BREEDING OF OCTOPLOID TRITICALE
Group of Polyploid Breeding Program, Crop Department, Peking Institute of Agricultural Sciences
The Breeding work of Octoploid Triticale since 1957 is summarized as follows:1. The use of crossable gene. The genetic analysis of the crossability between common wheat and rye has shown that s, ss, SA, SN and SQ belong to a multiple allelic series of a single locus. The degree of crossability of these genes can be arranged in such an order, namely, s ss SA SN SQ. According to the degree of dominance, the order should be reversed as: SQ SN ss SA s. These findings were properly used in the routine work of crosses between wheat and rye.2. Chromosome doubling. Before treatment the wheat-rye hybrid seedlings should be slightly wounded on crown part by a sharp razor blade. Then the hybrid seedlings are exposed in 0.04-0.05% aqueous solution of colchicine for 4 days in room temperature not over 15℃. More than 90% of the treated seedlings could be recovered in greenhouse below 10℃. Among the recovered seedlings, about 40.8% of the sterile F1 hybrid plants would be turned to be partial fertile and various amount of seeds could be obtained from these successful plants. By this procedure, 4,700 primary Triticale strains have been created. In 1961, a new polyploidizing agent was discovered. The name of the agent is Fumiron, or Phenyl mercury-p-toluene sulfonanilide which is a fungicide and has comparable cfficiency in chromosome doubling as colchicine does.3. Fertility and seed plumpness. It was suggested that recombination of genes by hybridization and molding the segregation generations by heavy selection pressure could be the effective measures for the improvement of the fertility and seed plumpness of the octoploid Triticale strains. About two thousand of cross-combinations have been made with various parental stocks which were mostly selected from the primary Triticale strains, and in recent years, hybrid strains and elite plants in segregation generation were used in crosses more frequently than the primary types. The hybrid strains thus developed with normal fertility and acceptible seed plumpness were released to different localities with various natural conditions for yield tests.4. Regional tests. The data collected from regional tests have shown a tendency that the Triticale hybrid strains at present state might be successful in those regions where the yield of common wheat is usually very low and unstable due to severe natural conditions. For example, 10 Triticale strains were tested for yield performance with one rye and two common wheat varieties as checks in 1972-1973 growing season in Weining, a mountainous region of Kweiehow with altitude between 2-3 thousand meters. Eight out of ten Triticale strains have higher yields than both rye and wheat varieties. The best strain, Triticale No. 2 has a yield about 20% higher than that of rye, and 24% and 61% higher than the two varieties of common wheat Ahpo and No. 778 respectively. However, it, should not thus be concluded that the octoploid Tri-ticale is especially suitable for the marginal habitats of common wheat. It is only apparently seeming so at the present state of the Triticale strains which were developed from selection solely directed to the improvement of fertility and seed plumpness without much consideration for other characteristics of agricultural importance. Now, only the hardiness from rye and good seed quality from common wheat generally incoporated in the amphiploid have shown their favourable effect in the marginal regions of these two crops. This might be considered therefore that it is merely a preliminary stage of the Triticale program.