Greenhouse Experiment Research Articles

Seed dispersal of Zoysia japonica by sika deer: An example of the “foliage is the fruit” hypothesis

AbstractZoysia japonica, a low growing grass, is tolerant to grazing and trampling. Kinkazan Island in northern Japan is inhabited by sika deer (Cervus nippon). The deer population increased in the 1970s at a shrine garden in the western part of the island, leading to expansion of Zoysia swards around the shrine garden and their colonization of remote open patches. The expansion around the garden is due to elongation of the rhizome, but expansion to remote places may be due to endozoochory by deer. This appears to be a good example of the “foliage is the fruit” hypothesis (the FF hypothesis) proposed by Janzen (1984; American Naturalist 123:338–353). To demonstrate this, we confirmed the expansion of the Zoysia swards and tested the traits of Zoysia by field surveys and indoor experiments. The Zoysia peduncles stood among the leaves, and sika deer fed on both the seeds and leaves. One deer fecal pellet contained about 20 seeds at its peak in June. In the feeding experiment, the survival rate through digestion was 38%. In the greenhouse experiment, the germination rate was 72%. An outdoor experiment showed that germination rates of the ingested seeds were 5% in a dark habitat and 58% in a bright habitat. Zoysia exhibited many of the traits presented by the FF hypothesis, and sika deer functioned as seed dispersal agents. Therefore, the Zoysia—sika deer relationship seems to support the FF hypothesis.

Organic Capillary Barriers for Soil Water Accumulation in Agriculture: Design, Efficiency and Stability

Acute shortage of water resources and high unproductive water losses are the key problems of irrigated agriculture in arid regions. One of the possible solutions is to optimize soil water retention using natural and synthetic polymer water absorbers. Our approach uses the HYDRUS-1D design to optimize the placement of organic water absorbents such as peat and composite hydrogels in the soil profile in the form of water-storing capillary barriers. Field testing of the approach used a water balance greenhouse experiment with the cultivation of butternut squash (butternut squash (Cucurbita moschata (Duchesne, 1786)) under sprinkler irrigation with measurement of the soil moisture profile and unproductive water losses in the form of lysimetric water outflow. In addition, the biodegradation rate of organic water absorbents was studied at the soil surface and at a depth of 20 cm. Organic capillary barriers reduced unproductive water losses by 40–70%, retaining water in the topsoil and increasing evapotranspiration by 70–130% with a corresponding increase in plant biomass and fruit yield. The deepening of organic soil modifiers to the calculated depth not only allowed capillary barriers to form, but also prevented their biodegradation. The best results in soil water retention, plant growth and yield according to the “dose-effect” criterion were obtained for a composite superabsorbent with peat filling of an acrylic polymer matrix. The study showed good compliance between the HYDRUS design and the actual efficiency of capillary barriers as an innovative technology for irrigated agriculture using natural and synthetic water absorbents.

Evaluation of Ergot Resistance in Hard Red Spring Wheat in North Dakota.

Higher levels of ergot (Claviceps purpurea [Fr.] Tul.) were reported in North Dakota hard red spring wheat (HRSW) in 2018, leading to questions pertaining to management and cultivar resistance. To better understand pathogen and HRSW cultivar responses, greenhouse experiments were conducted from 2020 to 2021 to evaluate the aggressiveness of nine C. purpurea isolates and ergot resistance in 21 HRSW cultivars. Results from the aggressiveness assay indicated significant cultivar-by-isolate interactions for the total weight of sclerotia produced and ergot incidence. Mean data across all cultivars by isolate combinations suggested isolates CC-3 and IA-Tim were the most aggressive, and these were subsequently used in ergot resistance experiments. Results from ergot resistance screening indicated that none of the HRSW cultivars were immune to C. purpurea because all cultivars produced sclerotia. However, differences in ergot incidence, kernel incidence, aborted kernel incidence, total sclerotia weight, sclerotia length, and sclerotia width occurred among cultivars. Both 'ND-Frohberg' and 'TCG-Spitfire' had the lowest ergot incidence values and were among the lowest in total sclerotia weight. 'Waldron' and 'LCS-Trigger' had the highest ergot incidence and the highest total sclerotia weight. Given that most concerns with ergot occur postharvest, we suggest two categories to describe ergot resistance: host resistance (fate of inoculation for a stigma) and logistical resistance (size characteristics of a sclerotium that influence its ability to remain with a seed lot after harvest and cleaning). This research provides a strong foundation for our understanding of HRSW resistance to ergot that will influence variety decisions in ergot-prone areas in North Dakota.

