Final Grain Research Articles

UAV Remote Sensing for Detecting within-Field Spatial Variation of Winter Wheat Growth and Links to Soil Properties and Historical Management Practices. A Case Study on Belgian Loamy Soil

Intra-field heterogeneity of soil properties, such as soil organic carbon (SOC), nitrogen (N), phosphorous (P), exchangeable cations, pH, or soil texture, is a function of complex interactions between biological factors, physical factors, and historic agricultural management. Mapping the crop growth and final yield heterogeneity and quantifying their link with soil properties can contribute to an optimization of amendment/fertilizer application and crop yield in a management variable zones (MVZ) approach. To this end, we studied a field of 17 ha consisting of four former fields that were merged in early 2017 and cropped with winter wheat in 2018. Historical management practices data were collected. The topsoil characteristics were analyzed by grid-based sampling and kriged to create maps. We tested the capacity of a multispectral MicaSense® RedEdge-MTM camera sensor embedded on an unmanned aerial vehicle (UAV) to map in-season growth of winter wheat. Relating several vegetation indices (VIs) to the plant area index (PAI) measured in the field highlighted the red-edge NDVI (RENDVI) as the most suitable to follow the crop growth throughout the growing season. The georeferenced final grain yield of the winter wheat was measured by a combine harvester. The spatial patterns in RENDVI at three phenological stages were mapped and analyzed together with the yield map. For each of these images a conditional inference forest (CI-forest) algorithm was used to identify the soil properties significantly influencing these spatial patterns. Historical management practices of the four former fields have induced significant heterogeneity in soil properties and crop growth. The spatial patterns of RENDVI are rather constant over time and their Spearman rank correlation with yield is similar along the growing season (r ≃ 0.7). Soil properties explain between 87% (mid-March) to 78% (mid-May) of the variance in RENDVI throughout the growing season, as well as 66% of the variance in yield. The pH and exchangeable K are the most significant factors explaining from 15 to 26% of the variance in crop growth. The methodology proposed in this paper to quantify the importance of soil parameters based on the CI-forest algorithm can contribute to a better management of amendment/fertilizer inputs by stressing the most important parameters to take into consideration for site-specific management. We also showed that heterogeneity induced by the soil properties can be described by a crop map early in the season and that this crop map can be used to optimize soil sampling and thus amendment/fertilizer management.

Quantitative Relationship Between Solar Radiation and Grain Filling Parameters of Maize.

A quantitative understanding of the factors driving changes in grain filling is essential for effective prioritization of increasing maize yield. Grain filling is a significant stage in maize yield formation. Solar radiation is the energy source for grain filling, which is the ultimate driving factor for final grain weight and grain filling capacity that determine maize yield. Here, we first confirmed the quantitative relationships between grain filling parameters and photosynthetically active radiation (PAR) by conducting field experiments using different shading and plant density conditions and cultivars in 2019 and 2020 in Xinjiang, China. The results showed that with every 100 MJ m−2 increase in PAR, the average grain filling rate (Gave), maximum grain-filling rate (Gmax), and the kernel weight at the time of maximum grain-filling rate (Wmax) increased by 0.073 mg kernel−1 day−1, 0.23 mg kernel−1 day−1, and 0.24 mg kernel−1, and the time of maximum grain-filling rate (Tmax) delayed by 0.91 day. Relative changes in PAR were significantly and positively correlated with relative changes in yield and Gave. With every 1% change in PAR, yield and Gave changed by 1.16 and 0.17%, respectively. From the perspective of grain filling capacity, DH618 was a more shade-resistant cultivar than XY335 and ZD958. It is urgent to breed maize cultivars with low light tolerance and high grain yield in the face of climate change, particularly the decrease in solar radiation.

