Diploid‐Tetraploid Comparisons in Rye. I. Forage Production1

Abstract

Autotetraploids differ from their diploid counterparts in many morphological, physiological, cytological, and ecological characteristics. The tetraploidy effect on the amount and environmental stability of rye (Secale cereale L.) forage production was examined in this study. Six populations consisting of three diploid (2x) cultivars (‘Florida Black’, ‘Gator’, ‘Explorer’) and their autotetraploid (4x) derivatives were grown in two late fall‐winter‐early spring forage seasons (1979–1980, 1980–1981) at Gainesville (29°40′ N Lat) and Quincy (30°35′ N Lat), Fla., at two seeding rates (0.5, and 1.0 viable seeds/linear cm of row). Forage weight was obtained at a total of 16 clipping dates among seasons and locations (Gainesville—four dates in both seasons, Quincy—three dates in 1979–1980 and five dates in 1980–1981). The direction and magnitude of the differences between the forage production of the 2x and corresponding 4x populations were not consistent and were influenced by genetic background (2x cultivar source) and clipping dates within season and location. Apparently, the tetraploid effect was altered by genetic factors and many interacting environmental forces. Significantly higher production from the higher seeding rate was obtained primarily at the earlier clipping dates within each season and location but seeding rate interactions with all genetic and environmental variables were not significant. No differences among populations in environmental stability were found.