Reproductive indicators in natural populations of Douglas-fir in Mexico |
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Authors: | M Mápula-larreta J López-Upton J J Vargas-Hernández A Hernández-Livera |
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Institution: | (1) Programa Forestal, Colegio de Postgraduados, 56230 Montecillo, México;(2) Programa de Semillas, Colegio de Postgraduados, 56230 Montecillo, México |
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Abstract: | The reproductive capacity in nine Mexican Douglas-fir populations was determined by analyzing seed production traits from
144 trees collected in 2001. Significant variation was found for all traits among populations; they contributed between 21%
and 43% of total phenotypic variation found in these traits, indicating broad differences in reproductive capacity for that
particular year. Seed efficiency (filled seed/seed potential) varied from 14% to 42% among populations; all populations from
Central Mexico had a seed efficiency below 25%. The proportion of developed that were empty seeds varied from 0.40 to 0.81
among populations, whereas seed size varied also from 0.88 to 1.21 g per 100 seeds among them. Average ratio of filled seed
weight to cone weight (reproductive efficiency) was 29.6 mg g−1, but it varied three-fold between populations with extreme values. Populations with larger cones had greater seed potential
and heavier seed but not necessarily higher reproductive or seed efficiency. Most reproductive indicators were significantly
correlated with latitude, with lower values in the marginal populations from Central Mexico, in the southern extreme of the
species range. Given these results, the need for conservation of Douglas-fir populations in Central Mexico is discussed. |
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Keywords: | Conservation Inbreeding index Pseudotsuga Reproductive indicators Reproductive success Seed production |
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