Mitigating chromium stress in tomato plants using green-silicone nanoparticles: Enhancing cellular oxidative stress management and chromium reduction

Nano-enabled approach has become the promising option for resolving heavy metal (HMs) contamination and improving the crop production. Here, current study explored mechanism involved in how green silicon nanoparticles (SiNPs) alleviating the chromium (Cr) induced toxicity in tomato. Green SiNPs in spherical shape with size 8–40 nm were synthesized with artemisia annua leaves extract and characterization performed by modern characterization method. The results of the green house experiment demonstrated that SiNPs at dose of 150 mg kg−1 surprisingly improved the biomass and root architecture of tomato plants. SiNPs supplementation also positively enhanced the photosynthesis pigments and leaf gas exchange attributes of Cr-stressed plants. Besides this, SiNPs150 mg kg−1 elevated antioxidant enzymes activities which scavenging ROS and reduced Cr-caused oxidative destruction. Furthermore, qPCR assay showed upregulation of the antioxidant defense related genes with the application of SiNPs under Cr stress. Transmission Electron Microscopy analysis showed that SiNPs application effectively alleviated Cr-induced damage to leaf ultrastructure and had a substantial impact on Cr and Si accumulation in plants. In conclusion, the utilization of green SiNPs as nano-fertilizers exhibits great potential as a strategy for agriculture to alleviate the adverse effects of HMs stress, safeguard food safety, and sustainable agriculture in the future.

Exploring nematicidal biomolecules from Xenorhabdus nematophila as a novel source for Meloidogyne incognita management

Attempts were made to evaluate the purified bioactive compounds of Xenorhabdus nematophila against Meloidogyne incognita. In order to extract the purified compounds, a solid-supported liquid-liquid extraction system with a flow rate (1 mL/min) was used to purify bioactive molecules. Compounds were individually collected concentrated and evaluated against M. incognita. Among 25 fractions the L19 fraction, exhibited 98% inhibition in egg hatching and mortality of juveniles. The biomolecules were identified through Liquid Chromatography- Mass Spectroscopy (LC-MS) technique. To decipher the mode of action of compounds, molecular docking studies were performed with potential protein targets such as acetylcholinesterase, β-1,4-endoglucanase, glutathione S-transferase-1, cytochrome c oxidase, G-protein coupled receptor and Fatty acid and retinol-binding proteins of M. incognita. The results revealed that among eight compounds from the L19 fraction, malonate and pidopidon exhibited greater binding affinity towards the selected protein targets of M. incognita. In vitro studies with malonate and pidopidon against M. incognita showcased a 99% reduction in egg hatching and juvenile mortality. Moreover, greenhouse experiments revealed that malonate compounds not only reduced 94% of the M. incognita population but also enhanced the plant growth parameters in tomato by 60%. Hence the present study stands novel in exploiting the nematicidal compounds from X. nematophila giving limelight to explore pidopidon and malonate as novel nematicidal compounds for the management of M. incognita.

Selecting Bacillus strains antagonist to Erysiphe necator (Schw.) Burr. the causal agent of grape powdery mildew

ABSTRACT Grape powdery mildew (GPM) control is based on the preventive use of sulfur and curative application of synthetic fungicides, increasing the risk for producers’ health and environmental and fruit contamination. This work aimed to select Bacillus strains isolated from the Brazilian tropical semi-arid region that are effective antagonists to GPM. In an initial screening performed by spraying bacterial suspensions in detached grape leaves, six strains of Bacillus spp. showed disease symptom reduction higher than 70.0%. Two greenhouse experiments showed that the bacterial strains LCB03, LCB28, and LCB30 showed control efficiency >80%, statistically similar to a commercial formulation with Bacillus amyloliquefaciens QST713. 16s rDNA sequencing showed that strain LCB03 showed 100.0% homology to B. velezensis, while LCB28 has high homology to B. tequillensis (99.93%), and LCB30 had 99.71% homology with B. siamensis. As an average for both greenhouse experiments, weekly application of Bacillus sp LCB03, Bacillus sp LCB28, and Bacillus sp. LCB30 reduced the average incidence by around 50% and more than 80% for GPM severity.

