CONE AND SEED SIZE IN PROVENANCES OF Pinus greggii Engelm. var. greggii ESTABLISHED IN DIFFERENT SOILS

Abstract

The accumulation of organic matter causes changes on the physical, chemical, and biological characteristics of the soil, which affect tree development and growth, as well as fruit (cone) production. In order to evaluate the effect of soil traits on cone and seed size, nine provenances of Pinus greggii var. greggii were established in three soil types in Galeana, Nuevo León, México. In June 2010, 31 closed cones were collected in each provenance and each soil type (837 cones in total), and their cone length and width, seed length, width and bulk measured. Significant differences between soil types (P ≤ 0.01) and between provenances (P ≤ 0.01) of P. greggii var. greggii were detected in cone size. In the soil with stones, moderately alkaline pH and clay texture, trees produced smaller cones (85.7 mm long and 36.3 mm thick), while in the soil without stones or caliche, alkaline pH and clay-sandy texture, cones were longer (89.4 mm) and thicker (37.6 mm). Soil type did not affect (P ≤ 0.10) seed size, except for a slight change on thickness: on soil without stones or caliche, trees produced seeds slightly thicker than in the stony soil (2.0 mm vs. 1.9 mm). The provenance Los Lirios, Coahuila produced the longest cones (96.1 mm) and La Tapona, Nuevo León formed the thickest cones (39.7 mm). The trees of Puerto San Juan, Coahuila produced the smallest seed, whereas in La Tapona they produced the largest ones (3.0 and 2.1 mm of width and thickness).