The aim of the diploma thesis was to find out the termination date of endogenous dormancy of bud flowers within the selected set of apricot varieties and simultaneously keep track of the development of various phases of microsporogenenesis. The last goal was to capture the phenological indicators of flowering and fruit development. The experimental part describes material and methodology tested on the peach varieties at Horticultural Faculty in Lednice in a two-year experiment during 2013-2014. The temperature curve was significantly different in both years. Year 2013 was characterized by gradual and lengthty progression of low temperatures, and by late termination of endogenous dormancy. Year 2014 was entirely unlike the previous one in its rapid progression of above-average temperatures and dynamic emersion of varieties from dormancy. After evaluating the results the varieties were divided into three groups with short, medium and long period preceding the termination of dormancy. The results of the observation of microsporogenesis phases shows that development of each phase is not uniform in all varieties of monitored peaches. The pollen grains development rate is greatly influenced by the temperature curve. Varieties with late termination of dormancy and slow development of microsporogenesis phases are less susceptible to impairment of the flower buds by late spring frosts.

Dissertation work deals with the evaluation of the selected characters of promising peach varieties grown in the genepool collection and pilot testing block. The evaluation took place between year 2011 to 2013. The work can be divided into three thematical units. The first part deals with the health condition, specifically monitoring of the occurrence of European stone fruit yellows phytoplasma (ESFY) and the plum pox virus (PPV). The second part focuses on the physiological events occurring in flower buds (dormancy, microsporogenesis, frost resistance) and the third unit deals with pomological characteristics of varieties and the economic evaluation of varieties which are already introduced in the commercial cultivation. In the literature section the origin and the spread, world production of peaches and the current situation in the Czech Republic are descibed and a chapter about peach breeding is included as well. Further, chapters characterizing dormancy, microsporogenesis and frost hardiness are described in the work. Literature section also includes content substances and health-promoting substances in peach fruit. The last chapter describes the diseases causing economically significant losses in peaches. In the experimental part the incidence and symptoms of phytoplasma ESFY and synergism between PPV and ESFY was evaluated. The effect of the PPV infection on content of the total polyphenols and the antioxidant activity of fruits was investigated. Further, the termination of dormancy, microsporogenesis and frost resistance of flower buds was evaluated. Significant part of work was the pomological evaluation of selected varieties from genepool collection and evaluation of varieties in pilot testing block conditions. The results show that in peach orchards trees infected by phytoplasma ESFY show various symptoms of the disease which depend on host genotype. Synergism between Plum pox virus (PPV) and European stone fruit yellows phytoplasma (ESFY) has not been confirmed. PPV infection results in increased amount of the antioxidant activity and total polyphenols in peach fruits.Varieties can be divided into 3 groups by the term of termination of endogenous dormancy, paticulary, varieties with early termination, varieties with medium termination and varieties with late termination of dormancy. Evaluated varieties differ, either, in duration and date of occurence of phases of microsporogenesis. The process of dormancy and microsporogenesis of individual varieties is different and is influenced by the weather conditions of the year. There are differences in frost resistance between peach varieties. The highest degree of frost hardiness was set by the 'Lesiberian'. Studied peach varieties show differences in pomological, biological and economic characters. From the evaluated group of varieties the promising are 'Venus', 'Fantasia', 'Fidelia', 'Neve' and 'W 14', where the highest assessment had the variety 'Venus'. Based on evaluation of peach varieties grown in commercial orchards the best variety was 'Symphonie', which achieved consistently high yields and is characterized by good health. 'Fidelia' and 'Orion' were chosen as a mediumly suitable varieties for commercial orchards.