Maize Crop Production Research Articles

Improvement of Maize Productivity and N Use Efficiency in a No-Tillage Irrigated Farming System: Effect of Cropping Sequence and Fertilization Management.

The sequence of the preceding crops in a no-tillage farming system, could interact with the integrated use of mineral and organic nitrogen (N) sources in a way that improves the growth and productivity of the terminal maize crop, meanwhile, enhancing its N use efficiency (NUE). In the current study, six legume-cereal crop sequences, including faba bean, soybean, Egyptian clover, wheat, and maize were evaluated along two experimental rotations that ended up by planting the terminal maize crop. In addition, the effects of applying variable mineral nitrogen (MN) rates with and without the incorporation of farmyard manure (FYM) on the productive performance of maize and its NUE were tested. The field experiments were conducted in a no-tillage irrigated farming system in Northern Egypt, a location that is characterized by its arid, Mediterranean climate. Results revealed that increasing the legume component in the evaluated crop sequences, up to 75%, resulted in improved maize ear leaf area, 1000-grain weight, and harvest index, thus, a higher final grain yield, with the inclusion of Egyptian clover was slightly better than faba bean. Comparing the crop sequences with 50% legume contribution uncovered the positive effects of soybean preceding crop on the terminal maize crop. Substituting 25% of the applied MN with FYM resulted in similar maize yields to the application of the equivalent 100% MN rates. The fertilizer treatments significantly interacted with the crop sequences in determining the maize grain yield, where the highest legume crop contribution in the crop sequence (75%) equalized the effects of the different fertilizer treatments on maize grain yield. The integrated use of FYM with MN in maize fertilization improved the NUE compared to the application of MN alone. Comparing fertilization treatments with similar MN content, with and without FYM, revealed that the difference in NUE was attributed to the additional amount of FYM. In similar conditions to the current study, it is recommended to grow faba bean two years before maize, while Egyptian clover could be grown directly preceding maize growth, with frequent inclusion of soybean in the sequence, this could be combined with the application of an average of 200 kg MN ha−1 in addition to FYM.

Plant Biostimulants: A Categorical Review, Their Implications for Row Crop Production, and Relation to Soil Health Indicators

Plant biostimulants are specialty products used to increase crop production and are quickly becoming common in the agricultural seed and chemical marketplace. Unlike traditional crop inputs, such as fertilizers or pesticides, biostimulants are unique in that a single product may have multiple avenues for influencing crop growth and development based on both the timing and the placement of application. This review presents a summary of the current status and descriptions of plant biostimulants with available literature on their uses in the row crop production of maize (Zea mays L.), soybean (Glycine max (L.) Merr.), wheat (Triticum aestivum), and other major crop species. Biostimulants have much potential to improve crop production through enhanced yields, grain quality, and increased sustainability of agronomic production systems, particularly in relation to nutrient management. However, there is great variability in the efficacy of biostimulants and a limited understanding of the mechanisms responsible in field-tested scenarios where differences are observed. These unknown mechanisms may align with the recognized soil health indicators, providing opportunities for unrealized biostimulant potential beyond crop growth and development. This review aims to identify the predominant types of crop biostimulants, the known understandings of their modes of action, and examples of their current field efficacy with an outlook for their future.

