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Timely and cost-effective crop yield prediction is vital in crop management decision-making. This study evaluates the efficacy of Unmanned Aerial Vehicle (UAV)-based Vegetation Indices (VIs) coupled with Machine Learning (ML) models for corn (Zea mays) yield prediction at vegetative (V6) and reproductive (R5) growth stages using a limited number of training samples at the farm scale. Four agronomic treatments, namely Austrian Winter Peas (AWP) (Pisum sativum L.) cover crop, biochar, gypsum, and fallow with sixteen replications were applied during the non-growing corn season to assess their impact on the following corn yield. Thirty different variables (i.e., four spectral bands: green, red, red edge, and near-infrared and twenty-six VIs) were derived from UAV multispectral data collected at the V6 and R5 stages to assess their utility in yield prediction. Five different ML algorithms including Linear Regression (LR), k-Nearest Neighbor (KNN), Random Forest (RF), Support Vector Regression (SVR), and Deep Neural Network (DNN) were evaluated in yield prediction. One-year experimental results of different treatments indicated a negligible impact on overall corn yield. Red edge, canopy chlorophyll content index, red edge chlorophyll index, chlorophyll absorption ratio index, green normalized difference vegetation index, green spectral band, and chlorophyll vegetation index were among the most suitable variables in predicting corn yield. The SVR predicted yield for the fallow with a Coefficient of Determination (R2) and Root Mean Square Error (RMSE) of 0.84 and 0.69 Mg/ha at V6 and 0.83 and 1.05 Mg/ha at the R5 stage, respectively. The KNN achieved a higher prediction accuracy for AWP (R2 = 0.69 and RMSE = 1.05 Mg/ha at V6 and 0.64 and 1.13 Mg/ha at R5) and gypsum treatment (R2 = 0.61 and RMSE = 1.49 Mg/ha at V6 and 0.80 and 1.35 Mg/ha at R5). The DNN achieved a higher prediction accuracy for biochar treatment (R2 = 0.71 and RMSE = 1.08 Mg/ha at V6 and 0.74 and 1.27 Mg/ha at R5). For the combined (AWP, biochar, gypsum, and fallow) treatment, the SVR produced the most accurate yield prediction with an R2 and RMSE of 0.36 and 1.48 Mg/ha at V6 and 0.41 and 1.43 Mg/ha at the R5. Overall, the treatment-specific yield prediction was more accurate than the combined treatment. Yield was most accurately predicted for fallow than other treatments regardless of the ML model used. SVR and KNN outperformed other ML models in yield prediction. Yields were predicted with similar accuracy at both growth stages. Thus, this study demonstrated that VIs coupled with ML models can be used in multi-stage corn yield prediction at the farm scale, even with a limited number of training data. [ABSTRACT FROM AUTHOR]

Heavy metal pollution is a significant environmental problem and has a negative impact on human health and agriculture. Phytoremediation has recently emerged as an efficient heavy metal remediation technology. To examine the phytoremediation potential, an experiment was conducted, where the influence of high and low concentrations of heavy metals, lead, cadmium and zinc (Pb, Cd and Zn) on the phenological characteristics of corn (Zea mays), as well as their accumulation in the underground and aboveground part was monitored. The experiment was carried out in outdoor conditions in pots in which corn was planted and the soil was contaminated with heavy metals in concentrations below and above the maximum allowable concentration prescribed by the Ordinance. The experiment lasted 45 days. By processing the results, statistically significant differences in plant development were determined. The highest concentration of Zn was recorded in the aboveground part of the plant, the stem in the amount of 24.443 mg/kg, and the lowest concentration in the leaf 0.216 mg/kg. The highest concentrations of Cd and Pb were recorded in the root, for lead 26.610 mg/kg and in the stem for cadmium 30.490 mg/kg, which is a statistically significantly higher established value compared to other parts of the plant. [ABSTRACT FROM AUTHOR]

