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Made available in DSpace on 2019-10-06T15:32:09Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-04-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Microsatellite loci were used to assess pollen contamination and mating patterns in an Eucalyptus urophylla seedling seed orchard (SO2) along with inbreeding and outbreeding depression in a second generation progeny test (PT2) established with SO2 seeds. We measured survival, diameter at breast height (DBH), and height (H) in SO2, PT2, and two other stands (SO1, PT) located at a distance of at least 210 m from SO2. Pollen contamination was substantial (11.9%), with the largest proportion coming from the closer SO1 stand (6.1%) than PT (4.7%) and 1.1% from unknown sources. The pollen dispersal pattern was isolation by distance but reached long distances (600 m). PT2 offspring were mainly the result of outcrossing (92.6%), but mating in SO2 was not random due to self-fertilization (7.4%), mating among relatives (6.6%), correlated mating (13.7%), and high male fertility success of trees with large DBH. Thus, families are a mixture of different levels of relatedness and some inbreeding (12.7%). Inbreeding depression was variable among traits; it was higher for selfing (39.6–49.5%) than mating among relatives (11.6–20.9%) and higher for mating between full-sibs (4.4%) than half-sibs (2.2%). Outbreeding depression was higher for pollen immigration from less improved sources (33.9–41.2%). Non-random mating resulted in a coancestry (0.152) higher than expected for half-sib families and an overestimation of heritability by 17.8%. Our results indicate that isolation distances greater than 600 m are necessary to avoid pollen contamination in Eucalyptus seed orchards. Furthermore, pollen immigration results in outbreeding depression, and selfing results in higher levels of inbreeding depression than mating among related trees. Universidade Estadual de São Paulo (UNESP/Ilha Solteira), Av. Brasil Centro, 56, CP 31, CEP 15385-000, Ilha Solteira Instituto Florestal de São Paulo (IF), CP 1322, CEP 01059-970 Universidade Estadual Paulista (UNESP/Botucatu), Rua José Barbosa de Barros, 1780, CEP 18.603-970 Instituto de Pesquisas e Estudos Florestais (IPEF), Via Comendador Pedro Morganti, 3500, CEP 13.415-000 Eldorado Brasil, Rodovia BR 158 – km 231, CEP 79.641-300 Suzano Papel e Celulose, Avenida Dr. José Lembo, 2215, CEP 18207-780 Universidade Estadual de São Paulo (UNESP/Ilha Solteira), Av. Brasil Centro, 56, CP 31, CEP 15385-000, Ilha Solteira Universidade Estadual Paulista (UNESP/Botucatu), Rua José Barbosa de Barros, 1780, CEP 18.603-970 FAPESP: 2014/03407-7

Seed from orchards, established from breeding programs, often dominate the planting stock in economically important tree species, such as Norway spruce. The genetic diversity in seed orchards’ crops depends on effective population size which in turn is affected by many factors such as: number of parents in the orchard, seed orchards’ design, fecundity, and pollen contamination. Even though seed orchards’ seed is extensively used over large regions, very few studies have addressed how well their crops reflect the genetic diversity present in the regions where they are planted. Here we have investigated the genetic diversity (by means of 11 microsatellites) of two Norway spruce seed orchard populations with different number of parents (60 and 25) and compared this with seed crops collected in the semi natural forest and natural unmanaged populations. We found that the ratio between the effective population size (Ne) and actual number of parents (N) varied between 0.60 and 0.76 in the orchards’ seedlots. A reduction in genetic diversity (mainly allelic richness) was detected in a few seedlots, mainly where the number of parents was low. Our results also show that pollen contamination play an important role in maintaining the genetic diversity in orchards’ seedlots, particularly when the number of parents is low. The population genetic structure among seed orhcards and natural populations is shallow suggesting that regeneration with seed from current seed orchards will have limited effect on the overall genetic diversity.