The Production of Dual-Purpose Triticale in Arid Regions: Application of Organic and Inorganic Treatments under Water Deficit Conditions

Most of the arid and semi-arid regions, particularly in the Mediterranean area, suffer from the lack of a sufficient quantity of high-quality feed, as well as a low amount of rainfall that is unevenly distributed, resulting in the region being highly vulnerable to drought. A field experiment was carried out at the experimental station of the Faculty of Desert and Environmental Agriculture, Fuka, Matrouh University, Egypt during the winter seasons of 2018/19 and 2019/20 to study the performance of triticale (X Triticosecale Wittmack), grown under water deficit conditions, in terms of productivity and quality. The study investigated the influence of five levels of potassium fertilization (PF; 0, 43.2, 86.4, 129.6, and 172.8 kg ha−1) and ascorbic acid (AA; 0, 25, 50, 75, and 100 mg L−1) that was applied to the triticale grains before sowing and humic acid (HA; 0, 2.4, 4.8, 7.2, and 9.6 kg ha−1) that was applied as powder to the soil 21 days after sowing followed by sprinkler irrigation on triticale forage and grain production when forage was removed at variable ages at cutting (AC), determined as days after sowing (AC; 40, 65, 90, 115, and 140 DAS) on forage yield and nutritive value, in addition to the final grain yield of triticale. The experimental design was a central composite design with one replicate. Results indicated that the PF*AC interaction was significant, and it gave values of 84.78 and 238.00 g kg−1 for crude protein (CP) and degraded neutral detergent fiber (DNDF). In addition, the interaction between AA and AC was significant for CP, acid detergent fiber (ADF), 100-grain weight (100 GW), number of spikes m−2 (NSM−2), and plant height (PH). Moreover, the AC*HA interaction was significant with values of 175.17 and 247.00 g kg−1 for CP and DNDF, respectively, and 0.55 t ha−1 for grain yield (GY). Age at cutting exerted the strongest effect on the studied characteristics. It was observed that the contents of neutral detergent fiber (NDF), ADF, acid detergent lignin (ADL), and non-fiber carbohydrates (NFC) in the triticale forage significantly increased when the crop was cut at an advanced age, unlike CP, DNDF, GY, NSM−2, 100 GW, and PH that decreased with advanced AC. The highest values of 271.00, 256.00, and 268.00 g kg−1 for DNDF were obtained with higher levels of either PF, AA, or HA, respectively. However, the highest value of GY (0.97 t ha−1) was obtained with higher levels of PF*HA averaged over the two seasons. The interaction between AA*HA resulted in 393.39, 311.00, 27.13 g kg−1, and 0.94 t ha−1, for NDF, DNDF, ADL, and GY, respectively. The highest significant NDF (413.11 g kg−1) and DNDF (307.50 g ka−1) values were obtained with the application of high levels of either AA or HA. In the dual-purpose production system, it is recommended to cut the triticale crop at 65 DAS to achieve the optimum balance between forage yield and quality on the one hand, and final grain yield on the other hand. In the arid regions, application of PF, AA, and HA could help in reducing the damage caused by water deficit.

Canopy management: the balance between lodging risk and nitrogen use for spring wheat production in the Canadian Prairies

Lodging risk in spring wheat has grown with the introduction of high-yielding cultivars that require high nitrogen (N) inputs to optimize grain yield and protein content. Canopy management (CM) strategies have been used to reduce lodging risk. However, the short growing season and unpredictable moisture supply may limit the use of these strategies in the Canadian Prairies. The objective of this study was to quantify the ability of agronomic practices to modify the early season crop canopy, and hence lodging risk, and to determine how these practices influence N use and final grain N yield. Split-plot field trials were established at four site-years (SYs) in Manitoba to evaluate CM strategies including three plant densities, a split N fertilizer application, and the application of chlormequat chloride (CCC) on canopy size (dry matter (DM) and height at anthesis), N uptake and remobilization, lodging and stalk strength, grain yield, protein, and grain N yield on the cultivar AAC Brandon. Precipitation was low during this study (64%–78% of long-term average (LTA)), resulting in modest yields and low lodging pressure. However, low plant density (PD), split N, and CCC applications all showed potential to reduce lodging risk without reducing grain yield or protein concentration. Split N and plant growth regulator (PGR) applications increased final grain N yield by 11.2% and 2.4%, respectively. Therefore, CM practices have potential in the Canadian Prairies to reduce lodging risk without compromising grain N, but results should be validated in higher precipitation environments and across additional cultivars and growing regions of western Canada.

