Maize In China Research Articles

The Fall Armyworm Spodoptera frugiperda Found on Rice Oryza sativa L. in China: Their Host Strain, Oviposition Preference and Survival Rate on Rice and Maize

The fall armyworm (FAW), Spodoptera frugiperda, is a serious pest that threatens a range of important crops worldwide. It originated in America and rapidly dispersed throughout Africa and Asia in 2018. There are two subtypes, corn-strain (C-strain) and rice-strain (R-strain), that have different host plant preferences, and the individuals damaging maize in China were identified as C-strain. In the present study, we found FAW individuals damaging rice plants in the field of Guangdong Province, China. FAW larvae and male adults were collected, and the majority of FAWs were characterized as CO I R-strain Tpi C-strain, which is similar to the FAWs damaging maize in China. The FAW adults preferred laying eggs on maize plants more than on rice plants. Compared to those that were fed maize leaves, the FAW larvae were unable to survive when fed 4-week-old rice plants, whereas they could complete their life cycle on 2-week-old rice plants, for which the total survival rate was 8%. The pre-adult- and pupal-stage durations were prolonged, and the fecundity of adult females decreased. Thus, the FAWs found in paddy fields showed better fitness on maize than on rice in the laboratory. Owing to their low survival rate on rice plants, they were unlikely to damage paddy fields in large areas, but populations of FAWs in paddy fields should be monitored.

High-efficiency fungicide screening and field control efficacy of maize southern corn rust

Southern corn rust caused by Puccinia dothidea is becoming one of the main diseases of maize planting in China, which seriously threatens the yield of maize in China. Currently, there is no registered pesticide to control southern corn rust in China. Therefore, it is urgent to screen out efficient pesticides to control southern corn rust and reduce the harm of multistem rust to maize yield in China. In the present study, the indoor virulence determination of spore-germination method and 2 years of field efficacy tests were used to screen the fungicides with good prevention and control efficacy on maize southern rust. The results of the indoor toxicity test in 2023 showed that the EC50 of P. dothidea to benzoflumizole was 0.0085 mg/L, and the sensitivity to thifluzamide was relatively poor, with an EC50 of 1.2585 mg/L. The mixture of pyraclostrobin and benzoflumizole at a ratio of 4:1 had the optimal synergistic effect, with an EC50 of 0.0181 mg/L and a cotoxicity coefficient of 128.36. The results of the field efficacy test revealed that 60 g/ha benzovinfluconazole had a good field control effect, and the control effect was 83.09%–85.95%. The combination of 30 g/ha benzodifluconazole and 93.75 g/ha pyraclostrobin had the optimal control effect, and the control effect was 86.92%–88.58% and safe for corn. The results indicated that the application of benzovindiflupyr and its mixture with pyraclostrobin had a good effect on the prevention and control of southern corn rust, which could provide a theoretical basis for the prevention and control of southern corn rust in production and scientific medication.

First report of Diaporthe eres causing white spot of maize in China

Maize (Zea Mays L.) is one of China's most widely grown cereals, a crucial food crop, and a vital source of feed and raw materials for various industries. In March 2023, a disease with typical white spot symptoms was observed on maize across 40% of the planted area in a farm field in Jiangcheng Hani and Yi Autonomous County, Yunnan Province, China. The disease initially showed water-soaked patches on leaves, which eventually faded to dark brown, forming irregular spots with yellow to brownish margins. The Dns14-1 strain, isolated from infected leaves, was identified as Diaporthe eres based on morphological and molecular identification. Pathogenicity tests found it to be one of the causal agents of white spots on maize leaves. To our knowledge, this is the first report of D. eres causing white spots on maize in China.

Does no-till crop management mitigate gaseous emissions and reduce yield disparities: An empirical US-China evaluation