Root-lesion nematodes, Pratylenchus spp., are economically important pathogens because of their detrimental and economic impact on a wide range of crops. In August 2018, two samples of both roots and rhizosphere soil were collected from a corn field in Liangyuanqu of Shangqiu city, Henan Province, China. Root-lesion nematodes were recovered from the roots and soil samples using the modified Baermann funnel extraction method. Both the morphological characters and molecular analysis of the internal transcribed spacer (ITS) and D2-D3 expansion region of 28S ribosomal RNA sequences confirmed that the root-lesion nematode population collected from corn in this study was P. neglectus. Phylogenetic analyses showed that this isolate formed a highly supported clade with other P. neglectus isolates. To the best of our knowledge, this is the first report of P. neglectus on corn in Henan Province of China. This study reports the first partial sequences of 28S D2-D3 region of P. neglectus on corn in China. Due to the great harmfulness of root-lesion nematodes to corn, care should be taken to prevent the spread of P. neglectus to other regions in China. At the same time, further study on the biological characteristics of P. neglectus is needed, which will be helpful to develop corresponding management and control strategies. [ABSTRACT FROM AUTHOR]

Copyright of Journal of the Institute of Science & Technology / Iğdır Üniversitesi Fen Bilimleri Enstitüsü Dergisi is the property of Igdir University, Institute of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

THIS STUDY aimed to investigate the response of maize to supper absorbent polymer (SAP) and exopolysaccharides (EPS) producing bacteria under drought stress conditions at Panjar El -Soukkar region, Alexandria government, Egypt. The functional groups and heavy metal contents of SAP were determined. The swelling capacity of the polymer increased with increasing the hydrolysis time up to 30 min and the de-swelling water ratios of the polymer varied from 0.25 to 8 days. EPS-producing bacteria, Klebsiella oxytoca, Serratia marcescens, and Pseudomonas aeruginosa were selected and classified based on their phenotypic, biochemical, and also their molecular criteria.The EPS production by the selected isolates ranged from 0.85 to 1.24 g/100ml and the total activity of antioxidant of the extracted EPS ranged from 1.464 to 1.827%. The bacterial isolates could tolerate up to -2.24 MPa of water stress and their production of EPS increased with increasing drought stress levels. Different plant growth promoting parameters of selected isolates were evaluated. Two field experiments were conducted during 2018 and 2019 summer growing seasons. The obtained data revealed that drought stress had significant adverse effects on growth and yield parameters of maize plant, NPK uptake by grains, nutrient availability and microbial activities in soil. Seed bacterization of maize with EPS-producing bacterial isolates in combination with SAP improved all measured characters compared to PGPR inocula or SAP used alone. The findings suggested that applying superabsorbent polymer in combination with EPS-producing bacteria could improve tolerance of maize plant toward drought. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N2O) is a major greenhouse gas and cultivated soils are the most important anthropogenic source. N2O production and consumption are known to occur at depths below the A or Ap horizon, but their magnitude in situ is largely unknown. At a site in SW Michigan, USA, we measured N2O concentrations at different soil depths and used diffusivity models to examine the importance of depth-specific production and consumption. We also tested the influence of crop and management practices on subsurface N2O production in (1) till versus no-till, (2) a nitrogen fertilizer gradient, and (3) perennial crops including successional vegetation. N2O concentrations below 20 cm exceeded atmospheric concentrations by up to 900 times, and profile concentrations increased markedly with depth except immediately after fertilization when production was intense in the surface horizon, and in winter, when surface emissions were blocked by ice. Diffusivity analysis showed that N2O production at depth was especially important in annual crops, accounting for over 50% of total N2O production when crops were fertilized at recommended rates. At nitrogen fertilizer rates exceeding crop need, subsurface N2O production contributed 25–35% of total surface emissions. Dry conditions deepened the maximum depth of N2O production. Tillage did not. In systems with perennial vegetation, subsurface N2O production contributed less than 20% to total surface emissions. Results suggest that the fraction of total N2O produced in subsurface horizons can be substantial in annual crops, is low under perennial vegetation, appears to be largely controlled by subsurface nitrogen and moisture, and is insensitive to tillage. [ABSTRACT FROM AUTHOR]

