Affecting Maize Production Research Articles

Stress-resilient maize hybrid adoption factors and impact: Evidence from rain-fed agroecologies of Karnataka state, India

Drought is one of the major abiotic constraints that adversely affect maize production in the rain-fed agro-environment in the Asian tropics. In view of the recurrent drought, stress-resilient (SR) maize hybrids were developed and deployed to minimize yield penalties and ensure minimum sustainable production of maize in mild to severe drought conditions. Data were collected from 180 farmers from two districts of northern Karnataka. Findings suggest that the household location, caste, access to credit, number of extension visits, and participation in field days significantly influence the adoption of the SR maize hybrid in the study area. The inverse probability weighting (IPW) estimator revealed that households adopting SR maize hybrid have higher yield and income (23% more yield and $137.86/ha more net income) than the non-adopters. As the SR maize hybrid has considerable scope for improving the livelihood and security of farmers, the agricultural policy should support and scale the stress-resilient maize hybrids in the region.

Effects of Phloem-Feeding Pest, Dalbulus maidis on Morphological Expression of Drought-Tolerant Traits in Maize

Drought is amongst the most important stressors affecting maize production globally. Existing strategies to offset drought impacts are centered around the rapid development of drought-tolerant cultivars through plant breeding. However, under both current conditions and projected climate changes, additional stressors such as insect pests will co-occur. To determine the impact of combined insect and drought stress on drought tolerance in maize, we assessed the effects of Dalbulus maidis, drought, and both stresses combined in drought-tolerant maize hybrids. We measured several maize morphological growth traits (i.e., plant height, stem diameter, shoot weight, root weight, root length, and root-to-shoot ratio) at the end of a 28-day period of pulse-stress and no-stress control exposure. We found that seedling growth declined when both stressors co-occurred. Nevertheless, drought-tolerant maize hybrids remained strongly tolerant to drought regardless of D. maidis infestation. While our results showed that drought tolerance is maintained in drought-tolerant maize seedlings, future studies should address any effects on maize yield. Our study highlights the importance of testing the combined effects of drought and insect stressors to better predict insect–plant interactions in the context of plant breeding for drought-tolerant traits in a changing climate.

Predicting Maize (Zea mays) productivity under projected climate change with management options in Amhara region, Ethiopia

Maize is an important cereal crop in Ethiopia. Maize yield has been declined in Ethiopia mainly due to water scarcity, low soil fertility and heat stress. Currently, limited technologies are available in the study region that increases maize productivity. If crop models are properly calibrated, they are effective tools to study crops responses to environmental factors. Assessing impact of future climate on maize crop may help to develop adaptation strategies. The objectives of this study were (1) to calibrate and evaluate the CERES maize model in DSSAT technology for simulating phenology and yield of maize (2) to assess impact of projected climate change on maize productivity (3) to develop promising management practices for maize. The impact of projected climate change was assessed using the 17 GCMs (CMIP5) run under RCP4.5 and RCP8.5 climate scenarios. Two water regimes treatments (rainfed and irrigated) and four rates of nitrogen (0, 46, 92 and 138 kg ha−1) were evaluated individually and in combinations for their effectiveness to increase maize productivity under the projected climate conditions. The model evaluation result revealed that the RMSE values were 2.5 days for anthesis, 4.4 days for physiological maturity, 258.3 kg ha−1 for grain yield and 1034 kg ha−1for above ground biomass yield with nRMSE values of 3%, 4%, 4.7% and 10%, respectively. The d-index values were 0.87, 0.80, 0.88 and 0.71 for the respective parameters. The good agreement between the simulated and the measured values indicated the maize genetic coefficients in the model were properly calibrated. The simulation results at Tehuledere site showed that maize grain yield may decrease by 11% and 20% in 2030s and by 26% and 29% in 2050s under RCP4.5 and RCP8.5 scenarios, respectively whereas in Kallu site yield may decrease by 13% and 15% in 2030s and by 17% and 19% in 2050s for the respective RCP scenarios. However, the management scenarios have shown that maize yield may substantially increase by the use of optimum nitrogen fertilizer and supplemental irrigation. Thus, it can be generalized that climate change may adversely affect maize production in the Semi-arid regions of Ethiopia but the impact could be reversed by using sound crop management practices.