Global agricultural systems face one of the greatest sustainability challenges: meeting the growing demand for food without leaving a negative environmental footprint. United States (US) and China are the two largest economies and account for 39 % of total global greenhouse gases (GHG) emissions into the atmosphere. No-till is a promising land management option that allows agriculture to better adapt and mitigate climate change effects compared to traditional tillage. However, the efficacy of no-till for mitigating GHG is still debatable. In this meta-analysis, we comprehensively assess the impact of no-till (relative to traditional tillage) on GHG mitigation potential and crop productivity in different agroecological systems and management regimes in the US and China. Overall, no-till in China did not change crop yields, although soil CO2 (8 %) and N2O (12 %) emissions decreased significantly, while soil CH4 emissions increased by 12 %. In contrast to Chinese no-till, a significant improvement in crop yields (up to 12 %) was recorded on US cropland under no-till. Moreover, significant decreases in soil N2O (21 %) and CH4 (12 %) emissions were observed. Of the three cropping systems, only wheat showed significant reduction in CO2, N2O and CH4 emissions in the Chinese no-till system. In the case of US, no-till soybean-rice and maize cropping systems demonstrated significant emission reductions for N2O and CO2, respectively. Interestingly, yields of no-till maize in China and rice in US exceeded those of other no-till cereals. In China, no-till on medium-texture soils resulted in significant reductions in GHG emissions and higher crop yields compared to other soil types. In both countries, the relatively higher crop yields under irrigated versus non-irrigated no-till and the significant yield differences on fine textured soils under US no-till are likely due to the substantial N2O reductions. In summary, crop yield disparities from no-till between China and the US were related to the insignificant effects on controlling CH4 emissions and successfully mitigating N2O, respectively. This study comprehensively demonstrates how cropping system and pedoclimatic conditions influence the relative effectiveness of no-till in both countries.

Spatiotemporal drought characteristics during growing seasons of the winter wheat and summer maize in the North China Plain

The North China plain (NCP) is an important production base for winter wheat and summer maize in China. Severe droughts seriously restrict agricultural production in this region, threatening food security. Based on the standardized precipitation evapotranspiration index (SPEI), this study explored the spatial and temporal drought characteristics during the winter wheat and summer maize growing seasons in the region. The study found that: 1) From 1980 to 2013, the drought trend of the winter wheat growing season in the NCP has intensified, with Huang-Huai Plain agricultural area (HH_P) showing the most significant drought trend. However, the summer maize growing season has become wetter, with the Shandong hilly agricultural and forestry area (SD_Q) showing the most significant wetting trend. 2) After the year 2003, the results from Mann-Kendall trend analysis revealed that the drought trend of HH_P during the winter wheat growing season became particularly pronounced, but the wetting trend of SD_Q and HH_P during the summer maize growing season became more evident. 3) The dominant spatial patterns observed in the NCP during the growing seasons of winter wheat and summer maize were marked by a consistent distribution of drought and wetness conditions. For winter wheat, the southern regions of the foothill plain area of Yanshan and Taihang Mountains (YT_P) and the low-lying plain area of Hebei, Shandong, and Henan (JLY_P) were more sensitive to the changes of drought and wet conditions. For summer maize, SD_Q was more sensitive to the changes of the drought and wet conditions. The results of this study could provide references for the formulation of drought relief strategies of winter wheat and summer maize in the NCP.

Competitive interactions between invasive fall armyworm and Asian corn borer at intraspecific and interspecific level on the same feeding guild.

Interspecific competition is an important factor in the population dynamics and geographical distribution of insect populations. Fall armyworm (FAW), Spodoptera frugiperda, an invasive species, and the Asian corn borer (ACB), Ostrinia furnacalis, a native pest species are major pests on maize in China, posing a threat to maize yield and grain quality. A series of laboratory, greenhouse, and field experiments were conducted to elucidate the competitive interactions between FAW and ACB. In the laboratory experiments, FAW exhibited aggressive behaviors more frequently when compared with ACB, while the latter species exhibited defense behaviors more frequently. Higher intraspecific competition was recorded in the FAW conspecific rather than in ACB, particularly in the 6th larval stage. FAW had a higher interspecific competitive advantage through intraguild predation over ACB, resulting in partial or complete displacement ACB when initially the ratio of the 2 species was 1 : 1. The interspecific competition also had significantly influenced on the population parameters, defensive enzymes, and nutrient of these 2 species. Competitive interaction proved that the response of superoxide, catalase, and soluble protein in FAW were significantly increased, whereas the total sugar content in both species was substantially decreased. Survival rate, and the plant damage that co-infested by both species varied significantly among the sequential combinations under greenhouse and field conditions. FAW consistently exhibited stronger intraspecific aggression than ACB under laboratory and field conditions when co-existing on the same feeding guild. These findings contribute to efforts toward the improvement of integrated pest management programs for FAW, in decision making for invasive and native pests' management strategies to reduce the high risks of FAW and ACB outbreaks.

