Diploid‐Tetraploid Comparisons in Rye. IV. Grain Production 1

In the subtropical lower latitudes, rye ( Secale cereale L.) is used primarily for late fall‐winter‐early spring forage and, secondarily, for grain. Diploid and tetraploid forms are available, with tetraploids having many advantages over diploids in the amount, distribution, and quality of forage. Information on grain production is essential to develop appropriate breeding strategies for forage and grain types at each ploidy level. Various grain production traits (grain yield GY, seed weight = SW, test weight = TW, percent fertility = %F) of five adapted diploid (2x) cultivars (‘Florida Black,’ ‘Gator,’ ‘Elbon,’ ‘Explorer,’ ‘Wrens Abruzzi’) and their colchicine‐derived tetraploid (4x) forms were examined. Tests were conducted in three seasons (1981–1982, 1982–1983, 1983–1984) at two Florida locations (Gainesville—29°4′0 N Lat; Quincy‐30°3′ 5N Lat) at two seeding rates (0.5 and 1.0 viable seeds per linear centimeter of row). Over all environment(ss easons, locations, seeding rates), highly significant differences amongc ultivars within each ploidy level were found for GY, SW, TW, and %F. The environmental stability values (means, b values, deviation mean squares) at each ploidy levels were inconsistent, indicating that ploidy level influenced the environmental response. Over all cultivars and environments, the tetraploid‐diploid relationship [(tetraploid/diploid ✕ 100)] was 59% for GY, 116% for SW, 89% for TW, and 84% for %F. However, substantial differences in this relationship resulting from genetic background( cultivars) were found for GY (range = 41–101%), SW (range = 98–134%), TW (range = 82–93%), and %F (range = 77–95%). Apparently, genetic background as well as environment influenced ploidy level differences. The results indicate that selection within each ploidy level should be effective in improving various grain characteristics, but testing and selection in a number of seasons and locations would be necessary.