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Future climate scenarios are predicting considerable threats to sustainable maize production in arid and semi-arid regions. These adverse impacts can be minimized by adopting modern agricultural tools to assess and develop successful adaptation practices. A multi-model approach (climate and crop) was used to assess the impacts and uncertainties of climate change on maize crop. An extensive field study was conducted to explore the temporal thermal variations on maize hybrids grown at farmer’s fields for ten sowing dates during two consecutive growing years. Data about phenology, morphology, biomass development, and yield were recorded by adopting standard procedures and protocols. The CSM-CERES, APSIM, and CSM-IXIM-Maize models were calibrated and evaluated. Five GCMs among 29 were selected based on classification into different groups and uncertainty to predict climatic changes in the future. The results predicted that there would be a rise in temperature (1.57–3.29 °C) during the maize growing season in five General Circulation Models (GCMs) by using RCP 8.5 scenarios for the mid-century (2040–2069) as compared with the baseline (1980–2015). The CERES-Maize and APSIM-Maize model showed lower root mean square error values (2.78 and 5.41), higher d -index (0.85 and 0.87) along reliable R 2 (0.89 and 0.89), respectively for days to anthesis and maturity, while the CSM-IXIM-Maize model performed well for growth parameters (leaf area index, total dry matter) and yield with reasonably good statistical indices. The CSM-IXIM-Maize model performed well for all hybrids during both years whereas climate models, NorESM1-M and IPSL-CM5A-MR, showed less uncertain results for climate change impacts. Maize models along GCMs predicted a reduction in yield (8–55%) than baseline. Maize crop may face a high yield decline that could be overcome by modifying the sowing dates and fertilizer (fertigation) and heat and drought-tolerant hybrids.

The recent introduction of maize chlorotic mottle virus (MCMV) and spread of the resulting maize lethal necrosis disease (MLN) in East Africa presents a threat to maize production in all Southern African countries. As MLND is the result of the synergistic action of MCMV and various cereal-infecting potyviruses, the existing virus status of maize in KwaZulu-Natal, a province of South Africa bordering Mozambique and Eswatini, was determined. Additional viruses identified in MLND affected plants in East Africa previously were also tested for in this study, including maize streak virus (MSV), Morogoro maize-associated virus (MMaV), maize-associated pteridovirus (MaPV), and two maize-associated totivirus (MATV) variants. No MCMV or potyvirus infections were detected. MSV was identified in 29% of the pools (consisting of five plants each), MaPV was detected in three plants, while only a single plant tested positive for MMaV. The presence of MMaV and MaPV was confirmed with next generation sequencing (NGS) and their complete/near complete genome sequences assembled. MMaV was also further confirmed with additional PCR primer sets. This is the first time MMaV and MaPV have been reported in South Africa. Two distinct MATV variants and two Zea mays chrysovirus 1 strains were also detected using NGS but no further tests were conducted, hence, these findings remain preliminary. Future research is required to determine the incidence and distribution of these new viruses in South Africa, their mode(s) of transmission, and effects on maize yield to determine the possible risk they may pose to the South African maize industry.

Understanding how fertilizer application (particularly N, the most used chemical fertilizer worldwide) interacts with soil microbes is important for the development of best management practices that target improved microbial activity to enhance sustainable food production. This study was conducted to determine whether urea N rate and time of application to maize (Zea mays) influenced soil enzyme activity. Enzyme activity was determined by monitoring fluorescein diacetate (FDA) hydrolysis, ß-glucosidase, acid-phosphomonoesterase, and arylsulfatase activities. Experiments were conducted from 2014 through 2016 to compare single (fall or spring applications) and split applications of N at varying N rates under irrigation (Becker) and rainfed conditions (Lamberton and Waseca) in MN, USA. Nitrogen rates varied by location and were based on University of Minnesota guidelines. Soil samples were collected seven times each season. Nitrogen application split into two applications increased FDA activity by 10% compared with fall and spring applied N at Waseca. Fall or spring N application decreased arylsulfatase activity by 19% at Becker and by between 13% and 16% at Lamberton. ß-Glucosidase and acid-phosphomonoesterase activities were unaffected by N application. Sampling time and year had the greatest impact on enzyme activity, but the results varied by location. A negative linear relationship occurred between FDA and ß-glucosidase activity at all three sites. In summary, urea N application had small effects on enzyme activity at the sites studied, suggesting that some form of organic N could be more important than the ammonium provided by urea.