Reduce carbon footprint without compromising system productivity: Optimizing crop rotation in the North China plain

The North China Plain (NCP) serves as a crucial production base for wheat and maize in China. However, the intensive winter wheat-summer maize (WM) cropping system has also led to high carbon emissions. It is imperative to optimize crop rotations to reduce greenhouse gas (GHG) emissions while ensuring food security. Thus, we conducted a 6-year field experiment in the NCP to evaluate the productivity, carbon footprint (CF), and sustainability of the five rotation systems. These included four 2-year rotation systems: spring maize → WM (WMME), spring millet → WM (WMML), spring peanut → WM (WMMP), and spring soybean→ WM (WMMS), with WM serving as the control. Our results indicated that the 2-year rotation systems significantly reduced GHG emissions and improved agricultural sustainability. Wheat yield following the spring crops was 38.6%–47.5% higher than that following summer maize. The energy use efficiency, energy productivity, maize economic equivalent yield (MEEY), and net income in WMMP were higher by 9.7%, 51.8%, 4.4%, and 15.5%, respectively, compared to WM. This was mainly attributed to the high yield, price, energy equivalent coefficient, and pre-crop effect of spring peanut. The reduction of N and electricity inputs in the 2-year rotation systems reduced on-farm N2O emissions and indirect emissions by 39.0%–56.2% and 41.9%–42.9%, respectively, thus lowering CF per unit area by 25.7%–36.6% compared with WM. WMMP demonstrated a 38.2% reduction in CF per kg MEEY, 16.1% reduction in CF per unit net energy, and 44.1% reduction in CF per unit net income, while increasing the sustainable evaluation index by 42.9% compared to WM. In conclusion, the 2-year rotation systems can reduce carbon footprint and improve agricultural sustainability in the NCP, among which the introduction of spring peanut into winter wheat-summer maize rotation can simultaneously enhance system productivity.

Residue determination and dietary risk assessment of mesotrione, nicosulfuron, atrazine and its four metabolites in maize in China

IntroductionTo improve maize yield in China, multiple herbicides have been simultaneously applied to control more weeds. However, this combined application raises concerns about potential residues and their subsequent risks to human health. Therefore, evaluating the residues and dietary risk of new herbicide formulations is critical for the sustainability of maize production.MethodsUsing UHPLC-MS/MS, we developed quick methods for the determination of residues of mesotrione, nicosulfuron, atrazine and its four metabolites with acceptable accuracy and precision. The limits of quantification (LOQs) were 0.01 mg/kg for mesotrione and atrazine-desethyl-desopropyl, and 0.005 mg/kg for nicosulfuron, atrazine, 6-deisopropyl atrazine, 2 hydroxyatrazine, and deethylatrazine. Field trials were conducted at 12 different locations in China. And the risk quotient (RQ) model was used to evaluate the chronic risk of residues of these herbicides.ResultsThe residues of straw samples were in the ranges of <0.01 mg/kg for mesotrione, <0.005–0.010 mg/kg for nicosulfuron, and <0.037–0.254 mg/kg for accumulated atrazine. In green straw, the observed ranges were <0.01 mg/kg for mesotrione, <0.005–0.007 mg/kg for nicosulfuron, and <0.037–0.211 mg/kg for accumulated atrazine. Meanwhile, for both green and fully-grown maize, residues were <0.01 mg/kg for mesotrione, <0.005 mg/kg for nicosulfuron, and <0.037 mg/kg for accumulated atrazine. And all RQ values of green and fully-grown maize were below 100%.ConclusionBased on the RQ model, the dietary risk of exposure to three herbicides through maize was acceptable by consumers. This study helps guide the rational use of mesotrione, nicosulfuron and atrazine to ensure the safe production of maize and our human health.

Identification, pathogenicity, and fungicide sensitivity of Eutiarosporella dactylidis associated with leaf blight on maize in China

Maize (Zea mays L.) is an economically vital grain crop that is cultivated worldwide. In 2011, a maize foliar disease was detected in Lingtai and Lintao counties in Gansu Province, China. The characteristic signs and symptoms of this disease include irregular chlorotic lesions on the tips and edges of infected leaves and black punctate fruiting bodies in dead leaf tissues. Given favourable environmental conditions, this disease spread to areas surrounding Gansu. In this study, infected leaves were collected from Gansu and Ningxia Hui Autonomous Region between 2018 and 2020 to identify the disease-causing pathogen. Based on morphological features, pathogenicity tests, and multi-locus phylogenetic analysis involving internal transcribed spacer (ITS), 18S small subunit rDNA (SSU), 28S large subunit rDNA (LSU), translation elongation factor 1-alpha (TEF), and β-tubulin (TUB) sequences, Eutiarosporella dactylidis was identified as the causative pathogen of this newly discovered leaf blight. Furthermore, an in vitro bioassay was conducted on representative strains using six fungicides, and both fludioxonil and carbendazim were found to significantly inhibit the mycelial growth of E. dactylidis. The results of this study provide a reference for the detection and management of Eutiarosporella leaf blight.

