Seed mass versus seedling performance in Scots pine: a maternally dependent trait

Abstract

It is generally accepted that larger seeds give rise to seedlings with better performance. On the other hand, the size that a seed reaches is genetically determined by at least two different traits ; the genetic variability of the developing embryo and the genetic variability of the maternal plant. Thus, the relative contributions of these two traits affect seedling performance by influencing seed size. In this paper, I investigate the effect of seed size on seedling performance in the Scots pine (Pinus sylvestris). From eight maternal plants, 50 seeds were planted in each of two soil types (800 seeds in total), and seedling performance was monitored for 1 yr. Seed mass proved to be highly constant within maternal plants. Soil type influenced emergence and survival ; however, the effect of soil type differed depending on maternal origin. Seed mass was positively correlated with seedling emergence, although this relationship was not found for seedling survival or date of emergence. The initial growth of the shoot was also positively correlated with seed mass. However, after one growing season, seed mass had no effect on seedling performace, which depended exclusively on maternal origin. Nevertheless, the mean mass of seeds produced by plants was positively correlated with mean values of growth parameters. Thus, first-year seedling performance seems to be a maternal trait indirectly associated with seed size.

Effect of seed mass and number of cotyledons on seed germination after heat treatment in Pinus sylvestris L. var. iberica Svob.

“…Some report a positive correlation (Simak & Gustafsson, 1954;Debain et al, 2003;Tíscas & Lucas, 2010), whereas other studies show no effect (Mikola, 1985;Zaborovskii, 1966;Parker et al, 2006;Bladé & Vallejo, 2008). In Spanish Scots pines, seed mass has been positively correlated with germination (Castro, 1999). This agrees with our results on Iberian Scots pine showing that seed mass is positively related to germination when seeds are unheated.…”

Provenance and seed mass determine seed tolerance to high temperatures associated to forest fires in Pinus pinaster

“…Metz et al 2010;Moles and Westoby 2004;Stock et al 1990;Violle et al 2009;Zas et al 2013). Favouring seeds as heavy as possible to the detriment of a higher number of light seeds allows the plant to develop bigger embryos with greater vitality and amount of reserves (Delgado et al 2001) and to give rise to more vigorous seedlings with lower mortality rate (Castro 1999;Escudero et al 2000;Moles and Westoby 2004;Reyes and Casal 2001; but see Moles and Westoby 2006). Heavy seeds are also thought to exhibit higher resistance to heat (Álvarez et al 2007;Delgado et al 2001;Reyes and Casal 1995), providing the plant with an advantageous adaptive trait against frequent fires (Escudero et al 1999;Keeley 1977;Reyes and Casal 2001).…”

“…To achieve this aim, we simulate temperature conditions experienced during a wildfire by experimentally exposing the seeds from P. pinaster populations with contrasting serotiny levels to a number of heat shocks for different exposure times (Álvarez et al 2005;Escudero et al 1999Escudero et al , 2000Martínez-Sánchez et al 1995;Reyes and Casal 2001;Reyes et al 2015).We expect the seeds obtained from highly serotinous populations to exhibit enhanced rate of seed germination at higher thermal shock temperatures (Fernandes and Rigolot 2007;Goubitz et al 2003;Tapias et al 2004). We also expect heavy seeds to germinate better (Reich et al 1994;Reyes and Casal 2001) and produce larger seedlings (Castro 1999;Escudero et al 2000;Reyes and Casal 2004) than light ones after exposure to the thermal treatments.…”

Direct sowing of holm oak acorns: effects of acorn size and soil treatment

“…This coincides with the results of Marañón et al [23] that plant weight (after 50 days of growth) was independent of initial weight of the acorn for three Quercus species (see [22,46]). In this sense, some authors [6,24,38] indicate that this positive relationship between seed weight and seedling growth may be restricted only to the first weeks or months after emergence, disappearing later during seedling development.…”