Agricultural Meteorology
Mehdi Asadi
Abstract
Introduction
Human activities and the substantial increase in greenhouse gas concentrations—particularly carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O)—have exacerbated global warming and triggered significant alterations in climatic patterns (Alston & Pardey, 2014; Pawlak ...
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Introduction
Human activities and the substantial increase in greenhouse gas concentrations—particularly carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O)—have exacerbated global warming and triggered significant alterations in climatic patterns (Alston & Pardey, 2014; Pawlak & Kołodziejczak, 2020). Consequently, climate change has emerged as a critical challenge for natural resource management and agricultural systems in recent decades. These changes, especially temperature and precipitation fluctuations, directly impact plant phenological and vegetative cycles and may even shift the suitable geographical ranges for cultivating certain plant species. Among these species is Ziziphus jujuba Mill. (Family: Rhamnaceae), a medicinally valuable plant (Cheng et al., 2000; Shen et al., 2009; Sabzghabaee et al., 2013) that exhibits relative adaptability to arid and semi-arid climates, such as those in Iran. However, it remains vulnerable to climate change impacts (Zittis et al., 2022; Waqas et al., 2024; Ghasemnejad et al., 2024). Historically cultivated in South Khorasan Province, this region now accounts for over 72% of Iran’s jujube production (Rad et al., 2020). Investigating climatic trends and their effects on the reproductive and vegetative thresholds of Ziziphus jujuba is both scientifically and practically significant. Such analyses enhance our understanding of regional climate change dynamics and facilitate predictive assessments of its agricultural consequences. Consequently, the objective of the present study is to identify the reproductive and vegetative thresholds of jujube throughout the year in the counties of South Khorasan Province and to spatially analyze these thresholds in terms of temperature and precipitation, both under baseline conditions and future scenarios influenced by trends in temperature and precipitation changes.
Material and Methods
In this study, the modified Mann-Kendall test, Sen's slope estimator, and linear regression analysis were employed to analyze trends in data related to determining the cultivation range of the jujube plant. The data under investigation included monthly temperature and precipitation averages from seven synoptic stations within the study area, covering a statistical period of 25 years from 2000 to 2024. These data were extracted from the National Meteorological Organization and served as the foundation for the study. Station data were converted into z-scores using the modified Mann-Kendall test in Minitab software. Additionally, linear trends of variables such as minimum temperature, maximum temperature, mean temperature, precipitation, sunshine hours, and hot days, along with their corresponding slopes, were examined.
Results and Discussion
Jujube plants, like other plant species, require specific temperature ranges for optimal growth during different vegetative and reproductive stages. This study examined the thermal thresholds that impact the growth of jujube trees. It was found that 25°C is the threshold at which reproductive growth stops, while 40°C is the threshold for the cessation of vegetative growth. (Yang et al., 2021, 2024; Hao et al., 2021). Additionally, the biological zero for jujube growth has been established at 11°C, and this plant can tolerate low temperatures down to -33°C (Wang et al., 2022). Some studies have even reported the plant's ability to withstand temperatures as low as -40°C (Hao et al., 2021). In this research, each of the seven studied stations in the region was individually analyzed in terms of maximum temperatures and critical points leading to the cessation of vegetative and reproductive growth.
Conclusion
The findings reveal that the Zirkuh station, with an average annual precipitation of 182.8 mm, receives the highest rainfall among the studied stations. Nevertheless, even at this station, jujube plants require supplementary irrigation of 267.2 mm. Fortunately, the region's climatic conditions are characterized by rare and minimal summer rainfall—a phenomenon that could otherwise cause fruit cracking—making this area particularly suitable for jujube cultivation. Analysis of climatic data from 2000 to 2024 demonstrates significant spatial heterogeneity in temperature trends. Modified Mann-Kendall test results indicate a warming trend across all stations, with the most pronounced increase observed in Nehbandan station (3.43°C) and the least in Zirkuh station (0.94°C). These spatial variations can be attributed to altitudinal differences, geographical positioning, and localized microclimatic conditions. Sen's slope estimator corroborates these findings, showing the steepest positive slope in Ferdows station (0.24) and the gentlest in Khosf station (0.03). Linear regression analysis reveals a decadal temperature increase ranging from 0.07°C in Birjand and Zirkuh stations to 2.48°C in Nehbandan station. Statistical analysis of p-values demonstrates significant spatial patterns in temperature changes. While northern and central stations (e.g., Birjand, Boshruyeh, and Ghaen; p ≤ 0.05) show no significant trend, southern stations, particularly Nehbandan (p ≤ 0.02), exhibit statistically significant warming. Regarding precipitation, all stations show decreasing trends, with a maximum reduction in Nehbandan (-3.32 mm) and a minimum in Birjand (-0.63 mm). Sen's slope analysis indicates the steepest decline in Ferdows (-0.34) and the mildest in Zirkuh (-0.13). Regression analysis estimates an annual precipitation decrease ranging from 0.04 mm/decade in Zirkuh to 1.80 mm/decade in Ghaen. Statistically, northern and central stations (p ≤ 0.05) show significant drying trends, while southern stations like Nehbandan (p = 0.28) exhibit no statistically significant trend.