Negative plant–soil feedback influences a dominant seeded species, Western yarrow (Achillea millefolium), in grassland restoration

Plant community ecology guides restoration of degraded lands, yet seed‐based restorations sometimes fail or result in unpredictable outcomes, necessitating a better understanding of community trajectory and stability. Western yarrow (Achillea millefolium) declined suddenly in two separate restoration projects after initial high relative abundance. To assess the potential role of soil pathogens, we surveyed plant and soil fungal communities in these restorations, and used an 8‐year‐old field experiment that crossed yarrow planted in varying densities with a fungicide treatment. Two greenhouse experiments then evaluated whether the suppressive effect in yarrow soil spread to native species used in restoration. Lower yarrow cover in a restoration project 5 years compared to 3 years after seeding coincided with higher relative abundance of fungal taxa that can cause disease, particularly Crown‐rot fungi (Paraphoma spp.). Paraphoma increased over time in experimental plots and coincided with yarrow decline. Decline onset was density‐dependent, occurring faster in plant communities where yarrow density was higher. Fungicide applications altered fungal pathogen communities and promoted yarrow cover relative to control plots. In the greenhouse, yarrow grew larger with fungicide, consistent with suppression of fungal pathogens. However, biomass of natives grown in yarrow‐conditioned soil was not affected by fungicides, suggesting pathogens did not spread. The rapid establishment and competitive nature of yarrow, followed by pathogen‐induced decline, make it an attractive early transitional “bridge species,” so long as its pathogens are species‐specific. Our results suggest negative plant‐soil feedback can drive rapid decline of individual species, and considering plant–soil feedback could improve restoration predictability.

Role of a medicinal plant in attracting Chrysopidae predators and controlling Leucopteracoffeella

Intercropping in agricultural systems can enhance biological pest control, yet selecting the appropriate companion plants remains challenging. This study investigated the potential of Varronia curassavica Jacq. (Cordiaceae), a medicinal aromatic plant, to improve the biological control of the coffee leaf miner, Leucoptera coffeella (Lepidoptera: Lyonetiidae) by Chrysopidae predatory species. We assessed the survival of Ceraeochrysa cubana (Neuroptera: Chrysopidae) larvae and adults, and the survival and reproduction of L. coffeella adults in the presence of V. curassavica inflorescences. Additionally, we evaluated whether V. curassavica in its vegetative stage, when associated with coffee plants, would influence the oviposition of another related Chrysopidae species, Chrysoperla externa, and L. coffeella. Our findings indicated that C. cubana larvae had increased survival in the presence of V. curassavica inflorescences, whereas the survival of C. cubana and L. coffeella adults was unaffected. However, the intrinsic growth and oviposition rates of L. coffeella were reduced in the presence of V. curassavica inflorescences. Furthermore, in a greenhouse experiment, the number of eggs laid by C. externa was higher when coffee plants were intercropped with V. curassavica in the vegetative stage, while the oviposition of L. coffeella was unaffected. These results suggest that V. curassavica can enhance populations of Chrysopidae predators in coffee crops and negatively impact the fitness of L. coffeella or provide no benefit to this pest. Therefore, incorporating V. curassavica into coffee cropping systems appears promising for managing L. coffeella populations by pulling in Chrysopidae predators.

Whitefly Detected: Light-Emitting-Diode Traps Enhance Monitoring of Trialeurodes vaporariorum in Greenhouse-Grown Tomato

Yellow sticky traps (YSTs) are common tools for monitoring the greenhouse whitefly (GWF), Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae), which can cause significant yield reduction in different greenhouse crops such as cucumber and tomato. In recent years, sticky traps equipped with green light-emitting diodes (LEDs) have also been (successfully) tested for catching GWFs. However, no study has observed GWF population dynamics at low population densities using such LED traps for early pest detection in crop stands. Therefore, a greenhouse experiment was conducted aiming to investigate the correlation between GWF populations on tomato crops (Solanum lycopersicum L. (Solanaceae)) and the numbers caught on yellow sticky traps and green LED traps, respectively. A small number of whiteflies was released into two pest-free greenhouse cabins, and populations on plants and traps were monitored for the duration of two months. The results show that the GWFs caught on LED traps correlate significantly positive with the population density on the tomato crops. Such a correlation was not found for standard YSTs. Moreover, the results indicate the possibility of early pest detection using LED traps. The findings are discussed in the context of the whiteflies’ ecology and population dynamics in greenhouses.