Cone rusts Thekopsora areolata and Chrysomyxa pirolata are widely distributed in northern hemisphere. In Fennoscandia, these rusts cause severe damage and great economical losses especially in seed orchards specialized to produce high quality seeds. The aim of this study was to investigate sporulation of cone rusts and factors affecting epidemics to develop new control practices against these rusts. Natural sporulation of T. areolata was investigated in Finnish Norway spruce seed orchards on Prunus padus and the effect of environmental variables on rust sporulation in 2018–19. A sample of Prunus leaves was collected from which the coverage and number of T. areolata pustules were estimated. The frequency of cones with cone rusts, T. areolata, Chrysomyxa pirolata and C. ledi, was also estimated in Picea abies cones and the sporulation of C. pirolata on Pyrola sp. leaves in the seed orchards. The T. areolata incidence on Prunus was modelled with temperature sum, rainfall, seed orchard and time of estimation. The T. areolata disease incidence was low (

Pinus koraiensis is a conifer species of ecological and economic importance in northeast China that has been excessively exploited in recent years. A clonal seed orchard (CSO) was established including potentially genetically differentiated provenances from the whole distribution area, we applied nine simple sequence repeat (SSR) makers to study the genetic diversity and population structure of six maternal populations as well as their progeny populations. The results showed a high genetic diversity in both maternal and progeny populations, with the average expected heterozygosity of 0.617 and 0.632, respectively. The level of genetic diversity in the progeny populations was slightly higher than that in the maternal populations, and almost all diversity descriptors were correlated between maternal and progeny populations, indicating that the CSO could preserve the established species’ gene pool. An overall low level of genetic differentiation of P. koraiensis (FST = 0.029 and 0.025 for maternal and progeny populations) was found. The six maternal populations clustered into two groups by Bayesian cluster analysis with the two northernmost populations comprising one group and the other four populations as another genetically differentiated group, potentially indicating regional adaptation. The northern group had significantly higher levels of within population diversity. Population structure was not evident anymore in the progeny populations, suggesting that mating among differentiated provenances within the CSO homogenized the different gene pools, although differences in diversity were still maintained. These results will inform efforts for the conservation and management of P. koraiensis and provide guidance for future studies of population genetics and breeding programs.

Teak Clonal Seed Orchards (CSO) in Perum Perhutani are an essential source of improved seeds that are managed with appropriate silvicultural practices including pest and disease monitoring. However, the attack of mistletoe has been observed recently in the orchard and become a significant parasite causing decrease fruit yields in many mother trees. Attempts to overcome of this problem have not yet been well formulated due to lack of basic information on the mistletoe. The main objective of this research was to assess the degree of teak mistletoe infestation within the teak CSO, located in Padangan near Cepu, East Java. The assessment was carried out in compartments of teak clones that have been designated as observation sample plots/OSPs (n = 4) with size of more than 1 ha depending on distribution observation measurement plots/OMPs within OSP following various infestation intensities, namely low, moderate, high and control (no infestation). Four OMPs (@ 50 m x 50 m) per OSP, each comprising of 25 trees, were made to record infestation intensity referring to modified TMR (true mistletoe rating) of 9-class systems, i.e. rating of mistletoe amount and infected branch intensity. Results showed that levels of mistletoe infestation ranging from rather slight to rather moderate (TMR 0.86 – 3.58). Additional data from map of teak mistletoe species distribution showed that Dendrophthoe pentandra and Macrosolen tetragonus were observed in the whole area, while Viscum articulatum was found only in certain area.

We investigated Fraxinus excelsior breeding system using field data collected in a natural population and in a seed orchard. First, we attested functional trioecy (co-occurrence of males, hermaphrodites and females), with males producing pollen, hermaphrodites producing both pollen and seeds simultaneously, and females producing seeds. Second, we found that the reproductive system of F. excelsior was not labile, as sex expression seemed to be stable through time. Third, gender is genetically determined since different trees belonging to the same clone in the orchard exhibit similar sexual phenotypes.