Preparation of Al4SiC4 with higher aspect ratio by a novel two-step method

Based on excellent comprehensive properties, aluminum silicon carbide (Al4SiC4) becomes a promising candidate as antioxidant for MgO–C refractories. However, its addition tends to reduce the densification of corresponding refractories due to the plate structure with low aspect ratio, which aggravates the slag corrosion and oxidation during the practical application. Increasing the aspect ratio of Al4SiC4 grains is a feasible approach to fabricate dense Al4SiC4-containing refractories. In this work, a strategy to fabricate Al4SiC4 grains with higher aspect ratio based on a novel two-step solid reaction method was proposed. Firstly, Al4SiC4 seeds was synthesized using Al4C3 and SiC as raw materials at 1700 °C for 6 h. Secondly, the mixture of Al4C3 and SiC with Al4SiC4 seeds added was resintered. The aspect ratio of final Al4SiC4 grains reaches up to 0.44 with the added proportion to be 50%. The growth mechanism follows the Ostwald ripening principle. This work can lay a good foundation for the practical application of Al4SiC4.

Binder Selection to Modify Hydrocarbon Cracking Properties of Zeolite-Containing Composites.

Activity, selectivity, and deactivation behavior of catalyst materials determine their efficiency in hydrocarbon conversion processes. For hydrocarbon cracking, the industrial catalyst is an important parameter in reaction technology to produce valuable compounds, e.g., light olefins (C3–C5) and gasoline from crude oil fractions with high molecular weight (C16+). One strategy to enhance the catalytic activity for precracking is increasing the matrix activity, which depends on the used binder and additives. In this work, three binders (water glass, aluminum chloride, and a mixture of colloidal silica with aluminum dihydrogen phosphate) were used in combination with active zeolite Y, kaolin as filler, and ZSM-5 as additive to produce composite materials. Specific surface area and surface acidity measurements were combined with catalytic testing of the formulated samples in order to find the relation between the catalyst morphology and its activity. In addition, constraint index was used as a control parameter for the determination of the shape-selective properties and their correlation with the catalytic activity. The results show that the binders determine the porosity of the matrix and so the accessibility to zeolite pores and active sites. Matrixes with low porosity and activity enhance coke production and deactivate faster than matrixes with mesopores. Furthermore, ZSM-5 modifies the individual morphological and catalytic effects of the binders. Everything considered, the small crystals of ZSM-5 together with mesopores increase the olefins yield, reduce coking, and therefore enhance the performance of the final grain.

Corn yield and nitrogen recovery following rye (Secale cereale L.) in monoculture and polyculture service crops

Planting service crops (SCs) with late summer manure applications has been promoted as an agronomic practice to capture manure nitrogen (N) and release it to the following season’s cash crop, thereby reducing fertilizer N requirements. The present study explored this hypothesis using a cereal rye ( Secale cereale L.) monoculture SC, along with two polyculture SCs (4 species and 12 species) both containing rye, planted after winter wheat ( Triticum aestivum L.) harvest, in systems with and without liquid hog manure. The following spring, SC regrowth was chemically terminated 1 week prior to corn ( Zea mays L.) planting, and a sidedress N application was made at the 6–8 leaf stage to half of the plots. Corn N accumulation and final grain yield were reduced up to 20% following the rye monoculture in both years, even though SCs did not reduce soil mineral N nor partial plant-available N over the corn-growing season. Additionally, the sidedress N application could not overcome the yield loss associated with rye. Thus, this study did not observe N release by SCs to the following cash crop and demonstrates that yield loss can occur when corn follows rye SCs irrespective of changes in plant available N. This research reinforces the importance of selecting appropriate species and their proportions in polycultures, to mitigate negative impacts of SCs, especially those of rye on corn.