Efficient Maize Tassel-Detection Method using UAV based remote sensing

Regular monitoring is worthwhile to maintain a healthy crop. Historically, the manual observation was used to monitor crops, which is time-consuming and often costly. The recent boom in the development of Unmanned Aerial Vehicles (UAVs) has established a quick and easy way to monitor crops. UAVs can cover a wide area in a few minutes and obtain useful crop information with different sensors such as RGB, multispectral, hyperspectral cameras. Simultaneously, Convolutional Neural Networks (CNNs) have been effectively used for various vision-based agricultural monitoring activities, such as flower detection, fruit counting, and yield estimation. However, Convolutional Neural Network (CNN) requires a massive amount of labeled data for training, which is not always easy to obtain. Especially in agriculture, generating labeled datasets is time-consuming and exhaustive since interest objects are typically small in size and large in number. This paper proposes a novel method using k-means clustering with adaptive thresholding for detecting maize crop tassels to address these issues. The qualitative and quantitative analysis of the proposed method reveals that our method performs close to reference approaches and has an advantage over computational complexity. The proposed method detected and counted tassels with precision: 0.97438, recall: 0.88132, and F1 Score: 0.92412. In addition, using maize tassel detection from UAV images as the task in this paper, we propose a semi-automatic image annotation method to create labeled datasets of the maize crop easily. Based on the proposed method, the developed tool can be used in conjunction with a machine learning model to provide initial annotations for a given image, modified further by the user. Our tool's performance analysis reveals promising savings in annotation time, enabling the rapid production of maize crop labeled datasets.

Using EPIC to simulate the effects of different irrigation and fertilizer levels on maize yield in the Eastern Cape, South Africa

Growing water scarcity and increasing Nitrogen (N) fertiliser prices in South Africa require more prudent N fertiliser and irrigation water use approaches. If the goal of sustainable agricultural intensification is to be realised, it is vital to develop location-specific agricultural land management strategies that promote increased crop productivity while minimising negative environmental impacts. In this study, a calibrated and validated Environmental Policy Integrated Climate (EPIC) model was used to simulate a range of N fertiliser and irrigation water levels on maize (Zea mays L.) yield in the Eastern Cape of South Africa. Results showed that a fertiliser and irrigation water management schedule combining approximately 200 kg N ha-1 and 580 mm irrigation water per maize growing season provided the highest average maize yield of 12.2 Mg ha-1 (an increase of +69% above farmers’ current maize yield levels). Nitrogen fertiliser application levels greater than 160 kg N ha-1 resulted in potential N fertiliser leaching losses of more than 35 kg N ha-1. The EPIC model can be considered a valuable tool to aid decision-makers in identifying optimal, site-specific irrigation water and N fertiliser application levels that contribute to increased maize crop productivity while maximising water use.

Effect of Integrated Use of Organic Manures and Chemical Fertilizers under Soil Test Crop Response Approach on Soil Properties and Yield of Maize (Zea mays L.)

A field experiment was conducted at Crop Research Centre, G.B. Pant University of Agriculture and Technology, Pantnagar, during kharif 2019 to study the effect of integrated use of organic manures and chemical fertilizers under STCR approach on physico-chemical, biological properties of soil and yield of maize crop in a Mollisol. The experiment comprised of 9 treatments replicated thrice. The treatment details were Control (no fertilizers), RDF, STCR (inorganic mode), STCR INM mode, 75% STCR dose of N (inorganic mode) + Green manure, 50% STCR dose of N (inorganic mode) + Green Manure, 75% RDN + Green Manure, 50% RDN + Green Manure and FYM + Green Manure + Intercropping with urd. The lowest yield and soil properties were observed under control. The highest water holding capacity (63.20%), available N (183.98 kg ha-1), available P (28.94 kg ha-1), microbial biomass carbon (335.35 µg/g soil) and urease enzyme activity (30.06 µg urea/g soil/h) was observed under T4 (STCR INM mode). The highest organic carbon (0.99%), available K (200.85 kg ha-1) and dehydrogenase activity (223.60 µgTPF/gsoil/day) was observed under T5 (75% STCR dose of N (inorganic mode) + Green manure). The highest maize yield was observed under T4 (STCR INM mode). Therefore, the present investigation clearly reveals the significance of balanced and efficient utilization of resources under STCR approach on soil and crop productivity of maize crop.