Transcriptomic and physiological responses of contrasting maize genotypes to drought stress.

Drought is a significant environmental stress factor that adversely affects maize productivity. However, many details regarding the molecular mechanisms of maize against drought are still unclear. In this study, leaf transcriptomics and physiological traits of two maize genotypes with differing drought resistance were analyzed. Transcriptome sequencing identified 8985 and 7305 differentially expressed genes (DEGs) in SD902 and SD609, respectively. Functional analysis suggested that numerous genes are highly involved in oxidative defense, protein modification, photosynthesis, phytohormone response, MAPK signaling, and transcription factors (TFs). Compared to SD902, SD609 had a higher expression of DEGs related to antioxidant enzymes, photosynthetic electron transport, heat shock proteins, and indole-3-acetic acid (IAA) signaling under drought conditions, which might contribute to its tolerance mechanisms to drought. Stress-induced TFs may play a crucial regulatory role in genotypic differences. Moreover, the physiological changes and gene expression abundance determined using quantitative reverse transcription polymerase chain reaction were consistent with the RNA sequencing data. The study results suggest that the higher drought tolerance of SD609 than SD902 can be attributed to stronger stress defense capabilities, IAA signal transduction, and more stable photosynthesis. Our findings provide new insights into the molecular mechanisms of maize against drought stress, and the candidate genes identified may be used in breeding drought-tolerant maize cultivars.

Unprecedented climate extremes in South Africa and implications for maize production

Maize is the most important crop grown in South Africa, but yields can be severely reduced by extreme high summer average temperatures and low precipitation, potentially adversely affecting both domestic consumption and regional food security exports. To help understand and manage climate risks to food security in Southern Africa it is essential to quantify the present-day likelihood and magnitude of climate extremes in South Africa’s maize-growing region and explore the potential for unprecedented climate conditions which would likely result in record low maize yields. We analyse a large ensemble of initialised climate model simulations, which provides almost 100 times as many plausible present-day summers as the equivalent observational dataset. We quantify the risk of unprecedented climate extremes affecting maize production in South Africa and examine the role of the El Niño-Southern Oscillation. We find that the South African maize region is at risk of experiencing record-breaking hot, cold, dry or wet events under current climatic conditions. We find that the annual chance of unprecedented high temperatures in South Africa is approximately 4%, increasing to 62% during very strong El Niño years. We also find that the chance of exceeding the present day seasonal high temperature record has increased across the 1979–2018 period, being five times more likely now than it was in 1980. These extreme events could result in a record-breaking number of days above the optimum, or even the maximum, temperature for maize production, and lead to more severe floods or droughts. Under climate change scenarios, the magnitude and frequency of climate extremes is projected to increase meaning that the unprecedented extremes studied here could become commonplace in the future. This suggests that significant investment is needed to develop adaptations that manage the climate-related risks to food systems now and build resilience to the projected impacts of climate change.

Effect of Metarhizium anisopliae on the nutritional physiology of the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae)

BackgroundThe fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), was recorded for the first time in Pakistan in 2019, and now it has spread in several regions, i.e., Punjab and Sindh, affecting maize production. Farmers are using widely synthetic pesticides to control the pest. Further, the resistance development in insects and the non-target effect of chemicals on the environment and humans pose serious threats of using insecticides. The use of entomopathogenic fungi (EPF) is being considered an important tool in integrated pest management program. The main objective of this study was to check the impact of different conidial concentrations of Metarhizium anisopliae fungus on the nutritional physiology of S. frugiperda.ResultsThe dose-dependent effect of tested EPF was observed, and the highest concentration (1 × 109 conidia/ml) considerably affected nutritional parameters. Reduced relative consumption rate (21.7%), relative growth rate (19.5%), the efficiency of conversion of ingested food (24.2%), and approximate digestibility (16.3%) were observed in treated larvae compared to the untreated by using a higher concentration of EPF. Pupal weight was also found lower (77.9 mg and 84.2 mg, respectively), when larvae were treated by 1 × 109 and 1 × 108 conidia/ml concentrations of EPF. Further, 46.7% of larvae were found dead with this conidial concentration.ConclusionsThis study suggests that the application of a higher concentration of M. anisopliae could be an effective option to control S. frugiperda. The EPF can enhance the integrated pest management programs and could be useful in reducing the environmental impact of synthetic insecticides.