hajar rajabi; A. Fallah Nosrat Abad; Gholamreza bakhshi Khaniki
Abstract
Introduction: sustainable development and the environment are interconnected. Sustainable agriculture is continuous utilization of a farm with respect to various aspects of environmental conditions by using fewer inputs (other than Bio-fertilizers). Phosphorus is one of the essential elements for the ...
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Introduction: sustainable development and the environment are interconnected. Sustainable agriculture is continuous utilization of a farm with respect to various aspects of environmental conditions by using fewer inputs (other than Bio-fertilizers). Phosphorus is one of the essential elements for the plants. Management of soil is possible by using biological fertilizers pillar of sustainable agriculture and providing some of the phosphorus needed by plants via bio-fertilizers. Phosphorus deficiency is extremely effective on the plant growth and productivity. The application of phosphorus fertilizers is expensive and dangerous. In addition, phosphorus in the soilmay become insoluble and will be unavailable to the plants. Studies showed that phosphate solubilizing bacteria in the soil rhizosphere are active and by root exudates solve insoluble phosphates such as tricalcium phosphate, and form absorbable P for plant. Consequently, the use of microbial fertilizers could reduce excessive use of chemical fertilizers and lead to decrease their harmful effects and protect the environment and conservation of available resources. The biological phosphate fertilizer industry uses sugar beet molasses as a binder and drying granules at high temperatures. Therefore, it is important to evaluate the durability of the bacteria in molasses at high temperature.
Materials and Methods: This study was designed as completely randomized design in a factorial arrangement.10 isolates were selected and the ratios of 50%, 25%, 15% and 10% of the apatite, organic matter, sulfur and soluble granule (ratio 1: 1 and 2: 1 bacteria and molasses), respectively, for each isolate was prepared. The final product was dried at 28 and 40 °C and remained for 4 months and population counted at first day and 10, 20, 30, 60, 90 and 120 days after the preparing. The population was counted by the serial dilution technique and cultured at Sperber media.
Results and Discussion:Comparing the average logarithm of population of bacteria in the granules indicated the highest proportion in the granules on the first day and the lowest population on 120 days (4 months), andthe ratio of 1: 1 inoculant and molasses had the largest population than the 2:1. The highest population was observed in 1:1 dried granules at 28 °C, but, some of 1:1 dried granules at 40 °C were consistent with the defined standards. Overall, bacteria I2-4, Z4 and C5-1 showed the greatest amount of population and the population had more power to maintain the standards among the isolates. The granules produced according to the defined standard (two-month period, 105 cell per gram of fertilizer) are dried at 28 °C in both 1: 1 and 2: 1 to the end of 4 months in the standard population. Granules dried at 40 °C for 1: 1 ratio of the population by the end of 4 months in the standard range. In the case of the most isolated granules at the ratio of 2:1 until the end of the second month, the population were within the standard range but at the end of the third month, they come lower than standard except I2-4, Z4 and C5-1. The total population of the granules was as following: Granules 1: 1, 28 °C> 2: 1, 28 °C> 1: 1, 40 °C> 2: 1, 40 °C. Considering to the fact that this standard is undefined for four months, but in this study, the population was 104 granules in the fourth month.
