Effect of Combined Growth Regulators on in vitro Multiplication of Recalcitrant Potato Varieties

Abstract

The potato varieties studied in this paper were created at the National Institute of Research and Development for Potato and Sugar Beet Braşov. They have a high biological production capacity and are attractive and very appreciated by farmers, potato producers, consumers and processors, but manifest recalcitrance to the in vitro culture techniques. Thus we tried to find an optimal culture medium variant for these varieties, in order to obtain healty potato seed material in a short time. The study compared the effects of five different culture media using MS medium containing various concentrations of gibberelic acid (GA3) in combination with α-naphthalene acetic acid (NAA) in micropropagation of two recalcitrant potato varieties, Marvis and Brasovia. The longest shoots, maximum number of nodes and leaves, the longest roots and the best rooting efficiency were recorded on MS medium containing 2 mgL-1 GA3 and 1 mgL-1 NAA, for both varieties. The use of a larger quantity of GA3 negatively influenced the potato shoots and roots growth. The culture media using MS medium containing 4 mgL-1 GA3 and 1 mgL-1 NAA had an inhibitory effect on all the studied plantlet characteristics. The results showed that a certain combination of growth regulators (NAA and GA3) improved the micropropagation capacity of the two recalcitrant potato cultivars studied and resulted in the maximum improvement in the parameters.