A direct, controlled comparison of the photodegradation of imazethapyr has been made between imazethapyr in aqueous solutions, imazethapyr on the surface of epicuticular waxes of corn and soybean plants, and imazethapyr on the surface of intact corn and soybean plant leaves. In some experiments, the imazethapyr solutions were allowed to evaporate partially or fully after application to better model environmental conditions. The photodegradation of imazethapyr was fastest in aqueous solutions (k = 0.16 ± 0.02 h−1) and slowest on the surface of corn and soybean plants (kcorn = 0.00048 ± 0.001 h−1 and ksoy = 0.00054 ± 0.003 h−1). Experiments allowing evaporation during irradiation have intermediate rate constants (e.g., kcorn = 0.082 ± 0.005 h−1). Finally, identification of photoproducts was also examined on epicuticular waxes of corn and soybean plants for the first time. [ABSTRACT FROM AUTHOR]

Aspergillus flavus colonization in developing kernels of maize single-cross hybrids resistant (Mp313E × Mp717) and susceptible (GA209 × T173) to aflatoxin accumulation was determined in the field over three growing seasons (2012-2014). Plants were hand pollinated, and individual kernels were inoculated with a needle dipped in a suspension of A. flavus conidia 21 days after pollination. Kernels were harvested at 1- to 2-day intervals from 1 to 21 days after inoculation (DAI). Kernels were placed in FAA fixative, dehydrated, embedded in paraffin, sectioned, and stained with toluidine blue. Kernels were also collected additional kernels for aflatoxin analyses in 2013 and 2014. At 2 DAI, A. flavus hyphae were observed among endosperm cells in the susceptible hybrid, but colonization of the endosperm in the resistant hybrid was limited to the wound site of the resistant hybrid. Sections of the scutellum of the susceptible hybrid were colonized by A. flavus by 5 DAI. Fungal growth was slower in the resistant hybrid compared to the susceptible hybrid. By 10 DAI, A. flavus had colonized a large section of the embryo in the susceptible hybrid; whereas in the resistant hybrid, approximately half of the endosperm had been colonized and very few cells in the embryo were colonized. Fungal colonization in some of the kernels of the resistant hybrid was slowed in the aleurone layer or at the endosperm-scutellum interface. In wounded kernels with intact aleurone layers, the fungus spread around the kernel between the pericarp and aleurone layer with minimal colonization of the endosperm. Aflatoxin B1 was first detected in susceptible kernel tissues 8 DAI in 2013 (14 mg/kg) and 2014 (18 mg/kg). The resistant hybrid had significantly lower levels of aflatoxin accumulation compared to the susceptible hybrid at harvests 10, 21, and 28 DAI in 2013, and 20 and 24 DAI in 2014. Our study found differential A. flavus colonization of susceptible and resistant kernel tissues, and that the aleurone and the outer layer of the scutellum slowed the rate of colonization by A. flavus. [ABSTRACT FROM AUTHOR]

Agronomic characteristics of genetically modified (GM) MON 89034 × TC1507 × NK603 × DAS-40278–9 (PowerCore™ Enlist™), MON 89034 × TC1507 × NK603 (PowerCore™), and DAS-40278–9 (Enlist™) corn, a non-GM near-isogenic hybrid, and 2 commercial non-GM hybrids were assessed in a field study to determine if the agronomic performance of the GM corn hybrids is equivalent to that of non-transgenic hybrid corn. The MON 89034 × TC1507 × NK603 × DAS-40278–9 hybrid corn was developed through stacking of 4 individual transgenic events, MON 89034, TC1507, NK603, and DAS-40278–9 by traditional breeding and contains thecry1A.105andcry2Ab2(MON 89034),cry1Fandpat(TC1507),cp4 epsps(NK603) andaad-1(DAS-40278–9) transgenes. These transgenes encode the proteins Cry1A.105, Cry2Ab2, and Cry1F, which confer insect resistance, PAT, CP4 EPSPS, and AAD-1, which confer herbicide tolerance. The following agronomic characteristics were assessed in the study: initial and final stand count, seedling vigor, time to silk, time to pollen shed, pollen viability, plant height, ear height, stalk lodging, root lodging, days to maturity, stay green, disease incidence, insect damage, herbicide injury, and yield. The agronomic assessment was conducted in 2 regions of Brazil (Indianopolis-MG; Cravinhos-SP). The agronomic attributes for all GM entries were statistically indistinguishable from the non-GM near-isogenic hybrid. In addition, most of the agronomic assessments fell within the range of the commercial varieties included in the study. Taken together, MON 89034 × TC1507 × NK603 × DAS-40278, MON 89034 × TC1507 × NK603, and DAS-40278–9 were found to be agronomically equivalent to non-GM corn. [ABSTRACT FROM PUBLISHER]

