Context: N is the vital element for the growth and development of plants out of all the required nutritious compounds. This element plays a key role in most plant metabolic processes. Objective: To ...review the literature related to the role of nitrogen in growth, yields, levels of chlorophyll pigments and efficiency in the use of nitrogen is carried out. Methods: In this article, an attempt has been made to provide a comprehensive review of nitrogen status in agriculture. Also, since nitrogen is the most used element by farmers, this research seeks to know its effects and impact on Nitrogen Use efficiency. Results: N deficiency affects plant growth, photosynthesis, and ultimately production. However, excessive N consumption reduces the quality of the product. Furthermore, N is one of the main components of chlorophyll structure in the plant. Chlorophyll content and N content in plants are closely related. Chlorophyll content plays a vital role in determining the plant's rate of photosynthesis and production. Leaf N content increases when N fertilizer is applied. Higher N content in leaves is associated with higher chlorophyll content and increased chloroplast activity and thus increased photosynthetic productivity. Conclusions: It is possible to reduce environmental pollution and increase productivity by understanding management methods that increase Nitrogen Use efficiency (NUE).
Plant productivity is impacted by drought stress, which adversely affects their morphological and physiological processes. In response, the plant activates its defense mechanisms, but severe drought ...impairs these responses. In this review, the morphological aspects of water deficit on plants were examined, including reduced germination, rooting, shoot development, and leaf growth, which ultimately lead to quantitative and qualitative yield losses. In addition, physiological aspects of drought were studied, including photosynthesis, chlorophyll content, respiration rate, stomata closure, water, and nutrients relations, and their efficiency. We also presented various agronomic and non-agronomic strategies to combat this global problem as part of the management approach. Breeding using modern methods such as marker-assisted selection, genomic selection, and targeted gene editing was proposed as a promising tool to develop more tolerant crop varieties. In addition, different agronomic methods (plant density, sowing date, crop rotation, conservation tillage, and use of biochar) were discussed. Furthermore, various strategies for improving drought tolerance of crops using nutrient management (salicylic acid, sulfate zinc, chemical fertilizers, and humic acid) were outlined. Mycorrhizae and growth-promoting bacteria were also discussed as effective approaches to achieving drought tolerance in crops. Overall, we concluded that developing drought-tolerant crops requires the use of multiple approaches, including agronomic and non-agronomic techniques and advanced breeding tools.
Phosphorus (P) deficiency is a primal limiting factor for crop yields, particularly during the early developmental phase. This nutritious element plays a key role in several physiological mechanisms ...such as seed and fruit formation, respiration, photosynthesis, energy storage, and transfer, cell division, cell enlargement, and many other processes in the plant. Part of P applied to soil as fertilizer is could be into insoluble forms, rendering it unavailable to plants and causing environmental pollution. Therefore, increasing p absorption ability by plants appears to be critical for increasing agricultural productivity and decreasing pollution. Improving the crops P use efficiency (PUE) could be an effective method to increase P uptake. The maximum PUE is observed where nutrient supply via chemical fertilizer is the lowest level. This review discussed the significance of plant growth, yield quality, and PUE.
The semicircular breakwater (SBW) is a composite breakwater consisting of a hollow empty reinforced concrete caisson seated on the rubble mound breakwater. In this research, smoothed particle ...hydrodynamics (SPH) method was used to examine the run-up and overtopping of solitary waves on SBW. At first the SPH model was validated for regular wave–SBW interaction against experimental results. Comparisons showed that the present modified numerical model has a good agreement with experimental data. Parametric study was then performed on the effect of water depth and wave height of the single solitary waves and height of the rubble mound on wave run-up. Furthermore, double solitary waves were generated to study their interaction with SBW by the model. Run-up and reflection coefficient for double solitary wave–structure interaction was then investigated. The results show that in sum run-up in double solitary wave mode is smaller than that of single solitary wave. Moreover, the second solitary wave run-up is smaller than that of the first solitary wave in double solitary wave train. Overtopping discharge of double solitary wave is nearly constant for
τ
/
T
greater than 1.3, where
τ
/
T
is the ratio of time distance between wave crests of double wave to effective period of single solitary wave. Also overtopping discharge decreases with increasing in
τ
/
T
for its value smaller than 1.3. The results show that this model is a useful tool for simulating the interaction of solitary waves–structures with complicated geometry.