Until recently, the most important factors affecting the economics and genetics of the seed crop from seed orchards were considered to be the timing and duration of flowering, variation in fertility and the total number of clones used to establish the seed orchards. Change in climatic conditions however is an emerging factor that could prove crucial regarding the timing of flowering and synchronization among clones and thus, the quality and quantity of seed production. The temporal and spatial variation in flowering phenology and the duration of flowering were studied in consecutive years in a Pinus nigra Arn. seed orchard. Sixty plus trees representing the distribution of the species in Northern Greece were used to establish the seed orchard, and nineteen ramets per clone were planted in a honeycomb experimental design in order to avoid kinship. Temporal variation among clones, as well as spatial variation among ramets within clones growing at different sites of the orchard were recorded, for initiation and duration of male and female flowering. The majority of clones were synchronized in dates of flowering during the year with weather conditions close to the long-term climatic conditions, except for a limited number of clones that were precocious or late flowering. The pronounced variability in climatic conditions over the 2 years strongly affected the flowering and synchronization among clones, resulting in almost complete asynchrony during the xerothermic year, which was characterized by a prolonged mean monthly temperature increase of 2.3 °C and a water deficit of 53% in a 7-month-period (November to May). These results suggest that one of the effects of a warmer and drier climate may be the lack of flowering synchronization, as pollen shedding might be completed before female conelets reach the phase of receptivity. The restriction of male parentage to a limited number of clones severely violates the panmixia assumption and could result in fertilization failure. The projected climate change for the Mediterranean region could potentially prove detrimental for fertility and flowering synchronization of forest trees, having consequences on the quantity and genetic diversity of the seed crop in seed orchards, and the natural regeneration of forest trees in forest ecosystems due to the reduced percentage of sound seed.

Paternity analyses using microsatellites were conducted in two conifer clonal seed orchards (CSOs). The aim was to study mating patterns and potential dysfunctions such as unbalanced male contribution, and how these factors influence genetic diversity. The effect of unequal male contribution was quantified by the status number (NS), which reflects build up of coancestry in the seed orchard crop due to low number of clones and unequal male contribution. This approach was also used to quantify the effect of clonal differences in germination percentages on effective population sizes. Furthermore the genetic diversity of the Abies alba and Larix kaempferi CSOs was compared to other alternative seed sources via observed heterozygosity and allelic richness. Both CSOs had a low pollen contamination rate (1.4% and 2.8%). The CSO with 12 A. alba clones showed a very skewed distribution of paternal contributions, where four clones (25%) sired more than 80% of the offspring, resulting in a status number of (NS) = 4.6. The CSO with 10 L. kaempferi clones showed a much more equal distribution of paternal contributions, with (NS) = 10.2. For both CSOs the paternal contributions varied significantly with sampling site within the seed orchards. The amount of selfing in the CSO seed crops was 4.7% in A. alba and 3.1% in L. kaempferi and selection against selfing could be observed. The relative self-fertility was estimated to 59% in A. alba and 33% in L. kaempferi. A study of early versus late germinating seedlings in two L. kaempferi clones indicated no increased proportion of selfed individuals in late germinating individuals. Clonal differences in germination percentages in the two CSOs had little impact on effective population sizes. The level of heterozygosity was not significantly different between CSOs and the alternative seed sources. Fixation indices (Fis) were significantly negative in the seed crops from both CSOs, indicating heterozygote excess. There were substantial differences in allelic richness between CSO seed crops and alternative seed sources. The number of alleles was 57% higher in the alternative A. alba seed source Mt. Gariglione and 25% higher in the alternative L. kaempferi seed source F410 Froslev.

