Early Growth Of Maize Research Articles

Drought risk assessment for early maize growth in Northeast China based on a reconstructed phenological dataset

AbstractDrought is one of the meteorological disasters to which maize is most vulnerable during its seedling stage in Northeast China. The absence of phenological data impedes the precise evaluation of the likelihood of drought during this phase. In response to these issues, this study develops a phenology model and reconstructing the data. Furthermore, it effectively assessed drought risk at the site scale by utilizing drought indicators. Using reconstructed phenological data from 217 sites from 1981 to 2015, we analysed the duration and trends of each phenological period and assessed the spatial and temporal distribution of drought frequency at each growth stage. The study demonstrated that the average date ranges for the sowing, emergence, three‐leaf, and seven‐leaf stages annually were 115–138 days, 130–151 days, 135–160 days, and 150–180 days, respectively. Additionally, there was a significant trend towards earlier dates in all phenological stages. Our research reveals notable fluctuations in drought frequency during various growth stages of early maize in Northeast China. Particularly, the period from the three‐leaf to the seven‐leaf stages emerges as the most drought‐prone, while the initial emergence to three‐leaf stage also shows considerable vulnerability. On average, the frequency of drought events during the critical three‐ to seven‐leaf stage stands at 35%. This average is surpassed in regions like Heilongjiang, northwest Jilin, northern Inner Mongolia, and southwest Liaoning, indicating a heightened risk in these areas. The early maize growth stage drought types are mainly light and moderate drought, with the three‐leaf to seven‐leaf stage, and Heilongjiang and Inner Mongolia, as the key stages and regions of concern, respectively. Identifying the principal types of drought and their occurrence in distinct regions and growth stages is pivotal for averting and reducing disasters.

Cadmium and copper-induced metabolic and proteomic changes in the root tip during early maize growth.

In this study, the metabolic adjustments performed by maize (Zea mays L.) seminal roots exposed to 25µM Cd2+ or 25µM Cu2+ at pre-emergence are compared, focusing on the proteomic changes after metal exposure. Root width was increased, and root length was decreased after 72h of metal treatment. Both metals induced H2O2 accumulation and lipid peroxidation in the root tip. These changes were accompanied by increases in lipoxygenase activity and 4-hydroxy-2-nonenal content. NMR spectroscopy revealed that the abundance of 38 water-soluble metabolites was significantly modified by Cd and Cu exposure; this set of metabolites comprised carboxylic acids, amino acids, carbohydrates, and unidentified phenolic compounds. Linoleic acid content significantly decreased in Cu-treated samples. The total amount of proteins detected in maize root apexes was 2,171. Gene ontology enrichment analysis of the differentially accumulated proteins was performed to detect pathways probably affected by metal additions. Both metals altered redox homeostasis, up-regulated oxylipins biosynthetic process, and shifted metabolism towards the oxidative pentose-phosphate in the root apexes. However, the methionine salvage pathway appears as a key metabolic module only under Cd stress. The integrative analysis carried out in this study suggests that most molecular features behind the reprogramming of maize root tips to cope with cadmium and copper toxicity are common, but some are not.

Increasing Legume Input through Interseeding Cover Crops: Soil and Crop Response as Affected by Tillage System

Legumes provide important benefits in rotations. Interseeding cover crops (CCs) allows an additional legume CC in case of a short window after the main crop. However, legume input level and management could modify the expected benefits. In a Mediterranean irrigated agroecosystem, we evaluated the responses of topsoil (0–10 cm) and early maize development to increasing legume CC input in a biannual maize–wheat rotation under traditional tillage (TT; CC incorporated) and minimum tillage (MT; CC rolled-crimped). In the third year, at two early maize stages, we tested three legume input levels: (i) R0, non-CC; (ii) R1, barley–vetch CC; (iii) R2, vetch interseeded into maize in addition to the CC mixture. Overall, MT enhanced soil properties, but frequently conditioned to legume input level. The tillage system affected R1 the most, with MTR1 showing the better overall soil response while TTR0 showed the poorest. MTR2 was the best combination for early maize development, but not for soil health. Moreover, a better overall soil health did not lead to a better early maize performance in the short term. In this alkaline soil, CC favored early maize growth, whereas mycorrhization, enhanced under TT, favored crop nutrition. Increased legume input under MT should be monitored to avoid negative effects in soil in the mid–long term.