New association between Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae) and native natural enemies: Bioprospection of native natural enemies as biological control agents

Fall armyworm (FAW) Spodoptera frugiperda is an invasive pest that enters Indonesia which can pose a serious threat to the continued production of maize and other crops. This condition is exacerbated if there are no natural enemies who can control the pests. This study aims to explore potential native natural enemies to control the population of FAW in Indonesia and the influence of habitat conditions on the distribution and population of natural enemies. The research was conducted in seven sub-districts in Bogor and three plots were selected from each district. Observation of natural enemies was carried out directly by collecting samples of eggs and larvae of FAW which attacked maize with the transect method on 200 individual plants. The samples collected will be rearing until the parasitoids emerged. We Collected seven genera of parasitoids that were associated with FAW: Apanteles, Charops, Euplectrus, Microplitis, Telenomus, Trichogramma, and two types of predators: ground beetles and Assasin bug. The highest parasitization rate of egg parasitoid was 93.4% while for larvae parasitoid was 12.44%. In conclusion, Telenomus and Microplitis are native parasitoids that can be used as potential natural enemies to control the S. frugiperda population in the field.

Genome-wide association mapping in maize: status and prospects.

The online version contains supplementary material available at 10.1007/s13205-021-02799-4.

Gluconacetobacter diazotrophicus Pal5 Enhances Plant Robustness Status under the Combination of Moderate Drought and Low Nitrogen Stress in Zea mays L.

Plant growth promoting endophytic bacteria, which can fix nitrogen, plays a vital role in plant growth promotion. Previous authors have evaluated the effect of Gluconacetobacter diazotrophicus Pal5 inoculation on plants subjected to different sources of abiotic stress on an individual basis. The present study aimed to appraise the effect of G. diazotrophicus inoculation on the amelioration of the individual and combined effects of drought and nitrogen stress in maize plants (Zea mays L.). A pot experiment was conducted whereby treatments consisted of maize plants cultivated under drought stress, in soil with a low nitrogen concentration and these two stress sources combined, with and without G. diazotrophicus seed inoculation. The inoculated plants showed increased plant biomass, chlorophyll content, plant nitrogen uptake, and water use efficiency. A general increase in copy numbers of G. diazotrophicus, based on 16S rRNA gene quantification, was detected under combined moderate stress, in addition to an increase in the abundance of genes involved in N fixation (nifH). Endophytic colonization of bacteria was negatively affected by severe stress treatments. Overall, G. diazotrophicus Pal5 can be considered as an effective tool to increase maize crop production under drought conditions with low application of nitrogen fertilizer.

A study some growth characteristics for maize, Bohooth 106 variety under affecting mechanical for machine (moldboard plow type )

The effect of the practical speed and tillage distances on maize Bohooth 106 variety and soil physical properties, under impact some mechanical properties for type tillage machine( moldboard plow ), were tested two practical speed levels of 2.409 and 3.543km.hr−1 and three levels tillage distances of 60, 65 and 70cm. The experiments were conducted in a factorial experiment under randomized complete block design with three replications. The results showed that the practical speed 2.409 km.hr−1was significantly better than the practical speed 3.543km.hr−1 as while tillage distances at range 60 cm was significantly superior to the other two levels 65 and 70 cm in all studied conditions. For practical speed 2.409 km.hr−1 and tillage distance 60cm, the fuel consumption, slippage percentage, machine efficiency, germination percentage, plant height, 1000–weight grain and the maize crop productivity, were 11.301, 10.153 L.ha−1, 10.240, 9.684%, 80.685, 82.002%, 90.803, 91.135%, 167.682, 169.163cm 223.341, 239.130 g, and 4.149, 4.258 t.ha−1. The best results have come from the overlap among the practical speed 2.409km.hr−1 and tillage distance of 60 cm, in all studied parameter.