A population of Norway spruce (Picea abies (L.) Karst.) from southern Poland, named Kolonowskie 0293, exhibited a very high breeding value among 1100 European populations tested in the IUFRO 1964/1968 provenance experiment. However, the original mother stand of that population no longer exists. Owing to international cooperative efforts, a reconstituted clonal seed orchard of that population was successfully established to protect the gene pool of the Kolonowskie 0293 population. Genetic analyses were conducted using 24 isozyme marker loci and a high level of genetic variation was found among progeny of the reconstituted 'Kolonowskie' seed orchard in Kornik, Poland. The observed variation was similar to that of naturally regenerated stands and likely descendants of the lost mother stand of provenance Kolonowskie 0293 found in the original area of seed collection for the IUFRO 1964/1968 experiment. Both the naturally regenerated stand and clonal seed orchard populations had a higher genetic variation than average among populations of Norway spruce from throughout Poland. These findings indicate that the reconstituted 'Kolonowskie' seed orchard as well as the naturally regenerated stands found in the area of seed collection for the IUFRO 1964/1968 experiment should be considered as seed sources for the very adaptable, well-performing population Kolonowskie 0293. Based on the procedure described herein, the effective restoration of any forest tree species population is possible if its progeny is found in sufficient numbers in any experimental trial.

The development of forest tree seed transfer research, guidelines, regulations and policy has a long history in Canada, as well as in many other parts of the world. While the implicit assumptions of what is involved in developing seed transfer limits, guidelines and policy are generally accepted, the scientific and biological processes that underpin their validity are not readily available to most foresters. We provide an overview of the historical and current technical approaches to the development of seed transfer in British Columbia, and the overall framework which incorporates key biological, statistical and administrative issues in regulating the movement of forest tree seed. An example of how seed transfer information is developed from field experiments to guidelines or limits is provided from the lodgepole pine provenance tests in BC. Seed transfer research as it relates to the movement of wild or seed orchard seed will need to factor in the complications being predicted with climate change. As such, seed transfer research will continue to evolve as field experiments mature, new tests are established, statistical approaches and geographic information systems improve, and climate prediction tools attain greater resolution.

Genetic diversity was determined and compared by using 86 random amplified polymorphic DNA loci in 450 families originated from 18 Pinus brutia Ten. (Turkish red pine) seed sources. These seed sources were sampled at three different categories and included six seed stands from six different breeding zones and six seed orchards, and six plantations which were originated from the respective seed stands. Genetic diversity parameters among the plantations, seed orchards and seed stands were compared. There was no significant difference in genetic diversity parameters of seed sources, but the percentages of polymorphic loci were slightly higher in seed orchards than their natural counterparts. These results suggest that through phenotypic selection practiced genetic diversity residing in natural stands seems to be successfully captured in seed orchards. Mean F ST values ( F ST = 0.10–0.11) did not vary among three different categories of seed sources. Seed orchards ( F IS = 0.03) and plantations ( F IS = 0.07) showed reduced locality inbreeding coefficients compared with seed stands ( F IS = 0.13). The dendrogram of seed stands based on genetic distances did not produce any clusters of populations that could be attributed to their geographic proximity. A representative portion of genetic diversity existing in natural populations of Turkish red pine appears to be captured in established seed orchards and plantations with seeds from seed stands.

Insects were collected in the canopies of wild and plantation forests with Malaise traps and hand nets during the flowering season of teak (August–October 1998) in and near the Maegar Seed Orchard in Phayao province, Northern Thailand. A total of 10,404 individual insects were collected representing 693 morphospecies from 115 recognizable families and 11 orders. Of these 11 orders, Lepidoptera had the highest number of morphospecies (32%) followed by Hymenoptera (29%). Among 693 morphospecies, 620 (89.5%) were non-pollinators and 73 (10.5%) were potential pollinators. Canopies of wild teak had greater insect biodiversity than plantation; however, the number of potential insect pollinators in the plantation canopies was greater than the wild trees. The total number of morphospecies was 552 in the canopies of wild trees, 340 in the plantation canopies and 199 appeared in both habitats. Mean numbers of morphospecies per individual tree for canopies of wild and plantation trees were 280 and 150, respectively. Total number of individuals collected in the canopies of wild trees was 6948 and 3456 in the plantation canopies. Mean numbers of individuals per individual tree in the canopies of wild and plantation trees were 2316 and 1152, respectively. The mean alpha diversity indices per individual tree in the canopies of wild and plantation trees were 84 and 49, respectively.