Nitrogen supply alleviates cold stress by increasing photosynthesis and nitrogen assimilation in maize seedlings.

Cold stress inhibits the early growth of maize, leading to reduced productivity. Nitrogen (N) is an essential nutrient that stimulates maize growth and productivity, but the relationship between N availability and cold tolerance is poorly characterized. Therefore, we studied the acclimation of maize under combined cold stress and N treatments. Exposure to cold stress caused a decline in growth and N assimilation, but increased abscisic acid (ABA) and carbohydrate accumulation. The application of different N concentrations from the priming stage to the recovery period resulted in the following observations: (i) high N supply alleviated cold stress-dependent growth inhibition, as shown by increased biomass, chlorophyll and Rubisco content and PSII efficiency; (ii) cold stress-induced ABA accumulation was repressed under high N, presumably due to enhanced stomatal conductance; (iii) the mitigating effects of high N on cold stress could be due to the increased activities of N assimilation enzymes and improved redox homeostasis. After cold stress, the ability of maize seedlings to recover increased under high N treatment, indicating the potential role of high N in the cold stress tolerance of maize seedlings.

Considering spatio-temporal dynamics of soil water with evapotranspiration partitioning helps to clarify water utilization characteristics of summer maize under deficit irrigation

Continuously increasing the utilization efficiency of agricultural water resources is vital to ensuring future water and food security. Deficit irrigation (DI) could provide a solution to optimize crop water productivity. Research on the spatio-temporal dynamics of soil water coupled with evapotranspiration partitioning is important for clarifying summer maize (Zea mays L.) water utilization characteristics and crop water productivity under different DI strategies, especially in semi-arid regions. Consequently, a three-year field experiment with full irrigation (CK) and eight DI treatments (T1–T8, comprised of combinations of 100 %, 80 %, and 60 % of crop evapotranspiration) was conducted. Data from large-scale weighing lysimeters, micro-lysimeters, and TDR sensors were combined to assess daily root water absorption at different soil depths, actual evapotranspiration (ETa) partitioning into plant transpiration (T) and soil water evaporation (E), and water use efficiency (WUE). Results showed that soil water consumption mainly occurred in the 0–40 cm, 0–60 cm, and 0–80 cm soil layers during the maize growth stages of planting–V6, V6–V12, and V12–R6, respectively. Water absorption above the 60-cm soil depth accounted for more than 92 % of the total water consumption. The appropriate irrigation wetting depth for summer maize could be controlled in the top 80-cm layer to avoid deep percolation. DI affected soil water distribution and availability, and thus decreased soil water consumption rate (WCR) and root water absorption amount. Under moderate water deficit conditions, WCR was rapidly restored to the non-water-stressed irrigation treatment level, and even exceeded that level in the deeper layers after a subsequent irrigation was applied, especially in the early maize growth stages. E/ETa was 31.0–32.5 % under full irrigation. DI decreased total soil water evaporation amount, but increased the E/ETa ratio. The threshold soil water value for defining when maize was subjected to water stress was 22.0 % (72 % of FC) during V3–V12, and 18.0 % (60 % of FC) during V12–R1. Our results suggest that less water was used in T1 (moderate DI) than with the full irrigation treatment. WUE increased by 5.5 %–7.5 % as irrigation amount decreased by 12.3–14.5 % and yield decreased by 3.3 %–8.0 %. These results improve our understanding of maize water consumption characteristics with regard to soil water absorption in different soil layers and evapotranspiration partitioning, and provide implications for efficient water management in arid areas of northwest China.

