GROWTH AND PHYSIOLOGICAL RESPONSES OF YERBA MATE SEEDLINGS AND MINI-CUTTINGS UNDER DROUGHT STRESS

ABSTRACT Yerba mate is a tree species whose natural distribution occurs in the countries of Argentina, Paraguay, and Brazil, where most of the plantations are concentrated. For the establishment of plantations seedlings are commonly used. But alternatively, there are ex vitro vegetative propagation techniques like mini-cuttings technology, which has the potential to facilitate plant production and increase the amount of plants needed for the industry. Yerba mate is sensitive to drought stress, negatively affecting the plantation productivity. Therefore, the objective of this work was to evaluate the growth and physiological responses of yerba mate seedlings and mini-cuttings to conditions of drought stress (field capacity, moderate drought, and severe drought). Total height, diameter at root collar, accumulation of dry weight (roots, leaves and stem), leaf number and area, and the content of chlorophylls were measured as response variables. Drought stress produced a decrease in height, dry wight accumulation, leaf number and area, and chlorophyll content, which was more pronounced in a situation of severe stress. The comparative analysis did not detect significant differences between seedlings and mini-cuttings, and there was also no interaction between the water restricted factors under consideration and type of propagule.