A novel maize microRNA negatively regulates resistance to Fusarium verticillioides.

Although microRNAs (miRNAs) regulate the defence response against multiple pathogenic fungi in diverse plant species, few efforts have been devoted to deciphering the involvement of miRNA in resistance to Fusarium verticillioides, a major pathogenic fungus affecting maize production. In this study, we discovered a novel F. verticillioides‐responsive miRNA designated zma‐unmiR4 in maize kernels. The expression of zma‐unmiR4 was significantly repressed in the resistant maize line but induced in the susceptible lines upon exposure to F. verticillioides exposure, whereas its target gene ZmGA2ox4 exhibited the opposite pattern of expression. Heterologous overexpression of zma‐unmiR4 in Arabidopsis resulted in enhanced growth and compromised resistance to F. verticillioides. By contrast, transgenic plants overexpressing ZmGA2ox4 or the homologue AtGA2ox7 showed impaired growth and enhanced resistance to F. verticillioides. Moreover, zma‐unmiR4‐mediated suppression of AtGA2ox7 disturbed the accumulation of bioactive gibberellin (GA) in transgenic plants and perturbed the expression of a set of defence‐related genes in response to F. verticillioides. Exogenous application of GA or a GA biosynthesis inhibitor modulated F. verticillioides resistance in different plants. Taken together, our results suggest that the zma‐unmiR4–ZmGA2ox4 module might act as a major player in balancing growth and resistance to F. verticillioides in maize.

Cover Image:

Southern corn leaf blight (SCLB), caused by Bipolaris maydis (B. maydis), is one of the most devastating diseases aff ecting maize production. Zhang et al. demonstrate that a cytosol‐localized ascorbate peroxidase 1 (ZmAPX1) confers SCLB resistance by reducing H2O2 accumulation and activating the JA‐mediated defense signaling pathway. The cover image shows that ZmAPX1 provides a barrier for maize against B. maydis infection (Page 1196–1211).

Development of efficient RNAi methods in the corn leafhopper Dalbulus maidis, a promising application for pest control.

The corn leafhopper Dalbulus maidis is the main vector of important stunting pathogens that affect maize production. Currently, there are no effective methods available to manage this pest without adverse impact on the environment. In this context, genomic-based technologies such as RNA interference (RNAi) provide a more environmentally friendly pest control strategy. Therefore, we aimed to assess the application of RNAi in D. maidis and determine the function of a candidate gene related to insect reproduction and propagation. We have characterized the core RNAi genes and evaluated the functionality of the RNAi machinery. We assessed the potential of RNAi technology in D. maidis via injection or ingestion of double-stranded RNA (dsRNA) to adult females. We chose Bicaudal C (BicC) as a target gene due to its important role during insect oogenesis. Administration of dsRNABicC caused significant reductions in the transcript levels (fold changes up to 170 times) and ovipositions. Phenotypic analysis of the ovaries revealed alterations in oocyte development, providing additional confirmation for our results and supporting the idea that Dmai-BicC is a key player of D. maidis oogenesis. This is, to our knowledge, the first report of efficient RNAi in D. maidis. We believe our findings provide a starting point for future control strategies against one of the most important maize pests in the Americas. © 2022 Society of Chemical Industry.

Ascorbate peroxidase 1 confers resistance to southern corn leaf blight in maize.