CN‐N: A gridded dataset of nitrogen rate for rice, wheat and maize in China developed using the county‐level nitrogen statistics

AbstractExisting agricultural nitrogen datasets in China are mostly developed using coarse national or provincial statistics. A crop‐specific nitrogen rate dataset based on the finest‐scale agricultural nitrogen statistics at the county level remains lacking. Here, we constructed a new dataset (CN‐N), which provides annual nitrogen rates for rice, wheat and maize in China at a 1‐km spatial resolution from 2004 to 2016. This dataset was developed by harmonizing county‐level and provincial agricultural nitrogen statistics with gridded crop distribution maps, resulting in 13 years of nitrogen rate maps for each crop covering 2004–2016. Validation against farmers' surveys by crop indicates CN‐N reliably quantifies average nitrogen rates and trends for each crop over 2004–2016, demonstrating improved spatial heterogeneity compared to previous datasets rasterized using only provincial statistics. Our study provides a crop‐specific, temporally consistent, gridded nitrogen rate dataset based on the finest‐scale county‐level agricultural nitrogen statistics. This can support future process‐based modelling for sustainable agricultural nitrogen management strategies.

Characterization of mating type, spore killing, and pathogenicity of Fusarium verticillioides populations from maize in China

Sexual reproduction in fungi promotes genetic diversity and helps the fungus to adapt to environmental stresses. Fusarium verticillioides is a heterothallic filamentous ascomycete that is a major cause of maize ear and stalk rot worldwide, while also posing a threat to human and animal health by producing various mycotoxins. Sexual reproduction in F. verticillioides is controlled by the MAT-1 and MAT-2 loci, which mandate that only strains of opposite mating types can mate to yield perithecia and ascospores. Nevertheless, there exists a phenomenon called ‘spore killing’, in which only four typical ascospores appear in the asci following a cross between a strain carrying the spore killer allele (SkK) and one with the spore killer sensitive allele (SkS). In this study, 31 isolates of F. verticillioides collected from eight provinces in China during the maize growing season from 2014 to 2020 were compared based on their mating type, spore killing genotype, and pathogenicity. To determine the mating types and spore killing genotypes of these isolates, partial sequences were amplified from the MAT loci and the SKC1 gene, respectively. The PCR results showed that out of the 31 isolates, 18 were MAT-1 and 13 were MAT-2, and that 25 had SkK genotypes and 6 had SkS genotypes. Genetic crosses between LNF15-11 (MAT-2) and 18 MAT-1 isolates produced normal perithecia with varying numbers. However, crosses between LNF15-11 and the 3 isolates (SDF18-36, HNF14-8, and GSF19-6) produced only four ascospores per ascus, while the remaining isolates except SDF18-28, yielded eight ascospores per ascus. These findings suggest that the SKC1 amplicon variation can be used to differentiate SkK and SkS genotypes in the field and that the 3 isolates are truly SkS genotypes with the MAT-1 allele. Altogether, this study contributes to our knowledge of the mating type and spore killing genotype of F. verticillioides in China and offers valuable strain resources for investigating heterothallic sexual reproduction.

Shallow-buried drip irrigation promoted the enrichment of beneficial microorganisms in surface soil

