Phenological phases (phenophases) are morphologically and functionally distinct development stages of the plant which repeat themselves in the growing season. The most important and very visible phenological phases in apricots are "beginning of blossoming", "beginning of picking maturity" and "end of picking maturity". Even though the different phenophases are influenced by the genetic nature of the plant, their course also depends on external conditions of the given year.Many authors throughout the world have evaluated the phenophases of apricots. MEHLENBACHER et al. (1998/99) reported that in northern areas the differences between the blossoming phenophases of different genotypes, from the earliest to the latest blossoming ones, reach an amplitude a little higher than a week. These differences are a consequence of different reactions of genotypes to the rise of temperatures after dormancy. Having tested seven cultivars of the species Prunus armeniaca L., VACHŮN (1974) found out that the temperatures from 7° to 9°C determined the start of the phenophase "beginning of the budflush". However it does not exclude the influence of lower temperatures. BAŽANT et al. (1999) reported that the date of apricot blossoming was also influenced by the sum of active temperatures above 5.5°C.The beginning of blossoming of the same cultivar from year to year can differ by 25 to 40 days depending on the cultivar and on the conditions of the year (VACHŮN 1986;KRŠKA 1994;BAŽANT et al. 1999;VACHŮN 2002). Even though the period of "beginning of blossoming" for the same cultivar differs from year to year, the classification of cultivars according to this phenophase shows that their rank is statistically significant to highly significant (r = 0. ABSTRACT:The phenophase course in a group of 20 apricot genotypes was evaluated in South Moravian conditions in Lednice, Czech Republic, from 1994 to 1999. The evaluated phases were as follows: "beginning of blossoming", "beginning of picking maturity" and "end of picking maturity". The aim was to evaluate the variability of these phenophases and their relationships. The amplitude of the phenophase "beginning of blossoming" did not exceed 9 days. The amplitude of phenophases between the different years was about three times higher than the average amplitude between the genotypes. The average amplitude of the factor "beginning of picking maturity" observed in all genotypes was 39 days, but a comparison between the years showed that the largest amplitude for a given genotype was only 16 days. No statistical correlation was found between the phenophases "beginning of blossoming" and "beginning of picking maturity" in any of the six observed years. The genotypes whose maturity occurs at the beginning or at the end of picking season showed higher year to year variability of the phenophase "beginning of picking maturity" than the genotypes maturing in the middle of the season. The rate of fruit development from blossoming to picking was considerably different depending on the apricot genotype. The...

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Productivity and its stability were evaluated in a set of 24 apricot genotypes of the world collection and some promising new selections in [1994][1995][1996][1997][1998][1999]. The productivity of most genotypes was higher than that of control variety Velkopavlovická LE-6/2. Genotypes with higher productivity in the years favorable for apricot productivity gave higher yields also in the years unfavorable for productivity. It was proved by a significantly close highly significant correlation (r = 0.64 ++ ). It is a reason for the necessary regulation of fruit set in highest-yielding varieties in the years favorable for apricot productivity when overproduction and undesirable reduction in the fruit size occur. The variability of yields in kg per tree, expressed by coefficients of variation over a six-year period, was high in the years of observation. The variability of yields was significantly lower in the years favorable for apricot productivity. To express yield variability the coefficient of variation and index of fluctuation can be used. Their similar conclusiveness was proved by the significant positive closeness of correlation between the values determined by both calculations (r = 0.51 + ). The varieties Vynoslivyj and Volšebnyj showed the highest and most stable productivity. From the producer's and breeder's aspects, of these two the Vynoslivyj variety is one of the most remarkable genotypes of the evaluated set due to its fruit quality and late ripening. number. Selected crosses (hybrids) are designated by working numbers where the letters LE and M indicate the origin from the Faculty of Horticulture at Mendel University of Agriculture and Forestry at Brno -Lednice. Velkopavlovická LE-6/2 variety was used as control. New genotypes (designated by abbreviations M, LE, LE-SEO and numerals) were included in the experimental orchard because they were interesting after previous evaluations from the producer's aspect. The other varieties were used for a comparison on the basis of evaluation and recommendation of foreign institutions that provided these varieties for this experiment. KeywordsTrees were planted in a long block design: five plants of each genotype were set out. Each tree was evaluated individually. Out of the originally planted 93 genotypes only those genotypes were included in final evaluation whose number of plants did not decrease below three trees by the end of experiment (1999) and whose values of all studied traits were complete in all years. The number of genotypes that could be evaluated decreased to 24. This set was evaluated in the present paper. Commercially important yields were produced from the fourth year after planting. Productivity was not regulated by fruit thinning during the six-year period of evaluation.Even though the long-term values of average annual temperatures are favorable for the experimental locality (9.0°C), there were significant differences between the years in the course of temperatures particularly in the blooming period. Four years in the period of ob...

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