Antioxidant activity, phytotoxicity and allelopathic potential of green walnut (Juglans regia L.) fruit extract

The potential allelopathic effect of a green walnut fruit extract on seed germination and early growth of three weed species (Chenopodium album, Amaranthus retroflexus, Daucus carota) was tested, as well as its phytotoxic effect on seed germination and early growth of maize (Zea mays). Another objective was to analyze the plant extract and assess its antioxidative activity. Antioxidative activity of the plant extract was evaluated based on its ability to neutralize DPPH (2,2-diphenyl-1-picrylhydrazyl) radical and capacity for iron reduction using the FRAP method. Inhibition of the evaluated parameters (total germination and seedling length) decreased proportionally with decreasing concentrations of extract solution of green walnut fruit. The parameters of seedling growth were also found to show greater susceptibility than total seed germination of all three of the tested weed species. Although the seed bioassay results indicated a high inhibitory effect on germination and early growth of the tested weeds, they also revealed phytotoxic activity during early growth of the cultivated Z. mays.

Maize response to nitrogen and phosphorus starter fertilisation in mineral-fertilised or manured systems

Phosphorus (P) is an essential nutrient for maize production, but in temperate areas the P uptake during early growing stages can be limited due to low soil temperature, even though the soil was tested high in P. The objective of this study was to assess the effects of nitrogen and phosphorous (NP) starter fertilisation during early growth stages and its carryover until maize harvest, in mineral-fertilised or manured systems. A field experiment was carried out in north-west Italy during the 2019 and 2020 growing seasons. The trial compared sub-surface placement of NP (diammonium phosphate) or N alone (ammonium nitrate) in bands close to the maize seed furrows, in differing long-term (LT) fertilisation managements: two doses of urea (Min-L and Min-H), two doses of bovine slurry (Slu-L and Slu-H) or two doses of farmyard manure (Fym-L and Fym-H). The two rates, low (L) and high (H), corresponded to 170 and 250 kg N ha−1 year−1 respectively. Compared to N fertilisation, NP starter fertilisation improved early maize growth assessed by leaf area index (LAI) and shoot dry weight (SDW) in all systems. The effects differed between the two years (2019: LAI + 63%, SDW + 67%; 2020: LAI + 36%, SDW + 38%), as 2019 was cool during the first growth. Higher LAI and SDW values were confirmed at crop flowering in the mineral-fertilised systems only. As shoot growth was enhanced by NP starter fertilisation, anthesis occurred 1 day earlier in all systems. However, a response to NP starter fertilisation at harvest was recorded in mineral-fertilised systems only (+1.3 and +3.2 t ha−1 in Min-L and Min-H, respectively). The uptake of P, used as a true indicator of soil nutrient availability, increased with increasing soil Olsen P until 39 mg kg−1. These results suggest that soil test thresholds should be revised for points above which P fertilisation should be suspended.

Biostimulant Activity of <i>Sargassum</i> sp. Extracts on Early Growth of <i>Zea mays</i> L. and the Phytohormones Content Analysis

Seaweed has been gaining global interest in agriculture for the development of marine-based plant biostimulants. This research aimed to study the effect of three different liquid extracts of Sargassum sp., acidic, alkaline, and water extract, on the germination and early growth of maize and to evaluate the phytohormones content responsible for the growth. Phytohormones content including Indole-3-acetic acid (IAA), gibberellins (GA), kinetin and zeatin were analyzed using high-performance liquid chromatography (HPLC) and bioassay was performed twice on maize. Parameters observed on the bioassay were germination percentage, number of roots, shoot length, shoot weight and root weight under 4 different concentrations with 0.5; 1.5; 3.5; and 5% in the first bioassay and 3.5% concentration in the second bioassay. Both bioassays following randomized complete design and the data were analyzed using one-way ANOVA using post hoc test of Duncan Multiple Range Test (DMRT) at error probability of 5% in Genestat software. Phytohormones content in the seaweed extract indicated that alkaline extract was rich in IAA, gibberellin, and zeatin content, while water extract showed the highest kinetin content. The first bioassay indicated that lower concentration of the seaweed extracts gave better growth in all extracts, therefore a 3.5% concentration was chosen for the second bioassay with higher replication for each treatment. The second bioassay confirmed alkaline extract resulted in the highest germination while the highest seedling height, number of roots, shoot and root weight were resulted from acidic extract treatment. In conclusion, Sargassum sp. extracts obtained from acidic, alkaline, and water-based extraction methods, were able to improve the shoot and root growth of maize plants. The acidic extract showed the highest growth promotion among other extracts with the lowest phytohormones content.