A survey to identify the distribution of virus diseases of maize was made in major maize growing regions of Ethiopia. Four surveys were conducted between 2015 and 2017. A total of 284 maize fields have been surveyed, of which 846 leaf samples with virus like disease symptoms were collected from 191 fields. There were no symptoms indicating for virus presence in maize grown in 93 fields which were exempted from sampling, while in contrast up to 100% disease incidence was recorded in maize grown in the Benishangul-Gumuz, Oromia and South Nations, Nationalities and People (SNNP) regions. Symptoms varied in maize ranging from the most common mosaic and streak to severe leaf mottling and necrosis as well as stunting and pre-mature plant death. Double or triple antibody sandwich (DAS or TAS) enzyme-linked immuno-sorbent assay (ELISA) to test for eight common maize viruses such as Maize chlorotic mottle virus (MCMV), Sugarcane mosaic virus (SCMV), Maize streak virus (MSV), Maize dwarf mosaic virus (MDMV), Maize mosaic virus (MMV), Maize stripe virus (MSpV), Wheat streak mosaic virus (WSMV) and Johnsongrass mosaic virus (JGMV) confirmed the presence of MCMV, SCMV and MSV in the leaf samples. Single or mixed infections with MCMV and SCMV frequently occurred and triple infections of MCMV, SCMV and MSV were found in 1% of samples from SNNP region. Sequence analysis of the coat protein genes of randomly selected seropositive samples of the three viruses showed little variability within the studied isolates and those retrieved from the GenBank. Our results indicated maize lethal necrosis disease (MLND) caused by MCMV and SCMV co-infection was the most important disease in SNNP and Oromia while maize streak disease was the predominant virus infecting maize in Benishangul-Gumuz.

Maize plays a vital role in enhancing food security, particularly in regions facing agricultural challenges such as poor soil conditions, erratic rainfall, and limited access to resources. It can be advantageous for smallholder farmers in developing countries, where it can enhance productivity on limited land and under suboptimal soil conditions. One of the potential means for improving crop yield under suboptimal soil conditions, such as acidic soils, is the application of soil amendments. However, the combined effects of functionalized biochar (a pyrogenic carbon) and microbes on phosphorus (P) bioavailability and plant growth performance are still not well understood. This study investigates the optimization of transplanted maize growth in acidic soil through the application of rice husk biochar (RHB) that was oxidized with 10% hydrogen peroxide and inoculated with Pseudomonas aeruginosa, a phosphate-solubilizing bacterium. The oxidized biochar’s pH was adjusted to 6.2 to enhance its effectiveness in challenging soil conditions. Soil properties and maize performance were determined using a pot culture. Results showed that the combined use of 10% oxidized RHB and Pseudomonas aeruginosa significantly increased P availability and phosphatase enzyme activity by 435% and 418%, respectively. Additionally, 10% Oxidized RHB treatment, microbes treatment and combination of biochar and microbes treatment showed yield increment 52%, 51% and 313% respectively, demonstrating the effectiveness of the treatment in improving soil fertility and crop productivity. This improvement in yield might have occurred due to an increase in soil pH, P bioavailability, and a reduction in Al toxicity since there were significant positive relationships between yield and soil pH and available P and a negative relationship with available Al concentration. These findings underscore the potential of integrating oxidized biochar and beneficial microbes, Pseudomonas aeruginosa, to enhance crop performance in acidic soils.

Secondary soil salinization in arid and semi-arid regions is a serious problem that severely hampers local agricultural productivity and poses a threat to the long-term sustainability of food production. the utilization of organic soil amendments presents a promising approach to mitigate yield losses and promote sustainable agricultural production in saline-alkali soil. In this study, we established four distinct treatments, chemical fertilizer (CK), humic acid with chemical fertilizer (HA), carboxymethyl cellulose with chemical fertilizer (CMC), and amino acid with chemical fertilizer (AA), to elucidate their respective impacts on the reclamation of saline soil and the growth of maize. The findings of our study reveal notable variations in desalination rates within the 0-40 cm soil layer due to the application of distinct soil amendments, ranging from 11.66% to 37.17%. Moreover, application of amendments significantly increased the percentage of soil macro-aggregates as compared to the CK treatment. Furthermore, HA and AA treatments significantly augmented soil nutrient content (HA: 48.07%; AA: 39.50%), net photosynthetic rate (HA: 12.68%; AA: 13.94%), intercellular CO 2 concentration (HA: 57.20%; AA: 35.93%) and maize yield (HA:18.32%; AA:16.81%). Correlation analysis and structural equation modeling unveiled diverse mechanisms of yield enhancement for HA, CMC, and AA treatments. HA enhanced yield by increasing organic matter and promoting soil aggregate formation, CMC improved soil water content and facilitated salt leaching due to its excellent water-holding properties, while AA increased yield by elevating soil organic matter and effective nitrogen content. Among the array of soil amendment materials scrutinized, HA treatment emerged as the most promising agent for enhancing soil conditions and is thus recommended as the preferred choice for treating local saline soils.

