No abstract

Two temperature regimes were applied during reproductive development of seed and pollen cones of interior spruce (Picea glauca (Moench) Voss and Picea engelmannii (Parry) complex) to determine temperature effects on the adaptive traits of progeny. In Experiment 1, identical crosses were made on potted interior spruce using untreated pollen followed by exposure to a day/night temperature of 22/8 or 14/8 degrees C with a 12-h photoperiod during the stages of reproductive development from post-pollination to early embryo development. Frost hardiness and growth of progeny from seed produced in the two temperature treatments were measured over a 4-year period. Elevated temperature significantly affected both seed-cone development and the adaptive properties of the progeny. Seed cones exposed to the 22/8 degrees C treatment reached the early embryo stage in 53 days versus 92 days in the 14/8 degrees C treatment. Seed yields, cotyledon emergence and percent germination were also significantly enhanced by the 22/8 degrees C treatment. Progeny from seed produced in the higher temperature treatment showed significantly reduced spring and fall frost hardiness, but the elevated temperature treatment had no significant effects on time of bud burst, growth patterns or final heights. In Experiment 2, single ramets of the same clone were subjected to a day/night temperature of 20/8 or 10/8 degrees C during pollen cone development, starting from meiosis and ending at pollen shedding. The two populations of pollen were then crossed with untreated seed cones. Compared with pollen cones exposed to the 10/8 degrees C treatment, pollen cones exposed to the 20/8 degrees C treatment during development reached the shedding stage 2-4 weeks earlier, whereas pollen yields, in vitro viability and fertility (seed set) were significantly lower; however, the resulting progeny displayed no treatment differences in frost hardiness or growth after 1 year. Results suggest that seed orchard after-effects could be caused by temperature differences between orchard site and parent tree origin and that this effect acts on maternal development. Gametophytic (pollen or megagametophyte or both) and early embryo (sporophytic) selection are possible mechanisms that may explain the observed results. Although the effects are biologically significant, they are relatively small and do not justify changes in current deployment strategies for seed orchard seed.

Seed orchards for the production of conifer seed in British Columbia are usually located in areas favorable (warm and dry) for flowering and seed development, often considerably south of the source location of the parent trees. Differences in environmental conditions between seed orchard location and location of origin can affect progeny performance. It is suspected that this is caused by environmental factors that affect reproductive processes of parent trees and lead to altered physiological traits (aftereffects). This study examined if aftereffects are present in white spruce (Picea glauca (Moench) Voss). Control pollinations were made at two locations, Red Rock, near Prince George (53°N) in central British Columbia, and Kalamalka, near Vernon (50°N) in southern British Columbia, on five female trees using a four-male polymix. Identical genotypes through grafting were present at the two locations. Pollen maturing at each site was only used in the polymix at that particular location. Progeny were raised and germination traits, number of needle primordia, greenhouse and field heights, and frost hardiness were evaluated in a common environment. The location of seed development significantly affected all traits evaluated. Height growth aftereffects in the second field season were much less than those observed in the first field season. These results suggest that aftereffects are detectable in white spruce progeny performance in British Columbia.Résumé : En Colombie-Britannique, les vergers destinés à la production de graines de conifères sont généralement établis dans des endroits favorables (chauds et secs), souvent considérablement plus au sud que l'origine géographique des sources parentales de graines, afin de favoriser la floraison et le développement des graines. Les auteurs rapportent que les différences environnementales entre le lieu d'établissement des vergers à graines et l'origine géographique des sources parentales de graines peuvent affecter la performance des descendances. Ceci serait causé par des facteurs environnementaux affectant les processus de reproduction des arbres parents et menant à l'altération des caractères physiologiques (effets reportés). Les auteurs ont voulu vérifier si ces effets reportés étaient présents chez l'épinette blanche (Picea glauca (Moench) Voss). Pour ce faire, des croisements contrôlés ont été réalisés dans deux endroits, à Red Rock près de Prince-George (53°N) en Colombie-Britannique centrale, et à Kalamalka, près de Vernon (56°N) en Colombie-Britannique méridionale. Les croisements ont été réalisés sur cinq arbres femelles à l'aide d'un mélange de pollen provenant de quatre arbres mâles. Les génotypes parentaux découlaient de greffes et étaient identiques d'un site à l'autre. Le mélange de pollen utilisé pour chacun des sites provenait de pollen ayant maturé sur le même site. Après avoir mis les descendances en production au sein d'un test comparatif, différents caractères furent évalués : des caractères de germination, le nombre de primordia foliaires, la hauteur e...

The hypothesis that pollen arriving first to receptive seed-cone buds has an advantage over pollen arriving later (first-on, first-in) was tested in Douglas-fir using two reciprocal pollination experiments. In the first test, one each of two outcross-pollen parents was applied first followed by the other 5 min or 24 h later. In the second test, self- and outcross-pollen parents were compared in a similar reciprocal arrangement 5 min, 6 h, and 24 h apart. Electrophoretic analysis of isocitrate dehydrogenase alleles was used to distinguish between the two pollen parents in resultant seeds. When a second pollen parent arrived within 5 min of the first, both contributed to the seed produced. However, when the second pollen parent arrived 6 or 24 h later, its contribution to the resultant seed was less. Pollen fertility potential interacted with arrival time and affected both seed yields and parental composition. When pollen of lower fertility was applied first followed by a higher fertility pollen, seed yields were lower; as the time interval for the arrival of the second pollen parent increased to 24 h, the percent contribution of the first pollen increased. However, when the higher fertility pollen was applied first, there was little effect of the lower fertility pollen arriving within 5 min or 24 h.

The occurrence of abscisic acid (ABA) in the dormant shoots of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) was confirmed by bioassay, thin-layer chromatography, gas–liquid chromatography, and gas–liquid chromatography – mass spectrometry. Seasonal variation of ABA in the buds, leaves, and stems was then determined using 2-trans-ABA as an internal standard. Concentrations of ABA were highest in the autumn for buds (2.1 μg/g) and needles (0.79 μg/g) and highest in January for stems (0.34 μg/g). The lowest concentrations for all tissues were in February and March, before bud burst. Close correlation of levels of ABA with previously measured physiological evidence of growth and metabolic activity suggests a possible role in the dormancy cycle of Douglas-fir.