Southern corn leaf blight (SCLB), caused by Bipolaris maydis, is one of the most devastating diseases affecting maize production. However, only one SLCB resistance gene, conferring partial resistance, is currently known, underscoring the importance of isolating new SCLB resistance-related genes. Here, we performed a comparative proteomic analysis and identified 258 proteins showing differential abundance during the maize response to B. maydis. These proteins included an ascorbate peroxidase (Zea mays ascorbate peroxidase 1 (ZmAPX1)) encoded by a gene located within the mapping interval of a previously identified quantitative trait locus associated with SCLB resistance. ZmAPX1 overexpression resulted in lower H2 O2 accumulation and enhanced resistance against B. maydis. Jasmonic acid (JA) contents and transcript levels for JA biosynthesis and responsive genes increased in ZmAPX1-overexpressing plants infected with B. maydis, whereas Zmapx1 mutants showed the opposite effects. We further determined that low levels of H2 O2 are accompanied by an accumulation of JA that enhances SCLB resistance. These results demonstrate that ZmAPX1 positively regulates SCLB resistance by decreasing H2 O2 accumulation and activating the JA-mediated defense signaling pathway. This study identified ZmAPX1 as a potentially useful gene for increasing SCLB resistance. Furthermore, the generated data may be relevant for clarifying the functions of plant APXs.

Climate change and maize productivity in Uganda: Simulating the impacts and alleviation with climate smart agriculture practices

CONTEXTClimate change continues to affect maize production, food security and livelihoods of smallholder farmers in most of the developing countries. Climate smart agriculture (CSA) practices can enhance agricultural production by alleviating adverse climate effects on maize productivity through improved soil moisture storage, water use efficiency, increased soil carbon (C) and nutrient supply with long-term resilience to climate change. OBJECTIVEThis study investigated the effectiveness of CSA practices (mulching at 0, 2, 4 and 6 cm thicknesses), permanent planting basins (20 and 30 cm deep), and halfmoon pits as a mitigation and adaptation strategy for improving maize productivity in rainfed production systems in the sub-humid regions of Sub-Saharan Africa. METHODSWe used the AquaCrop model of the Food and Agriculture Organization (FAO, 2018), AquaCrop version 6.1 to evaluate potential benefits of the CSA practices: half-moon, mulching (using different thickness) and permanent planting basins compared to a control treatment in rainfed production systems. The performance of CSA practices was evaluated using field experiments under present and future conditions. We first parameterized the model based on a three-season field experiment (2019-2020). We then run the model under projected future trends (2010–2039) using four general circulation models in each two greenhouse gas (GHG) emission representation concentration pathways (RCP4.5 and RCP8.5) for the Coupled Model Inter-comparison Project 5 (CMIP5). Finally, we evaluated resulting maize growth, grain yield, and water use efficiency for all the treatments. RESULTS AND CONCLUSIONSOur results indicated that use of mulching, especially 6 cm thick mulch increased maize grain yield and water use efficiency under present and future conditions. It was noted that CSA practices would increase grain yield by 14–37% under RCP8.5 climate scenario. Projections revealed increases in mean temperature of 0.5 °C and 1.0 °C under RCP4.5 and RCP8.5, respectively, in the 30 years (2010–2039). The model also projected a decrease (4.7%) and increase (2%) of the annual averages of rainfall in the future under RCP4.5 and RCP8.5, respectively. SIGNIFICANCEOur findings highlight the key role of CSA practices in reducing the climate change effects on maize production in the sub-humid regions. Therefore, national governments should prioritize adoption of climate smart agriculture practices as a key strategy for improving and sustaining maize productivity in rainfed systems of the sub-humid region.

QTL Mapping Low-Temperature Germination Ability in the Maize IBM Syn10 DH Population.

