Uso de meta-topolina, una citoquinina no convencional en la multiplicación in vitro de Opuntia stricta Haw.

The erect prickly pear ( Opuntia stricta Haw) is an important alternative used to feed ruminants during prolonged periods of drought. The objective of this research was to evaluate the effect of different types and concentrations of cytokinins on the morphophysiological aspects of in vitro multiplication of O. stricta . Segments of O. stricta were grown in liquid and semisolid Murashige and Skoog (MS) medium supplemented with 2.22 or 1.11 µM l -1 of 6-benzylaminopurine (BAP) and 1.11 µMl -1 meta-Topolin (mT). The experiment was conducted in a growth room at 25±2 °C over a period of 45 days. It were evaluated multiplication rate, shoot formation index, rooting and callus formation, fresh biomass, height, activity of antioxidant enzymes, and content of hydrogen peroxide and malondialdehyde. The experiment was carry out in a completely randomized design with six treatments and twelve replicates. The results showed that the consistency of the medium had influence on the shoots development and roots emission. The increase in BAP concentrations resulted in a reduction in the length and fresh biomass of the shoots and in the root system. The enzymatic activity and oxidative stress were inducted with the use of 6-benzylaminopurine. The micropropagation of O. stricta was improved with the use of mT, verified through shoot with better morphophysiological quality for acclimatization, with longer shoot length, rooting and reduction in the occurrence of hyperhydricity, a morphophysiological disorder that leads to large losses in micropropagation of this specie. Keywords: antioxidant enzyme, hyperhydricity, in vitro stress, morphophysiological anomalies