Soil temperature has a strong influence on plant growth and development, the processes taking place is normally only between plant-specific thermal limits, and each phase of vegetation. With falling temperatures below 0 0 C, involved process of freezing, which in some conditions can become harmful to plants cultivate.To prevent the damages from these phenomena, it is necessary to know mainly the types of freezing that can affect crops, the period of freezing, etc. Frosts can occur in three different periods: winter, autumn and spring. Winter frosts called "black frost" causes, in general, less damage to agriculture, since intervening in a dormant period. However, these frosts, have a sensible action on vegetation when a period of several days, the temperature values fall below a threshold lowered. In the same time autumn frosts cut off vegetation cultures by providing  the date of harvesting. In South Dobrogea was analyzed duration and period of freezing, using climate data for a period between 1965-2000, the main weather stations (Constanta, Mangalia, Medgidia, Adamclisi, Harsova). Based on these data, using statistical methods as the frequency and duration, could determine the index of the persistence of freezing that can characterize the degree of harshness of the climate. To calculate the index of thepersistence of freezing in the territory of South Dobrogea werw used multiannual average annual number of days with frost and no frost during the annual interval, resulting lenghth  of days with  frost possible. Thus, one can notice a lower persistence of frost in the Black sea, because of its moderating influence, while in the freezeng high plateau is greater persistence due to thermal inversions. In conclusion, the index of  the persistence of frost can characterize the degree of harshness of the climate particulary for crops. Depending on these results we can see the consequences of these phenomena on crops, but also measures may be taken to prevent damage crops.

black frost; crops

Presentation: oral