Chilling injury poses a serious threat to seed emergence of spring-sowing maize in China, which has become one of the main climatic limiting factors affecting maize production in China. It is of great significance to mine the key genes controlling low-temperature tolerance during seed germination and study their functions for breeding new maize varieties with strong low-temperature tolerance during germination. In this study, 176 lines of the intermated B73 × Mo17 (IBM) Syn10 doubled haploid (DH) population, which comprised 6618 bin markers, were used for QTL analysis of low-temperature germination ability. The results showed significant differences in germination related traits under optimum-temperature condition (25 °C) and low-temperature condition (10 °C) between two parental lines. In total, 13 QTLs were detected on all chromosomes, except for chromosome 5, 7, 10. Among them, seven QTLs formed five QTL clusters on chromosomes 1, 2, 3, 4, and 9 under the low-temperature condition, which suggested that there may be some genes regulating multiple germination traits at the same time. A total of 39 candidate genes were extracted from five QTL clusters based on the maize GDB under the low-temperature condition. To further screen candidate genes controlling low-temperature germination, RNA-Seq, in which RNA was extracted from the germination seeds of B73 and Mo17 at 10 °C, was conducted, and three B73 upregulated genes and five Mo17 upregulated genes were found by combined analysis of RNA-Seq and QTL located genes. Additionally, the variations of Zm00001d027976 (GLABRA2), Zm00001d007311 (bHLH transcription factor), and Zm00001d053703 (bZIP transcription factor) were found by comparison of amino sequence between B73 and Mo17. This study will provide a theoretical basis for marker-assisted breeding and lay a foundation for further revealing molecular mechanism of low-temperature germination tolerance in maize.

Effectiveness of several nutritional sources on the virulence ofBeauveria bassianas.l. CEP147 against the planthopperDelphacodes kuscheli

AbstractDelphacodes kuscheliFennah (Hemiptera: Delphacidae) is the main planthopper vector ofMal de Río Cuarto virus(MRCV), aFijivirusthat severely affects maize production in Argentina. The effect of several nutritional sources on the virulence ofBeauveria bassianas.l. CEP147 (Balsamo‐Crivelli) Vuillemin (Hypocreales: Cordycipitaceae) against this planthopper was evaluated with the aim to select some of them to be incorporated in future mass production studies. Ten agar‐agar 2% media were used. Media were supplemented with 10 g of sucrose and 4% flour of either amaranth, chia, flax, oat bran, parboiled rice, poppy, quinoa, or wheat germ. Sabouraud dextrose agar with 1% yeast extract (SDAY) was used as control, and sucrose agar medium supplemented with 2% chitin was used as a possible inductor of enzymatic activity. We evaluated the effect of each medium on colony growth, conidial yield, viability, size, adherence, hydrophobicity, protease activity, cumulative mortality, and median survival time (MST). Principal component analysis indicated that conidial viability and adherence explained the most of the total variance, indicating that these variables can be used as indicators of fungal virulence. Medium supplemented with chia flour not only increased conidial viability (100%) and adherence (0.09 A550) with respect to the control medium, but also produced highD. kuschelimortality (91.7%), with the lowest MST (5.2 days). We suggest that chia flour, which is rich in carbohydrates, proteins, vitamins, and minerals, might be incorporated as a nutritional supplement to solid substrates in order to increase the virulence ofB. bassianas.l. CEP147 against this and other pests. However, future studies are necessary to evaluate the effectiveness of this nutritional source on solid‐state fermentation.

The impact of drought and heat stress at flowering on maize kernel filling: Insights from the field and laboratory

