CORRELATION OF PHOTOPERIOD WITH TUBERIZATION AND SUSCEPTIBILITY OF POTATO TO VERTICILLIUM ALBO-ATRUM

Photoperiod was found to control both initiation of tubers and susceptibility of potato to Verticillium wilt. Plants grown in a short-daily photoperiod (long dark period) formed tubers and such plants, when inoculated with Verticillium albo-atrum, developed moderate to severe wilt symptoms. Plants grown in a long-daily photoperiod did not form tubers and developed no disease symptoms when inoculated with Verticillium. When a 2-hour light period was interjected in the middle of the long dark period, no tubers were formed and plants developed no symptoms of disease when inoculated with Verticillium. The resistance to Verticillium exhibited by plants was not limited to the root but was present throughout the plant.