Some data on selection in tetraploid rye

Abstract

1. Six populations of winter rye were chromosome-doubled in 1951 by means of colchicine. After one generation of multiplication the populations were grown as spaced plants (1954). Records were taken on a number of quantitative characters. Grain yield and number of ears per plant showed very skew distributions, whereas strawlength was approximately normally distributed. Highly significant positive phenotypic correlations were found between grain yield and ear number per plant, and between grain yield per plant and strawlength. 2. From a total of 2,767 plants grown in 1954 84 plants were selected for high number of grains per plant and per head. These plants were progeny-tested and selected in the following years. Among the families tested great differences occurred in yielding capacity, winter survival and strawlength, but not in fertility. Selection for grain yield led to an increase in strawlength, showing that the phenotypic correlation found between these characters at least partly must begenetic. 3. One of the selected families has proved to be extremely winterhardy and to possess a very high yielding capacity. 4. Unselected populations of tetraploids have been compared with the corresponding diploids with respect to a number of characters. Significant differences between diploids and tetraploids were found in strawdiameter, heading time, number of ears per plant, number of flowers per ear, strawstiffness and resistance to Fusarium nivale. Tetraploid Kungs II had almost significantly better winter survival than the corresponding diploid strain. Superiority in resistance to Fusarium nivale has been suggested as a possible explanation for the discrepancy between frosthardiness in artificial freezing experiments and winter survival of diploids and tetraploids.