Days After Emergence Research Articles

Oxyfluorfen use in Combination with Clomazone or Quinclorac

Abstract Oxyfluorfen, a Herbicide Resistance Action Committee (HRAC)/Weed Science Society of America (WSSA) Group 14 herbicide that inhibits protoporphyrinogen IX oxidase, has shown significant potential in controlling barnyardgrass. Despite its current lack of labeling for use in midsouthern U.S. rice due to the potential for crop injury, the introduction of a trait in rice that confers resistance to oxyfluorfen could provide producers with an effective alternative site of action for weed control. Field experiments were conducted during the 2021 and 2022 growing seasons near Stuttgart, AR, and near Lonoke, AR, to determine the optimum rates of clomazone (280 or 336 g ha-1) and oxyfluorfen (673 or 840 g ha-1) to use in sequential preemergence (PRE) and postemergence (POST) applications on a silt loam soil and to assess the efficacy of oxyfluorfen when combined with clomazone and quinclorac PRE, followed by oxyfluorfen POST. No differences in barnyardgrass control were observed among treatments 14 days after emergence (DAE) in three site years, as all control was ≥90%. By 35 days after the postemergence application (DAPOST), all barnyardgrass control was ≥94% for herbicide treatments in all site years. All herbicide treatments resulted in lower barnyardgrass seed production than the nontreated in 2021. Contrasts revealed that oxyfluorfen applied PRE on a silt loam soil resulting in barnyardgrass control similar to clomazone or quinclorac alone at 14 DAE. Although oxyfluorfen combined with clomazone or quinclorac did not increase barnyardgrass control, an additional site of action for control of this weed could help reduce the evolution of resistance. Mixing oxyfluorfen with clomazone in a dry-seeded rice production system in the midsouthern U.S. would effectively control barnyardgrass and reduce the risk for resistance to both herbicides, further highlighting the potential of oxyfluorfen in rice production.

Effects of cowpea aphid-borne mosaic virus infection on the growth and yield parameters of Sesamum indicum plants

The potyvirus cowpea aphid-borne mosaic virus (CABMV) is the main viral agent present in crops of Sesamum indicum in several regions of Paraguay. However, information about the effects of CABMV infection in S. indicum plants is scarce and the critical period for virus infection in S. indicum plants is unknown. This study aimed to evaluate the damage caused by CABMV on the development and yield of S. indicum plants experimentally infected at three phenological stages. Mechanical inoculations of CABMV were performed on S. indicum plants at the early vegetative stage, at the beginning of flowering, and during capsule and seed formation. An enzyme-linked immunosorbent Assay (ELISA) test was used to confirm virus infection on the inoculated plants using specific CABMV antisera. Plants inoculated 30 days after emergence (DAE) had severe systemic symptoms, but they were mild in mid and late-infected plants (60 and 90 DAE). Plant aerial dry weight was significantly affected by CABMV infection, reducing up to 71.6% compared to the control. Mid and late-infected plants experienced a lower level of damage, with an average aerial dry weight reduction of 17 and 14.2%, respectively. Furthermore, plants with early, mid, and late CABMV infections showed an average capsule per plant reduction of 97, 33.3, and 13.3%, compared to healthy plants. Seeds per capsule produced by CABMV-infected plants decreased by 93.5%, 21%, and zero, respectively. Viral infections also affected the 1000-seed weight in early infected plants, with a reduction of up to 93.3%. To prevent economic losses, it is crucial to have effective strategies for managing CABMV, particularly during the early stages of the crop.

