Effect of Photoperiod and Growth Regulators on Growth of Three Cactaceae

Abstract

Abstract Chamaecereus silvestri (Spreg.) Britt & Rose ‘Peanut cactus’, Mammillaria elongata D.C. ‘Gold Star’, and Opuntia microdasys (Lehm.) Pfeiff. ‘Bunny Ears’ were grown on an 8-hr natural photoperiod (short) or an 8-hr natural plus 4-hr incandescent light from 10:00 pm to 2:00 am photoperiod (long) and treated with single sprays of growth regulators. Ethephon or the long photoperiod increased shoots on Opuntia. Gibberellic acid alone or BA alone increased Mammillaria and Chamaecereus shoot number linearly, whereas GA plus BA reduced shoot number. Chamaecereus and Opuntia plants grown on a long photoperiod produced more shoots than plants grown on the short photoperiod. Ethephon reduced the dry weight of all cacti tested. Dry weight of untreated Mammillaria and Opuntia plants exceeded that of growth regulator-treated plants. Opuntia plants produced more dry weight on the long photoperiod than on the short photoperiod. GA increased the growth of glochids on Opuntia and Mammillaria. Chemical names used: A-(phenylmethyl-1H-purin-6-amine (BA); (2-chloroethyl)phosphonic acid (ethephon); and gibberellic acid (GA).