Potential suppressive effects of Mexican poppy weed residues on germination and early growth of maize and pearl millet crops

Argemone ochroleuca allelochemical properties have been reported but not empirically tested on economically important staple cereal crops. Therefore, the objective of this study was to determine the potential Allelopathic effects of the alien weed’s residues on germination and early-growth of maize (Zea mays L.) and Pearl millet (Pennisertum glaucum). Allelopathic effects of A. ochroleuca on maize and millet seed germination were tested in a 2 (shoot and root) x 11 (0, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100g/L water) factorial treatment arrangement in CRD in an incubator placed in a laboratory. Whereas effects of the weed extracts on the same crops’ early-growth were tested in a 2 (shoot and roots) x 8 (0, 2, 4, 6, 8, 10, 12 and 14g ground-powdered extracts) factorial arrangement in RCBD under laboratory conditions. Maize and millet germination percentage, germination speed, mean germination time, mean daily germination, plumule and radicle length were measured for germination test, whereas, plant height, stem diameter, root and shoot mass were used as indicators of A. ochroleuca suppression of early plant growth. Relative to untreated control, concentration equal to and greater than 10g/L aqueous extracts of A. ochroleuca reduced millet and maize seed germination variables by 10–100% and 28–56%, respectively, while early-growth variables were reduced by 66–100% and 4–37%, respectively. Argemone ochroleuca shoot extracts were more suppressive than root extracts on germination and early growth of the two crops. In conclusion, A. ochroleuca Allelopathic effects were concentration and plant-part dependent, inhibitory effects increased with concentrations, with extracts from shoots being more Allelopathic on measured variables when compared to root extracts. As A. ochroleuca continues to spread yearly without any control strategies in place, a threat exist on maize and Pearl millet production especially in communal farming areas where improved management strategies are non- existent. Key words: Allelopathic, Argemone ochroleuca, germination, growth, millet, maize, plumule, radicle

Effects of Humic Acid Added to Controlled-Release Fertilizer on Summer Maize Yield, Nitrogen Use Efficiency and Greenhouse Gas Emission

Humic acid plays an important role in improving grain yield and reducing N losses. In order to explore the effects of humic acid added to controlled-release fertilizer on summer maize yield, nitrogen use efficiency (NUE) and the characteristics of greenhouse gas (GHG) emissions in maize farmland soil, a two-year field experiment was set up. The treatments consisted of two fertilizers: 3% humic acid added to controlled-release fertilizer (HACRF), controlled-release fertilizer (CRF) and a control (without N fertilizer, N0). The results demonstrate that the yield and NUE of summer maize were significantly increased with the addition of humic acid in N fertilizer. Compared with N0 and CRF, the yield of maize was increased by 99.1% and 5.0%, respectively. Compared with CRF, the contents of soil ammonium–nitrogen (NH4+-N) and nitrate–nitrogen (NO3−-N) in HACRF were higher during early maize growth stage but lower during the late grain-filling stage. The NUE and soil nitrogen interdependent rate of HACRF were significantly increased by 4.6–5.4% and 7.2–11.6%, respectively, across the years compared with those of CRF. Moreover, the annual cumulative N2O emissions in HACRF were decreased by 29.0% compared with the CRF. Thus, the global warming potential and greenhouse emission intensity of HACRF were significantly decreased by 29.1% and 32.59%, respectively, compared with CRF. In conclusion, adding humic acid to controlled-release fertilizer can result in higher yield and nitrogen uptake, improve nitrogen use efficiency and reduce greenhouse gas emissions, which have better yield and environmental effects.