Resistance of Sesame (<i>Sesamum indicum L</i>.) Genotypes Against Bacterial Blight (<i>Xanthomonas campestris pv. sesami</i>) in Benishangul Gumuz Region, Northwestern Ethiopia

Bacterial blight poses a significant threat to sesame production in Ethiopia, especially in regions with high rainfall. It causes yield reduction and affects seed quality by inducing premature leaf defoliation. To address these challenges, evaluating existing germplasm for disease resistance is crucial. This study assessed various sesame genotypes for resistance to bacterial blight and their performance in seed yield and seed yield related traits. Seventeen genotypes were evaluated in a randomized complete block design at Kamashi research sub-station. Resistance evaluations were conducted every 14 days from emergence up to 72 days, along with recording seed yield and related agronomic and morphological traits. The mean area under the disease progress curve (AUDPC) varied from 673.86 to 825.01, indicating differing susceptibility levels to disease advancement. Approximately 46.67% of the tested genotypes exhibited lower AUDPC compared to Benishangul-1, a variety specifically developed for its adaptability and resistance for bacterial blight-prone regions. Initially, at 14 and 28 days after emergence (DAE), no noticeable bacterial blight symptoms were observed across the genotypes. However, at 42, 56, and 72 DAE, the average severity index steadily rose to 16.92%, 20.78%, and 27.71%, respectively. This transition from immunity to moderate susceptibility underscores the dynamic nature of disease progression and the significant challenge posed by bacterial blight in later sesame growth stages. Notably, significant differences (P<0.05) were noted in days to 50% flowering, days to 90% maturity, plant height to the first branch, overall plant height, length of the capsule-bearing zone, and seed yield. This comprehensive evaluation offers valuable insights into the genetic diversity to improve crop performance and yield potential.

Critical period of weed competition in cowpea

Weed competition is one of the factors that limit cowpea production in the world, causing losses of up to 90% of grain yield and quality. Knowledge of the critical period of weed competition (CPC) is important to prevent significant losses of grain and resources in the production process. The objective was to determine the critical period of weed competition in the cultivation of cowpea beans, Missouri cultivar, in two sowing seasons: dry (2022B) and rainy (2023A) of warm dry Colombian Caribbean. The randomized complete block design was used with eight treatments and four repetitions. The first four treatments corresponded to manual control of weeds in the intervals 0-10, 0-20, 0-30 and 0-50 days after emergence (DAE), the second four treatments corresponded to the crop-weed coexistence, in the same intervals. Cowpea grain yield, dry mass, cover and weed community composition were evaluated. The critical period of competition of weeds in the cowpea crop for the dry and rainy seasons was 14-33 and 14-29 days after emergence, respectively. The reduction in grain yield was 65.2% in the dry season and 80.46% in the rainy season. Rottboellia cochinchinensis had the highest occurrence rate with 30.3% and a density of 90 individuals per m2; which is important for the agronomic management of the crop in the humid Caribbean subregion.

Nitrogen use efficiency of drip irrigated sugar beet as affected by sub-optimal levels of nitrogen and irrigation

Sugar beet has strong drought resistance and requires a large amount of nitrogen (N) during growth. Can deficit irrigation combined with low N supply of sugar beet improve water productivity (WP) and N use efficiency (NUE)? In this field study in 2020–2021, two irrigation regimes (W1, field capacity (FC) of the 0–60 cm soil layer was not lower than 70% from 45 days after emergence (DAE) to harvest period; W2, FC of the 0–60 cm soil layer was not lower than 50% in 45–90 DAE, but was consistent with that of W1 after 90 DAE) and three N application rates (0 (N0), 150 (N1), and 225 (N2) kg N ha−1) were designed. Then, their impacts on taproot yield (TY), water consumption (WC) and N uptake (NU) were explored. The results showed that there was no significant difference in TY between W2 and W1 treatments under the N1 and N2 levels. Under the N1 and N2 levels, the daily water consumption (DWC, 0.121 and 0.125 mm ℃d−1) and daily N uptake (DNU, 53.6 and 71.6 g N ℃d−1) of W2 treatment were significantly lower than the DWC (0.161 and 0.164 mm ℃d−1) and DNU (60.6 and 86.5 g N ℃d−1) of W1 treatment in 0–90 DAE. The W2N1 treatment had similar WP and higher NUE compared with the W1N2 treatment. In addition, the fertilizer-15N recovery rate in W2N1 treatment was 8.8% higher than that in W1N2 treatment, the fertilizer-15N loss rate was 6.6% lower than that in W1N2 treatment, but there was no difference in the fertilizer-15N residue between the two. This study clarified that implementing W2 deficit irrigation (50% FC at the canopy rapid growth stage (45–90 DAE)) and N1 nitrogen application rate (33% nitrogen reduction based on 225 kg N ha−1) could not reduce TY but improve WP and NUE.

