| Data in Table 2, also, shows that some alloplasmic
common wheats with Ae. squarrosa cytoplasm headed significantly earlier
than their nucleus donors. FUKASAWA (1953) firstly reported the significant
delay of heading time in alloplasmic emmer wheat (T. durum) with
Ae. ovata cytoplasm, and KIHARA (1975) proposed the possible usefulness
of cytoplasmic substitution lines by taking advantage of cytoplasmic effect
on maturity in wheat breeding. The results in the present experiment indicates
that heading time could be varied by introduction of alien cytoplasm into
wheat varieties. Though the cytoplasmic effect on heading time varies depending
on the nucleus donors and the locations of experiments, the degree of influence
by the alien cytoplasms was in the order of Ae. ovata>Ae. umbellulata>Ae.
vavilovii>Ae. squarrosa. 2. Alteration of growth habit The delay on heading time of alloplasmic common wheats with Ae. ovata cytoplasm was manifested more remarkably when those alloplasmic lines were grown in Sapporo by spring sowing than in Kurashiki by fall sowing (Table 2.). Therefore, it is implied that the venalization during winter in Kurashiki affect the reduction of the delayed period for heading time in alloplasmic common wheats with Ae. ovata cytoplasm. The strains shown in Table 1b were used as the indicators in the experiment to examine the effect of vernalization in alloplasmic common wheats with Ae. ovata cytoplasm. Before the trans-planting into the field at Sapporo (in case of spring sowing), the seedlings of the single leaf stage were treated with low temperature (8C) under continuous illumination for 40 days for vernalization. Table 3 shows the heading dates of vernalized and non-vernalized plants of (ovata)- Chinese Spring and (ovata)-P168, together with the four indicator strains for the growth habit. Chinese Spring and P168 are of spring growth habit, but the heading date of two alloplasmic lines resembled that of the winter wheat Oku after the vernalization. On the other hand, the treatment shortened the duration until heading in (ovata)-Chinese Spring and (ovata)-P168 by 11.2 and 12.8 days, respectively, which was quite similar to the case of Aoba. It has been proved in barley and wheat that the time of flag leaf emergence correlats closely with the grade of spring and winter growth habit, under the condition of continuous illumination with high temperature (TAKAHASHI 1943, YASUDA and SHIMOYAMA 1965). Therefore, an experiment was conducted to examine the effect of alien cytoplasm on the growth habit in controlled environment of growth chamber. Materials were grown under continuous illumination with the temperature of 20C, and days until the flag leaf emergence from seeding were scored. The degree of spring or winter habits were classified into five grades based on the time of the flag leaf emergence; I (extreme spring habit) - less than 30 days for flag leaf emergence, II (spring habit) - 31-40 days, III (weak spring habit) - 41-50 days, IV (weak winter habit) 51-90 days, and V or over (winter habit) - more than 91 days. Result of the experiment were summarized in Table 4. Most of the cytoplasmic substitution lines remained in the same grade as their nucleus donors. (ovata)-Chinese Spring, however, showed grade IV in spite of that the control Chinese Spring was ranked in grade III together with the other alloplasmic lines of Chinese Spring. This fact suggests Ae.ovata cytoplasm caused the alteration of growth habit from spring habit to winter habit in Chinese Spring. In this connection, (ovata)-Chinese Spring were survived and produced plump kernels when it had been sown in September, 1978 in Sapporo, although some plants were killed during the winter. |
| <-- Back | | | --> Next |