Drought and exposure to high temperature at flowering strongly affect maize production. However, previous studies mostly focused on the effects of the stressors on kernel number. The impacts of drought and heat in isolation and combination at flowering on maize kernel filling and final kernel weight have received limited attention. Here we investigated the effects of three stressors (drought, heat, and drought plus heat) at flowering phase (from tasseling to seed setting completed) on maize kernel filling in field site plots covered with a rainout shelter and under laboratory conditions with kernel in vitro culture. In two experiments, the kernel weight of plants exposed to flowering stressors was significantly decreased relative to controls. In the field experiment, exposure to stressors decreased kernel weight by 5.0–8.3% for the basal kernel and 5.6–11.0% for the apical kernel. Accelerated leaf senescence and decreased rate of photosynthesis were observed in the field. Kernel weight was also reduced by 18.0–37.6% in the laboratory with kernel in vitro culture, suggesting that early stressors at flowering led to a sink (kernel) limit. Carbohydrate metabolism and starch biosynthesis were impaired by drought and heat individually and their combination. During the early kernel filling stage, the activities of sucrose invertase, sucrose synthase, ADP-Glc pyrophosphorylase, and starch synthase were decreased at 10 and 20 days after pollination (DAP) in the stress treatment. For both basal and apical kernels, the correlation analyses indicated the mean kernel filling rate correlated positively with zeatin riboside content at DAP 10 and indole-3-acetic acid content at DAP 20. This study provides useful information to support the development of drought- and heat-tolerant hybrids and effective management strategies to improve crop yields.

Maize diversity for fall armyworm resistance in a warming world

AbstractCurrently, maize (Zea maysL.) production is under threat from climate change, drought, and pests such as fall armyworm (FAW) [Spodoptera frugiperda(J.E. Smith) (Lepidoptera: Noctuidae)]. Since its first detection outside of its native range in 2016, FAW has spread into 76 nations across Africa and Asia adversely affecting maize production and, in turn, the livelihoods of millions of smallholder farmers. Thus, there is a strong need for the development of cost‐effective and biologically based integrated pest management (IPM) practices including host‐plant resistance (HPR). However, most of the commercial maize cultivars have lost some defensive traits through selective breeding for yield during domestication. The majority of the commercially cultivated hybrids and cultivars in Asia and Africa are highly susceptible to FAW. Therefore, this review summarizes information about various maize landraces, native germplasm, and crop wild relatives (CWRs) possessing FAW resistance traits and about their potential resistance mechanisms, namely antibiosis, antixenosis, and tolerance. There is clear evidence of FAW resistance acting through diverse mechanisms in several maize landraces, germplasm lines, native populations, and CWRs such as Antigua race, FAW Tuxpeno, Zapalote Chico 2451F, Doce Flor da Serra, FAWCC (C5), CMS 14C, PopG (C2), MpSWCB‐4, Mp708, Mp 704, CML 67, and FAW 7050, as well as a few species of teosinte andTripsacumL. Further, a scheme that outlines strategies and approaches for prebreeding and their introgression into elite cultivars for developing FAW‐resistant maize is proposed as a possible way forward.

Optimum Planting Density Improves Resource Use Efficiency and Yield Stability of Rainfed Maize in Semiarid Climate.

Increasing planting density is an effective strategy for improving maize productivity, but grain yield does not increase linearly with the increase in plant density, especially in semiarid environments. However, how planting density regulates the integrated utilization of key input resources (i.e., radiation, water, and nutrients) to affect maize production is not clear. To evaluate the effects of planting density and cultivar on maize canopy structure, photosynthetic characteristics, yield, and resource use efficiency, we conducted a successive field experiment from 2013 to 2018 in Heyang County (Shaanxi Province, China) using three different cultivars [i.e., Yuyu22 (C1), Zhengdan958 (C2), and Xianyu335 (C3)] at four planting densities [i.e., 52,500 (D1), 67,500 (D2), 82,500 (D3), and 97,500 (D4) plants ha–1]. Increasing planting density significantly increased the leaf area index (LAI) and the amount of intercepted photosynthetically active radiation (IPAR), thereby promoting plant growth and crop productivity. However, increased planting density reduced plant photosynthetic capacity [net photosynthetic rate (Pn)], stomatal conductance (Gc), and leaf chlorophyll content. These alterations constitute key mechanisms underlying the decline in crop productivity and yield stability at high planting density. Although improved planting density increased IPAR, it did not promote higher resource use efficiency. Compared with the D1 treatment, the grain yield, precipitation use efficiency (PUE), radiation use efficiency (RUE), and nitrogen use efficiency (NUE) increased by 5.6–12.5%, 2.8–7.1%, and −2.1 to 1.6% in D2, D3, and D4 treatments, respectively. These showed that pursuing too high planting density is not a desirable strategy in the rainfed farming system of semiarid environments. In addition, density-tolerant cultivars (C2 and C3) showed better canopy structure and photosynthetic capacity and recorded higher yield stability and resource use efficiency. Together, these results suggest that growing density-tolerant cultivars at moderate planting density could serve as a promising approach for stabilizing grain yield and realizing the sustainable development of agriculture in semiarid regions.

