Determination of Cardinal Temperatures and Effect of Fluctuation Temperature on Tuberous Root Germination of Invasive Weed Lesser Celandine (Ranuculus ficaria)

Ranunculus ficaria is an invasive perennial and tuberous root weed. Tubers are the most important reproduction and dispersion means for this weed. In order to study Cardinal Temperature and effect of fluctuation temperature on Germination of Lesser ceandine tuberous root two separated experiments were conducted at Weed Science Laboratory of Faculty of Agriculture Ferdowsi University of Mashhad in 2008. The experiments were a completely randomized design with four replications, In first experiment, temperatures included 1, 5, 10, 15, 20 and 25 ◦C for cardinal temperature. In second experiment fluctuation temperature, included 5/10, 7/12, 10/15 and 15/25 ◦C (13 H night/11 H day). Results indicated that optimum temperature was different for big and small tuberous roots. But between base and maximum temperature were not difference. Base and maximum temperatures were about 0 ◦C and 25◦C for both big and small tuberous roots. The optimum temperature for big tubers and small tubers were 8◦C and 14◦C, respectively. The result of fluctuation temperature showed that the highest germination occurred in low temperatures. Percent and rate of germination were highest at fluctuation temperatures of 5/10, 7/12 ◦C