Existence of Ecotypes Among Populations of Entireleaf Morningglory (Ipomoea hederaceavar.integriuscula)

Abstract

Field experiments were conducted using entireleaf morningglory seed collected from areas of adaptation throughout the United States to determine whether biotypes or ecotypes exist and whether differences in susceptibility to acifluorfen exist. Initiation of first flower for the entireleaf morningglory populations ranged from 63 to 81 d after emergence. The interval between emergence and initiation of first flower decreased 2.8 d for each increase in degree of latitude from which the seed was collected. Plants originating from southern latitudes remained in the vegetative phase longer and tended to produce more total dry-weight biomass than plants originating from northern latitudes. Thus, ecotypes do exist for entireleaf morningglory because of adaptation to a specific environment. The adaptation allows ecotypes to utilize the length of the growing season associated with the area of origin. Trichome density on the adaxial leaf surface ranged from 147 to 206 cm−2across the ecotypes and was not correlated with latitude or differences in acifluorfen susceptibility. Ecotypes differed in susceptibility to acifluorfen, but resistance among ecotypes was not evident.