Resistencia a bajas temperaturas en Pinus hartwegii sometido a diferentes tratamientos con potasio

in order to improve frost resistance in pinus hartwegii lindl, different concentrations of potassium nitrate were tested on 13-month-old seedlings in a forest nursery. an experimental design with randomized complete blocks was used, with four replications. the treatments consisted of five additional applications each of 180 ppm k, 150 ppm k, and 114 ppm k, the last being the regular fertilization dosage applied in the forest nursery during the hardening phase. sixteen seedlings per treatment were placed in a controlled environment chamber, where they were exposed to a -5 °c frost for two hours. afterwards, the damage level (%) in the stems, roots and foliage was visually estimated. using a logistic model, the probability of the seedlings in each treatment suffering frost damage was obtained. both this probability model for frost damage in stems and roots, and the one used for foliage were significant. in the latter, the higher the potassium dosage, the lower the probability of frost damage in the seedlings.