Abstract
1. The present report has dealt with the external characteristics, fertility and the somatic chromosomes of F3 plants (TperRF3) raised from Triticum persicum×Secale cereale.
2. Very many grains of F3 seed were obtained from 25 F2 individuals: 43 of them obtained from 3 F2 plants, were sown in separate pots in October 1954 and '56; 34 grains germinated and 33 of them matured (Table 1). The germination of F3 seeds showed variance according to their parents, and the percentage of germination was from 28.75 to 96.67 (Table 1).
3. The number of somatic chromosomes of 31 out of 33 matured individuals of TperRF3 hybrids varied according to the parental plants showing 40-44, 34-54, 44-48 chromosomes respectively (Table 2).
4. Some individual differences of external characteristics were observed in F3 plants, even between the plants having the same number of somatic chromosomes.
a, The length of culms was longest in F3 individuals with 42 chromosomes (2n) raised from F2 with 42 chromosomes (2n), and the somatic chromosomes increase or decrease from 42, the length of culms seems to decrease gradually. On the other hand, the individuals raised from F2 with 35 and 46 chromosomes (2n) had longer length of culms, when they had much more chromosome number.
b, As to the length of spikes, it was longest in F3 plants with 41 chromosomes, raised from F2 with 42 chromosomes, and as the somatic chromosomes increase or decrease from 41, the length of spikes showed a tendency to decrease gradually. The other plants raised from F2 with 46, however, showed longer spikes when they had smaller number of chromosomes.
c, As to the length of awns and the spike density, the number of florets per spikelet and the number of tillerings, there seems to be no correlation between those characteristics and the number of chromosomes of the parental plants.
d, The number of spikelets per spike, as it the case of culms, showed highest value in the individuals which had 42 chromosomes, raised from F2 with 42 chromosomes, and as the somatic chromosomes increase from 42, the number of spikelets showed a tendency to decrease gradually. In the F3 raised from F2 which had 35 chromosomes, the individuals having smaller number of chromosomes were inferior in these characteristics to those having a large number of chromosomes, but on the contrary, the F3 raised from F2 which had 46 chromosomes showed the opposite result.
Generally speaking, the external characteristics of F3 plants were somewhat superior to those of the parental F2 plants.
5. Fertility of F3 plants: As in Table 3, 28 of 30 F3 plants showed fertility though it was not so high. The fertility was better than that of the parental F2 plants (Table 3).