Streptomyces avermitilis MICNEMA2022: a new biorational strain for producing abamectin as an integrated nematode management agent

BackgroundAbamectin (ABA) is considered a powerful insecticidal and anthelmintic agent. It is an intracellular product of Streptomyces avermitilis; is synthesized through complicated pathways and can then be extracted from mycelial by methanol extraction. ABA serves as a biological control substance against the root-knot nematode Meloidogyne incognita. This investigation is intended to reach a new strain of S. avermitilis capable of producing ABA effectively.ResultsAmong the sixty actinobacterial isolates, Streptomyces St.53 isolate was chosen for its superior nematicidal effectiveness. The mycelial-methanol extract of isolate St.53 exhibited a maximum in vitro mortality of 100% in one day. In the greenhouse experiment, the mycelial-methanol extract demonstrated, for the second-stage juveniles (J2s), 75.69% nematode reduction and 0.84 reproduction rate (Rr) while for the second-stage juveniles (J2s), the culture suspension demonstrated 75.38% nematode reduction and 0.80 reproduction rate (Rr). Molecular identification for St.53 was performed using 16 S rRNA gene analysis and recorded in NCBI Genbank as S. avermitilis MICNEMA2022 with accession number (OP108264.1). LC-MS was utilized to detect and identify abamectin in extracts while HPLC analysis was carried out for quantitative determination. Both abamectin B1a and abamectin B1b were produced and detected at retention times of 4.572 and 3.890 min respectively.ConclusionStreptomyces avermitilis MICNEMA2022 proved to be an effective source for producing abamectin as a biorational agent for integrated nematode management.

Alleviation of salt stress on Zea mays L. plant by PGPR isolates as an effective sustainable strategy

Among the major constraints for the production of economic crops, such as maize, is salinity. Plenty of research has suggested the use of various strains of plant growth-promoting rhizobacteria (PGPR) as a sustainable approach to improve plant tolerance to salinity. Nonetheless, the exploration of the rhizosphere in Egyptian agricultural lands with salt affected soil remains incomplete. In this research, two newly isolated local bacterial species were finally selected and identified as Alcaligenes sp. strains. E1 (BS-45) and E2 (BS-57). IAA production by both isolates was confirmed by TLC. Several bioactive metabolites were identified in Alcaligenes sp. E1 and E2 by gas chromatography-mass spectroscopy (GC-MS). These include 9,12,15-octadecatrienoic acid, 2,3-bis [(trimethylsilyl)oxy] propyl ester, (z,z,z), 2 (1H)-Naphthalenone, octahydro-1-methyl-1-(2-propenyl)-, (1à,4aá,8aà), dodecane and isopulegol which have a defensive role against biotic and abiotic stress of the plant. Interestingly, the selected bacteria Alcaligenes sp. E1 and E2 significantly improve the overall maize growth attributes, antioxidant scavenging activities and photosynthetic pigments in maize plants grown under salt stress (150 mM NaCl) compared to the control plants as analyzed by greenhouse experiment. Therefore, this study recommends the Alcaligenes sp. strains (E1 and E2) to alleviate the negative impact of salinity on the growth and development of maize seedlings.

Impact of CO2 Enrichment on Growth, Yield and Fruit Quality of F1 Hybrid Strawberry Grown under Controlled Greenhouse Condition

Carbon dioxide enrichment inside a greenhouse is a sustainable approach to increasing crop production worldwide. Recently, the F1 hybrid strawberry became an alternative to runner-propagated cultivation as an innovative method to shorten the production period and increase strawberry production. This work aims to present CO2 enrichment as a sustainable tool that improves the yield in a controlled greenhouse and addresses the efficiency of three F1 hybrid strawberry varieties grown under Saudi Arabian conditions. A greenhouse experiment was conducted at the National Research and Development Center for Sustainable Agriculture (Estidamah), KSA, to study the impact of two CO2 levels (400 ppm (“ambient”) and 600 ppm (“enrichment”)) on the growth, photosynthesis traits, fruit yield and fruit quality of three F1 hybrid strawberry varieties grown under soilless culture conditions. The results show that CO2 enrichment significantly improved the phenotyping of strawberry growth traits at 60 days post-transplanting. The physiological response of the varieties to CO2 enrichment reveals a significant increase in the photosynthetic rate (129.7%) and intercellular CO2 (43.7%) in the leaves of strawberry exposed to CO2 enrichment rather than in ambient conditions, combined with a significant increase in the number of fruits per plant (27.5%) and total fruit yield (42.2%). A similar pattern was observed with varieties D and S in terms of fruit number, length and diameter. However, CO2 at 600 ppm promoted total soluble solid accumulation and vitamin C for the tested varieties. In contrast, CO2 enrichment significantly decreased nitrogen, phosphorus, potassium and magnesium accumulation in the leaves of the exposed plants in comparison to 400 ppm of CO2. These results suggest that increasing CO2 enrichment could contribute to an increase in strawberry yield and nutritional value and demonstrate that understanding the response of each variety to CO2 enrichment is important to support selecting suitable greenhouse strawberry varieties to improve crop yield.