Weed control and rice response to microencapsulated acetochlor and a fenclorim seed treatment on a clay soil

AbstractRecent research has demonstrated the ability of a fenclorim seed treatment to reduce rice (Oryza sativa L.) injury to acetochlor. However, all studies were conducted on silt loam soils and have not evaluated rice tolerance or weed control on clay soils. Experiments were initiated in 2021 and 2022 at the Northeast Research and Extension Center near Keiser, AR, to determine rice response and the effectiveness of delayed‐preemergence (DPRE)‐applied microencapsulated (ME) acetochlor (1.1, 1.7, and 2.3 lb ai acre−1) when applied to a clay soil with and without a fenclorim seed treatment at 0 or 2.5 lb ai 1000‐lb−1 of seed. Averaged over the fenclorim seed treatment, acetochlor at 1.1 and 1.7 lb ai acre−1 caused similar injury levels to rice; however, barnyardgrass [Echinochloa crus‐galli (L.) P. Beauv.] control increased at 1.7 lb ai acre−1, eliciting 19% injury to rice and 82% barnyardgrass control at 28 days after emergence (DAE). Palmer amaranth (Amaranthus palmeri S. Watson) control ranged from 82% to 93%. Additionally, fenclorim did not influence barnyardgrass or Palmer amaranth control, but it did reduce rice injury and increase shoot density, plant height, and rough rice grain yield. At 14 and 28 DAE, fenclorim at 2.5 lb ai 1000‐lb−1 of seed (averaged over acetochlor rates) reduced visible rice injury from 61% to 13% and 40% to 8%, respectively. Results from this study indicate ME acetochlor could be successfully applied to rice grown on a clay soil when a fenclorim seed treatment is used, providing producers a new site of action for use in U.S. rice production.

Winter wheat irrigation parameters in the Brazilian Cerrado

Wheat is the second most produced cereal in the world. The gap between production and consumption in Brazil shows that wheat production must be increased to meet the domestic demand. In this context, the objective of this study was to determine the crop coefficient of wheat and the ideal moment for irrigation, based on the soil water depletion rate (f). The study was carried out in the tropics, on an Oxisoil (Typic Haplustox), in an experimental field of Embrapa Cerrados in Planaltina, Federal District of Brazil. The experimental design consisted of randomized blocks with three replications. The treatments were differentiated by the soil water depletion index (f) of 0.2, 0.4, 0.6, and 0.8. In other words, irrigation was initiated when 20, 40, 60 and 80% of the available soil water capacity (AWC) at a soil depth of 0.4 m was consumed by the crop. Wheat yield and yield components were evaluated. The phenological development was monitored based on Zadok’s scale, in days after emergence, and the management parameters crop coefficient (Kc) and irrigation timing were determined. The results indicated a soil water depletion index of 0.4 as the best indicator for beginning wheat irrigation. Under this condition, Kc can be estimated daily as a function of days after emergence (DAE) by the quadratic polynomial regression or curve fitting method, adjusted as follows: Kc = −0.000298 × DAE² + 0.036695 × DAE + 0.332486. Alternatively, the means of Kc of each phenological crop phase can be used: Kc = 0.45 (establishment); 0.81 (tillering); 1.21 (booting); 1.43 (flowering); 1.27 (grain formation); and 0.89 (maturation). Thus, there is a limit of consumption of soil available water, at which wheat still achieves the full yield potential, with a rational use of water which varies according to the development phase.

