GENETIC CONTROL OF Pinus oocarpa SEEDLINGS GROWTH TRAITS IN THE NURSERY

Abstract

A nursery test using half-sib progenies of Pinus oocarpa Schiede originated from trees randomly selected in natural stands near Uruapan, Michoacán, México, was evaluated to estimate narrow sense heritabilities and phenotypic and genetic correlations among seedling traits. Number of cotyledons, length of the longest cotyledon, seedling height at two and six months-of-age, and stem basal diameter at five months-of-age varied significantly among families (P ≤ 0.0001). Traits with the highest genetic control were number of cotyledons (h²_i = 0.89; h²_f = 0.90) and length of the longest cotyledon (h²_i = 0.64; h²_f = 0.84). Traits with lowest genetic control were seedling height at the age of two months (h²_i = 0.39; h²_f = 0.76) and six months (h²_i = 0.38; h²_f = 0.74) and stem basal diameter at five months-ofage (h²_i = 0.28; h²_f = 0.69). The highest genetic correlations were between length of the largest cotyledon and seedling height at twomonths-age (r_g = 0.645), and between two-months-age and sixmonths-age seedling height (r_g = 0.515). In contrast, there were negative genetic correlations between stem basal diameter at five monthsof-age and number of cotyledons (- 0.160) and six months-of-age seedling height (- 0.222). If there were relevant genetic correlations among the evaluated traits and economically important traits at later ages, it would be feasible to obtain genetic gains based on early selection for best individuals or best families and best individuals within families.