The large-scale cultivation of crops may lead to biodiversity decreases as a result of habitat loss and degradation of natural habitats. A popular strategy for enhancing insect diversity in intensively cultivated habitats involves maintaining plant diversity in field margins by means of sown grass and wildflower strips., Despite extensive cultivation of maize/corn (approximately 3.1 million ha) in the grassy biomes of South Africa, little effort has been made to understand whether plant groups maintain insect biodiversity within these agro-ecosystems., The diversity relationships between three prominent guilds of arthropods (herbivores, parasitoids and predators) and three large plant families ( Asteraceae, Fabaceae and Poaceae) are described at regional scale across the Grassland and Savanna Biomes of South Africa., The results obtained indicate general positive relationships between plant and arthropod diversity of the lower vegetation layers (≤2 m)., An increased abundance of members of the grass family ( Poaceae) led to significantly higher invertebrate numbers in maize fields and adjacent vegetation. This suggests that grasses play a significant role in supporting arthropod diversity within these agro-ecosystems., When considering farm design in maize-agro-ecosystems, our results indicate that maintaining grassy natural vegetation patches adjacent to actively cultivated maize fields may be sufficient to maintain and conserve arthropod diversity within agricultural landscapes. [ABSTRACT FROM AUTHOR]

This study investigated the water balance, crop yield, and water use efficiency (WUE) of a water table management system compared to a conventional drainage system at three nitrogen levels. A two-year field study was conducted using three blocks; each block was composed of two water management treatments: controlled drainage with subirrigation (CD-SI) and conventional or free drainage (FD). The water table depth was maintained at 60 cm below the soil surface in the CD-SI plots. Three nitrogen treatments (low, medium, and high) were applied in strips across all blocks. The seasonal water balance indicated surplus water conditions in the CD-SI plots, while the FD plots had deficit conditions. In 2008 and 2009, the corn grain WUE for the FD plots was 2.49 and 2.46 kg m-3 respectively. The corn grain WUE for the CD-SI plots was 2.43 and 2.26 kg m-3 in 2008 and 2009, respectively. The WUE of corn grain responded to the water treatments (p < 0.05) in 2009 but not in 2008. In 2009, at low and high nitrogen levels, the water management treatments demonstrated significant differences (p < 0.05) in grain yields. However, water management demonstrated no significant effect (p > 0.05) on grain yields at the normal nitrogen level. Furthermore, the two water treatments had no effect on the aboveground dry biomass yields in both years. [ABSTRACT FROM AUTHOR]

The article discusses results of a study that examines the ammonium sulfate (AMS) and water hardness effect on glyphosate and glufosinate activity in corn in fields near Harrow and Ridgetown, Ontario. The study showed that water hardness has no effect on control of velvetleaf, common lambsquarters, redroot pigweed and annual grasses green foxtail and barnyardgrass. It concludes that AMS and water hardness have little benefit on glyphosate efficacy in corn.

