FLUCTUATING TEMPERATURE AND LIGHT INFLUENCE SEED-GERMINATION OF GOOSEGRASS (ELEUSINE INDICA)

This research examined the effect of duration of the warm cycle and nu mber of fluctuating temperature/light cycles on goosegrass seed germin ation. Less than 10% goosegrass seed germination occurred at constant temperatures of 20, 25, and 35 C, while 99% germinated at daily fluctu ating temperature regimes of 20 C for 16 h and 35 C for 8 h with light . Increasing the number of fluctuating temperature cycles increased go osegrass seed germination. Fluctuating temperature cycles with 22 h at 20 C and 2 h at 35 C with light strongly stimulated germination, but not as much as the cycle with 8 h at 35 C. Goosegrass seed germination ceased once the fluctuating temperature regime was discontinued, and constant 20 C with 8 h light daily was reimposed. Germination occurred only on resumption of fluctuating temperature cycles. Seed incubated for several weeks in a moist environment at constant 20 C had 81 to 91 % germination with two cycles of 20 C for 16 h and 35 C for 8 h, compa red to 14% for fresh seeds.