The biology and management of coniferous forest seeds: Genetic perspectives

Abstract

The biological impact of forest tree reproductive processes and L'impact biologique des processus reproductifs des arbres the extent of management practices of seed orchards and nurseries forestiers ainsi que l'application des pratiques d'amenagement des on the genetic representation of new forests, are discussed in a holisvergers a graines et des pepinieres dans un contexte de representatic fashion. All the steps in tree reproduction, their timing and duration genetique des nouvelles for& est discute selon une approche tion, and how seeds are used to produce new plants for artifi cia1holistique. Toutes les etapes de reproduction des arbres, la date de regeneration, especially in containerized nurseries, are intimately declenchement et la duree, la f a~o n dont on se sert des graines pour related, cumulative, and bear directly on the genetic composition produite de nouvelles plantes a des fins de reproduction artifiof the seedling crop. These processes and their interactions need cielle, spkialement dans le cas de pepinieres de plants en recipients, to be more fully understood to maximize genetic gain, and for the sont etroitement reliees, cumulatives et influencent directement la sustainability of genetic diversity.composition genetique des semis formant le peuplement final. Ces processus ainsi que leurs interactions doivent etre mieux compris afin

Forward selection in a maritime pine polycross progeny trial using pedigree reconstruction

“…Both genetic gain and diversity depend on the variation of reproductive success in the CSO, synchrony in reproductive phenology, pollen quality and contamination, self-fertilization rates, seed germination, and other factors. Many studies have shown that there can be a considerable gulf between expectations and reality (Askew 1988;Burczyk et al 1997;Edwards and ElKassaby 1996;Funda et al 2009;Gomory et al 2003;Hansen 2008;Kang and Lindgren 1998;Machanska et al 2013;Matziris 1994;Na et al 2015), making it difficult to predict genetic quality. Moreover, the selfing rate in the CSO and inbreeding depression were not taken into account in the estimation of genetic gain and diversity.…”

Genetic comparison between natural and planted populations of Pinus brutia and Cupressus sempervirens in Syria

“…Given that some RAPD markers might be affected by selection if they are of close linkage to loci that experience different selection pressure (Latta and Mitton, 1997), genetic differentiation can increase when the selection is strong (Le Corre and Kremer, 2003). We suspect that such a pattern of among-plantation genetic differentiation was created because unsuitable seedlings were discarded during the silvicultural selection process (Edwards and El-Kassaby, 1996;Korshikov et al, 2004;Stefenon et al, 2008). The likely fact that seeds originated from only a few populations, and that planted progenies were derived from a low number of seed trees, could also have led to a stronger genetic differentiation among plantations (El-Kassaby and Namkoong, 1994;Gauli et al, 2009).…”

“…In contrast to natural populations, planted tree populations are specifically selected for their favorable traits, a process that may result in an increase in genetic diversity in the following generations and an undermining of local adaptation in native populations (Ledig, 1992). Moreover, the associated activities that are considered throughout tree management practices may lead to some losses of genetic variation in stocks used for artificial plantation (Edwards and El-Kassaby, 1996;ElKassaby, 2000). While a low number of genetic parents can increase inbreeding among progeny (White et al, 2007), high genetic diversity and low differentiation among planted populations can result from large numbers of seed trees effectively contributing to the planted progenies (Gauli et al, 2009).…”

Improving Sorghum Biomass and Productivity through Application of Moringa Leaf Juice

“…This native species is the second most important regarding to domestication but has a higher genetic base than Moringaoleifera. According to the Flora of Ethiopia, the species occurs in Kaffa, Gamo-Gofa and Sidama, between 500 and 1600 m.a.s.l and in conditions extend to 2000 m.a.s.l (Edwards et al, 1996). Moringaoleifera is an important food commodity that has had enormous attention as the natural nutrition of the tropics.…”