GERMINATION AND CHARACTERISTICS OF Pinus montezumae LAMB. SEEDLINGS IN POPULATIONS OF CENTRAL MEXICO

Abstract

Populations of Pinus montezumae in central Mexico are essential for their contribution in environmental services to more than 25 million people in this area. These forests have been threatened by changes in land use and fragmentation, reducing their regeneration. The objective of this study was to determine seed germination and some morphological characteristics of P. montezumae seedlings of eight populations of central Mexico, as well as analyzing the influence of stand density and climatic and soil variables on seed quality. Seeds from 10 trees per population were used. Several germination parameters and morphological characteristics of seedlings were evaluated at 40 days after emergence. A generalized mixed linear model was used to evaluate the significance of the population factor for each trait and Pearson correlation analyses were performed with soil, environmental and density variables. There were statistical differences (P ≤ 0.05) in the variables evaluated. The average germination was 84 %, with variation from 80.7 to 87 % between populations. Seedlings showed, on average, 6.5 cotyledons (3-10, but 6-7 more common) with a length of 29 mm and a hypocotyl of 16.4 mm. Germination was related to precipitation (r = 0.75) and the number and length of cotyledons to the temperature of the populations site of origin (r = 0.84, r = 0.87, respectively). Organic matter showed negative correlation with cotyledon length (r = -0.94). Phosphorus content in the soil of origin positively correlated with germination (r = 0.94) and the number of cotyledons (r = 0.77), while nitrate correlated with hypocotyl length (r = 0.80). The density of trees did not correlate with the variables evaluated, so the low number of trees is not limiting for repopulation.