Agroclimatic conditions of existence of almond trees in Plovdiv region during the winter period

D. Ivanova, N. Shopova
Abstract. The great interest toward the almond tree is due to the high value of the almond kernel as nutritional, dietetic, healing and technical raw material. The species is a plant of warm and mild climate with marked love for light. It develops in its best way in regions with short winters without big temperature fluctuation, early and sunny springs – without crucial frosts and with a lot of precipitations, and prolonged summers. During the period when the almond is in the state of rest and at an absolute minimum of the air temperatures up to minus 27.5°С in 1993 damages of the yearly growth up to 96 % were established under the form of decayed blossoms ovaries (Ivanova, 2002). The frequent warmings speed up the physiological processes and the subsequent spells of cold weather damage the generative organs – fruit-bearing buds and blossoms. The agro-climatic method for defining the conditions for winter survival is based on the accumulation of a certain active temperature sum exceeding the biological minimum needed for each stage of the development of an almond tree. The change in the active temperature sum depends on the temperature course, on the extreme values, on the duration of sun shine, as well as on the continental characteristic of the climate and on the mode of precipitations. The papers described here were conducted in the period 2000–2011 and aimed at tracing the influence of some basic meteorological elements (temperature, humidity, precipitations) during the autumn-winter period of the almond development in Plovdiv region. In relation to the scientifically justified division into regions for these plant species in Bulgaria it is necessary to clarify the role of one of the basic factors in their development – air temperature under the conditions of changing winter climatic parameters.