II. 13 Comparison of growth retardation of alloplasmic plants with nuclei from different vulgare cultivars.
T. Fukuyama, The Ohara Institute for Agricultural Biology, Okayama University, Kurashiki, Japan.
The present writer reported before that an alloplasmic plant, having 2x vulgare nucleus in bulbosum cytoplasm, showed growth retardation which was especially evident at low temperature (Fukuyama and Takahashi 1976 in Barley Genetics III:351-360).
This experiment was planned to know the appearance of differential interaction between vulgare genotypes and bulbosum cytoplasm with regard to growth retardation. Forty cultivars of different geographical origin were crossed respectively to either of the allo- or bulbosum-plasmic (B) and normal-plasmic (V) dihaploid plants having the nucleus of a cultivar Shin Ebisu 16 in common. Five plants of each of the Fl's and their parental cultivars were simultaneously grown in two rooms of a phytotron, which were kept at 10° and 20° C, respectively. Measurement was made of dry weight of 30 days old seedlings of each of cultivars and Fl's. For the comparison of the grade of growth retardation among the different F1 plants, ratio of dry weight of (B)-F1 to that of (V)-F1 was calculated for each cross.
Figure 1 shows variation curves of the dry weight ratios for the F1 plants raised at 10° (solid line) and for those at 20° C (dotted line). It is evident that at 10°C all of (B)-F1 plants is markedly lighter in dry weight than (V)-Fl's with an average ratio of 0.61 + 0.18 (S.D.), indicating marked growth retardation at low temperature. On the other hand, at 20°C the average ratio is 0.74, but its variation becomes much larger (S.D.=0.39). It should be mentioned here that seven out of 40 crosses were larger in dry weight ratio, namely, their (B)-F1 plants were heavier than the corresponding (V)-Fl's. However, the remaining 33 crosses were smaller in dry weight ratio, and some of them were much less in ratio than those grown at 10°C. It is very interesting to know the cause of the differential grade of growth retardation like this, but this will require further investigation about the interaction between vulgare genotype and bulbosum cytoplasm.
Finally, relation of dry weight ratio, (B)-F1/(V)-F1, with origin of the cultivars or genetical factors involved, such as Av, Nn, and Ss, were examined. Results are shown in Table 1, which indicates no definite relationship among them.