Conclusion: Based on the results, some of these conditions could keep their population and population decline was less. In general, it can be concluded that the granular organic fertilizer phosphorus in the industry of phosphate solubilizing bacteria with sugar beet molasses as a binder and drying at 40 °C can be used The results were positive and the granules can be cited to the production of this type of microbial fertilizer. Considering to the results, it was found that the proportion of molasses and inoculant, drying temperature and storage time were effective on viability of bacteria. Also, instead of using a train of bacteria, phosphate solubilizing bacteria, a combination of any of these bacteria in a field lead to better results. It is clear that by a comprehensive study, the molecular identification of bacteria, and detection of desire genetic loci and then gene transfer between bacteria for increasing of high temperature resistance by spour production and also, gene transfer between bacteria with high population and non-tolerance to sugerbeet molasses and tolerant bacteria to sugar beet molasses but low population; we can achieve bacteria with high population and high tolerance to sugar beet molasses and consequently achieve to favorable results. This result could decrease chemical phosphate fertilizers usage and their harmful effects and help to protect the environment and available resources.
vajiheh mohammadi sabet; Mohammad Mousavi Baygi; Hojat Rezaee Pazhand
Abstract
Introduction: The Southern Oscillation is a large scale phenomenon that changes the Normal oscillating air pressure on both sides of the Pacific Ocean. It disrupted the normal conditions and the patterns of temperature and precipitation change in the nearby region and other regions of the world. This ...
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Introduction: The Southern Oscillation is a large scale phenomenon that changes the Normal oscillating air pressure on both sides of the Pacific Ocean. It disrupted the normal conditions and the patterns of temperature and precipitation change in the nearby region and other regions of the world. This phenomenon is caused by changing the water slope in the Pacific Ocean between Peru (northwestern South America) and Northern Australia (about Indonesia and Malaysia). ENSO phenomenon is formed of Elnino (warm state) and La Niña (cold state). There is high pressure system in the East and low pressure system in the West Pacific Ocean in normal conditions (Walker cycle). The trade winds blow from East to West with high intensity. ENSO start when the trade winds and temperature and pressure balance on both sides of the PacificOcean change. High pressure will form in the west and low pressure will form in the East. As a result, west will have high and east will have low rainfall. Temperature will change at these two locations. Enso longs about 6 to 18 months. This research investigated the impact of ENSO on monthly precipitation and temperature of Mashhad.The results showed that temperature and rainfall have a good relation with ENSO.This relation occurs in 0-5 month lag.
Materials and Methods: The severity of ENSO phenomenon is known by an index which is called ENSO index. The index is the anomaly of sea surface temperature in the Pacific. The long-term temperature and precipitation data of Mashhad selected and analyzed. The Rainfall has no trend but temperature has trend. The trend of temperature modeled by MARS regression and trend was removed.The rainfall data changed to standard and temperature changed to anomaly for comparison with ENSO index. The 2016 annual and monthly temperature of Mashhad is not available. The 2016 Annual temperature was forecasted by ARMA (1,1) model. Then this forecast disaggregated to monthly temperature. For each period of occurring high ENSO, these three indexes (ENSO index, standardized rainfall and anomalies temperature) were compared. The co-variation of these indexes was compared. Also, the correlation and cross correlation for each period of occurring ENSO, with rain and temperature of Mashhad was calculated.
Results and Discussion: Mashhad monthly temperature and precipitation were compared with the extreme values of ENSO index in periods of the occurrence this phenomenon (1950-2016). In addition, the correlation and cross-correlation between ENSO-Rainfall index and ENSO-temperature index for this period were calculated.Forecasted temperature for 2016 by ARMA (1,1) was 13.2 Degrees Celsius, which has 0.2 degree increase in comparison to last year. Results showed thatthere is no an obvious relation between ENSO-Temperature and ENSO-Rainfall in interval (-1, +1). But there are good relation between ENSO-Temperature and ENSO-Rainfall beyond of (-1,+1). The results of Elnino showed that the monthly precipitation and temperature increase with a lag of 2 to 5 months and 0 to 4 months, respectively. The results of Lanina showed that the monthly precipitation and temperature decrease with a lag of 3 to 5 months and 1 to 4 months, respectively. Also when ENSO index is located in the interval (-1, +1), there is no certain harmony with temperature and precipitation of Mashhad.