The Xiliao River plain is situated in the “Golden Belt of maize production worldwide” and it is one of the few high-yield areas of well-irrigated maize in China. Drip irrigation is recognized as one of the most water-efficient techniques for farmland irrigation. However, because of the flawed recovery mechanism of plastic film, many years of continuous accumulation of plastic film mulch have resulted in a considerable amount of plastic film residue in the soil, extensively harming the soil environment. This study aimed to investigate the effects of two primary irrigation methods, shallow-buried drip irrigation and under-mulch drip irrigation, with varying levels of irrigation on soil microbial diversity in the Xiliao River plain. A split-plot experiment was conducted, and the amount of irrigation was sub-treated at three levels: 40% (1440 m3 ha−1), 50% (1800 m3 ha−1), and 60% (2160 m3 ha−1) of that used for traditional irrigation. We studied the effects of water saving on soil bacteria and fungi using high-throughput sequencing. The results showed that in the 0–20 cm soil layer, with the same irrigation, the operational taxonomic unit number of bacteria in shallow-buried drip irrigation was greater than that of the under-mulch drip irrigation. In the 20–40 cm soil layer, as irrigation decreased, the operational taxonomic unit numbers of bacteria and fungi in both drip irrigation methods decreased. There was a significant difference in the relative abundance of microorganisms between the two drip irrigation methods with 50% irrigation. Compared with film drip irrigation, shallow-buried drip irrigation increased the relative abundance of Proteobacteria, Bacteroidetes, Firmicutes, and Acidobacteria in the 0–20 cm soil layer and increased the relative abundance of Proteobacteria and decreased the relative abundance of Firmicutes in the 20–40 cm soil layer. With reduced shallow-buried drip irrigation, the relative abundance of Pseudomonas initially decreased and then increased, whereas the abundance of other genus pairs remained stable. Under-mulch drip irrigation reduced the stability of the soil microbial network in the topsoil. With decreasing irrigation, the relative abundance of Zygomycota, Glomeromycota, and Chytridiomycota increased in the 0–40 cm soil layer when using shallow-buried drip irrigation, whereas the relative abundance of Zygomycota and Chytridiomycota decreased when using under-mulch drip irrigation. Shallow-buried drip irrigation enriched microbial communities, which were significantly positively correlated with organic matter and available nutrient content, including Holophagae, which prefers a dominant plant rhizosphere soil, Thermoanaerobaculaceae, which plays an important role in nitrogen transformation, and Microtrichales, which is crucial for the hydrolysis and utilization of complex organic matter. The microplastic-degrading Nocardioidaceae was enriched in the soil of under-mulch drip irrigation, and Propionibacteriales, which maintained a high proportion of species under high salinity, were enriched in the soil of under-mulch drip irrigation.

First Report of Penicillium oxalicum Causing Leaf Blight on Maize in China.

In August 2022, two-month-old maize plants (Zea mays cv. 'Zihei'; "Chinese purple corn") exhibited irregular lesions on leaves and leaf blight symptoms (Figure 1). Although the lesions were yellow at the early infection stages, they turned brown during the pathogen advancement and culminated in leaf blight. Nearly 60% of plants from a non-commercial maize field (0.2 ha) in south-eastern Jiangsu (Nantong municipality, China; 120.54º E, 31.58º N) exhibited brown lesions, and about 4% of the diseased plants showed advanced leaf blight symptoms. The disease resulted in approximately a 9% yield loss compared to previous years when no disease symptoms were observed. Thirty small leaf pieces, approximately 0.3 cm2 in size and showing disease symptoms, were surface sterilized in 1.5% NaOCl for 1 min and washed twice with sterile ddH2O. The pathogen was cultured on PDA medium in the dark at 25 ºC, with grayish colonies observed after 5 days. Morphological analysis showed the presence of round/oval conidia (8.81 ± 0.50 μm diameter; n = 86) and branched conidiophores, which was consistent with the morphology of Penicillium spp. (Visagie et al. 2014). Nine representative isolates were obtained from different leaf pieces via single spore isolation, and the internal transcribed spacer (ITS), β-tubulin (TUB2) and calmodulin (CMD) genes were amplified using ITS1/ITS4, BT2a/BT2b and CMD5/CMD6 primers, respectively. The obtained ITS (OP954496-OP954497 and OP942428-OP942434), TUB2 (OP966781-OP966784 and OQ025045-OQ025049) and CMD (OQ078664-OQ078672) sequences were submitted in GenBank. Two isolates belonged to the P. citrinum species, while seven of the isolates belonged to the P. oxalicum species. A blast search revealed that the obtained P. citrinum ITS and CMD sequences had 99.39% and 100% homology to the ex-type strain P. citrinum NRRL 1841; GenBank numbers: AF033422 and GU944638 (Peterson & Horn 2009). Additionally, the obtained P. oxalicum ITS and CMD sequences had 99.82-100% and 94.64-95.49% homology to the ex-type strain P. oxalicum NRRL 787; GenBank numbers: AF033438 and KF296367 (Visagie et al. 2015). A molecular phylogenetic tree was constructed using MEGA7 to confirm the identity of the pathogen (Figure 2). To confirm pathogenicity, 3-week-old healthy 'Zihei' plants were used. The leaves were sprayed with aqueous solutions (sterilized ddH2O) that contained 1 × 106 spores/mL of each isolate. For the control experiment, sterilized ddH2O was used. After 5 days in a growth chamber at 25 ºC and 70% relative humidity, yellow lesions were observed. The number of lesions was higher when inoculating with P. oxalicum than when inoculating with P. citrinum. This result, together with the higher occurrence of P. oxalicum isolates, suggests that P. oxalicum is the main species causing the disease symptoms. The pathogen was recovered from the infected plants, and its identity was confirmed by ITS sequencing and morphological analysis. As far as we know, this is the first report of P. citrinum and P. oxalicum causing maize leaf blight worldwide. These species have previously been associated with maize kernels, as a source of mycotoxins posing relevant hazards to human health (Keller et al. 2013; Yang et al. 2020). P. citrinum was recently identified as the causal agent of green mold on Dictyophora rubrovalvata in China (Qin et al. 2022), while P. oxalicum was reported to cause citrus rot, pineapple leaf spot, and blue mold on Gastrodia elata, Astralagus membranaceus and muskmelon (Tang et al. 2020; Wu et al. 2022; Zheng et al. 2022). China is one of the world's largest producers of maize, harvesting more than 171 million tons in 2021. This report will help to better understand the pathogens that affect China's maize production.

