| Abstract: | Diverse photoperiodic responses were shown by three populations of Xanthium strumarium L. originating between 22 degrees and 25 degrees N on the western coast near Culiacán, Sinaloa; in the Chihuahuan Desert near Matehuala, San Luis Poto?; and on the Gulf Coast near Ciudad Mante, Tamaulipas, respectively. A combination of differences in critical night length and in ripeness-to-flower response (maturity) appears to be the basis for reproductive adaptation of these populations to different climatic regimes that prevail at the same latitude (and photoperiodic regime). |