Protein hydrolysates enhance germination and early growth of maize and sugarcane

Protein hydrolysates have been reported as a plant biostimulant due to their activity like phytohormones. This research aimed to study protein hydrolysate’s effect on the germination and growth of maize and sugarcane. Chicken feather meal (TB) and trash fish meal (TI) based protein hydrolysates were tested their ability to promote rooting and shooting in the early growth of maize and sugarcane, following an adequately dipping. In the maize bioassay, seeds were soaked for 1 hour in aquadest and 10 ppm of TB and TI hydrolysates in three replicates. Shoots and roots length were measured 5 days after germination. In the sugarcane assay, setts having a single bud on top and bottom stalk of PSJT-941 were grown in a polybag. The experiment was performed in eight treatments and 10 replicates, comprising setts from top and bottom, followed by 5, 10, and 30 minutes dipping in 20 ppm of TB hydrolysate. The setts soaked in aquadest was the negative control. Maize treated with TB hydrolysate had the highest shoots and roots length, while sugarcane setts from the top stalk soaked for 30 minutes in the TB hydrolysates showed germination in all replications besides the best in rooting and number of shoots.

Seed treatment for managing fall armyworm as a defoliator and cutworm on maize: plant protection, residuality, and the insect life history.

The highly polyphagous and invasive fall armyworm (FAW, Spodoptera frugiperda) can feed on different plant parts of host crops, damaging whorls and stalks in early maize growth stages. Systemic insecticide seed treatment (IST) could minimize this damage, although the residual efficacy may vary with the plant tissue damaged. Using damage rating scales and artificial infestation in controlled conditions, we determined the potential of IST against FAW attacking maize whorl leaves or the stalk base. Chlorantraniliprole, cyantraniliprole, or thiodicarb + imidacloprid IST similarly killed > 80% FAWs for 1 or 2 weeks after plant emergence depending on the plant tissue attacked. The residual efficacy (i.e. time after plant emergence sustaining > 80% larval mortality) lasted from the first to the eleventh day (VE-V3 maize growth stages), while for cutworm on the maize stalk base, it lasted 3-7 days after plant emergence (V1-V2 stages). In terms of damage, the ISTs lasted 15 days after emergence (V4 stage) for FAW on whorl leaves and 10 days (V3 stage) for FAW feeding on the stalk base. The larvae surviving on the seed-treated plants underwent sublethal effects in growth and development, reducing insect fitness. Diamide or carbamate + neonicotinoid seed treatments kill FAW larvae on maize whorls or stalks in favorable edaphoclimatic and insecticide-susceptibility conditions. The cumulative impacts of systemic IST on aboveground insect pests go beyond mortality. The ISTs studied can be valuable against FAW in maize, for instance, to help protect varieties that may not express sufficient insect resistance in maize early growth stages.

Seed Treatment with Biostimulants Extracted from Weeping Willow (Salix babylonica) Enhances Early Maize Growth.

Biostimulants can be used as innovative and promising agents to address current needs of sustainable agriculture. Weeping willow tree (Salix babylonica) extracts are rich in many bioactive compounds, including, but not limited, to salicylates and phenolics. In this study, the potential of willow bark (WB) and willow leaf (WL) extracts is evaluated as plant-based biostimulants to improve the early growth of maize (Zea mays) under control and salinity stress conditions. In 3 days, seed treatment with salicylic acid and willow extract increased the shoot FW of maize seedlings 130% and 225%, respectively. The root area was, on average, enhanced by 43% with SA and 87% with willow extract applications. Moreover, these extracts increased the leaf protein concentration and reduced the negative effects of salinity during early growth. Reductions in lipid peroxidation and specific activities of antioxidative enzymes by seed treatments with willow extracts suggests a mitigation of salinity-induced oxidative stress. For most reported traits, WL applications were at least as effective as WB applications. Results indicate that aqueous extracts of weeping willow leaves, as well as bark, can be used as seed treatment agents with biostimulant activity to improve seedling growth and establishment under control and stress conditions.