Tracking indirect water footprints, virtual water flows, and burden shifts related to inputs and supply chains for croplands: A case for maize in China

Increasing crop yields to ensure an adequate food supply under water and land scarcity is dependent on intensive agricultural inputs (such as fertilizers, pesticides, agri-films, or energy) which consume water resources and generate water pollution. However, the burden shifting of water quantity and quality stress from producers to importer and consumers through agricultural input production, trade, and consumption have been largely overlooked. Here, taking maize in China as the study case, we mapped step-by-step indirect water footprint (IWF) of maize production, virtual water (VW) flows related to inputs driven by maize consumption, and the resulting burden shifting of water quantity and quality. Bottom-up WF accounting approach was applied. The maize consumption was intercepted into two stages: the crop production stage (CPS) from raw materials to the farm, and the crop trade stage (CTS) from farm to fork. Results show that the national average blue and grey IWF of maize production was 3.91 and 26.86 m3/t, respectively. In the CPS, the input-related VW flowed from the west and east coast to the north. In the CTS, the VW flows from the north to the south. Blue and grey VW flows in CTS caused by secondary flows of VW in CPS accounted for 48% and 18% of the total flows, respectively. In total VW flows along the maize supply chain, 63% of blue VW and 71% of grey VW net exports occurred in the north of severe water scarcity and water pollution levels. The analysis highlights the impact of the crop supply chain on water quantity and water quality in the consumption of agricultural inputs, the importance of step-by-step supply chain analysis for regional crop water conservation management, and the urgent need for integrated management of agricultural and industrial water resources.

1 km-resolution gridded dataset of phosphorus rate for rice wheat and maize in China over 2004–2016

Crop-specific, high-resolution phosphorus rate information is essential for sustainable agricultural fertilizer management in China. However, substantial uncertainties exist in the current phosphorus fertilizer dataset because of only coarse national statistics used in dataset development and no crop-specific information provided. This study harmonized provincial and county-level phosphorus and component fertilizer statistics and crop distribution data to generate 1 km gridded maps of phosphorus rate for rice, wheat and maize in the years of 2004–2016 (CN-P). CN-P provides a comparable estimate on phosphorus rate for each crop over 2004–2016, and demonstrates an improved spatial heterogeneity. Existing dataset developed using national statistics tends to smooth out the variability within country and significantly underestimates actual phosphorus rate. CN-P shows that, during 2004–2016, wheat received the most phosphorus rate (8.7 g P2O5 m−2), while maize showed the rapidest increasing trend (2.36% yr−1). The CN-P dataset has the potential to be widely applied in modeling studies on sustainable agricultural fertilizer management strategies and phosphorus pollution.

First report of Corn Ear Rot Caused by Fusarium asiaticum in China.

