Efecto de la incorporacion de polimeros hidrofilicos al sustrato de propagacion de frambuesa de brote etiolado.

In order to evaluate the effect of three hydrophilic polymers on the propagation of raspberry (Rubus idaeus L.) plants by etiolated root-shoot, two trials were carried out: one to determine the effect of Masorb 5003 incorporation to the substrate over the period of shoot production under greenhouse conditions. The other trial was to evaluate the development of the shoots of plants growing on pots with a medium that contained either Masorb 5000 or Waterstore in shade conditions. Masorb 5003 was incorporated to the shoot producing substrate in rates of l.0, 2.0 and 5.0 g/kg. The 2.0 g/kg rate was the only one that increased the speed of shoot emission (statistically significant) and reduced the incidence of rots as well. All the rates increased the water holding capacity of the substrate which resulted in decreased number of watering (18, 27 and 63% for the l.0; 2.0 and 5.0 g/kg rates, respectively). Likewise, the period of time between watering decreased in 9.8, 38.0 and 136% in relation to the control. At the highest rate, there was an increased rotting in the plants. The salinity of the substrate measured at the end of the trial was not affected by this polymer. For the rooting of the shoots in pots two hydrophilic polymers were used: Masorb 5000 at rates of 15.0, 20.0 and 25.0 g/kg substrate and Waterstore at rates of 1.5, 4.0 and 7.0 g/kg substrate. Shoot growth was determined for a three-month period. The highest rates of Masorb 5000 produced taller plants with longer internodes, wider shoots stems, and increased leaf area. When Masorb 5000 was utilized, the foliar N and K concentrations were increased and the Na levels were reduced, whereas there was no effect in P and Ca foliar concentrations. In the field experiment, plants treated with Masorb 5000 had a greater height growth, a greater number of leaves per plant, and a lower incidence of scorched leaves. There were no significant differences with the control plants in relation to the survival to the transplanting stress. With Waterstore, the results were detrimental for all the parameters considered, and caused a high rate of plants mortality. Moreover, it lowered Ca foliar levels and increased those of Na, the latter being related to marginal necrosis of leaves and plant death. Foliar concentrations of N and P were not affected although K showed a slight increase. Both products, once the irrigation was suppressed, at all the doses prolonged the period prior to the permanent wilting point of plants.