| Colchicine-induced tetraploids of Aegilops speltoides
D. METTIN Institut fuer Pflanzenzuechtung der Martin-Luther-Universitaet Halle-Wittenberg Hohenthurm b. Halle/S., Germany (DDR) In the last years there were several publications which deal with artificial polyploids in the genus Aegilops. The representatives of the Sitopsis section have got special interest in being the possible donors of the B-genome in the tetra- and hexaploid wheats. In "WIS" some reports are given on autotetraploids of Ae. bicornis (SbSbSbSb), Ae. Iongissima and Ae. sharonensis (both S1S1S1S1) resp. For crossing experiments it seemed to be important to have polyploid types of Ae. speltoides (S S S S) too. The present author could not find any information in literature about autotetraploid Ae. speltoides. After several attempts we got two tetraploid individuals of Ae. speltoides in C2-generation by colchicine treatment with an aqueous solution of 0.05% for 10h with pre-soaked seeds of var. ligustica. The tetraploid plants were raised in pots and showed normal growth. There were only slight differences in the seedling stage between diploid control plants and the tetraploids. Later on the morphological differences became more evident. The culms of the polyploids were somewhat thickened and tillering was consider ably reduced. While the diploids (measured on 4 plants) had an average number of 36 (32 - 45) tillers / plant, the tetraploids showed a corresponding value of 24 (21 and 28 resp.). The date of ear emergence was something delayed in the tetraploids. The plant heights of the two tetraploid individuals were decreased markedly. The average height of the diploids at flowering stage was found to be 66 cm (65 - 68) compared with 50 cm (48 and 53 resp.) in the tetraploids. Regarding ear characters the following differences were observed between 2n - and 4n - types: Length of the ear in cm ; 9.8 (9.7 - 10.0) vs. 8.0 (7.9 and 8.2 resp.). Average number of spikelets / ear; 12.2 (ll.5 - 12.7) vs. 11.0 (10.9 and 11.0 resp.). Average number of seeds / spikelet; 2.61 (2.44 - 2.76) vs. 0.54 (0.51 and 0.58 resp.). The lengths of the spikelets and of the awns were reduced markedly, while the number of florets / spikelet remained unaffected. The seed size of the tetraploids was somewhat increased. More intensive investigations will be carried out the next time to support these preliminary data. |