Dwarf and semi-dwarf mutation induced in T. aestivum (L.) THELL. ssp. vulgare (VILL.) MK. with X-rays and EMS

K. P. DJELEPOV

Dobrudja Agricultural Research Institute, Gen. Toshevo, Bulgaria

Dry seeds of the sorts Bezostaya 1 and Mironovska 808 were irradiated with X-rays with doses of 10, 15 and 20 kr, and a part of the seeds in M₁ were treated with EMS using concentrations of 0.2 and 0.4 at 25C during 24 hours. In M₂ after the treatment lowstem mutant forms were chosen, in M₁ their inheritance was checked and in M₄ and M₅ reproduction was carried out of the more potentially valuable forms. Well equalized lines of M₅ were checked for productivity and the indices showing the character and quality of the grains as well as the resistance to cold. Table 1 shows that the induced mutation lines are characterized with stems, low in height and resistant to down-beating. The average height of the mutation lines of Bezostaya varies from 19.3 to 53.6 cm. while that of the initial sort was 76.8 cm.; the average heit of the mutation lines of Mironovska 808 varies from 31.2 to 55.2 cm., while that of the initial sort was 93.0 cm. A definite correlation has been found between height of stem and length of ear. The form of the ear of the dwarfs is compact and of the semi-dwarfs is square-headed or normal. The short ears are compact and the number of spikelets approach the original sorts. Nearly all short-stem lines have more protein and sedimentation value. All have smaller grain, lesser germination and assure lower yield of grain per plant. The latter is due mainly to the smaller grain.

For this reason the wheat short-stem sorts used in the selection being predominantly spring varieties it is of utmost importance that the investigated sorts should be mutants resistant to cold. Four of them originated from the sort Bezostaya 1 have a higher resistance to cold than Benzostaya 1 and have shown 12, 18, 33 and 72% of the plants resistant at - 15C. A high resistance to cold is shown also by the lines of the sort Mironovska 808 being lower initially but higher than the resistance of Bezostaya 1. The higher resistance of some of the mutants coincides with the results obtained by SHKVARNICOV (1964), TAVCAR and KENDJELIC (1966) and by DOUBININ (1969) and collaborates the theory that the mutation is one of the methods to stiplate resistance to cold and winter-hardness genetically for wheat, through polymeric factors stipulating such qualities.

The advantageous combination of short stem and high resistance to cold, good technological and productivity characterizes the studied short-stem mutants as suitable components in the selection of short-stem wheat sorts.

Figure 1. Short-stem mutants chosen from the sort Mironovska 808

Literature cited

DOUBININ, N. P. 1969. Genetics and Agriculture. Edited by "Znanie"

SHKVARNICOV, P. K. 1964. Izv. Sib. Otd. AN USSR. Seria Biol. Med. Sci. 4(1): 64-73.

TAVCAR, A. and V. KENDJELIC 1966. Mechanism and Induc. factors. Prague, 101-111.

(Received May 27, 1970)