Modern agriculture has a major impact on natural resources in terms of exploitation and use. Land and water resources are being exploited by ever-increasing population pressures. High nutritional ...inputs such as mineral nitrogen (N) fertilization are required to achieve higher and sustainable yields. Although crop production depends on N fertilizers, the excessive and inefficient use of N inputs is a worldwide issue that increases production costs and pollutes the environment. Strategies to increase N use efficiency (NUE) would be the key to reducing these negative impacts by improved agronomic practices. To develop effective management approaches, it would be helpful to understand the effect of N on various aspects of crop growth, development, and physiological processes in crops. In this review, we highlighted recent agronomic progress made to improve NUE by adopting primarily agronomic practices that may be more environmentally and economically beneficial, including site-specific-nitrogen management, enhanced use efficiency of fertilizer resources, conservation approaches, drip fertigation, crop modeling, and precision agriculture. The first section discusses the morphological and physiological effects of N on crops while in the second section, agronomic strategies for growing crops with higher NUE are discussed.
•Influence of drought duration and severity on drought recovery period was explored.•MODIS-based vegetation health index was used for drought monitoring.•Drought recovery period was estimated using ...gross primary productivity.•Shrub lands and agriculture classes experienced elongated drought than forest.
Drought is a slow-onset phenomenon driven by the lack of precipitation, affecting the performance of plants and functionality of terrestrial ecosystems. In addition to the length and severity of drought, the period it takes for the plants to return to normal conditions is critical. Remote sensing data with appropriate spatial and temporal coverage facilitates monitoring drought and its consequences on local and global scales. This study investigated the influence of drought duration and severity on the drought recovery period (DRP) for different land use and land cover (LULC) types in Iran. The moderate resolution imaging spectroradiometer (MODIS)-based vegetation health index (VHI) was used to monitor drought in the period 2000–2020. The results identified 2000, 2001, and 2008 as drought years. DRP was estimated using gross primary productivity (GPP). The findings revealed that shrubland and cropland experienced more prolonged droughts than forests, which experienced the shortest drought duration. Similarly, shrublands and croplands had the most prolonged recovery, and forests had the shortest recovery time. A direct relationship was observed between drought severity and DRP in all LULC types, however the local correlation between drought duration and recovery time better revealed the heterogeneity of relationships. This study provides valuable information on the drought resilience of different LULC types for use in achieving better management and a deeper understanding of drought.
This study was carried out to evaluate the energy flow, GHG emissions, and global warming potential (GWP) in corn production in western Iran. The Data was collected by split plot Design based on ...randomized complete block design with four replications. The treatments consisted of a combination of three levels of the main tillage factor including conventional tillage (CT), minimum tillage (MT), no-tillage (NT), and three levels of chemical fertilizer including no fertilizer or N0P0K0 (NPK)
0
, N50P50K50 (NPK)
50
and N100P100K100 (NPK)
100
. The results of this study showed that the total input energy in CT systems, MT, and NT was 56113.24, 51403.70, and 49144.45 MJ ha
−1
, respectively. The output energy in this tillage systems was 111989.11, 113312.80 and 109516.68 MJ ha
−1
respectively. By reducing the rate of fertilizer, the amount of input and output energy was decreased. The NT and MT systems had higher energy efficiency than the CT one. Energy efficiency in (NPK)
0
, (NPK)
50
and (NPK)
100
was calculated to be 2.62, 2.53, and 1.88, respectively. The highest amounts of CO
2
, N
2
O, and CH
4
were observed in corn production with CT systems. In no-fertilization treatments, GHG emissions were also lower. Moreover, the results showed that by decreasing tillage and increasing amount of fertilizer, GWP decreased. According to the results of this study, changing the practice of tillage from CT to MT and reducing fertilizer amount could increase energy efficiency in the region and reduce GHG emissions.
