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Showing 3 results for Phenology
Determination of suitable areas cultivation of maize Based on the supply of heat needs in northwestern Iran
Zeinab Ebrahimighalelani, Dr Javad Khoshhal Dastjerdi, Dr Hojatolah Yazdanpanah,
Volume 0, Issue 0 (3-1921)
Abstract
plants needs a certain amount of heat at the time of planting and during its growth period, The temperature requirements of the 704 single-cross cultivar of maize in Moghan weather conditions have been found in this study to determine its temperature requirements in its different growing stages in order to investigate the feasibility of its planting in the north west regions of Iran. Daily weather statistics presenting the minimum, maximum and average temperature of 51 Synoptic stations from Meteorological Organization of Iran have been used in this study, their statistical periods range from 1 to 30 years (1365-1395), the statistics and information about 5 main phenology stages of 704 single-cross variety maize which are recorded continually in Agricultural Weather Service of Moghan station in Pars Abad from 1390 to 1391 are provided. Then the 15-day averages from April 21st to July 22nd is obtained. The relationship between the temperature and the height in the linear regression is calculated .Map of heat supply date for seed sowing in all stations from the first half of May was drawn in the GIS. The plant collective growth degree days and the number of days in every phenology phase are calculated for all of the stations and the related maps are plotted.Then,the final map plotted by combining the layers thermal, height, slope and land use in the study area. The results of this study only 27.6% of the study area is able of maize cultivating.

Evaluation and zoning of thermal and phenological conditions of grape cultivation in Hamadan province
Akbar Shaemi- Barzoki, Nasrin Nikandish, Abolfazl Baghbani- Arani, Samira Aligholi,
Volume 23, Issue 70 (10-2023)
Abstract
Agriculture in the context of climate arrives at a favorable outcome. One of the important goals in agricultural researches is the investigation of effects of atmospheric parameter on various agricultural products. In this research we study the thermal and phenological conditions of grape cultivation in Hamadan province. In this study we analyzed thermal conditions for grape based on minimum and maximum daily temperatures of Meteorological stations in Hamadan province, by use of  thermal potential, normal distribution, optimal deviation, growing degree days (GDD), phenology interphase methods. We also used SMADA software for statistical analyses and by Arc GIS Software to determine the possibility of frost and IDW technique for zoning and presentation of spatial distribution results. The results show that from the southern to the northern of Hamadan province the total heat units is reduced. An examination of the probability of a late spring frost at 95% showed that the date varies from late April in the southern regions of the province to the first decade of May in the northern half of the region. The probable date of late spring frost was seen at the end of April in the southern half (Malayer and Nahavand) areas, which coincides with the phenological stage of germination. The date of these phenological stages complete with a delay of ten days from south to north. The deviation from optimal temperature conditions in each grape phenological stage, in the northern half is more than that of the southern half. According to the research results, early varieties of grapes is suitable for cultivation in the northern half of the region, due to the lower heat potential.[D1] 


Estimation of Phenology Stages of Rapeseed Using Remote Sensing Vegetation Indices and Digital Camera Images Index
Akbar Mirahmadi, Hojjatollah Yazdan Panah, Mehdi Momeni,
Volume 24, Issue 72 (6-2024)
Abstract
In recent years, the technology of crop production has been greatly expanded using satellite data. Today, Landsat 8 and OLI sensor data, with a spatial resolution of 30 meters, allow the discovery of factors that control phenology on a local scale. In this study, the remote sensing indices - NDVI, EVI, Greenness, and Brightness - obtained from the OLI sensor and the GCC index obtained from digital camera images were used to estimate the phenological stages of the rapeseed plant. The Savitzky-Goli filter was used to remove outlier data and to produce smooth curves of time series of plant indices. The results showed that the curves obtained from the indices of NDVI, EVI, GCC show all four stages of remote sensing phenology – green-up, dormancy, maturity, and senescence - well, but the Greenness index did not show the dormancy stage well. The Brightness index curve shows the inverse behavior to other curves. According to Pearsonchr('39')s correlation test, GCC index data are correlated with NDVI and Brightness index data .we used the ratio threshold, rate of change and first derivative methods, to estimate "start of season" and "end of season" and the results showed that the first derivative and ratio threshold methods with an average difference of 18 and 19 days in the "start of the season"  and the rate of change method, with an average difference of 8 days, has the best performance in estimating the “end of the season”. Also, the Brightness index with an average difference of 16 days and the EVI index with an average difference of 7 days have the best performance in estimating "start of season" and "end of season", respectively.

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