivation-dependent method. Diazotrophy of the bacterial isolates was confirmed by acetylene reduction assay and amplification of the nifH gene. ERIC-PCR-based DNA fingerprinting, followed by 16S rRNA gene analysis of isolates recovered at different time intervals, demonstrated the highest bacterial diversity during early (up to 28 DAS (Days after sowing)) and late (63 DAS onwards) stages, as compared to the vegetative growth stage (28–56 DAS). Among all species, Pseudomonas aeruginosa was the most dominant endophyte. Assuming modulation of the immune response as one of the tactics for successful colonization of P. aeruginosa PM389, we studied the expression of the profile of defense genes of wheat, used as a host plant, in response to P. aeruginosa inoculation. Most of the pathogenesis-related PR genes were induced initially (at 6 h after infection (HAI)), followed by their downregulation at 12 HAI. The trend of bacterial colonization was quantified by qPCR of 16S rRNAs. The results obtained in the present study indicated an attenuated defense response in host plants towards endophytic bacteria, which is an important feature that helps endophytes establish themselves inside the endosphere of roots.

Multi-trait selection of tomato introgression lines under drought-induced conditions at germination and seedling stages

To be considered drought-tolerant, a tomato cultivar is required to present some level of tolerance at all developmental stages of plant growth. Since drought tolerance is a stage-specific phenomenon, genotype assessment must be performed separately at all developmental stages. In this study, we used a multi-trait index based on factor analysis and genotype-ideotype distance (FAI-BLUP index) to properly rank 49 tomato genotypes according to their tolerance to drought stress conditions at germination and seedling stages. Seeds of 47 introgression lines, which cultivar M82 is considered drought-sensitive, and the Solanum pennellii wild accession LA 716, which is considered drought-tolerant, were subjected to a control condition, where seeds were soaked in distilled water, and a drought condition, where seeds were soaked in a polyethylene glycol (PEG) solution (-0.3 MPa). Drought stress, induced by PEG, had a significant impact on all nine germination and growth performance-related traits; there was a reduction in shoot length (SL), total length (TL), initial germination percentage (IGP), final germination percentage (FGP), germination velocity index (GVI), and germination rate (GR). In contrast, the root-to-shoot ratio (R/S) and time to reach 50% germination (T50) increased under drought stress. Root length (RL) was less affected by drought, and in some genotypes, it was even increased. As expected, LA 716 ranked closest to the drought tolerance ideotype. IL 1-4-18, IL 2-3, IL 1-2, IL 9-2, and IL 10-1 were the most drought-tolerant at the germination stage. These results will serve as guidance for breeders who are aiming at developing drought-resistant tomato cultivars.

FfCOX17 is Involved in Fumonisins Production, Growth, Asexual Reproduction, and Fungicide Sensitivity in Fusarium fujikuroi.

Fusarium fujikuroi, a causal agent of Rice Bakanae Disease, produces secondary metabolites such as gibberellin, pigments bikaverin, and mycotoxins fumonisins. Fumonisins produced by F. fujikuroi pose a severe threat to human and animal health. The copper chaperone protein plays a critical role in different growth stages of plants, fungi, and yeasts, but their functions and regulation in fumonisin biosynthesis are still unclear. Here, a copper chaperone protein, FfCOX17, was identified in F. fujikuroi. The FfCOX17 deletion mutant (∆FfCOX17) exhibited decreased vegetative growth and asexual reproduction. The transcriptional level of the FfFUM2 gene was significantly induced in ∆FfCOX17, and the fumonisin production in ∆FfCOX17 mutants was significantly increased compared to wild-type F. fujikuroi, but the pathogenicity of ∆FfCOX17 mutants was unaffected, which may be caused by the no significantly changed gibberellin content. ∆FfCOX17 showed decreased sensitivity to oxidative stress, osmotic stress, and increased sensitivity to cell wall stress, heat shock stress, and high concentration glucose. In addition, ∆FfCOX17 also showed increased sensitivity to fungicide fluazinam and fludioxonil, and decreased sensitivity to phenamacril and prochloraz. Taken together, this study suggested that FfCOX17 is critical for fumonisin production, vegetative growth, asexual reproduction, and fungicide sensitivity, but is not required for the virulence function of F. fujikuroi on rice.

