RT Journal Article SR Electronic A1 Spitz, Pavel A1 Hemerka, Ivo T1 The occurrence of moisture deficits for representatives of main crop sorts in their critical development stages in driest regions of the Czech Republic in years 1961-2000 JF Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis YR 2014 VO 56 IS 2 SP 157 OP 166 DO 10.11118/actaun200856020157 UL https://acta.mendelu.cz/artkey/acu-200802-0020.php AB The article presents acquired results of moisture deficits for representatives of main crop sorts in their very critical development stages on soil moisture in our driest regions (Žatecko, Litoměřicko, Middle Bohemia, East Bohemia, Southern Moravia, South-East Moravia, Middle Moravia) in the years 1961-2000. The calculations were realized by the specially developed program BIVPROG 1 (the balance moisture program) for PC for perennial wheat (as representative of cereals), perennial rape (technical crops), potatoes (root-crops) and alfalfa (fodder crops), in its first crop year. The results of the calculations are probabilities of over fullfilment of maximum number days successive with moisture below the lower limit of soil moisture Θ<sub>Z</sub> found out in very critical development stages on moisture for every chosen crop. The probabilities of over fullfilment were determined from quadragenarian line (the years 1961-2000) of calculations made for every technical line of climatological data and pertinent phenological station with phenological data of chosen crop and they were worked into graphs. With regards to the extent of graphical outcome, the results are worked in tables VI. to IX. The fortnightly criterion was derived for comprehensive evaluation of acquired results, the values of comprehensive evaluation are presented in table X. This table reflects that the fortnightly criterion in the years 1961-2000 was exceeded in more then 20 years for all chosen crops, also in the case of perennial wheat and rape which are considered as secondary from the aspect of their irrigation requirements. From the obtained data also follows, that the lack of soil moisture usually starts to show signs before the very critical development stages of the crop, and then often continues. The results were acquired for medium soil, for mild soil the results would be even more unfavourable. The obtained results from our driest regions evoke the concern for irrigation requirements in these regions.