ANALYSIS OF DEVELOPMENT OF PHYSIOLOGICAL AND YIELDING CHARACTERS OF CZECHOSLOVAK WINTER-WHEAT FROM THE BEGINNING OF 20TH-CENTURY

The basic aim of presented paper is to establish principal trends in t he development of wheat cultivars in the course of the past 80 years. The old and new wheat genotypes originated from the gene bank of the R esearch Institute for Crop Production, Praha-Ruzyne were grouped into three clusters according to the date of origin of the cultivars, that is first quarter of the 20th century, the period of 1926 - 1950 and 19 51 - 1980. Genetic and physiological components of plants had profound effects on the yield and other characters. Owing to the above relatio ns between traits genotypes were tested for yielding characters, chara cters of roots, physiological characters and for resistance to drought , osmotic stress and low pH. On the basis of presented results the fol lowing conclusions were obtained: Among contemporary varieties there i s a lower divergency in majority of every measured morphological trait . On the basis of statistical analysis, then: was a decrease of the fo llowing traits during the period of 1900 - 1980: number of seminal roo ts, dry matter of seminal roots, dry matter of aboveground biomass, to lerance to osmotic stress, tolerance to low pH, crude protein content, sedimentation test, length of internode below spike, height of plant, length of spike, number of spikelets per spike, drought resistance. O n the basis of statistical analysis, there is an increase in the follo wing characters during the period of 1900 - 1980: length of seminal ro ots, diameter of the internode below spike, diameter of the first inte rnode below spike, weight of spike, density of spike, weight of grain per spike, spike index number of grains per ear, harvest index, electr ical capacity of roots. We can conclude that in plant breeding much at tention must be paid to the development of genetic variability as ther e is a large similarity in the present cultivars.