Growth Stimulation of Tropical Grass (Megathyrsus maximus Jacq.) by Humic Substances and Herbaspirillum seropedicae

This study aimed to evaluate the effect of soluble humic substances and plant-growth-promoting bacteria on the vegetative growth of Mombaça grass. A greenhouse experiment was conducted to study the effects of foliar applications of humic substances (0, 12, 24, 48, and 96 mg C L−1) on the growth of Mombaça fifteen days after germination. After determining the optimal concentration range, a field trial was carried out in which humic substances at the best concentration were applied simultaneously with Herbaspirillum seropedicae strain UENF-H19 fifteen days after germination in three replicates. The best growth of Mombaça in the greenhouse was obtained with 48 mg C of the humic substance L−1, which promoted a shoot fresh weight 80% higher than in the control treatment. The increase was almost identical to that observed during the 50-week field experiment in plots treated with humic substances combined with H. seropedicae. The treated plants produced an 81% higher shoot fresh weight than the control, with no dry mass, nitrogen content, or crude protein change during the one-year evaluation period. Despite the efficiency of the selected microbial inoculants under controlled-environment experiments, the agronomical significance under field conditions remains a subject of debate and improvement. The present study demonstrates that combining Herbaspirillum seropedicae with humic substances (plural) could significantly increase pasture production under field conditions.

Effects of Soil Type, Irrigation Method, and Biomass Application on Grain Yield and Its Determinants in Irrigated Lowland Rice of Agusan

Information about the influence of soil type, irrigation method, and biomass use on rice productivity in Agusan is insufficient, despite their importance in developing or improving irrigated lowland rice production. Hence, this study determined the influence of these factors on grain yield and yield-contributing crop traits. It also explained grain yield based on yield determinants and recommended water management for improving grain yield. The greenhouse experiment was laid out in a three-factor randomized complete block design with 10 replications. The treatments were [a] Butuan sandy loam soil (SLS) and Butuan loam soil (LS); [b] continuously flooded (CF) and controlled irrigation (CI); and [c] applied and unapplied biomass. Data on grain yield and yield determinants were gathered weekly, during harvesting, and after harvesting. Relative to LS, SLS had a statistically greater grain output owing to its higher root and water permeability and better balance among soil nutrients, leading to closer-to-the-optimum soil nutrient uptakes and better yield-contributing crop traits. Compared with CI, CF had a statistically superior grain output as it induced the crop to produce more robust tillers, leading to significantly better yield-contributing crop characteristics. Biomass application modified the soil type x irrigation method interaction since the degree at which CF was exhibiting higher grain yield than CI was significantly greater in SLS than LS for experimental units or pots applied with biomass. Moreover, the level at which CF was attaining greater grain yield than CI was statistically similar in SLS and LS for pots unapplied with biomass. It is therefore recommended that rice be grown in Butuan sandy loam instead of Butuan loam, and that CF instead of CI be used in soil with a mild zinc deficiency or sufficient zinc status.

Effects of pollination and plant genotype on Ustilago maydis disease development on the ears of maize inbreds and maize‐teosinte near‐isogenic lines