Corn (Zea maysL.) ear rot, caused by various pathogens, is one of the most significant diseasesofcorn worldwide. In September 2020, a survey was undertaken to identify pathogenic fungi associated with corn ear rot in Suihua city (46.63°N 126.98°E), Heilongjiang Province, China. The average disease incidence was 14.2% and 15.6% in each of two fields sampled (~5 ha) usingafive-pointmethod (100 plants/each point). Twenty tissue samples from 20 diseased ears, showing white or pink mold on the surface of corn ears, were surface disinfected in 0.5% NaOCl for 5 min, rinsed 3 times in autoclaved distilled water. After drying, four treated corn kernels (one kernel/each ear) were placed onto potato dextrose agar (PDA) amended with 50 µg/mL streptomycin. The plates were sealed with parafilm sealing film and cultured in the dark at 26℃ with 80% RH for 3 days inanincubator. A total of 12 morphologically similar fungal isolates were obtained and subcultured by transferring hyphal tips for 3-5 days. Single-conidium isolates were generated with methods reported previously (Leslie and Summerell 2006). Colonies on PDA, reaching 20.3-20.9 mm·d-1 at 26℃, consisted of white to pale yellow, locculent, lush and dense aerial mycelium with red to apricot color. Macroconidia of six isolates randomly selected on carnation leaf agar (CLA) were falciform with a foot cell, three- to six-septate, measuring 12.6-67.2 × 2.6-5.4 µm (n = 100) in the dark at 26℃ with 80% RH for 5 days. No microconidia were observed. Based on these characteristics, the isolates were preliminarily identified asFusarium asiaticum (Chang et al. 2020; Leslie and Summerell 2006). Genomic DNA of three representative isolates YSF2, YSF4 and YSF7 were extracted and the translation elongation factor 1-α (TEF-1ɑ) gene was amplified and sequenced using the primers EF1-728F/EF1-986R (Carbone and Kohn 1999). The DNA sequences of YSF2, YSF4 and YSF7 were deposited in GenBank (OL631287.1, OP272129 and OP272130). Analysis of TEF-1ɑ sequences of YSF2, YSF4 and YSF7 showed that they were 100% identical to F. asiaticumisolates NRRL 26156 (AF212452.1) in NCBI and NRRL 13818 (AF212451.1) in Fusarium MLST. A pathogenicity test was performed on corn cv. Xinxin 1. Four days after silk emergence, 3 mL conidial suspension (106 macroconidia/ml) of each 12 isolates was individually injected into the center of the ear through the husk sideways, penetrating the kernels to a depth of about 5 mm (6 ears/each isolate) in the field (Guo et al. 2020). Six corn ears treated with sterile distilled water were used as the control. After inoculation, normal field management was carried out. All inoculated ears showed symptoms similar to those observed in the field 50 days after inoculation, while no symptoms were observed on the blank control ears. Five fungal isolates with the same colony morphology as the naturally occurring ear rot in the field were re-isolated from the inoculated corn kernels and confirmed to be F. asiaticum according to morphological characteristics and sequence analysis of five fungal isolates. F. asiaticum has previously been reported to cause corn ear rots in Japan (Kawakami et al. 2015). To our knowledge, this is the first report of F. asiaticum causing corn ear rot in Northeast China. Corn ear rot poses a threat to significantly reduce the quality of corn in a major production zone of maize in China. Therefore, its distribution needs to be investigated and effective disease management strategies developed.

Seven Years of Monitoring Susceptibility to Cry1Ab and Cry1F in Asian Corn Borer.

Resistance monitoring in the Asian corn borer, Ostrinia furnacalis, is necessary to accommodate the commercial introduction and stewardship of Bt maize in China. The susceptibility of 56 O. furnacalis field populations, collected between 2015 and 2021 from the corn belt regions of China, to Cry1Ab and Cry1F toxins was determined. Neonate larvae (within 12 h after hatching) were placed on the surface of semi-artificial agar-free diet incorporating a series of concentrations of purified toxins, and mortality was evaluated after 7d. The median lethal concentration (LC50) values of Cry1Ab and Cry1F were 0.05 to 0.37 µg/g (protein/diet) and 0.10 to 1.22 µg/g, respectively. Although interpopulation variation in susceptibility to the toxins was observed, the magnitude of the differences was 5.8-fold and 8.3-fold for Cry1Ab and Cry1F, respectively. These results suggested that the observed susceptibility differences reflect natural geographical variation in response and not variation caused by prior exposure to selection pressures. Therefore, the O. furnacalis populations were apparently still susceptible to Cry1Ab and Cry1F across their range within China. The monitoring data established here will serve as a comparative reference for early warning signs of field-evolved resistance after the cultivation of Bt maize in China.

