| I. Research Notes Some notes on autotetraploid Triticum monococcum G. STAUDT Forschungsstelle fur Geschichte der Kulturpfianzen, Berlin-Dahlem Max-Planck-Institut fur Zuchtungsforschung Koln-Vogelsang, Deutschland Preliminary investigations were carried out in studying the effect of colchicine treatment on germinated grains of Triticum monococcum. Various concentrations of watery colchicine solution were applied for various times. Each group of treatment including 100 grains. the grains were germinated before treatment for 12 hours (Table 1). On the basis of these results, 200 grains of Triticum monococcum var. Hornemanni (T. 482, a variety which is still cultivated in Wurtternberg, South-West-Germany) were treated in spring 1953 for 6 hours, and 200 grains for 12 hours with a colchicine solution of 0.025 %. The seedlings (C1) were planted in late spring. As doubling of chromosomes usually effects a reduction of fertility, all spikes with reduced seed setting were selected after harvest. All the grains of 5 spikes which showed a distinct reduced fertility were sown in Petri dishes in spring 1954. Before planting these seedlings, the chromosome number was determined in root tips (Table 2). All the plants of C3, descending from plants with 2n=28 chromosomes had 28 chromosomes, as expected. By selfing a plant of C2 with 2n=27 chromosomes 48 grains were obtained. Of these, however, only 11 germinated ; they all had 2n=28 chromosomes. The tetraploid plants differed from the diploids by their darker green colour of leaves and culms. The extent of tillering and the length of culms are diminished. The density of the spike is significantly reduced. This is the result of the reduced number of spikelets per ear and the increase of the length of spikelets. Development of the tetraploid plants is delayed as compared with the diploids. Earing (the time when the ears are escaped entirely from the upper leaf sheath) takes place in the tetraploid, plants in average 2-3 days later than in the diploids. The stage of maturity is reached 4-5 days later than in the diploids (Table 3). The disturbed meiosis of the tetraploid plants leads to a reduced fertility. The percentage of spikelets with 2 grains is reduced in the tetraploid plants. But there are differences between the years (Table 4). (Received May 10, 1957) |