AbstractUstilago maydis, the fungus that causes corn smut disease, leads to significant economic losses in maize cultivars. A key feature of successful plant pathogens is their ability to utilize the plant–pathogen relationship to influence disease progression. Greenhouse experiments examined how pollination and plant genotype affect disease incidence and severity of U. maydis infection. Four U. maydis susceptible maize inbreds (B73, H95, Mo17, and Golden Bantam), and two U. maydis resistant maize‐teosinte near‐isogenic lines (NIL1 and NIL2) were utilized for this work. Three‐hundred and sixty plants (pollinated and unpollinated) from the six plant genotypes were inoculated with U. maydis and assessed based on five phenotypic traits [(1) disease incidence, (2) gall number, (3) gall weight, (4) disease severity, and (5) area under disease progress curve]. All pollinated plants demonstrated significantly (p < .001) lower disease incidence, gall number, gall weight, area under the disease progress curve, and severity in comparison to the unpollinated plants. Both pollinated resistant NILs demonstrated significantly (p < .001) less disease development than the pollinated susceptible maize plants and two unpollinated NILs. Therefore, disease resistance to U. maydis was dependent upon pollination and plant genotype. This provides novel evidence that pollination can significantly improve resistance to U. maydis in different plant genotypes. Enhanced disease resistance observed in the resistant NILs after pollination indicates pollination‐mediated resistance is one of the resistance mechanisms functioning in the resistant NILs. Integration of pollination‐mediated resistance and resistance introgressed from a maize progenitor will be useful for improving resistance to U. maydis and management of the disease.

Genomic analysis of Bacillus subtilis sub sp. subtilis GEB5 reveals its genetic assets for nematicidal and plant growth promoting mechanisms

The immense benefit of chemical nematicides in controlling plant parasitic nematodes in high-value crops is counterbalanced by the development of resistance in nematodes due to their overuse. Bacillus subtilis is a promising bacterium that not only confers resistance against plant parasitic nematodes but also promotes plant growth through nutrient acquisition. Considering the multifaceted action of B. subtilis attempts were made to sequence the whole genome of endophytic B. subtilis GEB5 to find the genome complexity of the potential bio-control agent isolated from the guava. The results confirmed the isolate as B. subtilis sub sp. subtilis with a circular genome of 8,341,276 bp (8.3 Mb) length and 41.8% GC content. The results of genome annotation revealed the presence of 8209 coding sequences (CDS) genes, 136 transfer RNA (tRNA) genes, and 6 ribosomal RNA (rRNA) genes. Nonribosomal peptide synthetase (NRPS) gene clusters in the genome of GEB5 included fengycin, bacillaene, plipastatin, subtilin, subtilosin A, bacilysin, surfactin, sporulation killing factor, bacillibactin. Moreover, the GEB5 genome assembly had 21 homologs corresponding to nematode-virulent proteases. Furthermore, the results of greenhouse experiments showcased that GEB5 quenched the population of M. enterolobii (72% reduction) and also boosted the plant growth of guava. A plurality of the putatively encoded nematode virulence protease and its ability to boost plant growth suggests its environmentally robust bio-control potential in protecting plants against invading plant parasitic nematodes.

Biocontrol of citrus melanose Diaporthe citri by Bacillus subtilis M23

Citrus melanose, caused by Diaporthe citri, is one of the most prevalent and important fungal diseases of citrus crops globally. However, the overuse of chemical fungicides for disease control has an adverse impact on citrus production. In contrast, biological control agents (BCAs) are environmentally friendly and have become essential tools for plant disease control. In the present study, Bacillus subtilis M23, a strain isolated from healthy citrus leaves, significantly suppressed the mycelial growth of D. citri, the causal agent of citrus melanose, in vitro. The fermentation broth of B. subtilis M23 also exhibited good antifungal activity against D. citri on citrus plants in greenhouse and field experiments. Lipopeptides (LPs) produced by M23 exhibited excellent antifungal activity against D. citri, with a 50 % effective concentration (EC50) of approximately 1.00 and 0.28 μg/mL for inhibition of mycelial growth and conidial germination, respectively. LP biosynthesis genes were identified in the M23 genome using a PCR assay. Notably, LP extracts significantly reduced the formation of pycnidia and ATP biosynthesis in D. citri. Comparative transcriptome analysis revealed significant differences in the expression of genes associated with fungal vacuole, oxidoreductase activity and endopeptidase activity in D. citri treated with B. subtilis M23. Both RNA-seq and RT-qPCR analysis provided similar results on the expression of selected genes. Collectively, our data provided convincing data supporting the biocontrol potential of B. subtilis M23 for the management of citrus melanose.