Physiological changes induced by hardening in seedlings of eucalyptus as a function of growth stages

Hardening appears as an interesting strategy to improve the quality of seedlings in forest nurseries, favoring their survival in the field. Thus, the objective of this research was to show the physiological alterations resulting from the application of methyl jasmonate and stem flexion in three stages of growth in Eucalyptus urograndis seedlings. The experiment was carried out in Marechal Cândido Rondon, Paraná, and Eucalyptus urograndis seedlings were used. Treatments consisted of weekly applications of methyl jasmonate (MeJA), daily imposition of stem flexion and a control treatment. Analyzes included quantification of flexural stiffness, lignin content in stems and roots, phenolic compounds in leaves and roots, electrolyte leakage in roots and field survival. In seedlings of Eucalyptus urograndis at 100 days after emergence (DAE) and at the three distances used to evaluate flexural rigidity, the highest averages were observed in seedlings submitted to chemical and mechanical treatments, coinciding with the increase in lignin content in the stem. In the roots, after quantifying the extravasation of electrolytes in Stage I, the means decreased with the application of treatments. In the field phase, there were no statistically significant differences between seedling survival assessments, quantified every 15 days, for a period of 90 days after planting. However, seedlings in Stage I were lost because they were too young and could not tolerate the stressful conditions observed in the field.

Effect of foliar application of naphthalene acetic acid on physio-morphological attributes and green biomass production of sorghum [Sorghum bicolor (L.) Moench.

The present study was aimed to evaluate the impact of foliar application of naphthalene acetic acid (NAA) on the physio-morphological attributes and green biomass production of sorghum under field conditions at the Agronomic Research Field, Gomal University, Dera Ismail Khan, Pakistan. Varying concentrations of NAA (0, 45, 90, 135, and 180 mL ha-1) were applied to sorghum seedlings at different intervals [30 and 90 days after emergence (AE)]. All plots equally received recommended agronomic practices and crop protection measures. The NAA foliar application in different levels caused a significant influence on the growth and biomass production of sorghum. The maximum plant tallness (434.3 cm), plant leaf area (419 cm2), number of nodes (17.01 plant-1), number of tillers (19.03 m-2), and chlorophyll contents (56.97 µg cm-2) were observed due to NAA supplementation at 90 days AE, while, the stem thickness (8.82 cm), photosynthetic efficiency (2.56%) and green biomass (34.72 t ha-1) were observed in the plots which received the foliar spray of 180 mL ha-1 NAA followed by 135 mL ha-1, that showed improvement in plant tallness (423.1 cm), plant leaf area (402.07 cm2), number of nodes/plant (16.71), tiller numbers (189.81 m-2), chlorophyll contents (56.59 µg cm-2), stem thickness (8.69 cm), photosynthetic efficiency (2.56%) and green biomass (36.10 t ha-1) compared to those in the control treatment. The findings of the study clearly depict that foliar application of NAA as 120 mL ha-1 at 90 days AE showed promising results in terms of enhanced production of green biomass of sorghum under arid agro-ecological conditions of Pakistan.

Growth of the Broad Bean (Vicia faba) Under the Edaphoclimatic Conditions of Florianópolis, Santa Catarina, Brazil

The cultivation of the Vicia faba, commonly referred to as broad bean, is still not widely spread in Brazil, mainly due to the lack of scientific information on the growth and development of the species. In this context, quantitative research on growth is necessary to better understand the various aspects related to development rates and carbohydrate accumulation in plant organs. Thus, the objective of this work was to analyze the growth of the Italian broad bean during the winter-spring period in Florianópolis, Santa Catarina. In the experiment, a randomized block design with plots subdivided over time was adopted, evaluating leaf area (LA), total dry mass (TDM), absolute growth rate (AGR), relative growth rate (RGR), and net assimilation rate (NAR) at 21, 35, 49, 63, 77, 91, 105, 119, 133, and 147 days after emergence (DAE). The distribution of assimilates in the different plant organs showed sigmoid patterns. A greater accumulation of LA and TDM was observed at 99 and 133 DAE, respectively. Regarding AGR, the maximum values were recorded at 119 and 133 DAE. The rates of AGR, NAR, and RGR varied throughout the cycle, without showing a defined quantitative performance pattern, possibly due to climatic fluctuations and the intrinsic growth rates of the species.