Fifty-one maize samples, intended for animal feed and human consumption, were collected from the four main maize production provinces in Iran and analyzed by high-performance liquid chromatography (HPLC) for contamination by four naturally occurring aflatoxin analogues (AFB1, AFB2, AFG1, and AFG2). AFB1 was detected in 58.3, and 80% of the maize samples obtained from Kermanshah and Mazandaran provinces, respectively. The maximum AFB1 (276.3 μg/kg) and highest level of total aflatoxins (AFT) (316.9 μg/kg) were detected in a maize sample collected from Kermanshah province. The mean aflatoxin level from contaminated samples (52.60 μg/kg) from Kermanshah was significantly higher ( P < 0.0001) than those in maize from the other three provinces and exceeded all the maximum tolerated levels (MTLs) set for AFT in maize. The level of AFB1 in 15.68% of the total samples was above the MTL (5 μg/kg) for AFB1 in maize in Iran. The mean contamination level of AFT (23.86 μg/kg) in the positive samples was higher than MTL for maize in Iran (20 μg/kg) intended for animal feed. The levels of AFB1, AFB2, AFG1, and AFG2 ranged between not detected (<0.1 μg/kg) and 276.3, 30.4, 9.1, and 1.1 μg/kg in maize grain, respectively. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Botany is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the intensely farmed corn-growing regions of the mid-western USA, surface waters have often been contaminated by herbicides, principally as a result of rainfall runoff occurring shortly after application of these to corn and other crops. In some vulnerable watersheds, water quality criteria for chronic human exposure through drinking water are occasionally exceeded. We selected three settings representative of vulnerable corn-region watersheds, and used the PRZM-EXAMS model with the Index Reservoir scenario to predict corn herbicide concentrations in the reservoirs as a function of herbicide properties and use pattern, site characteristics and weather in the watersheds. We compared herbicide application scenarios, including broadcast surface pre-plant atrazine and alachlor applications with a glyphosate pre-plant application, scenarios in which losses of herbicides were mitigated by incorporation or banding, and scenarios in which only glyphosate or glufosinate post-emergent herbicides were used with corn genetically modified to be resistant to them. In the absence of drift, in almost all years a single runoff event dominates the input into the reservoir. As a result, annual average pesticide concentrations are highly correlated with annual maximum daily values. The modeled concentrations were generally higher than those derived from monitoring data, even for no-drift model scenarios. Because of their lower post-emergent application rates and greater soil sorptivity, glyphosate and glufosinate loads in runoff were generally one-fifth to one-tenth those of atrazine and alachlor. These model results indicate that the replacement of pre-emergent corn herbicides with the post-emergent herbicides allowed by genetic modification of crops would dramatically reduce herbicide concentrations in vulnerable watersheds. Given the significantly lower chronic mammalian toxicity of these compounds, and their vulnerability to breakdown in the drinking water treatment process, risks to human populations through drinking water would also be reduced. [ABSTRACT FROM AUTHOR]

The rate of electron transfer from NADH to ferricyanide associated with corn root plasma membrane vesicles was not significantly affected by the presence of Ca2+, Cd2+, Zn2+, or Co2+. However, unlike Ca2+, other tested divalent cations induced an electron transfer-dependent increase in light scattering by the vesicles. The efficacy in inducing the light scattering increase followed the order of Cd2+>Zn2+>Co2+. The extent of the light scattering change increased as the concentration of added Cd2+ increased. Using phase contrast microscopy, the increase in light scattering was related to an expansion of the vesicles. Accompanying the volume increase, a decrease of Cd2+ concentration in the external space was observed by the use of Arsenazo III, a metallochromophore specific for divalent cations. Under a specified electron transfer condition, a similar percentage of decrease over a wide range of initial Cd2+ concentration was detected. The presence of A23187 decreased the rate and extent of light scattering increase and its associated Cd2+ concentration change. However, A23187 had no effect on scattering changes already established by the electron transfer and Cd2+. These results suggest that the NADH linked electron transfer reaction may induce a Cd2+ uptake by the vesicles of corn root plasma membrane with inside-out orientation. [ABSTRACT FROM AUTHOR]