Impact of weather parameters on maize agroecosystem and adaptation strategies under changing climatic conditions: A review: Sustainable and climate-resilient adaptation strategies in maize agroecosystem

Change in precipitation patterns and increase in the frequency and intensity of extreme weather events (high temperatures and heat waves) harm crop productivity. As per the future prediction, the temperature may increase by 2.5 0C by 2050 and by 2-30 C by the end of the century. The present review evaluates the impact of a rise and fall in temperature, solar radiation, and CO2 on the productivity of maize and other crops. Agronomic management practices during the crop growth period of selecting crop cultivars, date of sowing, plant population, dosage, timing, and methods of application of inputs are influenced by temperature, rainfall, solar radiation, and CO2 concentration in the atmosphere. Overall crop productivity will reduce by 50.9 % in wheat in the USA, 46% in maize in China,17% in cotton in India, and 30% in sugarcane in India. Changing the sowing date and adopting improved early and short-duration varieties of corn and other crops are becoming significant under low-cost adoption technologies to mitigate climate change. Info Crop-SORGHUM simulation model predicts that change in the sowing date of a variety in sorghum reduces the impact of climate change and vulnerability to 1- 2 % by 2020, 3-8 % by 2050, and 4-9% by 2080. The review highlights the impact of heat stress and drought on soil processes, and overall soil health. The authors conclude to implement climate adoption technologies based on Agriculture 4.0 to sustain crop production globally.

ChinaCropSM1 km: a fine 1 km daily soil moisture dataset for dryland wheat and maize across China during 1993–2018

Abstract. Soil moisture (SM) is a key variable of the regional hydrological cycle and has important applications for water resource and agricultural drought management. Various global soil moisture products have been mostly retrieved from microwave remote sensing data. However, currently there is rarely spatially explicit and time-continuous soil moisture information with a high resolution at the national scale. In this study, we generated a 1 km soil moisture dataset for dryland wheat and maize in China (ChinaCropSM1 km) over 1993–2018 through a random forest (RF) algorithm based on numerous in situ daily observations of soil moisture. We independently used in situ observations (181 327 samples) from the agricultural meteorological stations (AMSs) across China for training (164 202 samples) and others for testing (17 125 samples). An irrigation module was first developed according to crop type (i.e., wheat, maize), soil depth (0–10, 10–20 cm) and phenology. We produced four daily datasets separately by crop type and soil depth, and their accuracies were all satisfactory (wheat r 0.93, ubRMSE 0.033 m3 m−3; maize r 0.93, ubRMSE 0.035 m3 m−3). The spatiotemporal resolutions and accuracy of ChinaCropSM1 km were significantly better than those of global soil moisture products (e.g., r increased by 116 %, ubRMSE decreased by 64 %), including the global remote-sensing-based surface soil moisture dataset (RSSSM) and the European Space Agency (ESA) Climate Change Initiative (CCI) SM. The approach developed in our study could be applied to other regions and crops in the world, and our improved datasets are very valuable for many studies and field management, such as agricultural drought monitoring and crop yield forecasting. The data are published in Zenodo at https://doi.org/10.5281/zenodo.6834530 (wheat0–10) (Cheng et al., 2022a), https://doi.org/10.5281/zenodo.6822591 (wheat10–20) (Cheng et al., 2022b), https://doi/org/10.5281/zenodo.6822581 (maize0–10) (Cheng et al., 2022c) and https://doi.org/10.5281/zenodo.6820166 (maize10–20) (Cheng et al., 2022d).

Optimization of sowing date for spring maize in China's loess plateau based on presowing temperature and soil water content.

The sowing date of spring maize in China's Loess Plateau is often restricted by the presowing temperature and soil water content (SWC). The effective measurement of the effects of presowing temperature and SWC on the sowing date is a major concern for agricultural production in this region. In this paper, we considered the average daily air temperature of ˃10 °C in the 7 days before sowing. The Decision Support System for Agrotechnology Transfer (DSSAT) model was used to simulate a spring maize yield under distinct combinations of SWC and sowing date for 51 years (1970-2020). Subsequently, through the cumulative probability distribution function, the contribution of presowing SWC to the spring maize yield was quantified, and the optimal sowing date of spring maize in each production location was determined. The results revealed that the daily average temperature of ˃10 °C for 7 days consecutively can be used effectively as the basis for the simulation of spring maize sowing date. The presowing SWC affected the spring maize yield but did not change the optimal sowing date. When the SWC of each study site is about 70% of the field capacity, Wenshui and Yuanping can properly delay sowing, and Lin county can sow early to obtain a higher yield. This study provides an effective approach for optimizing presowing soil moisture management and the sowing date of spring maize in the semiarid regions of the Loess Plateau. © 2023 Society of Chemical Industry.