ИССЛЕДОВАНИЕ ВЫДЕЛЕНИЯ СКЛЕРОЦИЙ СПОРЫНЬИ ИЗ ЗЕРНОВОГО МАТЕРИАЛА В ВОДНОМ РАСТВОРЕ СОЛИ

Food products from rye grain have the most valuable properties for improving human health. However, crops of this crop often infect poisonous ergot sclerotia. Modern grain cleaning machines do not provide complete isolation of ergot sclerotia from rye grain during cleaning in one technological cycle due to the similarity of their physical and mechanical properties. Repeated passage of the grain material through the cleaning mechanisms in order to completely isolate the poisonous ergot sclerotia from the grain material dramatically increases the cost of the cleaning process. Ergot sclerotia have a lower density than a full-fledged rye grain, which makes it possible to separate them according to this criterion in an aqueous solution of an inorganic salt. The aim of the study is to determine the efficiency of the isolation of poisonous ergot sclerotia and to identify the loss of grain Pz into waste during in-line immersion of the grain material in a liquid, depending on the specific grain load gsp at different densities ρzh of an aqueous salt solution. As objects of research, it was accepted to study the isolation of ergot sclerotia from winter rye grains of the Falenskaya 4 variety with a moisture content of 14% by density in an aqueous salt solution and to determine the possible losses of high-grade grain to waste. Studies have been carried out when grain material is supplied by a flow from a height h = 60∙10-3 m into water (ρzh = 1000 kg/m3) and an aqueous solution of sodium chloride (NaCl) with a density ρzh = 1030…1180 kg/m3 with varying specific grain load gsp with values of 0.674…7.221 kg/(s∙m). It has been established that at a density of an aqueous solution of salt ρzh = 1150 kg/m3 and a specific grain load gsp = 0.674…1.469 kg/(s m), 100% ergot sclerotia emerge to the surface of the solution, and the loss of grain Pz to waste does not exceed 2.52%, which meet the agrotechnical requirements for final grain cleaning machines

ANALYSIS OF SPECIFIC FEATURES OF THE FORMATION OF STRUCTURAL INHOMOGENEITY OF CARBON STEEL (REVIEW)

Purpose. To consider possible factors of influence on the formation of structural and grain unevenness of carbon steel. Methodology. Based on the analysis of the existing literature, the influence of various factors on the structural heterogeneity in carbon steels is analyzed. Results. From the analysis of the literature, a number of reasons were identified that affect the formation of heterogeneity in the structure of carbon steels. These factors include: chemical composition, dendritic liquation and processing liquation, non-metallic inclusions, mechanisms of austenite grain formation, initial grain size, and steel contamination with gases. Scientific novelty. On the part of the chemical composition, chemical elements such as carbon, copper, aluminum, silicon, nitrogen, sulfur and phosphorus affect the liquation formation. The formation of the microliquation level is also significantly influenced by the type of the formed structure. It has been shown that the level of segregation with directional crystallization is much higher than with equilibrium crystallization. Also, the formation of the final structure is associated with a hereditary influence in the production of metal products of the structural features of the parent metal, which depend on various technological factors. The contribution of certain metallogenetic signs of technological heredity occurs at all stages of melting, crystallization, structure formation, solid-phase transformations; different types of thermal, deformation-thermal, deformation processing, etc. In most cases, it is technological factors that are responsible for the structural features and manifestations of the metallurgical and structural heredity of metals and alloys. The dispersion of the dendritic structure, which grows with an increase in the crystallization rate, has a significant effect on the development of dendritic segregation in the ingot. With an increase in the dispersion of the dendritic structure, the total crystallization surface grows and a significant part of the liquid metal solidifies at higher temperatures. Practical significance. As a result of the performed review of the literature, the main factors influencing the formation of the final structural and grain unevenness were determined in accordance with modern points of view. Determination of the basic principles and the most effective factors will make it possible to confidently assume the possible microstructure of steel both in the cast state and after heat treatment.

Influence of Parallel Tubular Channel Angular Pressing (PTCAP) Processing on the Microstructure Evolution and Wear Characteristics of Copper and Brass Tubes.