Impact of Hydrogels on Early Growth of Maize in Sandy Regosols: Progress towards Improving Growth Performance by Enhancing Water and Nutrients Retention Capacity of the Soil

Super Absorbent Polymers or hydrogels are known for enhancing the water-holding properties of soils. This experiment was conducted to evaluate the influence of four different locally-produced hydrogels and one commercially available hydrogel on the early growth of maize in sandy Regosols. Maize variety, Pacific 984 was tested with six treatments in Randomized Complete Block Design. T1 - Reference hydrogel (Sodium polyacrylate-based), T2 - Acrylic acid and acrylamide-based hydrogel where urea has incorporated chemically up to 11.08% (g/g), T3 - without urea incorporating to the hydrogel used in T2, T4 - similar to T2, but urea incorporated only up to 6.17% (g/g), T5- agriculture grade commercial hydrogel (Potassium polyacrylate-based) and T6 - control (without hydrogel) were used for the study. Soil properties and plant growth parameters were quantified. A significant difference was observed in soil pH, total N and available P among treatments after one month of application. Treatment 2 showed the highest total N (0.19%) while T4 showed the highest P (18.94 ppm). The highest growth performances were given by locally produced hydrogels over commercial hydrogel and control treatments. Treatment 2 recorded the highest leaf area (1153.3 cm2/plant), plant height (128.90 cm) and total dry mass production (49.36 g/plant) while T4 has recorded the highest stem girth (4.87 cm). It was observed that locally produced hydrogels including the hydrogel without incorporating urea, have given superior performance over commercial hydrogels. Therefore, it can be concluded that locally produced hydrogel-formulations can enhance the growth of maize effectively than imported commercial hydrogels.

Placement depth and distribution of cattle slurry influence initial maize growth and phosphorus and nitrogen uptake

AbstractBackgroundPlaced cattle slurry (CS) provides essential nutrients such as nitrogen (N) and phosphorus (P) to young maize (Zea Mays L.) plants and may substitute the use of mineral starter fertilizers. However, placement depth and distribution of slurry may influence the plant growth response.AimsThe objective was to evaluate the effects of slurry placement depth and distribution on initial maize growth, and N and P uptake on loamy sand and coarse sandy soil.MethodsIn a pot experiment, CS spiked with (15NH4)2SO4 was placed either 2, 5, or 8 cm below the seed in a thick layer covering 50% of the central pot area or 5 cm below the seed in a thinner layer covering the whole pot area.ResultsIn the loamy sand soil, maize biomass and P uptake at the five‐leaf stage were higher when slurry was placed in a thick‐centered layer 2 or 5 cm below the seed than at 8 cm. In the coarse sandy soil, maize biomass increased by 21%, when slurry was placed in a thinner layer covering the whole pot area, compared to slurry placed in a thick layer, whereas slurry placement depth had no effect on this soil type. Nitrogen use efficiency (NUE) and 15N recovery (15NRE) were not affected by slurry placement depth, but the application of slurry in the thick layer increased NUE and 15NRE in loamy sand soil as compared to the thin slurry layer at the same depth.ConclusionsPlaced CS could replace starter N and P fertilizer for the early growth of maize. The beneficial effect of placed slurry depended on slurry placement depth in the loamy sand soil and slurry distribution in the coarse sandy soil, and distribution of slurry in broader bands seems a promising strategy in coarse sandy soils.