Conclusions: The aim of this study was evaluating the effect of the ENSO phenomenon on monthly temperature and precipitation of Mashhad.Mashhad monthly temperature and precipitation, respectively, for 132 and 124 years were available.Precipitation was static and has no trend, but temperature was not static and has two changed (jumped) point in 1976 and 2000. MARS regression was used for patterning the process. Removing the trend was done by MARS model and the data was obtained without trend. Monthly ENSO index since 1950 from reliable websites worldwide (NOAA) was obtained. Mashhad monthly temperature data was animalized and precipitation data was standardized. This was performed for comparing Temperature and Rain with ENSO index. The effect of the ENSO phenomenon on Mashhad precipitation and temperature in both graphical and cross-correlation was performed.As a final result, there is a good relation with latency zero up to 5 months for temperature and precipitation of Mashhad beyond the interval (-1, + 1). It cannot be claimed that after the phase of La Nina, El Nino must be entered and vice versa. This note is important for forecasting the temperature and precipitation of 2016coming months. If ENSO index in the coming months, especially in autumn and winter, decrease and inter in La Nina phase, the winter will be cold with low rainfall.
abolfazl Mosaedi
Abstract
Prediction of precise forage production and proper management strategies requires identifying key climatic factors in different regions. The objective of this research is to compare forage production in different region based on climatic factors and drought indices. The study sites include Arak, Roudshore, ...
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Prediction of precise forage production and proper management strategies requires identifying key climatic factors in different regions. The objective of this research is to compare forage production in different region based on climatic factors and drought indices. The study sites include Arak, Roudshore, Baghic, and Gharahso in Central and Qom provinces. Climatic factors and drought indices include precipitation, temperature, evapotranspiration, standardized precipitation index (SPI), and Reconnaissance Drought Index (RDI). For each climatic variable/or indices, 33 time periods of 1, 2, 3, 4, 6, and 9-month were specified. We have used Principle Component Analysis to decline the number of variables and then, the appropriate time periods were selected. By using stepwise and best subset, the relationship between forage production and each of the climate factors and indices was modeled. To select model, assessment statistics of R, MBE, RMSE, MARE, and IPE were used. Finally, to predict forage production in Roudshore, Baghic, and Gharahso sites, models based on evapotranspiration (RMSE=7.7, r=0.99), RDI (RMSE=3.1, r=0.99) and precipitation (RMSE=4.0, r=0.99) were selected respectively. The best model was based on the combinations of climatic factors and drought indices (RMSE=0.2, r=0.99) for Arak. In general, the relation between forage production and drought condition based on RDI is stronger than its relationship with precipitation and temperature. As we have used precipitation and evapotranspiration simultaneously in RDI, so this index is more precise than SPI.
B. Rostamian; E. Maroufpoor; N. Azarboo; F. Farzankia
Abstract
Correct understanding of the factors affecting the rate of evaporation l and wind draft losses on sprinkler irrigation systems is important in order to provide guidelines for the development and utilization of water resources. This study was performed to identify the factors affecting the rate of evaporation ...
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Correct understanding of the factors affecting the rate of evaporation l and wind draft losses on sprinkler irrigation systems is important in order to provide guidelines for the development and utilization of water resources. This study was performed to identify the factors affecting the rate of evaporation and wind draft losses and also equations presents for estimating of evaporation and wind draft losses on the fixed head sprinkler irrigation systems, under various conditions of hydraulic and atmospheric. In this study sprinklers of ZK30, ZM22 and AMBO was used. The tests were carried out at the University of Kurdistan research farm located in the village of Doshan with single sprinkler method Accordance with the ISO 7749-1 and ISIRI 8995-3 standards. Evaporation and wind draft Losses were measured at different applied pressures under various conditions of atmospheric. The results showed that parameters of vapor pressure deficit and temperatures had the highest correlation with evaporation and wind draft losses in all three types of sprinklers, and this correlation is significant at the 1% probability level. Also results showed that the correlation between wind velocity and losses is in sprinklers of ZM22 and ZK30 significant at the 1% and 5% probability level respectively and in the sprinkler AMBO is no significant correlation. In overall evaporation and wind draft losses increase to 9.4 percent by increasing of 1 meter per second of wind velocity.