Inducing drought tolerance to rice variety CAU-R1 by the influence of seed priming

Experiments were conducted as pot experiment during the 2019 of kharif seasons to investigate the inducing drought tolerance to rice variety CAU-1 by seed priming at poly house of College of Agriculture, Central Agricultural University, Imphal. The experiment was laid out in Completely Randomized Design (CRD) with four replications and six treatments. Seeds were soaked in 1 % and 2 % solutions of KNO3 , CaCl2 , 40 ppm and 50 ppm of salicylic acid for 12 hours. Rice plants were induced to drought by applying mannitol solution (100 mM) at 10 days after emergence (DAE) of seedlings. The results revealed that seeds primed with 2 % KNO3 showed the lowest days to 50 % germination and mean emergence time, maximum number of seedling leave, seedling height, root length, and root biomass. The treatment of 2% KNO3 followed by 50 ppm salicylic acid were found to be superior among other treatments in most of the parameters.

Critical Period of Weed Control in Maize as Influenced by Soil Tillage Practices and Glyphosate Application

Increasing evidence on environmental and economic benefits has raised farmers’ interest in adopting alternative, less intensive soil management practices. To evaluate the influence of weed-competitive ability in response to a different tillage regime, a field study was conducted in maize under humid Central European climatic conditions in Slovenia. This study was established as a split-plot arrangement with three tillage practices (TPs) as the main plot: conventional (CN), conservation (CS), and no tillage (NT); this was combined with glyphosate application and the weed removal timing as the subplot. The weed removal timings were at the V3, V6, V9, V15, and R1 maize stages, with weed-free and weed season-long monitoring. The beginning and the end of the critical period of weed control (CPWC), based on a 5% maize yield loss rate, were determined by fitting the four-parameter log-logistic equations to the relative maize dry grain yield. The weed dry biomass from maize germination until the R1 growth stage in the NT TP was consistently lower than that in the CN and CS TP. Moreover, the NT TP resulted in a shorter CPWC (39 days after emergence (DAE)) compared to the CN (57 DAE) and CS (58 DAE). The results of CTWR (critical timing of weed removal) showed that less intensive tillage operations in the CS resulted in an earlier need for weed control (V2 and 23 DAE) compared to the CN (V3 and 39 DAE) and NT (V3 and 40 DAE). Our study suggests that the intensive tillage operations performed in the CN TP and the pre-sowing use of non-selective burndown herbicide in the NT delay the CTWR by more than 2 weeks, thus reducing the need for early post-emergence herbicide application in maize.

Effect of ZnO Nanoparticles During the Process of Phytoremediation of Soil Contaminated with As and Pb Cultivated with Sunflower (Helianthus annuus L.)

Urbanization and industrialization have caused the production of pollutants in the soil, water, and air systems, negatively influencing plants, animals, humans, and the ecosystem. Heavy metals, such as arsenic (As), lead (Pb), cobalt (Co), chromium (Cr), mercury (Hg), and nickel (Ni), affect the development of organisms. In this study, as a novel alternative, the performance of zinc oxide nanoparticles (ZnO NPs) in sunflower plant growth (Helianthus annuus L.) and the decontamination of soils with As and Pb was investigated. For this purpose, in natural soil contaminated with As (0.02 mg kg of dry soil) and Pb (0.2 mg/kg of dry soil), sunflower plants were allowed to grow in pots for 25, 35, and 45 days after emergence. Morphological parameters were measured for the plants. The stems, leaves, and roots were dried (80 °C), ground, and finally, mineral analysis was performed by plasma atomic emission spectrometry (ICP). ZnO NPs were applied to the soil at two concentrations (0.3 and 0.6 mg/kg) and the control. ZnO NPs application resulted in plant growth and root length 25 days after emergence (DAE). The interaction between ZnO NPs and metals significantly negatively affected the variable root length. The roots, stems, and leaves accumulated metals at 25 and 45 DAE. Bioconcentration (BCF) and translocation (TF) factors were higher in Zn at 45 DAE. The phytoextraction by H. annuus assisted with ZnO NPs helps remediate polluted soils, potentiating the plant's hyperaccumulation characteristics. The results of this experiment offer basic information on the interaction of ZnO NPs in the phytoremediation process of soil contaminated with heavy metals. However, it is crucial to know the potential of NPs in soils with higher concentrations of contaminants in the soil, which we consider one of the limitations of this work, using low concentrations of heavy metals. Therefore, more research is required to corroborate the effectiveness of ZnO NPs in soils contaminated with Pb and Zn during the phytoremediation process with sunflower plants.Graphical

