Influence of photoperiod on tuber production in various races of Hydrilla (Hydrilla verticillata)

The potential for asexual reproduction throughproduction of tubers was evaluated in various races ofan International Hydrilla [Hydrilla verticillata (L.f.)Royle] germplasm collection. Interracecomparisons were made under both shortday and longdayphotoperiods in environmental growth chambers. Allthe races evaluated produced rates varying from91-7182 tubers per sq m of production under shortdayconditions. Tuber production occurred under longdayphotoperiods in several races. Under propertemperature conditions, all the monoecious racescurrently established in the U.S. appear capable oftuber production throughout the year.