Response to Freezing and High Temperatures of Detached Cladodes from Opuntia Species
Keywords:Opuntia cladodes; cold and hot stresses; simulated frost and heat; yield after stress
Extreme temperatures are among stress factors than can affect Opuntia species. We experimented with detached cladodes, testing their potentiality to endure the actions of freezing and high temperatures. Cladodes of two provenances of Opuntia ficus-indica L. f. inermis (Web.) Le Houér. and O. spinulifera Salm-Dyck f. nacuniana Le Houér., f. nov. were treated with temperatures of –5ºC and –10ºC combined with 5 and 10 hours exposure. On the other hand, O. spinulifera and O. robusta Wendl. were treated with a temperature of –10ºC for 18 hours. In a different trial, the last two species were subjected to high temperature (52ºC) from 3 to 26 days. Each experiment followed a completely randomized design with four replications comprising four cladodes each. At the end of each treatment, cladodes were planted in pots and grown under field conditions during 8 to 9 months. Response to extreme-temperature treatments was evaluated through the number and the dry weight of cladodes produced per plant. Under freezing treatments, although some differences in frost tolerance were found among species, they were tolerant to a temperature of –10ºC for 10 hours. O. robusta and O. spinulifera resisted –10ºC for 18 hours and appear to be the species most tolerant to freezing treatments. Cladodes of O. spinulifera and O. robusta from the heat-stress treatment were not affected when they were exposed to continuous heat (52 ±2ºC) for 5 days. Cladodes under more than 8-day heat treatment lost completely the capacity to sprout under field conditions.