Socio-Economic Determinants of Maize Production of Smallholder Farmers in Eastern Oromia, Ethiopia

Agricultural sector is a mainstay of farmers’ livelihoods in Ethiopia. Maize is a largest crop being grown in Ethiopia; however, currently, yield gaps are the challenges faced by the producers. This study has an objective of identifying the determinants of maize production of smallholder farmers. Data were collected from 200 farmers living in the selected kebeles (communes) of Meta district in the East Hararge zone of Oromia region, Ethiopia. The collected data was analyzed using multiple linear regression model. The result showed that the production of maize was influenced by several factors. Non-farm activity had a positive impact on the production of maize. Thus, the farmers who had money from non-farm sources utilized these additional incomes as inputs to gain more maize production. The cultivated areas of land have a positive influence on the higher yields of maize. The maize crop production of smallholder farmers was negatively affected by Development Agent’s office. The study suggests that policy makers should encourage the current maize production by supplying improved seeds and fertilizers, which tend to support improving the smallholder farms.

Total Factor Productivity of Major Crops in Southern Ethiopia: A Dis-Aggregated Analysis of the Growth Components

(1) Background: Even though agriculture is the backbone of the Ethiopian economy, the improvements made regarding crop productivity appeared insufficient and had slow progress. Several studies suggest possible ways to identify the challenges in the productivity of the crop sub-sector. Nevertheless, there are gaps in the empirical literature in both knowledge and methods. The current study intends to identify the factors that affect growth in the productivity of teff, maize, barley, wheat, and sorghum crops. (2) Methods: Cobb-Douglass stochastic production function is estimated using a panel data set of the Living Standard Measurement Survey. To address the objectives of the study, a parametric estimation with a time-varying decay model with deterministic and stochastic components was adopted. (3) Results and Discussion: The effect of inputs on aggregate output was positive and significant at the 1% significance level, implying the presence of economies of scale. Variation in the inefficiency term explained 46.4% of the total variance in the composed error term. The average productivity of major crops was 6.19 per year. This study implied that technical change in the production of major crops increased by 22% with better use of available technology. (4) Conclusions and Policy Implication: The findings pinpoint that farmers should focus on technical change and intensification of improved agricultural inputs.

The Hidden Costs of Land Degradation in US Maize Agriculture

AbstractThe United States is a world leader in the production of maize and other crops and the agricultural success of the country is directly linked to the intensive use of fertilizers and irrigation. However, even in advanced agricultural systems, soils can become degraded over time due to factors such as soil organic matter (SOM) loss and erosion. Here, we use a series of scenario‐based model analyses to show that about one‐third of current annual US. N fertilizer use in maize agriculture is used to compensate for the long‐term loss of soil fertility through erosion and organic matter loss. This leads to over a half billion dollars per year in extra fertilizer supply costs to US farmers. These results highlight the potential to reduce both the input costs and environmental impacts of agriculture through the restoration of SOM in agricultural soils.

Empirical Analysis of the Factors that Affecting Maize Production of Farmers among Smallholders: The Case of Eastern Oromia, Ethiopia

In Ethiopia, maize is the second largest in production areas and first in its productivity but there are high yield gaps between the actual yield currently producing and the potential yield. Therefore, this study was aimed to identify factors that affecting maize production of smallholder farmers at the farm level in the Meta district in the east Hararge zone, Oromia, Ethiopia. A two-stage random sampling technique was employed and a total of 200 smallholder farmers were randomly and proportionally selected to collect primary data. Multiple linear regression models were used to analysis factors that affect maize production among smallholder farmers. The result showed that the production of maize was influenced by several factors. The coefficient provided that as the farmers obtained 1 dollar from non-farm activity, the maize production of farmers increased by 293.2 kg, keeping other factors constant. Thus, the farmers who had money from non-farm sources used as additional income to gain agricultural inputs for maize production and thus generate more maize quantity. The result was pointed out that the size of the cultivated areas of land had a positive influence on the quantity of maize production of farmers. The coefficient entailed that as the size of the cultivated areas of land increased by one hectare, the farmer‘s quantity of maize production increased by 140.4 kg by keeping other factors constant. The result was also indicated that other factors being constant, the maize crop production of smallholder farmers of Meta district was decreased by 4 kg as Development Agent‘s (DA‘s) office distance increased by one minute. The possible explanation was that extension services were a critical source of information on agronomic practices. Therefore, policy makers should encourage the current maize production and supplying improved seed and chemical fertilizer which support to improve smallholder farm households‘ welfare by increasing their sources of income.