Cucumber Bioassay and HPLC Analysis to Detect Diuron Residues in Remineralized Soils Following Canavalia ensiformis Cultivation as a Phytoremediator

The aim of this study was to evaluate the role of rock powder in the phytoremediation of Inceptisol (sandy loam) and Oxisol (clay) contaminated with diuron. Canavalia ensiformis plants were grown in pots containing 7.5 kg of both soils, with doses of 0, 4, and 8 t ha−1 of rock powder. Diuron was applied in doses ranging from 875 to 3500 g of a.i. ha−1. The injury level was assessed at 42 days after emergence (DAE), and the morphological characteristics were assessed at 120 DAE. After phytoremediation, the soil was analyzed using High Performance Liquid Chromatography (HPLC) and by bioassay with cucumber (Cucumis sativus) to detect diuron. In Oxisol, no injury was observed, and the rock powder (4 t ha−1) benefited the growth of C. ensiformis regardless of the dose of diuron. In Inceptisol, the greatest reduction in growth occurred with 3500 g a.i. ha−1 of diuron and 8 t ha−1 of rock powder. Diuron was detected after 120 days in Inceptisol with 2625 g a.i. ha−1 without rock powder and 3500 g a.i. ha−1 with and without rock powder. The cucumber bioindicator in Inceptisol showed an increase in the level of injury as the dose of diuron increased. The rock powder favored the growth of C. ensiformis and was able to phytoremediate high concentrations of diuron, which supports the safe use of this herbicide for weed control, minimizing environmental impacts.

Canavalia ensiformis enhances the phytoremediation of remineralized and sulfentrazone-contaminated tropical soils

The objective of the study was to assess the phytoremediation potential in two remineralized soils contaminated with sulfentrazone. Two soil types were evaluated: Oxisol (clayey) and Inceptisol (sandy loam), in pots, with and without the incorporation of the rock powder, at rates of 0, 4, and 8 t ha−1. Following this, sulfentrazone was applied at rates of 200, 400, 600, and 800 g a. i. ha−1, in addition to the control treatment without herbicide application, followed by the sowing of Canavalia ensiformis (jack bean). Injury level (IL) was assessed at 42 days after emergence (DAE), and biometric evaluations of the phytoremediating species were conducted at 70 and 120 DAE in the Oxisol and Inceptisol, respectively, for the following variables: height (HT), diameter (DM), trifoliate leaf number (TN), leaf area (LA), above-ground dry biomass (DB), and root dry biomass (RDB). At the end of the phytoremediation experiment, the soils were analyzed using High-Performance Liquid Chromatography (HPLC) and with Sorghum bicolor (sorghum) as a bioindicator to verify the residue of sulfentrazone. IL and DB assessments of the bioindicator species were conducted at 21 DAE. In both soils, higher herbicide rates (600 and 800 g a. i. ha−1) resulted in greater IL and reduced HT, LA, DB, and RDB of the phytoremediating species. C. ensiformis reduced the sulfentrazone residues in the soils. Although it did not directly influence phytoremediation, the rock powder improved soil fertility. In conclusion, C. ensiformis has the potential for effective phytoremediation of soils contaminated with sulfentrazone, providing safety for cultivating sensitive crops and benefiting the environment.

