咸豐草（Bidens pilosa L.）及大花咸豐草（Bidens pilosa L. var. radiata Sch.）開花後不同天數之種子大小及發芽特性

Abstract

Two species of Bidens, B.pilosa L. and B.pilosa L. var. padiata Sch. were used to study the relation between seed weight and germination ability. After flowering, on July 1999, the flower stalk of two species of Bidens were labeled separately every day. The seeds (achene) were collected with 1-15 days intervals. After drying, the weight, length and width of seeds were measured, and the germination ability was tested.1. The seed weights were not increased ten days after flowering in two species of Bidens. B.pilosa L. had greater in 100-seed weight than that of B. pilosa L. var. raditata Sch. The difference of length was not significant between two species of Bidens, but B. pilosa L. was wider in seed width than B. pilosa L. var. radiata Sch.2. B.pilosa L. had the germination ability six days after flowering, and it was five days after flowering in Bidens pilosa L. var. radiata Sch. The more the days after flowering, the more germination percentage and speed of germination in two species of Bidens. It was found reversed in mean days to germination.3. Except mean days to germination, correlations between characters (100-seed weight, seed leanth, seed width, germination percentage, and sped of germination) were positively correlated.