The dual mechanisms of composite biochar and biofilm towards sustainable nutrient release control of phosphate fertilizer: Effect on phosphorus utilization and crop growth

The low utilization rate of phosphorus fertilizers is a common concern and is caused by high leaching loss rates and rapid nutrient release. While the precipitation with soil components also brings a series of problems. To address these problems, we propose a composite biochar and a hydrophobic biofilm to act as a synergistic mechanism for nutrient release control and to provide the required nutrients for crop growth. We optimized the preparation of composite biochar materials (1:1.2, 1.5 h, 450 °C) and explored the nutrient loading mechanism by different adsorption kinetic model fitting. The fitting curve showed that PO43− best fit with the Redlich-Peterson model with a high correlation coefficient (R2 = 0.9933). The water contact angle of a cotton stalk hydrophobic membrane material was 109°. Leaching experiments showed phosphate leaching losses increased with an increase in the amount in hydrophobic biofilm (2%, 4%, 6%), which showed a decreasing trend of 24%, 16% and 10%, respectively. After 31 d of nutrient release, the cumulative release rate of HCP2 was 65%, which matched the growth demand of corn maize crops and had a significant effect on early maize growth. All agronomic data showed optimized root length (32.5 cm), plant height (58.7 cm), dry weight (0.527 g) and fresh weight (4.907 g). This showed that the phosphate fertilizer carrier and co-release system constructed by the combination of biochar and biofilm has great advantages in promoting crop growth and a sustainable agricultural economy.

Seed Priming with Multiwall Carbon Nanotubes (MWCNTs) Modulates Seed Germination and Early Growth of Maize Under Cadmium (Cd) Toxicity

Application of multiwall carbon nanotubes (MWCNTs) could have promotive effects on crop plants; however, their effects on seed germination and early growth of maize under cadmium (Cd) stress have rarely been investigated. A pot experiment was conducted with two maize varieties, Yuebaitiannuo7 and Yuecainuo2, grown under three Cd levels, i.e., 0, 100, and 200 mg L−1 (denoted as Cd0, Cd100, and Cd200, respectively) and three MWCNT levels, i.e., 0, 100, and 200 mg L−1 (denoted as M0, M100, and M200, respectively) as seed priming treatments to assess the MWCNT-induced modulations in seed germination rate, seedling growth, and related physio-biochemical attributes under Cd stress. Yuebaitiannuo7 showed higher seed germination rate and less root and shoot growth than Yuecainuo2. The MWCNT application promoted the seed germination rate of Yuecainuo2 by 11.42% at M100 and 24.76% at M200 under Cd100 at 4 days after sowing; however, these effects remained non-significant for Yuebaitiannuo7. Moreover, the MWCNTs enhanced root and shoot fresh weight and antioxidant enzyme activities, including peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) activities, and reduced the malonaldehyde (MDA) content under Cd across MWCNT treatments. Nevertheless, the toxic effects were also observed, indicating a potential risk posed by MWCNTs at high concentrations. Application of MWCNTs alleviated the Cd toxicity in growing maize plants; however, their effects were concentration dependent. Yuecainuo2 performed better than Yuebaitiannuo7 with the application of MWCNT under Cd stress.

Improved Aflatoxins and Fumonisins Forecasting Models for Maize (PREMA and PREFUM), Using Combined Mechanistic and Bayesian Network Modeling-Serbia as a Case Study.