Productivity and Econometric Analysis of Leguminous Monkey-nut (Arachis hypogaea L.) as Influenced by Growth Retardant

Background: Groundnut (Arachis hypogaea L.) holds significant importance as a staple food legume and a key economic crop, serving as a valuable source of edible oil and protein in India. However, its full yield potential is often hampered by excessive vegetative growth, which leads to suboptimal yields. With this background, a field experiment was conducted at the Perunthalaivar Kamaraj Krishi Vigyan Kendra in Puducherry during 2020 and 2021. The objective was to investigate the influence of different concentrations and timing of paclobutrazol (PBZ) application on the growth and yield of groundnut. Methods: The experiment was laid out in a split-plot design with three replications, six main plot treatments (Including PBZ concentrations of 25, 50, 100, 150, 200 ppm and a control) and three sub-plot treatments (Involving single sprays at 30 days after emergence (DAE), single sprays at 50 DAE and double sprays at 30 and 50 DAE). Result: The results revealed that the application of paclobutrazol at different concentrations had a positive effect on reducing plant height during the later stages of growth, particularly when a double spray was applied at 30 and 50 DAE. Notably, the application of paclobutrazol at a concentration of 200 ppm in groundnut cultivation proved to be economically viable, resulting 29% increase in pod yield compared to the control group. Specifically, PBZ at 200 ppm, with a double spray, significantly boosted the total pod yield to 2724 kg ha-1. Furthermore, the correlation and regression analyses indicated a positive relationship between growth and yield.

Simulation of oat yield through biological and environmental variables for reducing fungicide application and increasing interval from application to grain harvest

Simulation models based on biological and environmental variables allow the analysis of scenarios in proposing more sustainable management. The objectives is to identify potential biological and environmental variables for inclusion and validation of multiple linear regression model for yield simulation and analyze scenarios that promote yield and satisfactory control of foliar diseases, with longer intervals between the last fungicide application and the grain harvest. The study was conducted in 2015, 2016, 2017, in Augusto Pestana, RS, Brazil. The soil is classified as Oxisol and the climate of the region as Cfa type, by the Köppen classification. The experimental design was randomized blocks, with three replications, in a 22 x 4 factorial, for 22 oat cultivars (10 recommended and 12 no longer recommended) and 4 fungicide use conditions (no application; one application 60 days after emergence (DAE); two applications, 60, 75 DAE; and three applications, 60, 75, 90 DAE. In 2015 and 2016, the fungicide FOLICUR® CE was used, and in 2017 PRIMO®, at a dosage 0.75 and 0.3 liters ha-1, respectively. Necrotic leaf area, rainfall depth, mean minimum and maximum temperatures, thermal sum, and crop cycle period (days) are potential variables by the Stepwise technique in the simulation of oat yield, validating the use of the multiple linear regression. The condition with three fungicide applications, at 60, 75, 90 DAE, resulted in satisfactory foliar disease control and grain yield, while maintaining a long interval between the last fungicide application and the grain harvest, thus improving the safety of the product obtained

Growth rates and nutrient accumulation in aerial biomass of sunn hemp juncea and spectabilis sown in spring

Crotalaria juncea and spectabilis have been widely used in green manuring, mainly due to the fact that they incorporate large amounts of N into the soil, through biological fixation of atmospheric N2, and also because they have a vigorous and branched root system, characteristics that help to recycle nutrients from the deeper layers of the soil. The present work was carried out in the municipality of Mercês, in the Mata Mineira area. Growth rates and nutrient accumulation were evaluated in the aerial part of sunn hemp and sunn hemp, grown in soil with good nutrient availability. The soil in the chosen area had good fertility, with no exchangeable aluminum in the 0 to 20 cm layer. Soon after the first spring rains, the soil was subsoiled, plowed, and harrowed, and the study was then installed, conducted in an experimental design in randomized blocks with five replications. The plots consisted of six furrows of five meters in length with 0.50 meters of spacing. Sowing was carried out in the first week of October. Evaluations of dry matter accumulation and plant height were carried out in the four central furrows of the plots, at 30; 45; 60; 75; 90 and 105 days after emergence (D.A.E.), with a sample area of 1.0 m of furrow (0.5 m2). In the biomass collected at 105 D.A.E, phenological stage of grain filling, the contents of nitrogen, phosphorus, potassium, calcium, magnesium and sulfur were determined, with the objective of quantifying the accumulation of these elements in the aerial part of sunn hemp. The results obtained in this edaphoclimatic environment led to the conclusion that sunn hemp juncea had faster vegetative development than sunn hemp spectabilis, therefore, a plant with greater soil protection potential against the impact of raindrops than sunn hemp spectabilis. Although they have very different growth rates, both for sunn hemp and sunn hemp, the highest rates of growth and dry matter accumulation in the shoots occurred in the periods from 45 to 60 D.A.E., with mean values, respectively, of 406, 7 and 140.0 kg per hectare per day. The accumulation of dry matter in the aerial part, as a function of the age of the plants, can be described by the quadratic equation, y = 0.0024 x2 + 0.5267x -11.8086 (R2= 0.9888), for sunn hemp, and y = 0.0008 x2 + 0.2003x -4.4657 (R2= 0.9928), for sunn hemp spectabilis. For the adopted production system, and in this climatic environment, sunn hemp was a better recycled/fixing plant than sunn hemp spectabilis, thus, green manuring with sunn hemp was more advantageous than with sunn hemp spectabilis.