Spatio-temporal analysis of the effects of biogas production on agricultural lands

With the subsidization of energy crops in Germany by the Renewable Energy Act, the production of biogas became increasingly dependent on agricultural land for biomass generation. The effects of increasing biogas plants’ capacities on the increase of maize and other energy crops area over the years have raised sustainability concerns in the German society. A periodic assessment of the impacts of biomass production is necessary to determine efficient and environmentally sustainable recommendations for future planning processes. Previous studies have neglected the effects of biogas plant capacity, which is directly linked with the amount of biomass required and, thus, is supposed to be a driver for the impacts of biogas production on agricultural lands. Combining the Integrated Administration and Control System (IACS) and Landsat satellite data provides a means to study present and past agricultural landscape. The aim of the study was to map the agricultural lands of Northern Hesse from 2000 to 2015, evaluate the change in maize area and structural diversity (i.e. field edge density) of agricultural fields, and assess if biogas production is a major driver of possible changes. Northern Hesse was consciously chosen, as it represents a typical European low-mountain range region with substantial geographical and agricultural variability. Our results show that from 2000 to 2015 on average, the shares of grassland and summer crops areas decreased by 5.7 percentage points (p.p.) and 5.8 p.p., respectively, while the shares of winter crops and maize areas increased by 9.2 p.p. and 2.2 p.p., respectively. Potential drivers of the change in maize area and structural diversity of agricultural fields, such as the mean capacity of biogas plants (kW), and topographical attributes, such as mean elevation (m) and slope (%) were employed as explanatory variables on a municipality level in multiple linear regression models. The mean biogas capacity and elevation were the most significant drivers of change in maize area (p < 0.05), while biogas capacity and slope were the significant drivers of the change in structural diversity. Maize area increased with an increasing capacity of biogas plants at lower elevations of the study area (p < 0.05). A decrease in the structure of fields, which is an indicator for species and habitat diversity, was observed and this was very much associated with the extent of maize and winter crop production. However, the drivers of the changes in the maize area and structure of fields were of low dimensions with model R2 of 0.21 and 0.35 respectively. Overall, our study demonstrates the potential of spatial data from different origins in mapping land-cover over longer time periods for monitoring bio-economy effects on agricultural landscape.

The Effect of Application of Vermicompost and NPS Fertilizer on Selected Soil Properties and Yield of Maize (&amp;lt;i&amp;gt;Zea May L.&amp;lt;/i&amp;gt;) at Toke Kutaye, Ethiopia

Low soil fertility and nutrient unavailability due to loss of soil organic matter content and low fertilizer input are among the major maize crop production constraints in Ethiopia, particularly, in Toke kutaye Woreda. An integrated use of vermicompost and NPS fertilizers are indispensible to improve this condition of soil. Cognizant of this fact, a study was conducted in 2019/2020 to assess the effect of combined use of vermicompost and NPS fertilizer on soil physicochemical properties and yield of maize. In order to achieve this objective field experiment was laid out in a randomized complete block design and replicated three times. The treatments consist of different combinations of vermicompost and NPS fertilizer rates. The results of the study showed that all the treatments applied were improved soil moisture and total porosity over control or NPS fertilizer alone, while, bulk density was decreased below the control due to the different rates of organic amendments. The higher pH value of vermicompost caused relative increase in soil pH over the control. It was observed that the application of vermicompost along with NPS fertilizers increased the contents of organic matter, total nitrogen, available phosphorus, available sulfur, exchangeable potassium over the control. Moreover, increasing doses of amendments applied to soil increased grain yield, than that of control treatment, sole use of vermicompost and NPS fertilizer, and low rate application. It can be concluded that the application of vermicompost along with NPS fertilizers were improved organic matter and nutrient contents of the soils which in turn increased crop yields. Hence, in order to maintain soil fertility and sustain maize crop production, farmers of the study area and similar agro ecologies are advised to make integrated use of vermicompost at (5 t ha-1) and NPS inorganic fertilizer at (50 kg ha-1) tentatively. Nevertheless, to develop a concrete recommendation further research studies are needed over long seasons, soil types and crop varieties.