The use of amino acids as bioactive substance: a strategy to increase yield in summer arugula (Eruca sativa L. Mill) crops

Foliar application of amino acids can assist crops to maintain homeostasis under diurnal temperature variations and excessive solar irradiance. The objectives of this study were to investigate the effects of the organic fraction and mineral nutrients of an amino acid solution on arugula plants and the effects of weekly applications of this solution on their growth and biomass yield. Two experiments were conducted in a completely randomized design, in a greenhouse (Experiment 1) and on open-field benches (Experiment 2), in Iracemápolis, SP, Brazil. Experiment 1 consisted of foliar applications of water (control), a solution containing 59 and 40.9 g ha-1 of nitrogen and sulfur, respectively (N+S), and a solution containing 85 g ha-1 of amino acids, with seven replications. Experiment 2 consisted of four different number (0, 1, 2, and 3) of weekly foliar applications of 85 g ha-1 of amino acids, with six replications. Chlorophyll a fluorescence, chlorophyll and carotenoid contents, and fresh and dry biomass weights were evaluated in both experiments. In Experiment 1, shoot fresh weight of plants treated with amino acids increased by 21% and 6% compared to those in the control and N+S treatment, respectively. Amino acid application increased chlorophyll and carotenoid contents, improving photosynthetic performance by increasing effective quantum efficiency of photosystem II and photochemical quenching. In Experiment 2, weekly application of 85 g ha-1 of amino acids increased shoot fresh weight by approximately 10% per application. Therefore, foliar application of amino acids can increase fresh biomass of arugula plants grown under both mild and warmer climate conditions.

Effects of glyphosate on glyphosate‐resistant maize growth and metabolic parameters in the greenhouse and field

AbstractThe potential adverse effects of glyphosate on glyphosate‐resistant (GR) crops are still a matter of controversy. The effects of glyphosate at recommended application rates (either a single application of 580 g ae ha−1 of glyphosate at stage V5 or a sequential application of 580 + 980 g ae ha−1 at stage V3 and V7, respectively) on growth, mineral content, and metabolic parameters of GR maize (Zea mays) were determined in greenhouse and field studies, each replicated in different years. No effects on any growth parameter (including grain yield), mineral content (leaf and grain), grain starch, crude protein, or total lipids were found. The only significant negative effect was a slight reduction in tyrosine content of leaf tissue with the sequential treatment, however, there was no increase in shikimic or quinic acids in leaf tissue with any treatment. In a separate greenhouse experiment, there was no sign of oxidative stress, as determined by levels of chlorophylls, carotenoids, and malondialdehyde (MDA) content as well as superoxide dismutase and guaiacol peroxidase activities 4 and 8 days after treatment with 1080 g ha−1 glyphosate. In fact, there was a reduction of MDA in roots of glyphosate‐treated plants 4 DAT, indicating reduced oxidative stress. No aminomethylphosphonic acid, the primary degradation product of glyphosate, was found in either leaves or grain of treated plants, and no glyphosate was found in grain of treated plants from the field studies. All the results are consistent with there being no adverse effects of glyphosate on GR maize at recommended application rates.

Genomic insights into organic acid production and plant growth promotion by different species of phosphate-solubilizing bacteria.

Bacteria can solubilize phosphorus (P) through the secretion of low-molecular-weight organic acids and acidification. However, the genes involved in the production of these organic acids are poorly understood. The objectives of this study were to verify the calcium phosphate solubilization and the production of low-molecular-weight organic acids by diverse genera of phosphate solubilizing bacterial strains (PSBS); to identify the genes related to the synthesis of the organic acids in the genomes of these strains and; to evaluate growth and nutrient accumulation of maize plants inoculated with PSBS and fertilized with Bayóvar rock phosphate. Genomic DNA was extracted for strain identification and annotation of genes related to the organic acids production. A greenhouse experiment was performed with five strains plus 150mg dm- 3 P2O5 as Bayóvar rock phosphate (BRP) to assess phosphate solubilization contribution to maize growth and nutrition. Paraburkholderia fungorum UFLA 04-21 and Pseudomonas anuradhapurensis UFPI B5-8A solubilized over 60% of Ca phosphate and produced high amounts of citric/maleic and gluconic acids in vitro, respectively. Eleven organic acids were identified in total, although not all strains produced all acids. Besides, enzymes related to the organic acids production were found in all bacterial genomes. Plants inoculated with strains UFPI B5-6 (Enterobacter bugandensis), UFPI B5-8A, and UFLA 03-10 (Paenibacillus peoriae) accumulated more biomass than the plants fertilized with BRP only. Strains UFLA 03-10 and UFPI B5-8A increased the accumulation of most macronutrients, including P. Collectively, the results show that PSBS can increase maize growth and nutrient accumulation based on Bayóvar rock phosphate fertilization.