Cytogenetical studies of triple hybrid from F<sub>1</sub>, <i>Triticum turgidum</i> ×<i>Secale cereale</i> and <i>Triticum vulgare</i>

Abstract

1. In the present research, the germination of F3 seed, and the number of somatic chromosomes, external characteristics and fertility of F3 plants of Triticum-Secale triple hybrid raised between F1 T. turgidum×S. cereale and T. vulgare were studied.2. 736 grains of F3 seed were obtained from 21 fertile individuals among 40 F2 plants, and 674 grains of them were sown in separate pots in October 1938 and 1939, and 177 F3 individuals were obtained (Table 1). The fertility of the F3 varies with the each parent, and the percentage of the F3 seed has been shown to vary from 2.50 to 65.37. As a whole, the percentage of the number of F3 seed obtained from the F2 plants having 2n=29-31 or 45 chromosomes showed a rather high percentage in germination.3. As seen in Table 2, the number of somatic chromosomes of the 177 F3 hybrids varies from 28 to 49. These individuals may be divided into three groups. The F3 individuals raised from F2 having 2n=29-33 chromosomes have 2n=28-32, and these seem to make a group, and most of them have 28-29 chromosomes (71.43% in this group). The number of chromosomes of other F3 individuals raised from F2 having 2n=43-47 chromosomes varies from 2n=40 to 49, and they make another group. The rest of the F3 raised from F2 having 2n=37-39 have 2n=32-43, making a group lying between the above two groups.4. The external characteristics were observed with 153 individuals of the 177 F3 plants. The length of culms and awns, spikelet number on a spike and spikelet density of F3 individuals having smaller number of chromosomes (2n=28-32) surpass the other F3 plants having the larger number of chromosomes, while, on the length of spikes, the former individuals were inferior to the latter.5. 126 individuals among the 153 triple F3 plants were somehow fertile. And the fertility per spikelet has shown to vary from 4.2 to 128.0% according to individuals (Table 3). Generally speaking, the percentage of seed fertility per spikelet has been higher in F3 plants having smaller number of chromosomes (28-29). and as the somatic chromosomes increase above these numbers the fertility falls gradually but again rises.