| Pitted morningglory (Ipomoea lacunosa L.) is an adaptable species with an indigenous range encompassing the southern Midwest and southeast United States. It is a prominent morningglory species in the Mississippi Delta region and extremely competitive with crops. Experiments were conducted in 2000 through 2003 to determine morphological, physiological (herbicide susceptibility), and genetic variability among pitted morningglory accessions collected from throughout its indigenous range.; Eight morphological clusters were observed with cluster analysis of 64 single-plant accessions. Accessions originally from Arkansas, Delaware, Kentucky, Louisiana, Mississippi, and Missouri were documented with leaf size, vine length, and day of flower initiation generally increasing with decreasing latitude. Accessions originating from Arkansas, Georgia, Louisiana, North Carolina, Oklahoma, and Tennessee had similar morphology. Leaf shapes of arrow, heart, an arrow and heart mixture, and heart with lobes and white or purple flower colors were documented.; Herbicide efficacy variation was documented among 40 multi-plant accessions. Visual control of accessions from fomesafen ranged from 48 to 89% 2 wk after treatment (WAT), but control was not related to original latitude or longitude. Control from chlorimuron 3 WAT ranged from 82 to 95% and was not correlated to latitude or longitude. Glyphosate controlled accessions 81 to 89% 3 WAT. Among eight morphologically distinct ecotypes, fomesafen and chlorimuron biotypes were documented, indicating that morphological characteristics did not influence efficacy of these herbicides.; Analysis of genetic similarity of 64 single-plant accessions resulted in separation of accessions into four clusters. From 14 ISSR primers, 1876 fragments were generated. Accessions from Southeast Arkansas, Georgia, and Louisiana were grouped together indicating a latitudinal separation. Accessions from north Arkansas, Delaware, Kentucky, Missouri, and Northeast North Carolina were genetically similar. Accessions from west-central Mississippi and one west-central Arkansas accession grouped together indicating that the Arkansas accession was derived from a similar ancestor as the Mississippi accessions. Accessions from Alabama, Arkansas, east-central Mississippi, central North Carolina, and east-central Oklahoma were grouped together illustrating little genetic variation across a wide geographic range. Compared to the morphological variation among accessions, genetic variability can be associated with leaf shape and flower color; however, flower color was more related to genetic variation. |