The Formation of the International Imperatives of the National (Food) Security Coefficient in Ukraine under Globalization

The purpose of the study is to review the academic literature on food security issues in order to examine the indicators of rational and minimal nutrition, facilitating the analysis of the existing system of indicators by which to assess the state of the food security system in a country. The aim of the article is to investigate and demonstrate the imperatives behind the formation of Ukraine’s national (food) security in the context of globalization. National food security in the broad sense should be considered as the state of the economy, and more narrowly – as the guaranteed ability of a state to meet the needs of the population by providing each citizen with the required volume, range and quality of food at a level that ensures the health and intellectual development of the individual, based on the principles of self-sufficiency of basic products and their economic and physical accessibility, regardless of the influence of external and internal factors. The Global Food Security Index Ranks of the European Union and Ukraine are analyzed. Consumer expenditure on food consumed at home in Ukraine is analyzed in the article. Average food security indicators of the EU and Ukraine are analyzed for 2001–2018, in particular for food exports, food imports, food production index, food, beverages and tobacco. The dynamics and forecasts of wheat and maize harvest and crop production in Ukraine and the EU are compared. The analysis of the Suite of Food Security Indicators of the EU and Ukraine is presented alongside a comprehensive analysis of the multifactor regression model of Food Production Index from foreign direct investment, net inflows, GDP growth, GNI per capita growth, short-term debt, tax revenue, total natural resources rents, and trade. The analysis has shown that for the analysis of the food production index it is effective to build a regression model, because it allows not only to estimate the degree of influence of the factor on the result, but also to most effectively predict the size of the food production index for the future.

The Effects of Zeolite on Ammonia, Nitrous Oxide Emission, and Forage Yield from Pig Slurry Applied to the Forage Corn Cropping

Pig slurry (PS) is the most applicable recycling option as an alternative organic fertilizer. The application of pig slurry has the risk of air pollution via atmospheric ammonia (NH3) and nitrous oxide (N2O) emission. The zeolite has a porous structure that can accommodate a wide variety of cations, thus utilizing for the potential additive of deodorization and gas adsorption. This study aimed to investigate the possible roles of zeolite in mitigating NH3 and N2O emission from the pig slurry applied to the maize cropping. The experiment was composed of three treatments: 1) non-N fertilized control, 2) pig slurry (PS) and 3) pig slurry mixed with natural zeolite (PZ). Both of NH3 and N2O emission from applied pig slurry highly increased by more than 3-fold compared to non-N fertilized control. The NH3 emission from the pig slurry was dominant during early 14 days after application and 20.1% of reduction by zeolite application was estimated in this period. Total NH3 emission through whole period of measurement was 0.31, 1.33, and 1.14 kg ha-1. Nitrous oxide emission in the plot applied with pig slurry was also reduced by zeolite treatment by 16.3%. Significant increases in forage and ear yield, as well as nutrient values were obtained by pig slurry application, while no significant effects of zeolite were observed. These results indicate that the application of zeolite and pig slurry efficiently reduces the emission of ammonia and nitrous oxide without negative effects on maize crop production.