Conventional design of pier structures is based on the assumption of fully rigid joints. In practice, the real connections are semi-rigid that cause changes in dynamic characteristics. In this study, ...quality of the joints is investigated by considering changes in natural frequencies. For this purpose, numerical and experimental modal analyses are carried out on related physical model of a pier type structure. When numerical results are evaluated, natural frequencies generally do not match the expected experimental results. Uncertainties in different aspects of engineering problems are always a challenge for researchers. The numerical models which are constructed on the basis of highly idealized scheme may not be able to represent all of the physical aspects of the physical one. For this study, determination of percentage of semi-rigid joints is considered as an optimization problem based on the numerical and experimental frequencies. Probabilistic sensitivity analysis is also used to determine the search space. A new technique of optimization problem is solved by a combination of smart particle swarm optimization (PSO) and genetic algorithms, and a complicated and efficient system for model updating process is introduced. It is observed that the hybrid PSO-Genetic algorithm is applicable and appropriate in model updating process. It performs better than PSO algorithm, considering the good agreement between theoretical frequencies and experimental ones, before and after model updating.
•Primary metabolites (PMs) and secondary metabolites (SMs) play pivotal roles in plant stress responses, which are main players in the signaling processes.•Secondary metabolites can react to ...environmental stimulants via complex and specific biosynthesis pathways.•Plant metabolites can be used as bio-stimulants to enhance plant resilience and mitigate the impact of biotic and abiotic stresses on agricultural productivity.
Plants are constantly exposed to a wide array of complex interactions involving various environmental factors, leading to disruptions in their metabolic processes and incurring physiological costs when faced with biotic and abiotic stress. In response to these stimuli, plants have developed diverse signaling mechanisms to adapt to the prevailing conditions. Plants equipped with different signaling pathways undergo changes at the transcriptomic and metabolic level to survive stress stimuli. The signaling pathways are divided into four major subsections: signal perception, signal transduction, regulation of gene expression and physiological responses. Transcription factors (TFs) play a crucial role in the organization of defense mechanisms by regulating downstream gene expression. Primary metabolites (PMs) and Secondary metabolites (SMs) represent fundamental compounds involved in these plant response mechanisms. These plant extracts are a promising method of increasing the tolerance of plants to environmental stresses and can be used as biostimulants. This review aimed to elucidate the contributions of PMs and SMs in plant reactions, as well as their biosynthesis pathways. Additionally, the interplay between these compounds was discussed. The molecular physiology of plant responses to environmental stimuli via signaling pathway was described in this research. Ultimately, plant metabolites were introduced as bio stimulants that can mitigate the adverse effects of various biotic and abiotic stresses.
Context: N is the vital element for the growth and development of plants out of all the required nutritious compounds. This element plays a key role in most plant metabolic processes. Objective: To ...review the literature related to the role of nitrogen in growth, yields, levels of chlorophyll pigments and efficiency in the use of nitrogen is carried out. Methods: In this article, an attempt has been made to provide a comprehensive review of nitrogen status in agriculture. Also, since nitrogen is the most used element by farmers, this research seeks to know its effects and impact on Nitrogen Use efficiency. Results: N deficiency affects plant growth, photosynthesis, and ultimately production. However, excessive N consumption reduces the quality of the product. Furthermore, N is one of the main components of chlorophyll structure in the plant. Chlorophyll content and N content in plants are closely related. Chlorophyll content plays a vital role in determining the plant's rate of photosynthesis and production. Leaf N content increases when N fertilizer is applied. Higher N content in leaves is associated with higher chlorophyll content and increased chloroplast activity and thus increased photosynthetic productivity. Conclusions: It is possible to reduce environmental pollution and increase productivity by understanding management methods that increase Nitrogen Use efficiency (NUE).
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