Does brassinosteroid mitigate salt stress in sorghum?

The objective of the present study was to assess the mitigating effect of brassinosteroid regulator plant on damages caused by salt stress in sorghum. The experiment was carried out in pots containing 5 kg of substrate, on benches in a greenhouse covered with transparent plastic film and with a 50% shade screen on the sides. A completely randomized design with four replications was used, in a 2×5 factorial arrangement consisted of application and non-application of brassinosteroids at concentration of 0.1 mg L-1 applied at the 30, 37, and 45 days after emergence (DAE) and five salinity levels of the irrigation water (electrical conductivities of 0, 2, 4, 8, and 16 dS m-1). The plants were irrigated with water from the public supplying system up to 45 DAE and, then, with brackish water up to 60 (DAE), when they were evaluated. Our results indicate that Brassinosteroids mitigated damages caused by salt stress by increasing the Ca to Na ratio. Sorghum is moderately resistant to salt stress by presenting a sodium extrusion mechanism activated by calcium. Further studies with longer exposure time to salt stress are recommended for a more thorough understanding and recommendation of the use of brackish water in sorghum crops

The effect of organic amendments on soil microbial activity and yield of faba bean (Vicia faba) inoculated with Rhizobium leguminosarum

A two year (2021 and 2022) field experiment was conducted to study the effect of organic amendments on soil microbial activity and yield of faba bean (Vicia faba L.) inoculated with Rhizobium leguminosarum at Savadkuh in the north of Iran as a factorial experiment based on a randomized complete block design with 3 replications. The treatments included seed inoculation at two levels (inoculation with Rhizobium leguminosarum bv. Viciae and non-inoculation) and fertilization at 5 levels [cattle manure (CM) @30 tonnes/ha, vermicompost of manure (VM) @20 tonnes/ha, vermicompost of Azolla (VA) @20 tonnes/ha, chemical fertilization based on soil analysis (NP), and control]. Present study found that the soil microbial biomass carbon (C) increased over time until 120 daysafter emergence (DAE). The maximum microbial biomass-C (441 mg/g soil) and bacterial count (545 × 105 cfu/ml) were obtained from the inoculated VA treatment. The highest yields of pods (14400 kg/ha) and seeds (1266 kg/ha) were obtained when the use of vermicompost was accompanied by inoculation of R. leguminosarum, so that in plants without inoculation, the use of vermicompost increased the yield of pods compared to the NP by 34% and compared to CM, it increased by 44%, but this increase was 39% and 19% for inoculated plants compared to NP and CM, respectively. Although the seeds of vermicomposted plants showed lower iron (Fe) content, they showed higher nitrogen (N), phosphorus (P), copper (Cu) and zinc (Zn) content than other plants. In total, the results showed a significant improvement in soil microbial activity, absorption of nutrients and bean yield by using vermicompost(especially VA) under R. leguminosarum inoculation. Therefore, in the low-fertile soils of Iran, the combined use of high-quality vermicompost together with R. leguminosarum can strengthen soil microbial activity and bean production and be a suitable alternative to chemical fertilizers.