Growing degree days (GDD) were calculated for 40 meteorological stations distributed across Greece, on the basis of daily maximum and minimum air temperature (T MAX and T MIN , respectively) for the 10 year period from 1978 to 1987. Duration of growing periods (classified in 10 d intervals) differed among stations. The longest period was from April 1 to November 30, and the shortest from May 1 to September 30. Growing season varies across Greece from about 1600 GDD in the northern mountainous areas to > 2900 GDD in the lowlands and the southernmost regions. Most spring-sown crops need no more than 1500 GDD to mature; consequently, there are no temperature limitations in Greece for crops such as corn, cotton and tobacco. Despite the sparse climatic network it was possible to create high resolution maps with statistically significant results (r = 0.83 to 0.89; p = 0.95), providing reliable information for agricultural planning.KEY WORDS: Growing degree days · Agriculture · Regional maps · GreeceResale or republication not permitted without written consent of the publisher
Serious economic damages in many regions of the world were caused by the changes in agroclimatic resources during the last 2–3 decades. The Balkan Peninsula is much affected by the temperatures rising, changes in the distribution of precipitation, and the increasing frequency of extreme events—basically, droughts and frosts. Bulgarian agriculture is developed under various agrometeorological conditions. The climate of the country is characterized by the atmosphere and soil moisture deficit in the time of active crop vegetation and yield formation. The aim of this research is to assess the changes in agrometeorological conditions for the growth of the main grain crops and the possibilities for reaction through agro-technologies. Furthermore, the features of contemporary varieties and hybrids of spring and autumn cereals will be taken into account. The next important factor is the specific requirements for hydro-thermal conditions at different phenological phases of agricultural crop development, i.e., sums of the temperatures and precipitations. Agro-technologies react to tendencies in changing agrometeorological conditions. For the adaptation of agro-technologies, the maximum use of natural agroclimatic resources should be included in activities for overcoming unfavorable conditions, as well as the increased frequency of extreme events. A detailed assessment of the agrometeorological conditions is necessary to choose the suitable agro-technology activity. The analysis of the main meteorological elements—temperatures, precipitations, air humidity, wind speed, and solar radiation for thirty years (1986–2015) was used to assess the changes in agrometeorological conditions on agricultural lands in Bulgaria. Appropriate agro-technical activities for growing the main grain crops are proposed in accordance with the observed changes.
Introduction. The condition of the vegetation cover can be traced from Space. Aim of the research. To assess the condition of the vegetation cover in Bulgaria during the last twenty years – its distribution over the country, its change in connection with the typical climatic changes, its seasonal change. Material and methods. The vegetation index NDVI according to NASA data was used to analyze the condition of the vegetation cover in Bulgaria for the years 2000-2020. The methods used were: seasonal data decomposition, t-test, GIS methods for spatial representation of data, Fourier analysis. Conclusions. 1. During the summer months the vegetation in the eastern parts of the territory of Bulgaria is noticeably weaker than in the western parts. The influencing factors-drought and frequent fires are probably related to global warming. 2. For the territory of Bulgaria there is a seasonal rotation of the horizontal gradient of the vegetation index in a counterclockwise direction-from east to west in summer, from northeast to southwest in autumn and from north to south in winter. 3. There is a winter increase in vegetation for Northern Bulgaria and to the greatest extent for Northeastern Bulgaria, as well as for Southwestern Bulgaria. Together with the decreasing snow cover, the winter vegetation contributes to the drought in the eastern parts of the country.
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