Optimizing interaction between crop residues and inorganic N under zero tillage systems in sub-humid region of Kenya

Conservation agriculture practices involving zero tillage and residue retention are promising nutrient management strategies for soil health restoration. Despite their potential positive impact on soil fertility, improved crop yields and increased revenues for smallholder farmers; their effect on nitrogen inputs and crop growth is not clearly understood. This may limit their potential as a nutrient management strategy that may remedy soil degradation and boost crop yields for farmers. This study investigated how different tillage practices, crop residues and inorganic nitrogen (N) options affect maize production, soil fertility and economics of smallholder farming systems. The study was conducted in a short-term (2 years) on-station trial, under randomized complete block design with three replications in a maize monocrop system. Six treatments, involving three different rates of maize stover residue (0, 3 and 5 t ha−1) and inorganic N (0, 3 and 5 t ha−1) inputs, respectively, were assessed under conventional and zero tillage systems. Mineral N and organic C were assessed at four depths (0–10 cm, 10–30 cm, 30–60 cm and 60–90 cm) whereas soil aggregate distribution was assessed at 0–5 cm, 5–10 cm, 10–15 cm and 15–20 cm depths. Application of inorganic N as the only input increased (p ≤ 0.05) grain yield (with the yields doubling in the short rains (SR) of 2015 and increasing by 1.4 times in long rains (LR) of 2016) compared to unfertilized control treatment. Treatment, soil depth and the time of sampling significantly affected soil mineral N concentration (p ≤ 0.05). Soil organic C reduced significantly (p ≤ 0.05) with sampling depths, but no differences were observed across treatments. At 0–5 cm depth, the proportion of large macroaggregates in zero tillage increased (48%; p ≤ 0.05) after application of crop residues at 5 t ha−1 relative to 3 t ha−1. Zero tillage treatment with application of 5 t ha−1 of residue and 80 kg N ha−1 was the most dominant and most profitable compared to the other treatments. This treatment had a benefit cost ratio (BCR) of 2.9 (in the short rains season of 2015) and 3.0 (long rains of 2016 seasons). Its marginal rate of return (MRR) was 368% (in the 2015 short rains season) and 416% (in the 2016 long rains season). This makes it a good nutrient management strategy with potential of optimizing maize yields.

Effect of weather parameters on growth stages of winter maize explain the grain yield

A study was conducted on research farm of National Maize Research Program (NMRP), Rampur, Chitwan, Nepal during winter season of 2015/16 laid out in split-split plot design with three replications consisting of two FYM levels (FYM at 10 t ha-1 and no FYM application), three nitrogen levels (100, 75 and 50% N of recommended dose P and K remaining constant) and two levels of seed inoculation (Azotobacter chrococcum seed inoculation and no inoculation) with Rampur-2 maize hybrid in Nepal. One of the major factor affecting maize production is weather and this paper is prepared to assess the suitability of weather condition at different growth stages of winter season hybrid maize in condition of western Chitwan, Nepal at NMRP. The result shows that the requirement of the maize crop during different growth stages i.e. temperature, rainfall, relative humidity were fulfilled which helped to obtain remarkably higher grain yield (4.26 t ha-1) in the experiment compared to average national grain yield (2.84 t ha-1) of maize

Ameliorative Effects of Calcium Sprays on Yield and Grain Nutritional Composition of Maize (Zea mays L.) Cultivars under Drought Stress

