INFLUENCE OF PHOTOPERIOD ON TUBER PRODUCTION IN VARIOUS RACES OF HYDRILLA (HYDRILLA-VERTICILLATA)

The potential for asexual reproduction through production of tubers wa s evaluated in various races of an International Hydrilla [Hydrilla ve rticillata (L.f.) Royle] germplasm collection. Interrace comparisons w ere made under both shortday and longday photoperiods in environmental growth chambers. All the races evaluated produced rates varying from 91-7182 tubers per sq m of production under shortday conditions. Tuber production occurred under longday photoperiods in several races. Unde r proper temperature conditions, all the monoecious races currently es tablished in the U.S. appear capable of tuber production throughout th e year.