Insect pollinators that frequently visited teak (Tectona grandis L. f.) flowers in a wild (W) and a clonal seed orchard (CSO) near the Maegar Seed Orchard, Phayao in Thailand were stingless bees and small carpenter bees. There were differences between the two habitats in numbers of pollen grains deposited on the stigma by these pollinators and in the pollinators foraging movements. The mean numbers of pollen grains observed on the stigma in the W was lower than in the CSO. Pollinators in the CSO moved longer distances, flying among inflorescences rather than staying within the same inflorescence. However, there were no differences in the number of flowers visited per minute between the two habitats. The time pollinators spent on each flower visit did not alter the percentage of pollinated flowers. Large pollinators typically landed on the tops of the flowers, whereas stingless bees and small carpenter bees approached flowers from both the top and side. Trigona collina was the most important pollinator in the CSO. It made the most frequent visits and contributed to 67% of teak flowers being pollinated. Its foraging time was high in the morning (10:00–12:00 h), which coincided with the receptive period of teak flowers. The behavior of other pollinators that may promote out-crossing is discussed.

Genetic variation in mortality was studied by comparing survival of 70 progenies of Dalbergia sissoo originating from different parts of Nepal. The analysis was based on their performance in a so-called seedling seed orchard (SSO) that was heavily infested by Aristobia horridula Hope; a beetle that has become a sever pest infesting and killing young trees in sissoo plantings. Large and highly significant differences were found between families in mortality, showing that some progenies seem to resist the attack much better than others. Although dealing only with resistance against the beetle attach, the results awakens hope that phenotypic selection in tree improvement programmes can be an important tool in tackling the general health problems in sissoo plantations. This calls for special interest facing the serious dieback syndrome that has seriously decreased health of sissoo planting in Nepal, Pakistan and India.

We evaluated the effect of plant genotype on resistance of black spruce (Picea mariana (Mill.) BSP) to the yellowheaded spruce sawfly (Pikonema alaskensis (Roh.)) in three half-sib family test sites and in a clonal seed orchard in New Brunswick, Canada. Heritability estimates were positively correlated to the percentage of trees defoliated by the sawfly in the half-sib family tests. At the site where the most damage occurred, the estimated individual heritability of resistance was 0.84, while that based on family means was 0.57. In the clonal seed orchard, the variability among clones explained 39.3% of the variation in defoliation, and individual clone heritability and clone mean heritability estimates were 0.40 and 0.82, respectively. Positive phenotypic and genetic correlations between tree height and damage suggest that selection for resistance may result in slightly slower tree height growth in some cases. These results suggest that there is good potential to select trees resistant to the sawfly that display other commercially desirable traits.

Genetic gain and diversity (status number) were estimated in a 12-year-old Quercus accutissima seedling seed orchard under three thinning scenarios. These scenarios were based on linear (ranged from the removal of individuals within families to the removal of entire families based on the family genetic values generated from conventional progeny test trials), systematic (removal of every second row), and truncation (families with genetic values below the specific threshold value were totally removed) thinning. Both genetic gain and diversity of each scenario were estimated and compared to those of before thinning. Truncation thinning produced the highest genetic gain that was coupled with the lowest diversity, while linear thinning produced the moderate balance between genetic gain and diversity. Systematic thinning, on the other hand, produced the lowest genetic gain and the highest diversity. Under the linear thinning option, the number of family completely removed was minimized to keep up options for further genetic evaluation and selection. This linear thinning was accomplished by applying within family thinning regime that was proportionate to the reverse of every family genetic gain (i.e., low numbers of trees removed from high genetic value families and higher numbers of trees removed from lower genetic value families).