Contamination of maize with aflatoxins and fumonisins is one of the major food safety concerns worldwide. Knowing the contamination in advance can help to reduce food safety risks and related health issues and economic losses. The current study aimed to develop forecasting models for the contamination of maize grown in Serbia with aflatoxins and fumonisins. An integrated modeling approach was used, linking mechanistic modeling with artificial intelligence, in particular Bayesian network (BN) modeling. Two of such combined models, i.e., the prediction model for aflatoxins (PREMA) and for fumonisins (PREFUM) in maize, were developed. Data used for developing PREMA were from 867 maize samples, collected in Serbia during the period from 2012 to 2018, of which 190 were also used for developing PREFUM. Both datasets were split randomly in a model training set and a model validation set. With corresponding geographical and meteorological data, the so-called risk indices for total aflatoxins and total fumonisins were calculated using existing mechanistic models. Subsequently, these risk indices were used as input variables for developing the BN models, together with the longitudes and latitudes of the sites at which the samples were collected and related weather data. PREMA and PREFUM were internally and externally validated, resulting in a prediction accuracy of PREMA of, respectively, 83 and 70%, and of PREFUM of 76% and 80%. The capability of PREMA and PREFUM for predicting aflatoxins and fumonisins contamination using data from the early maize growth stages only was explored as well, and promising results were obtained. The integrated approach combining two different modeling techniques, as developed in the current study, was able to overcome the obstacles of unbalanced data and deficiency of the datasets, which are often seen in historical observational data from the food safety domain. The models provide predictions for mycotoxin contamination at the field level; this information can assist stakeholders of the maize supply chain, including farmers, buyers/collectors, and food safety authorities, to take timely decisions for improved mycotoxin control. The developed models can be further validated by applying them into practice, and they can be extended to other European maize growing areas.

Negative impacts of excessive nitrogen fertilization on the abundance and diversity of diazotrophs in black soil under maize monocropping

Excessive nitrogen (N) fertilization (ENF) and low utilization efficiency of fertilizer-derived N in high-input, high-yield cropping systems are serious ecological and economic problems in China. To examine the effects of long-term ENF on soil diazotrophs in relation to maize growth, we performed a 5-year field trial whereby 0–300 kg N ha−1 were added to black soil under a maize monocropping system in Northeast China. At the end of the 5-year field trial, the abundance and community structure of diazotrophs in the bulk soil and rhizosphere were investigated at the maize jointing stage by real-time quantitative polymerase chain reaction (qRT-PCR) and high-throughput sequencing. The results showed that: 1) ENF (N300) limited maize growth in the early stages and did not increase grain yield compared with moderate N supplementation (N180); 2) ENF significantly reduced nifH copy number, species richness, and Shannon index values of soil diazotrophs by 53.7%–79.7%, 37.2%–47.6%, and 20.0%–31.6%, respectively, reduced the relative abundance of Burkholderia, and increased the relative abundance of Sphingobium; 3) ENF decreased soil pH and increased electrical conductivity, which were the main factors affecting soil diazotrophic community structure as determined by Mantel test; and 4) diazotrophs were 1.3–3.0 times more abundant in the rhizosphere than in bulk soil, but no differences in α-diversity and community composition of diazotrophs were observed between rhizosphere and bulk soil. Thus, long-term ENF has negative impacts on the soil diazotrophic community, inhibiting maize growth in the early stage. Split N fertilization or slow/controlled-released N fertilizer should be used to avoid the negative effects of ENF on the soil diazotrophic community structure and early maize growth.

Effect of watering frequency on germination and early growth of maize (Zea mays) seed

Maize (Zea mays) is one of the most important cereal crops grown principally during the raining season in Ethiopia which is commonly used for both human consumption and poultry feed. Green house experiment on the effect of watering frequency on germination and early growth of maize was carried out at Ambo Agricultural Research Center using a hybrid maize variety (Jibat) (Zea mays) from December 1 to January20th, 2018/19. The study was conducted to determine the effect of watering frequencies on germination and early growth of maize seed (Zea mays). The highland maize hybrid variety of AMH-851 (Jibat) was used as a test crop for the experiment. Three watering frequencies one day interval, three days intervals and five days intervals were used as an experimental treatment, and they were laid out in a Completely Randomized Design (CRD) with four replications. The watering frequencies showed statistically significant differences, on plant shoot length and biomass weight, but the treatments didn’t reveal statistical difference on seedlings emergence. Therefore, one day watering interval shows better performance on shoot length, fresh and dry biomass.