| The importance of partial vernalization for the transformation of the
"winter habit" character Partial vernalization and sowing winter plants in spring makes labile plant material even during the first year. Growth and developmental conditions determine whether the offspring will be spring-habited or become in time winter-habited. The influence of the conditions of different years (for instance, favourable summer in 1971 and very hot summer in 1972) on the vernalization of winter wheat seeds of the variety Kavkaz is seen from the data of Table 1. As it is seen from the given data, in 1971 the process of complete vernalization under field conditions did not go so easily as in 1972. In the second case the partial vernalization (10, 15, 20, 25 and 30 days) induced heading of 2 ; 3 and even 4 fold greater number of plants than in the previous year. Maximum of headed plants was observed when seeds were vernalized during 20 and 25 days. The heading also began a little earlier. One can suppose that plants will also behave differently in the next generations. This is proved by the study of the first generation obtained from partial vernalization of seeds of the variety Kavkaz (Table 2). The given data show that the conditions in 1971 ensured better heading of the first generation when compared with the year 1972. Almost in all treatments the number of spring plants was a little higher in the complete vernalization treatment in 1971 than in 1972. For instance 10 days of vernalization gave in the first case 39.7% of headed plants and in the second case only 18.7%, while 30 days of vernalization gave 39.5 and 0% of headed plants respectively. Very interesting is also the fact that partial vernalization during 20 and 30 days in 1971 ensured complete heading. 1.9 and 47.7% of total families respectively, while in the first generation from the vernalization in 1972 this was not the case. Similar data were obtained in the experiments with the variety Bezostaya 1. The vernalization during 25, 30 and 40 days in 1968 ensured mass and early heding of the first generation plants, grown in 1968 (96.6, 78.9 and 50.5%). The partial vernalization in 1969 gave considerably less headed plants in the first generation (10.5, 10.0 and 2.1%), the heading took place almost a month later. The examined material allows us to come to a conclusion that the influence of the conditions of the first year of growing on the vernalized seeds difines the extent of the transformation of the character "winter habit - spring habit" in subsequent generations. |
| <-- Back |