Unlocking maize crop productivity through improved management practices in northern Tanzania

Addressing the problem of low crop productivity and food insecurity can be accelerated through community-centered implementation of good agricultural management practices. This study was conducted in Babati,Northern Tanzania. The objective of the study was to determine nitrogen (N)and phosphorus (P)application requirements for maize,and demonstrate economically viable best bet yield-improving management technologies under three ecozones namely; ‘low elevation low rainfall’, ‘medium elevation high rainfall’ and ‘medium elevation low rainfall’ ecozone. Two sets of trials were conducted: N (0, 45, 90, 120 and 150 kg ha-1) and P (0, 15, 30, 40 kg ha-1) response trials in 16 representative fields in three seasons of 2013/14, 2014/205 and 2015/16 and; demonstrations trials in 8 farmer-selected fields in 2015/16 season. Combined N and P application increased maize yields by 32 to 62% over single nutrient applications.In the medium elevation low rainfall ecozone, 60-86%yield response to nitrogen was observed.Largely, modest applications of 50 kg N ha-1and 20 kg P ha-1resultedin profitable (marginal rate of return (MRR) of 2.4 to 3.0) yield increases of upto 214% over the farmers practice (unfertilized), varying with variety and ecozone. The source of P (DAP or Minjingu Mazao) had little influence on maize productivity except under low altitude low rainfall where Minjingu Mazao is unprofitable. Farmer rankings and agronomic indices showed new maize hybrids namely Meru H513, Meru H515 and SC627 as priority across the ecozones; Mams H913 is suitable mainly in medium elevation low rainfall ecozone. The conclusion is that use of new maize hybrids and appropriate rates of locally available N and P nutrient sources can bridge existing yield gaps and reduce food insecurity. Technologies from community-driven research in development are easily adopted by a large number of farmers and could result in a quick,yet lasting productivity gains.

EFFECTS OF HEAVY METAL TOXICITY ON MAZE SEEDLINGS GROWTH TRAITS

Maize is an edible cereal crop that belongs to family Gramineae and use as an energy source for human and animals. In our country the industrial and municipal wastewater has been being used for irrigation purposes that contain heavy metals. These heavy metals affect production of maize crop and soil quality. The purpose of this study was to investigate the affect of different heavy metals on maize growth and to asses more tolerant and more sensitive maize variety. Different concentrations of Mn and Cr (0, 0.25Molar, 0.50Molar) were applies in combined form and individually. Total three replicates were carried out during research. Analysis of variance (ANOVA), Tukey’s rang test (p ≤ 0.05) were applied as statistical tool among treatment means. ANOVA indicated the differences among five different genotypes and 9 different treatments for all parameters were significant. Tukey’s test indicated that higher toxic effect was shown under treatment 0.5M Mn + 0.25M Cr while less toxic effect was observed under treatment 0.50M Mn in maize plant. The genotype 31R88 was more sensitive for metal toxicity because most of 31R88 traits were affected under heavy metal treatments while more tolerant variety was Neelum. Hence the results of our study have suggested that the genotype Neelum may be used for the improvement of grain yield and productivity under heavy metal stress conditions.

MAIZE PRODUCTIVITY AS A RESULT OF APPLICATION OF CONTROLLED AND SLOW RELEASE UREA

Nitrogen (N) is the main limiting nutrient for productivity and yield components of maize crop. Urea is the main nitrogen source used, which, despite the high N concentration (45%), presents many losses through leaching and volatilization. In view of that, the purpose of the experiment was to evaluate the effect of applying N doses with urease inhibitor, nitrification inhibitor and slow-release urea, in relation to the conventional urea, on productivity and yield components of maize crop. The experiment was conducted in the municipality of Santa Rosa do Sul, state of Santa Catarina, in a 4x5 factorial scheme, where factor A corresponded to four nitrogen protection mechanisms (urea with urease inhibitor, urea with nitrification inhibitor, slow-release urea and conventional urea) and factor B corresponded to the surface-applied nitrogen percentage for the aforementioned protection mechanisms (0%, 25%, 50%, 75% and 100%). Under the edaphoclimatic conditions of the present study, fertilizers with inhibitors (nitrification and urease) and with slow release do not significantly increase maize productivity in relation to the conventional urea and, regardless of the source used, it is possible to reduce the recommended dose by 25%, based on soil analysis, without significantly impacting maize productivity.