VARIABILITY FOR TEMPERATURE OF GERMINATION IN SERICEA-LESPEDEZA GERMPLASM

Poor and slow seed germination are major problems in growing sericea l espedeza [Lespedeza cuneata (Dumont de Courset) G. Don.]. Knowledge ab out the temperatures for optimum seed germination is vital to selectin g the best seeding date for this forage legume. The objectives of this study were to determine the variability of sericea lespedeza germplas m for germination under several temperatures and the effect of seed we ight on percentage and rate of germination. Germination response to te mperature of 54 breeding lines and 26 accessions were tested. Mechanic ally-scarified seed of each of the 80 genotypes were weighed and germi nated in the dark in a germinator at constant temperatures of 10, 15, 20, 25, and 30 degrees C. An additional temperature (35 degrees C) was included to test the germinability of the 26 accessions. Germination counts were recorded daily for 14 d to calculate total percent germina tion (TPG) and Maguire germination rate index (GRI). Temperature had a significant effect on TPG and GRI. Optimum germination temperature fo r sericea lespedeza ranged between 20 and 30 degrees C. Thus, seeding time for this species for a particular location should be selected to match the optimum range of soil temperatures provided that adequate so il moisture is available. Mean TPG and GRI were significantly differen t among the genotypes at each temperature. However, genotypes with a c onsistently high TPG and GRI at a wide range of temperatures were foun d. Seed weight was correlated with TPG at 10 (r = 0.401) and 15 degree s C (r = 0.459), and also with GRI (r = 0.388-0.475) at all temperatur es for the breeding lines. However, seed weight was not correlated wit h TPG or GRI for the 26 accessions. The TPG and GRI were highly interr elated, thus, measuring TPG alone should provide adequate information when describing response to environmental stresses in sericea lespedez a.