Identification of Diploid and Tetraploid Lolium Cultivars Grown Under Controlled Environmental Conditions 1

Seven cultivars of ryegrass, Lolium sps., were grown under controlled environmental conditions in an attempt to use the characters of leaf blade length or width, dry weight accumulations, and leaf blade proteins as a means of cultivar or ploidy identification. Leaf width measurements after 2 weeks of growth at 20 C and 20‐hour photoperiods provided the most definitive statistical separation of cultivars. Dry weight measurements of plants grown at 20 C and 12‐, 16‐, or 20‐hour photoperiods for 4 weeks provided reasonable separation of cultivars but not to the degree noted for leaf blade width measurements. Leaf length measurements provided cultivar separations similar to those observed for the dry weight measurements. In all cases, cultivar separation was not specifically related to degree of ploidy (diploid vs. tetraploid). Seed weights of four of the five tetraploid cultivars were statistically separate from the two diploid cultivars and the tetraploid cultivar, ‘Petra.’ Gel electrophoretic patterns of leaf blade proteins showed sufficient uniqueness to be potentially useful for cultivar identification. Chromosome counts of root tip cells were time‐consuming and in some instances difficult to interpret as to degree of ploidy. The most satisfactory procedure for making chromosome counts may be unique for each cultivar. These studies illustrate the feasibility of using growth characteristics of plants grown under controlled environment conditions for cultivar identification.