Climate change has a distinct impact on agriculture in China, particularly in the northeast, a key agriculture area sensitive to extreme hydroclimate events. Using monthly climate and agriculture data, the influence of drought on maize and soybean yields—two of the main crops in the region—in northeast China since 1961 to 2017 were investigated. The results showed that the temperature in the growing season increased by 1.0 °C from the period 1998–2017 to the period 1961–1980, while the annual precipitation decreased slightly. However, precipitation trends varied throughout the growing season (May–September), increasing slightly in May and June, but decreasing in July, August and September, associated with the weakening of the East Asian summer monsoon. Consequently, the annual and growing season drought frequency increased by 15%, and 25%, respectively, in the period 1998–2017 relative to the period 1961–1980. The highest drought frequency (55%) was observed in September. At the same time, the drought intensity during the growing season increased by 7.8%. The increasing frequency and intensity of drought had negative influences on the two crops. During moderate drought years in the period 1961–2017, 3.2% and 10.4% of the provincial maize and soybean yields were lost, respectively. However, during more severe drought years, losses doubled for soybean (21.8%), but increased more than four-fold for maize (14.0%). Moreover, in comparison to the period 1961–1980, a higher proportion of the yields were lost in the period 1998–2017, particularly for maize, which increased by 15% (increase for soybean was 2.4%). This change largely depends on increasing droughts in August and September, when both crops are in their filling stages. The impact of drought on maize and soybean production was different during different growth stages, where a strong relationship was noted between drought and yield loss of soybean in its filling stage. Given the sensitivity of maize and soybean yields in northeast China to drought, and the observed production trends, climate change will likely have significant negative impacts on productivity in the future.

In maize, doubled haploid (DH) lines are created in vivo through crosses with maternal haploid inducers. Their induction ability, usually expressed as haploid induction rate (HIR), is known to be under polygenic control. Although two major genes ( MTL and ZmDMP ) affecting this trait were recently described, many others remain unknown. To identify them, we designed and performed a SNP based (~9007) genome-wide association study using a large and diverse panel of 159 maternal haploid inducers. Our analyses identified a major gene near MTL , which is present in all inducers and necessary to disrupt haploid induction. We also found a significant quantitative trait loci (QTL) on chromosome 10 using a case-control mapping approach, in which 793 noninducers were used as controls. This QTL harbors a kokopelli ortholog, whose role in maternal haploid induction was recently described in Arabidopsis. QTL with smaller effects were identified on six of the ten maize chromosomes, confirming the polygenic nature of this trait. These QTL could be incorporated into inducer breeding programs through marker-assisted selection approaches. Further improving HIR is important to reduce the cost of DH line production.

Consequences of drought stress in crop production systems are perhaps more deleterious than other abiotic stresses under changing climatic scenarios. Regulations of physio-biochemical responses of plants under drought stress can be used as markers for drought stress tolerance in selection and breeding. The present study was conducted to appraise the performance of three different maize hybrids (Dong Dan 80, Wan Dan 13, and Run Nong 35) under well-watered, low, moderate and SD conditions maintained at 100, 80, 60, and 40% of field capacity, respectively. Compared with well-watered conditions, drought stress caused oxidative stress by excessive production of reactive oxygen species (ROS) which led to reduced growth and yield formation in all maize hybrids; nevertheless, negative effects of drought stress were more prominent in Run Nong 35. Drought-induced osmolyte accumulation and strong enzymatic and non-enzymatic defense systems prevented the severe damage in Dong Dan 80. Overall performance of all maize hybrids under drought stress was recorded as: Dong Dan 80 > Wan Dan 13 > Run Nong 35 with 6.39, 7.35, and 16.55% yield reductions. Consequently, these biochemical traits and differential physiological responses might be helpful to develop drought tolerance genotypes that can withstand water-deficit conditions with minimum yield losses.

The APSIM‐Maize and CERES‐Maize models are widely used in impact studies to analyze the effect of climate change on future maize yield. The study objectives were to develop climate scenarios, assess crop model's sensitivity, and predict the impact of climate change on rainfed maize yield based on five global climate models under two RCP (RCP4.5 and RCP8.5) scenarios. The scenarios were based on the mid‐century and tested for sowing dates (SDs), maize cultivars, and nitrogen fertilizer rates (N). For field calibration and validation, the split‐split‐plot experimental design with three replicates was set up at Mount Makulu, Zambia. The treatments were SD, cultivar, and N‐rate were the main plot, subplot, and subsub plot, respectively. The APSIM‐Maize and CERES‐Maize models were used to run simulations using seasonal analysis. The impacts of climate change on maize yield were simulated for the future 2040–2069/1980–2010 using the AgMIP Protocols. The ensemble means from the simulation result in precipitation decrease and temperature increase. Days after planting to anthesis and maturity would reduce in 2050 (2040–2069). The % change in grain yield would range from 2.78% to 9.94%, −3.81% to −8.88%, and −2.33% to 10.63% under N1 (55.2 N kg/ha), N2 (110.4 N kg/ha), and N3 (165.6 N kg/ha) as affected by SDs, respectively. The simulation showed evidence of climate change and hence affect maize growth and yield. Therefore, there is a need to put in place strategies for alleviating the impact of climate change in maize production in Zambia. APSIM‐Maize and CERES‐Maize model were used to simulate the impact of future climate scenarios (2040–2069) on maize yield relative to the baseline (1980–2010) using the AgMIP Protocols. The APSIM‐Maize and CERES‐Maize models simulated reduced DAP to anthesis and maturity relative to the baseline. The projected changes in temperature and rainfall would reduce/increase simulated maize yield depending on the sowing date in 2050.