Evaluation of Bioactive Compounds and Mineral Composition in Thai-Variety Amaranths

Amaranth is one of the high nutrient vegetables with high proteins, vitamins, and mineral contents. However, the accumulated pigments and nutrients may change by plant growth stages. Therefore, this study explored the phytonutrients and mineral composition in three amaranth varieties with five harvesting stages. The results revealed that plant pigments were highest accumulated at the reproductive stage with anthocyanin and β-carotene contents of 0.82 and 141.21 mg/g fresh weight (FW), respectively. Contrastingly, vitamin C contents were highest at the marketing stage (1,904 mg/g FW). Accumulations of Ca and K increased over cultivation time, whereas Zn contents were higher at the younger stages. However, Fe contents were not different by growth stages or varieties. From all measurements, only β-carotene and vitamin C accumulations were different among plant varieties. Compared to the WHO food recommendations, amaranths are excellent sources of β-carotene, antioxidants, calcium, potassium, and iron. Additionally, the associations among traits were evaluated and found that most traits were positively correlated with the growth stage, whereas zinc contents were strongly negatively correlated. These results provide a clear picture of amaranth’s nutrition for consumers and suggest the appropriate harvesting time for specific nutritional benefits as well as promoting the consumption of these vegetables.

Plant organ- and growth stage-diversity of endophytic bacteria with potential as biofertilisers isolated from wheat (Triticum aestivum L.)

BackgroundChemical fertilisers are extensively used for crop production, which may cause soil deterioration and water pollution. Endophytic bacteria with plant-growth-promoting (PGP) activities may provide a solution to sustainably improve crop yields, including in-demand staples such as wheat. However, the diversity of the PGP endophytic bacteria in wheat across plant organs and growth stages has not been thoroughly characterised.ResultsHere, we report the isolation of endophytic bacteria from root, stem, leaf and seed of three winter wheat varieties at tillering, jointing, heading and seed-filling growth stages that were identified via 16S rRNA gene sequence analysis. Strains were screened for indole-3-acetic acid (IAA) production, potassium and phosphate solubilisation and the ability to grow on a nitrogen-free medium. Strain's capacity to stimulate various plant growth parameters, such as dry root weight, dry above-ground parts weight and plant height, was evaluated in pot trials. A total of 127 strains were randomly selected from 610 isolated endophytic bacterial cultures, representing ten genera and 22 taxa. Some taxa were organ-specific; others were growth-stage-specific. Bacillus aryabhattai, B. stratosphericus, Leclercia adecarboxylata and Pseudomonas oryzihabitans were detected as wheat endophytes for the first time. The IAA production, inorganic phosphorous solubilisation, organic phosphorus solubilisation, potassium solubilisation and growth on N-free medium were detected in 45%, 29%, 37%, 2.4% and 37.8% of the 127 strains, respectively. In pot trials, each strain showed variable effects on inoculated wheat plants regarding the evaluated growth parameters.ConclusionsWheat endophytic bacteria showed organ- and growth-stage diversity, which may reflect their adaptations to different plant tissues and seasonal variations, and differed in their PGP abilities. Bacillus was the most predominant bacterial taxa isolated from winter wheat plants. Our study confirmed wheat root as the best reservoir for screening endophytic bacteria with potential as biofertilisers.

Optimized Design and Experiment of a Spatially Stratified Proportional Fertilizer Application Device for Summer Corn.

In this study, a spatially stratified proportional fertilizer application device was designed, which was mainly composed of a fertilizer equalization and stirring structure, fertilizer guide plate, and fertilizer plate. This was aimed at solving challenges presented by current fertilizer devices that include a poor layering effect due to untimely return of soil, excess nutrients in the early stages of plant growth, and insufficient quantities in the later stages. The “seed fertilizer + chasing fertilizer” is time-consuming and laborious; seed and fertilizer (without layering) are applied to the soil at once, which tends to cause too much nutrients for plants in the early stage and not enough nutrients in the later stage; and the layered fertilizer machines currently on the market have a poor layering effect due to untimely soil return. Through theoretical analysis and calculation, the structural parameters of the device were determined, and the main influencing factors of the movement law of fertilizer in the device were analyzed. Through simulating soil tank tests, the main factors affecting the effect of fertilizer spatial stratification were designed by quadratic regression orthogonal rotation combination designs. The optimal parameters including the length of the first fertilizer plate was 100 mm, the installation angle of the fertilizer plate was 80°, the spacing of the fertilizer port was 30 mm, and the uniform stirring speed was 650 r/min. The results of the bench test showed that the fertilizer granules could be uniformly stirred at the optimized stirring speed, with average values of 74.56, 76.56, and 105.19 g, which met the agronomic fertilizer application requirements, and the coefficient of variation of fertilizer application amount in each layer was less than 1%. The field test results showed that the stratified proportional fertilizer application device could achieve the stratified proportional application of fertilizer in the soil in ranges of 80.2–95.4, 150.3–180.2, and 230.3–250.4 mm for the upper, middle, and lower layers, respectively, with an error within 10 mm from the designed theoretical application depth. Compared with the conventional fertilizer application method, this fertilizer application method had a more obvious promotion effect on the 100-grain weight and yield of corn.