The influence of the number of passes and the tube materials on the microstructural evolution, mechanical properties, and wear behavior of Cu and brass tubes after parallel tubular channel angular pressing (PTCAP) was investigated. The grain size decreased to final grain sizes of 138.6 nm and 142.7 nm, after PTCAP of the Cu and brass tubes was conducted in up to 4 and 2 passes, respectively. PTCAP contributes to obtaining an ultra-fine grain (UFG) microstructure, with a mixture of different grain sizes that conferred high hardness. The present results indicate the superior wear resistance of Cu and brass PTCAP tubes, relative to Cu and brass samples that were previously deformed by different severe plastic deformation (SPD) processes. The wear mechanism of the Cu tubes changed from delamination and cracks with a high degree of adhesive wear before PTCAP into a combination of adhesive and abrasive wear, with a decrease in the presence of oxygen content after the PTCAP procedure. The wear mechanism also changed from a combination of adhesive and abrasive mechanisms into abrasive ones with the absence of oxygen after the PTCAP of brass tubes.

Comparative Analysis of Canopy Cooling in Wheat under High Temperature and Drought Stress

The size and the weight of wheat grains vary across the length of each spike (Triticum aestivum L.). High temperature and water scarcity often reduce the single grain weight, and this reduction also varies across the spike length. Plants tend to cope with high temperature and drought stress through inherent mechanisms such ascanopy cooling through transpiration, which can contribute to yield stability. The effect of canopy cooling on the average grain weight at different positions in spike is still unknown. In this study, we planned to assess the role of canopy temperature, yield-related traits, and spike shape in final grain weight. For two years (2017–2018 and 2018–2019), fifteen diverse genotypes released for cultivation in different environmental conditions were grown in the field. They were examined for canopy temperature, spikelets spike−1, grain number spike−1, grain yield spike−1, and grain weight of the spike’s basal, median, and distal regions. The Pearson correlation coefficient (r) was obtained for all pair-wise combinations of traits under different treatments and spike shapes. The results indicated that cooler canopy is correlated to grain weight in normal spike shape at all three positions within the spike irrespective of stress. The advantage of the cooler canopy in improving grain-filling at basal, median, and distal regions was more conspicuous in the high temperature stress conditions compared to non-stressed and drought conditions.

Ultra-fast high-temperature sintering of strontium titanate

Ultrafast High-temperature Sintering (UHS) is a novel sintering process enabling extremely high heating rates by direct contact of sample to electrically heated thin carbon strips. Using strontium titanate as a model system, the densification behavior by UHS was investigated. Controlled experiments via maximum current limitation were used to study the influence of the applied current on the degree of densification and resulting final grain size. Simulations by Finite Element Modeling (FEM) allow estimating the sample temperature reached during UHS, which is in good agreement with the experimental data. Moreover, the FEM simulations show a self-stabilization of the sample temperature by thermal radiation. UHS results suggest that rapid densification can be achieved with an extremely high heating rate. The microstructure of the undoped strontium titanate samples shows exaggerated grain growth and pore-boundary separation, which results in pore entrapment inside grains. The addition of 2 mol% iron in strontium titanate is beneficial by limiting the grain growth during the UHS sintering cycle. Uniform densification and grain growth in the sample is consequently observed. Scanning transmission electron microscopy/energy dispersive x-ray spectroscopy (STEM/EDS) is utilized to analyze grain boundary segregation. Measurement of the electrical conductivity of the UHS sintered samples by impedance spectroscopy suggest that rapid densification by UHS enables full access to the functional properties of strontium titanate as compared to the conventionally sintered material.

