Culm length was measured from the crown to the base of the spike of the longest tiller of each plant and length of the spike was measured on the same tiller. Averages for F₁, F₂ and Sava monosomics were determined for both characters by means of frequency distribution and the averages for each of the monosomic lines, or monosomic progenies were compared to normal F₁, F₂ and Sava using the Student's test (t test).

Results and Discussion

Culm length : Variety Sava had the average culm length about 65 cm (Tab. 1). The differences in that character between plants grown in glasshouse or in field, even in different years, were not high but the differences in culm length between Sava and F₁ or F₂ disomics were highly significant. None of the F₁ monosomics or F₂ populations from F₁ monosomics were significantly longer than normal F₁ or F₂ plants. The lines involving chromosomes belonging to group 2 and 4 (except 4A) and 3B chromosomes had average culm length smaller than corresponding disomics and the differences were highly significant. The differences in culm length between Sava monosomics and normal Sava were significant for most of the monosomics (Tab. 1. Graph. 1).

Length of the Spike : Variety Sava had spike length about 9 cm and spike length means of normal F₁ and F₂ were slightly smaller. Significant differences were found between spike length means of the F₁ monosomics and normal F₁ for chromosomes 4B (shorter) and 5A and 6D(longer). Besides 5A and 5D chromosomes in F₂ population all three members of homoeologous group 1 and chromosomes 6B and 7B had significantly longer spikes and only for 4B and 3D shorter (Tab. 2). Spike length means of several Sava monosomics are significantly smaller than normal Sava and none of them significantly longer (Graph . 2).

Each character is controlled by the genes located on several chromosomes and for different character different chromosomes are critical ones.

The effects observed for critical chromosomes were mainly in decreasing the mean values. The mean values for critical lines are mainly the results of the effects due to the chromosome missing.

According to LARSON (1959) the F₂ monosomic analyses of quantitative characters is the most effective in identifying critical chromosomes of the monosomic donor parent. In the present study variety Chinese Spring was the monosomic donor parent and that might be the reason that the results obtained were rather parallel to the results presented by SEARS (1954).

Finally, the use of F₁, F₂ monosomic analyses is not the best way for the chromosomal location of the quantitative genes and some other methods should be used.

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