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- Title
تدوین تقویم زراعی کشت ذرت دانه ای براساس توان اقلیمی آن در جنوب ایران .
- Authors
زینب ابراهیمی قل; جواد خوشحال; حجتاله یزدانپنا&
- Abstract
Introduction: Maize is the third most widely-used product in the world, which is classified as a tropical and subtropical cereal. Among maize varieties, the single cross hybrid 704 has high efficiency and yield. Environmental conditions, climatic factors, in particular, considerably affect the growth of maize and its phenological responses, among which temperature and light are two very important variables affecting growth rate and eventually influence the bio-production rate and product yield. The best method to optimally use the environment without spending major costs is an adaptation to climatic conditions. This adaptation is achieved by determining agricultural climates and recognizing these climates within agricultural climatic zones and is a valuable tool for controlling climatic potentials for crop production. The present study research aims to find the thermal requirements of single cross hybrid 704 in Darab, Zarghan, Rudan and Arzoieh climates to define the thermal requirements of various stages of growth for its planting potential in southern Iran. Methodology: To conduct the present study, the minimum, maximum, and average temperatures of 61 synoptic weather stations were obtained from the Iran Meteorological Organization, the statistical period of which varied from 1 to 30 years (1986-2016) and were examined in terms of validity. The statistics and information on the 10 main stages of single cross hybrid 704 phenology, which have been recorded in the Agricultural Meteorological Research and Monitoring Farm of Darab, Zarghan and Rudan, Arzooieh stations from 2001 to 2017, were given. These stages include planting, germination, greening, three-leaf, leafing, male catkin emergence, male clustering, silking, milk, and ripening. Date, the number of days, average temperature, and daily heat index were determined based on cumulative growing degree-day of single cross hybrid 704 in each phenological stage in Darab, Zarghan, and Rudan Arzooieh stations (statistical period 2001-2017). Then, the authors take into account the starting planting date in each region by reaching the average daily temperature of 15°C and the average temperature above 10°C after planting to meet the required growth temperature and avoid damage to the plant. To do this research, the average temperature (over 20 years) was calculated by MATLAB software for all days of the year based on the solar calendar. Then, 15-day averages were obtained for all months of the year. The relationship between temperature and altitude in linear regression was calculated by SPSS software. Hot inhibitor temperature (above 38°C) and cold inhibitor temperature (below 10°C) were determined and plotted. Cumulative growing degree-day of plant and the number of days in each phenological stage were calculated for all stations and the relevant maps were plotted. Finally, the map of desirable areas was combined with the land use map, height, and slope in terms of temperature supply. Discussion: According to the information obtained, the starting date of maize planting was plotted as a zoned map for all southern regions of the country in the GIS environment. The thermal requirements for planting during the year are met in a part of the southern shores and Shahdad Desert with an altitude of less than 500 m with very hot and humid weather as explained in the climate of the region. In other regions, this crop is provided depending on the climate, hot/cold, and low/high latitude, from the first half of February to the second half of May. This research has been done by developing a crop calendar for this product for the first and second planting in different regions. The first planting date in cold regions began with an altitude above 2000 m in the second half of May. In this region, due to the cold weather, maize can be selected only as the first crop. From the first half of June, maize planting begins in the regions with hot and temperate climates. After determining the planting time for maize in each region, the required days of maize from planting to ripening were calculated based on the total energy obtained in terms of growing degree-day in the southern region of Iran and mapped in 4 vital stages. The length of catkin emergence was 51-98 days, silking was 8-25 days, milk was 10-24 days, and ripening was 15-60 days. In some areas, the thermal requirement was not met for the milk stage and ripening, thus, the plant growth period would remain unfinished. The hot inhibitory temperatures in all coastal areas (except for Jask, Bandar Abbas, Khamir, Dayyer, and Bandar Lengeh) were possible from the second half of May to September. The cold inhibitor temperature in areas such as the high altitudes of Lalehzar in Kerman and the cities of Izadkhast, Eghlid, Safashahr, and Bavanat in the north of Fars province with a cold and temperate climate in mountainous and foothill areas, began from the second half of October. According to the maps, the study area was divided into 4 regions in terms of capacity to meet thermal requirements during the growing season including very favorable areas, favorable areas, partly favorable areas, and unfavorable areas. By integrating the layers of favorable areas for maize planting based on meeting the thermal requirements, height, slope, and land use in the study area, the final map was plotted. The results of the study showed that very favorable areas covered 12% of the study area and are very favorable in terms of temperature, topography, and land use. Concerning favorable areas, this region covered 8% of the total study area. In these areas, the topography and land use were partly suitable and the thermal requirements were met at all maize planting stages, but the length of the milk stage was longer. In partly favorable areas, sufficient growing degree-day is not met for full ripening. The partly favorable areas have covered 3% of the study area. In unfavorable areas, thermal conditions, land use, land slope, and altitude for this crop were not suitable. Conclusion: By comparing the results of this research and other studies conducted in this region and the reports of the Ministry of Agriculture Jihad, it can be observed that this method has a similar outcome with other methods and models. About 23% of the study area is capable of maize planting. The farmer or promoter can select the most appropriate planting date for the crop by finding the place of maize planting on the maps and achieve the occurrence time of all phenological stages by finding the date. The reviews indicate that if the planting date is not adjusted in accordance to conditions of meeting the thermal requirements of the plant in its phenological phases in the study area, the plant is forced to change the length of each phase to acquire the required thermal units and this will disrupt the growth process and cause heat or cold stresses.
- Subjects
IRAN; METEOROLOGICAL research; PLANT phenology; LAND use mapping; COLD (Temperature); TEMPERATE climate; AGRICULTURAL productivity; FRUIT ripening
- Publication
Geography & Environmental Planning, 2021, Vol 32, Issue 1, p45
- ISSN
2008-5362
- Publication type
Article
- DOI
10.22108/gep.2021.125664.1367