Heterosis Selection Method
Remote hybridization method. G. D. Karpechenko (1924, 1927) received a constant amphidiploid form of the hybrid Raphanus sativus L. X Brassica oleracea L.
This method is promising in the selection of new root forms of Raphanobrassica. The hybridization of radish and cabbage reveals a large breadth of morphogenesis (G. A. Makarova, 1963, 1964, 1981). G. A. Makarova crossed after a preliminary vegetative rapprochement by grafting (direct and reverse) six-week-old plants with a “wedge-extruded”. The use of a wet chamber provided a high percentage of intergrowth. Seed setting was higher in those cases when radish plants were maternal forms, as many other authors pointed out.
In the first generation, cells with 18, 36, and 72 chromosomes were found, and in the second generation an even greater heterogeneity appeared. A polyploid row appeared with 24, 27, 30, 32, 34, 36, and 54 somatic chromosomes. The fourth generation amphidiploids during the cultivation of seed plants in the same site with triploids did not undergo subsequent cleavage, which indicates a biological barrier to their hybridization.
Intergeneric hybrids of tetraploid oil radish with tetraploid feed cabbage in F1 exhibit heterosis in yield (I. A. Koryabin, 1978). A characteristic feature of amphidiploids is the absence of pubescence of leaves.
Polyploidy method. In 1939, the first tetraploid variety of Mino-Tetra-Daikon radish was obtained in Japan, which is distinguished by high productivity, good quality root crops, and resistance to low temperatures and diseases.
In the USSR, the first tetraploid variety of radish was Sibirsky 1 (authors: I.P. Savoskin, V.D. Rud, A.P. Lutkov, A.A. Romantsova) obtained by the method of selection of tetraploid forms resulting from colchicination of plants of the Rozovo variety -red with a white tip. Compared with the initial form, plants of the Siberian 1 variety have a longer vegetative period and a long preservation of marketable qualities, a large mass of root crops. The variety was highly appreciated in production in Western Siberia and the Non-chernozem zone of the RSFSR. Late ripening and relatively low productivity of seed plants hinder the wide spread of the variety. In the experimental preparation of radish polyploids, the most effective is the treatment of the growth points of the flower stalk at the basal rosette of leaves with a 0, 1–0, 2% solution of colchicine in the form of an emulsion with a lanolin cream (E. I. Tarasevich, 1963). This method provides a high percentage of polyploid yield and plant survival.