Impacts of barley root cortical aerenchyma on growth, physiology, yield components, and grain quality under field waterlogging conditions

Waterlogging is a major ecological threat that restricts crop growth and yield in high rainfall zones across the globe. Waterlogging tolerance is conferred by several complimentary mechanisms, with root cortical aerenchyma (RCA) formation being one of the major ones. In this study, three pairs of near-isogenic lines (NILs) of commercial barley varieties which we introgressed a quantitative trait locus (QTL) for RCA formation, and eight other genotypes contrasting in waterlogging tolerance were subjected to growth under waterlogged and control (non-waterlogged) conditions. Field trials were conducted in 2019 and 2020. The waterlogging treatment began at the two-three leaf stage and continued for two months. The water was subsequently drained, and the crops allowed to recover for final grain yield. Under waterlogging conditions, genotypes with RCA-QTL had significantly higher aerenchyma, white adventitious roots, leaf normalised difference vegetation index (NDVI), higher shoot biomass, tiller number, compared with genotypes without RCA-QTL. Across the three commercial varieties in waterlogged conditions, the average boost to yields from the introgression was 1.8 t/ha. The genotype YF225 showed a degree of waterlogging tolerance but had no RCA-QTL. This appears to be an alternate waterlogging tolerance mechanism that is not yet understood. Importantly, the addition of the RCA-QTL to three commercial varieties showed no significant negative effects on plant growth, yield, and grain quality attributes under control conditions. We conclude that the introgression of an RCA-QTL into other varieties is a promising breeding target for mitigating losses caused by waterlogging. • The formation of aerenchyma can significantly increase root survival and final grain yield under waterlogging conditions. • The addition of the QTL for aerenchyma formation showed no significant effects on plant growth under control conditions. • Pyramiding RCA-QTL with other tolerance mechanisms could create varieties with significantly better waterlogging tolerance.

Quantitative simulations of grain nucleation and growth at additively manufactured bimetallic interfaces of SS316L and IN625

This paper provides a quantitative understanding of grain nucleation and growth at the interface of SS316L and IN625 bimetallic structures during directed energy deposition (DED) through multi-physics simulations, including phase-field models and computational fluid dynamics analysis. The main finding is that the flow behaviors would lead to composition redistribution and the change of liquidus temperature in the mixing zone at the interface, which further influences the solidification sequence and the final grain structure that are different from general single-metal counterparts without the mixing zone. The results show that during depositing IN625 on SS316L, a gradual transition in composition distribution and liquidus temperature in the well-mixing zone caused by simple clockwise flow leads to epitaxial grain growth from the SS316L substrate and the prevalence of columnar grains with a low undercooling (<1 K) condition. However, when depositing SS316L on IN625, it turns out that initial solidification can occur due to abrupt compositional change at the interface where the well-mixing breaks are caused by two opposite (clockwise and counterclockwise) flow behaviors. Such an abrupt compositional change results in high liquidus temperatures that may trigger the grain nucleation in the middle melt pool due to a high undercooling (>30 K); thus, a mixed grain microstructure is present.

Biochar and Selenium Nanoparticles Induce Water Transporter Genes for Sustaining Carbon Assimilation and Grain Production in Salt-Stressed Wheat

In a controlled environment experiment, we studied how physiological changes in leaves during the vegetative phase regulate final grain yield of wheat crops in salt-affected soils. We also hypothesized that amendments such as biochar (SB) and selenium-chitosan nanoparticles (Se-NPs) can protect wheat plants from salt injury. 20-day-old wheat plants were submitted to 4-week salt stress (3000 ppm NaCl). Soybean straw biochar was mixed with soil media at planting and Se-NPs (30 ppm) was sprayed 5 days after the first salt stress treatment. At the end of 4-week Se-NPs treatment, one set of plants was harvested for studying leaf level physiological changes. The salt-stressed plants accumulated significantly high leaf Na+ (~ 13-fold increase), which trigged oxidative and osmotic damage. This salt-induced cellular injury was evident from significantly high levels of lipid membrane peroxidation and inhibited photosynthesis. Our study suggested that leaf physiological impairment in wheat plants was translated into poor biomass production and grain yield loss at crop maturity. Compared with control, salt-stressed plants produced 43% lesser biomass during vegetative phase, and 62% lesser grain yield at maturity. Amendments such as SB and Se-NPs protected the plants from salt-induced cellular injury by restricting Na+ transport toward leaf tissues. Plants treated with NaCl + SB + Se-NPs accumulated 50% less Na+ concentrations in leaves compared with NaCl-treated plants. Our study also suggested that SB and Se-NPs can restore ionic homeostasis and carbon assimilation in salt-stressed wheat by upregulating key transporter genes in leaves.

