The objective of the research was to define bioclimatic coefficients of vegetable crops and potato for improving methods and means of adjusting their irrigation modes in the conditions of the Rostov region. The method of A. M. and S.M. Alpatyevy was used for calculating the bioclimatic coefficients of these crops. On the basis of conducted study it is established, that the maximal values of bioclimatic coefficients for potatoes and vegetables reached at the critical period of moistening during the vegetation of plants. Further changes of these indicators depended on biological features of the crop. Bioclimatic coefficients of potato changed during the vegetation period evenly: the lower values were marked at the beginning and the end of growth, reaching the highest rate (0.24) at the flowering period of the crop, which corresponded to the sum of active temperatures 1000-1400 °?. Similar patterns were observed for cabbage, where the maximum values (0.25) were during head setting – beginning of technical maturity, when the sum of active temperatures was 1600-1900 °?. The dynamics of bioclimatic coefficients for onion reflected the high moisture requirements at the initial period of the crop vegetation with its substantial reduction at the period of maturation. The maximum value (0.22) was achieved during the bulb initiation – beginning of lodging, which corresponded to the sum of active temperatures 1100-1800 °?. The same patterns of the dynamics of bioclimatic coefficients were marked for tomato and cucumber. The greatest values reached at the second half of vegetation of these crops: for tomatoes at the period from the beginning of flowering to the first harvest – 0.24 (while the sum of active temperatures from 1900 to 2200 °?); for cucumber during fruiting – the first harvest – 0.27 (while the sum of active temperatures 1000-1300 °?). However, at the final phase of growth and development of tomatoes and cucumber their bioclimatic coefficients didn’t decrease sharply, which reflected the high moisture requirements of the crops during mass harvest.