Drought stress is seriously affecting maize production. To investigate the influence of calcium (Ca) foliar application on maize production and chemical composition of grains under drought stress, two experiments were carried out at Cairo University Research Station, Giza, Egypt, during the summer seasons of 2018 and 2019. The experimental design was split-split plot design with a completely randomized blocks arrangement with three replications. Water regimes were assigned to the main plots [100 (control), 75, and 50% of estimated evapotranspiration]. Calcium levels (zero and 50 mg/L) were assigned to the sub plots. Maize cultivars (SC-P3444, Sammaz-35 and EVDT) were assigned to the sub-sub plots. Three maize cultivars were sprayed with Ca solution concentration (50 mg/L) under normal and drought conditions. The control treatment (0 mg/L) was sprayed with an equal amount of distilled water for comparison. Results indicated a significant decrease in total yield and grain characteristics [protein, ash, total sugars, nitrogen (N), phosphorus (P), potassium (K), and iron (Fe) contents] as a response of drought. Calcium foliar application significantly increased maize yield, protein, ash, carbohydrates, starch, total sugars, and ionic contents of grains, except for manganese (Mn), under all irrigation levels. Based on the drought tolerance index (DTI), only cultivar SC-P3444 showed drought tolerance while cultivars Sammaz-35 and EVDT were sensitive to drought stress. Foliar application of Ca on SC-P3444 cultivar achieved the highest grain yield per hectare (8061 kg) under the water regime of 100% of the total evapotranspiration, followed by Sammaz-35 (7570 kg), and EVDT (7191 kg) cultivars. At the water regime of 75% of estimated evapotranspiration (75% irrigation), Ca foliar application increased grain yield by 16, 13 and 14% in SC-P3444, Sammaz-35, and EVDT, respectively. At the water regime of 50% of the estimated evapotranspiration (50% irrigation), Ca foliar application increased grain yield by 17, 16, and 13% in SC-P3444, Sammaz-35, and EVDT, respectively. In brief, Ca had a clear impact on productivity and grain quality with important implications for maize yield under normal and water stress conditions. Our findings demonstrate that foliar application of Ca enabled drought stressed maize plants to survive better under stress. The most water stress tolerant cultivar was SC-P3444 followed by Sammaz-35 and EVDT under drought stress.

Biochemical and physiological changes in maize plants supplied with silicon and infected by Exserohilum turcicum

AbstractNorthern leaf blight (NLB), caused by Exserohilum turcicum, is one of the most important diseases affecting maize production worldwide. The effect of silicon (Si) on maize resistance against NLB was investigated through an in‐depth analysis of physiological and biochemical changes (measurements of gas exchange and chlorophyll (Chl) a fluorescence parameters, activities of host defence enzymes and those involved in the antioxidative metabolism, and the determination of other metabolites) on plants non‐supplied (−Si) or supplied (+Si) with Si and inoculated with E. turcicum. Higher foliar Si concentration contributed to reducing the foliar NLB symptoms in +Si plants. Both antioxidant (ascorbate peroxidase, catalase, glutathione reductase and peroxidase) and host defence (chitinase, β‐1,3‐glucanase, polyphenoloxidase and phenylalanine ammonia‐lyase) enzymes had their activities greater for +Si plants compared to −Si plants. Lower levels of hydrogen peroxide and malondialdehyde were obtained for +Si plants in contrast to −Si plants. Net CO2 assimilation rate, stomatal conductance to water vapour, transpiration rate and internal CO2 concentration had their values significantly increased for +Si plants compared to −Si plants from 5 to 20 days after inoculation. The maximum quantum yield of photosystem II, effective quantum yield of the photosystem, quantum yield of regulated energy dissipation and quantum yield of non‐regulated energy dissipation were less impacted on the leaves of +Si plants compared to −Si plants. The Chl a concentration was kept higher for +Si plants than for −Si plants. Taken together, this study brings biochemical and physiological pieces of evidence that a more robust antioxidative metabolism, great activities of host defence‐related enzymes and the preservation of the photosynthetic machinery were all potentiated by Si contributing, therefore, for less NLB symptoms.