Nitrogen application affects maize grain filling by regulating grain water relations

Grain water relations play an important role in grain filling in maize. The study aimed to gain a clear understanding of the changes in grain dry weight and water relations in maize grains by using hybrids with contrasting nitrogen efficiencies under differing nitrogen levels. The objectives were: 1) to understand the changes in dry matter and percent moisture content (MC) during grain development in response to different nitrogen application rates and 2) to determine whether nitrogen application affects grain filling by regulating grain water relations. Two maize hybrids, high N-efficient Zhenghong 311 (ZH311) and low N-efficient Xianyu 508 (XY508), were grown in the field under four levels of N fertilizer: 0, 150, 300, and 450 kg N ha–1 during three growing seasons. Dry weight, percent MC and water content (WC) of basal–middle and apical grains were investigated. The difference in the maximum WC and filling duration of basal–middle and apical grains in maize ears resulted in a significant difference in final grain weight. Grain position markedly influenced grain drying down; specifically, the drying down rate of apical grains was faster than that of basal–middle grains. Genotype and grain position both influenced the impact of nitrogen application rate on grain filling and drying down. Nitrogen rate determined the maximum grain WC and percent MC loss rate in the middle and the late grain-filling stages, thus affecting final grain weight. The use of high N-efficient hybrids, combined with the reduction of nitrogen application rate, can coordinate basal–middle and apical grain drying down to ensure yield. This management strategy could lead to a win–win situation in which the maximum maize yield, efficient mechanical harvest and environmental safety are all achieved.

Simulating the effect of climate change on barley yield in Ethiopia with the DSSAT‐CERES‐Barley model

AbstractClimate change is expected to have a major effect on crop production in sub‐Saharan Africa. Crop models can help to guide crop management under future climate. The objective of the study was to investigate the possible effects of climate change on Ethiopian barley (Hordeum vulgare L.) production using the Decision Support System for Agrotechnology Transfer (DSSAT)‐Crop Environment Resource Synthesis (CERES)‐Barley model. The study included field data of two barley cultivars (Traveller and EH‐1493) and four climate study areas in Ethiopia over 5 yr. Climate change scenarios were set up over 60 yr using representative concentration pathways (RCP; RCP4.5 and RCP8.5) and five global climate models (GCM). The model results indicated that the prediction of days to anthesis and maturity, as well as final grain yield, was highly accurate for cultivar Traveller with normalized RMSE (nRMSE) of 2, 1, and 12%, respectively, and for cultivar EH‐1493 with nRMSE of 2, 4, and 11%. A consistent increase in average temperature up to 5 °C and a mixed pattern of rainfall (‐61 to +86%) were projected. Yield simulations showed a potential reduction in yield up to 98% for cultivar Traveller and 63% for cultivar EH‐1493 in the future. Within a sensitivity analysis, different sowing dates, sowing densities, and fertilizer rates were tested as potential adaptation approaches to climate change. The negative effects of climate change could be mitigated by early sowing, with an increased sowing density of 25% and fertilizer rate of 50% more than what is recommended. Overall, the results indicated the ability of the CERES‐Barley model to evaluate climate change effects and adaptation options on rainfed barley production in Ethiopia.

EVALUATION OF SEVERAL WHEAT CULTIVARS IN RESPOND TO DIFFERENT TYPES OF FERTILIZERS INCLUDING BIO-FERTILIZER UNDER RAINFED CONDITIONS

