Этюды в области гибридизации, иммунитета и трансплантации растений

stems and leaves and very largegrain as compared with the parental species. For our cytological studies we fixed the F 3 embryo roots in Navashin’s fluid. The sections were cut about 8—12 thick and were stained in iron haematoxylin after Heidenhain. The complete amphidiploids showed 56 chromosomes (2n) in all the metaphase plates of the periblem, plerome and dermatogen. Characteristic is the great number of nucleoli usually amounting to 5—6. . After having obtained our F 4 harvest, after having checked constancy and fertility, after three years of experimental work on the infection of the hybrid with winter and summer spores of parasi­ tic fungiy we have sufficient reason for regarding our hybrid as an independent wheat species which we have called Triticum fungici- dum Zhuk. The plant is pubescent. The leaf vaginae and the lamina of the lower leaves are usually pubescent wiht long tough hairs. The stem nodes are velvety pubescent. The mature ears are awned, pubescent and black and. the stem of the ear is somewhat brittle. The ears are three flowers. The ear. scales covered with short awns. Weight of one thousand grains amounts to about 70,65 gr. The plant is very is resistant to rust, smut and powdery mildew. In the somatic cells there are 56 chromosomes (2n). The following negative characters should be mentioned. This new kind of wheat is rather difficult to thrash, the mature ears are b rittle/som e of the spi possess one grain. Fertility increases in the winter kinds. The positive charactersasу for instance, vigour, tough straw, large vitreous grain, complete resistance to fungus diseases, render this kind of wheat irreplaceable in permanently infected regions. Therefore in specially infected regions, we propose sowing gua­ ranteed areas of this wheat. The mew wheat has two complete chromosome sets of two wheat species—Triticum Timopheevi and Tr. persicum fuliginosum. The characters of «Timopheevi» are more pronounced than those of «per­ sicum». This new wheat is more resistant to fungi than both pa­ rental species. Size of microspores (of pollen grain) in Tr. fungicidum amounts to 42—50 fi., sometimes rizing to 60 jl . The most usual are micro­ spores of 45—46 jl . In Tr. Timopheevi the size of the microspores ranges between 32 and 50 ft and in Tr. pers. fuligin.—between 23— 49 ft. Thus, in amphidiploids the size of the pollen varies less than in the parental species. The constancy and fertility of the new wheat species should be emphasized. Some amphidiploids, for instance Haynatricum, an intergeneric combination between Haynaldia villosa and Triti­ cum dicoccum, is very constant in characters, but is not completely fertile. The phenomenon of partial sterility of the amphidiploids is confirmed in the literature. In the progeny a certain segregation may be stated. We examined 1150 F 4 ears of Tr. fungicidum for fertility; 791 ears were completely fertile, 280 ears were partially Электронная Научная Сельскохозяйственная Библиотека