Этюды в области гибридизации, иммунитета и трансплантации растений

group, shook up the extract with spores and poured it over the seeds of wheat sown into open furrows (flower pots with humid soil). Next, the furrows were filled with fine earth. The experiments were carried on in spring, when the temperature of the soil out of doors amounted to 5—6е G and that of the hot-house to 10 C. This tempera­ ture favours infection with mycelum. However, under these experi­ mental conditions the harvest was also normal. Thus, it was possible to prove the absolute immunity of Tr. fungicidum to both parasites (Tilletia tritici and Ustilago tritici). This is especially interesting since very few kinds of wheat are known, stable towards these parasites. Control experiments with these parasitic spores, carried on with awnless summer varieties of Tr. compactum var. Humboldtii resulted in complete infection. In the experimental infection of our wheat with Erysiphe grami- nis f. tritici, used as control the easily infected Indian wheat Tr. sphaerococcum. Infection was carried on in the spring and in sum­ mer on plants in pots, placed into the hot-house and into the open air. In spring we used cleistocarpium as infection material. For in ­ fection we used the germination stage since this stage is the most liable to Erysiphe gram inis. However, our greatest attention was given to the infection by means of fresh conidia which were collected on dry days as soon as their mass appearance on «Lutescence 062» takes place. The well infected leaves were cut off, rinsed in warm distillated water and this suspension of conidiospores was sprinkled by means of a large pulverizer over the plants. After that the plants were covered with gauze/ In several days the plants were again besprinkled. Besides, infection was also made by sim ply' placing the infected leaves onto those of the experimental plants. Control plants of Tr. sphaerococcum were wery easily infected. Production of wheat hybrids with ball- and barrel-like. grain, tough straw, as the result of interspecific crosses. Tr. sphaerococcum, endemic for agriculture of indian Pendjaba, which has been descri­ bed for the first time by Dr Percival, is a markeldy pronounced wheat'species. # This species has not been utilized in selection, although it has a number of valuable characters, such as, for instance, (a) completely round grains (b) very tough straw, owing to the vigorous growth of the sclerenchyme; (c) erect habit of plant and erect leaf lamina, favouring dense sowing; (d) very early ripening. v We decided to utilize these properties, since they have never been made use of so far. < The shape of the grain plays a great role in the yield ratio of flour and bran. The ball has the smallest surface therefore, the least relation exists between surface and volume. Thus, the more the shape of the grain approaches a ball the less the percent of bran yield in any kind of cereal (under other equal conditions); - : : . 7 ' . * Diminution of the percent of bran yield may be also produe.ed by grain enlargement. - 43 - Электронная Научная Сельскохозяйственная Библиотека