Genetic control of stem form in Pinus pinaster Ait. seedlings exposed to lateral light

Abstract

AbstractmIn order to compare family differences in stem form determination, seedlings of eight half-sib progenies of Pinus pinaster were exposed to three different light treatments: fixed lateral light (T1), alternate lateral light (T2), and direct sunlight (T3). From spatial coordinates of several points along the stem we computed four variables: global leaning (GL), apical leaning (APL), flexuosity index (FL) and length of the stem (LEN). Based on comparisons of the four variables, the phototropic stimulus caused different responses in stem form at the familial level. Treatment had an important effect on stem form, although the familial response to treatments was quite variable. Heritability values (h 2 ) of the four analyzed variables showed a different pattern of variation for the three treatments, being very stable for LEN and FL, whereas h 2 of APL was much greater based on T1 and T2 compared to T3, and h 2 of GL based on T2 was much greater compared to T3 and T1. Differences in stem form were due not only to photomorphogenetic response to different light stimuli, but also to the straightening processes such as compression wood formation. The results suggest that lateral light treatments may be useful in revealing differences in efficiency of the mechanisms involved in stem form determination.

Population genetic structure in a Mediterranean pine (Pinus pinaster Ait.): a comparison of allozyme markers and quantitative traits

“…Differences between lowland and mountain populations in the paired-population model (pairs 3-4, 4-5, and 5-6 in Figure 4) reflect the influence of these strong selective factors. Selection in this species could act by means of the higher capacity of mountain races to reorientate the stem as has been shown in experiments of response of maritime pine families to phototropic stimuli (Sierra-de-Grado et al, 1997). Stem growth traits, such as total height, have been reported to be probably under selection in P. contorta ssp.…”

Genotype × Environment interactions in Pinus pinaster at age 10 in a multienvironment trial in Portugal: a maximum likelihood approach

“…Provenance trials are of fundamental importance in evaluating the adaptive capacities of provenances and patterns of genotype × environment (GE) interaction, guiding allocation of resources for afforestation, improvement and conservation programs at a relatively low cost. Provenance tests conducted in France (Danjon, 1994), Spain (Alía et al, 1995), Morocco (Destremeau et al, 1976), Greece (Matziris, 1982), Turkey (Simsek et al, 1985) and Australia (Hopkins and Butcher, 1993) report significant variations in morphologic and adaptive traits throughout the species range, and altitude is an important factor contributing to the interactions (Alía et al, 1997). However, more information is needed on the adaptive variation of provenances in the southwestern Atlantic frontier of Europe.…”

Influence of individual tree and stand attributes in stem straightness inPinus pinasterAit. stands

“…I). All environmental factors traditionally reported in the literature as causal agents of stem curvatures (wind, snow, and soil creeping) [33][34][35][36][37][38][39][40][41][42][43][44][45] could be related to the three site attributes analysed in the present study. However, a problem of spatial scale can obstruct the analysis of this result and no relationship between stem straightness and altitude, slope or exposure of the sites could be found.…”

“…This kind of damages induces lateral branch dominance that causes curvatures in the bole [16,24,44]. Lateral incidence of light plays also an important role in stem form [38]. This factor particularly affects intermediate or suppressed trees and trees growing at the edge of a stand.…”

“…Although there are information on silvicultural practices and population structure of maritime pine in the Mediterranean Spain [7,18,19,[28][29][30][31], references in the literature to stem straightness in young and mature stands are scarce [38,39]. On the other hand, there are few studies that focus in the relation between stand and tree variables and stem straightness [5,22,27,44].…”