The research was conducted during 2018-2019 growing season to study the growth and yield of various wheat cultivars under various methods of fertilizers application including bio-fertilizer under rainfed conditions of two different isohyets conditions. Randomized complete block design was applied with four replications. Potential grain yield is highly affected by the number of reproductive tillers; differences in final grain yield were highly and positively correlated to the number of tillers (r= 0.54**) and above ground biomass (r= 0.68**). The grain yield was about three times higher in Rikava location (3.19/1.01 t.ha-1). Both of Cihan and Adana99 wheat significantly produced higher grain yield (2.44 and 2.43 t.ha-1 respectively) followed by Tammoze and Italy, the Criso durum wheat was the inferior with only 1.65 t.ha-1 grain yield. DAP fertilizer (2.58 t.ha-1) was the best fertilizer treatment followed by YARA and BIO and all treatments were significantly higher than the check unit which produced only 1.7 t.ha-1. The interaction of Adana99 with DAP (2.79 t.ha-1) and Cihan with DAP (2.71 t.ha-1) recorded highest grain yield; these two cultivars with BIO fertilizer produced significant grain yield and each gave (2.5 t.ha-1). Financial analysis revealed the superiority of both Anana99 and Cihan cultivars with DAP fertilizer followed by BIO fertilizer as they contributed positively with the highest final revenue.

Alternative Solution to Synthetic Fertilizers for the Starter Fertilization of Bread Wheat under Mediterranean Climatic Conditions

Under the high temporal variability of the Mediterranean climate, the prompt emergence of wheat seedlings and early vigor are pivotal attributes, positively affecting the final grain yield. Phosphorus (P) fertilization at sowing is largely used in wheat cultivation to support the early-season growth and promote a more rapid crop establishment. While conventional farming can rely on a wide variety of synthetic fertilizers, the number of options available for the starter fertilization of organic wheat is restricted and many are often unsuitable. Nanotechnology applied to fertilizers could provide a valuable means to combat this issue. This study aimed to evaluate the starter effect of a granular soil bio-enhancer (SBE) on bread wheat grown in two locations of Northern Tunisia as compared to conventional fertilization with diammonium phosphate (DAP). The SBE was obtained by physically grinding phosphate rocks at a nanoscale level and further mixing it with azotobacters. Aerial dry biomass, plant height, crop density, tiller density, leaf area index (LAI), and leaf P concentration were determined up to 70 days after emergence (DAE) to assess the early vigor of wheat seedlings. The application of SBE before sowing resulted in a greater early vigor of wheat seedlings as compared to commercial DAP over three consecutive growing seasons. Specifically, the aerial dry biomass and the plant height at 7 DAE were found to have increased by 56% and 48%, respectively. LAI at 70 DAE was enhanced by 8.5%, while moderate percentage increases were detected for both crop and tiller density. Finally, wheat plants fertilized with SBE showed a significantly higher leaf P concentration than DAP-fertilized plants in 2020 and 2021 (+21% and +32%, respectively).

Simulating Maize Productivity under Selected Climate Smart Agriculture Practices Using AquaCrop Model in a Sub-humid Environment

Crop models are crucial in assessing the reliability and sustainability of soil water conservation practices. The AquaCrop model was tested and validated for maize productivity under the selected climate smart agriculture (CSA) practices in the rainfed production systems. The model was validated using final biomass (B) and grain yield (GY) data from field experiments involving seven CSA practices (halfmoon pits, 2 cm thick mulch, 4 cm thick mulch, 6 cm thick mulch, 20 cm deep permanent planting basins (PPB), and 30 cm deep) and the control (conventional practice) where no CSA was applied. Statistics for coefficient of determination (R2), Percent bias (Pbias), and Nash–Sutcliffe (E) for B and GY indicate that the AquaCrop model was robust to predict crop yield and biomass as illustrated by the value of R2 &gt; 0.80, Pbias −1.52–1.25% and E &gt; 0.68 for all the CSA practices studied. The relative changes between the actual and simulated water use efficiency (WUE) of grain yield was observed in most of the CSA practices. However, measured WUE was seemingly better in the 2 cm thick mulch, indicating a potential for water saving and yield improvement. Therefore, the AquaCrop model is recommended as a reliable tool for assessing the effectiveness of the selected CSA practices for sustainable and improved maize production; although, the limitations in severely low soil moisture conditions and water stressed environments should be further investigated considering variations in agroecological zones.