Resumo

SANCHEZ MENDOZA, José Luis; JIMENEZ CASAS, Marcos; RAMIREZ HERRERA, Carlos  e  VIVEROS VIVEROS, Héctor. Seed quality and plant growth in populations and altitudes of Pinus hartwegii Lindl. Rev. mex. de cienc. forestales [online]. 2023, vol.14, n.75, pp.143-165.  Epub 17-Mar-2023. ISSN 2007-1132.  https://doi.org/10.29298/rmcf.v14i75.1297.

Reproduction and growth of high mountain species adapted to low temperatures could be affected by global warming, particularly at marginal altitudes where stress is more intense. This study evaluated seed quality and initial growth in various altitudinal gradients of three Pinus hartwegii populations (two in the State of Mexico and one in Veracruz State); seeds were collected between 3 400 and 4 100 masl. The experimental design was completely randomized and data on seed germination, cespitose stage breakage, and plant growth were recorded. Seed germination capacity was 87 %, with a peak value of 3.2 and germination of 10.9, but with significant variation among populations and gradients. The lowest germination capacity (50 %) was obtained with seeds from the highest altitudinal gradient (4 100 m). The breakage of the cespitose stage varied according to population and altitude. Regarding the seedlings from Veracruz, 75 % of them broke the cespitose stage at five months of age, in contrast with those from the State of Mexico, where the percentage was below 35 %. Regarding altitude, the plants from the highest interval prolonged the break of the cespitose stage for more than two months, which influenced the low initial growth of the plants. This indicates that the 4 000 m population may be in decline, unlike the other altitudinal gradients, which exhibited excellent seed quality and plant growth.

Palavras-chave : High mountain; adaptive traits; cespitose stage; altitudinal gradient; germination parameters; reproduction.