Clones of superior pollen- and seed-producing plants of 4 fourwing saltbush ( Atriplex canescens [Pursh] Nutt.) ecotypes were planted in a seed orchard in west-central Texas to determine if seed production and quality could be enhanced by irrigation and fertilization. Subplots of nitrogen (N) at 112 kg·ha −1 , phosphorous (P) at 112 kg·ha −1 , N + P at 112 + 112 kg·ha −1 , or no fertilizer were superimposed on irrigated or dryland main-plots. Neither irrigation nor fertilization affected estimated seed yields or utricle fill during the third growing season after planting. Fertilization did not affect seed germination of any of the saltbush ecotypes on irrigated plots or that of the 2 more xeric ecotypes (Grandfalls and Valentine) on dryland plots. Fertilizer N on dryland plots increased germination of the San Angelo ecotype, and N + P increased germination of the Texon ecotype. Estimated gross value of the first seed crop was about $4 648·ha −1 even though the superior reproductive traits of parental pistillate plants were poorly expressed by the clones. Fertilization did not affect estimated seed yields in irrigated plots, but N and N + P increased seed yields in dryland plots in the fourth growing season. Fertilization effects on seed weights varied among irrigated and dryland plots and among saltbush ecotypes. Mortality of the shrubs during the period extending from 1988 to 1990 was not affected by irrigation or fertilization but increased among ecotypes as the xeric nature of their sites of origin increased and as the distance of their sites of origin from the seed orchard increased. Evidence from this study did not strongly support cloning, irrigation, or fertilization for improving seed harvests of fourwing saltbush in west-central Texas.

Southeastern fox squirrels were observed feeding preferentially on seeds of certain clones of loblolly pine in a central Georgia seed orchard in the early 1990s and, similarly, on slash pine seed in an orchard in central Florida in the late 1990s. In each orchard, the degree of feeding preference and avoidance among selected clones was documented and quantified. We tested three hypotheses to explain this phenomenon: (1) seeds of preferred clones have greater nutritional quality or energy content; (2) cone armature differed between preferred and avoided clones; or (3) preferred clones have lower quantities of deterrent compounds present in cone tissue. Hypothesis 1 was tested using cones collected from three preferred and two avoided clones within a loblolly pine seed orchard. We found no consistent differences in total number of seeds per cone, viable seeds per cone, seed weight per cone, average weight per seed, energy content per seed, and energy content per cone between preferred and avoided cones. Hypotheses 2 and 3 were tested using cones collected from four preferred and four avoided clones within a slash pine seed orchard. We found a strong positive association between spine length and cone avoidance. Avoided cones had significantly higher concentrations of myrcene, α-phellandrene, β-phellandrene, β-caryophyllene, and α-humulene but lower concentrations of α-pinene. These physical and chemical cone defenses may increase handling time or reduce seed palatability and therefore act as significant deterrents to seed predation by fox squirrels when preferred feeding options are readily available, such as in a seed orchard.

The objectives of this study were (a) to identify individual plants of Prosopis alba and P. pallida that could grow at near seawater salinities to use directly as clonal propagules and to establish seed orchard and (b) to analyse the population structure to aid in future germplasm collections for salinity tolerance in Prosopis. This hydroponic greenhouse study compared the growth and survival of 27 Prosopis families (seed from single mother trees) as a function of salinity from 10 to 45 dS m−1. Nine P. alba families from one saline area (provenance) near Santiago del Estero, Argentina were compared to 14 P. pallida families from six provenances in Peru and to one family each of P. alba/flexuosa from Chile, P. juliflora from Senegal, P. flexuosa from Argentina and P. ruscifolia from Argentina. The mean of the P. pallida families had a significantly greater survival (61.1% vs. 41.7%) and percentage of seedlings that grew (37.4% vs. 23%) at seawater salinities of 45 dS m−1 than P. alba. Families from P. pallida had the greatest mean growth at the highest salinity but P. alba families were ranked third and sixth from the top in growth. There were little differences in maximum height growth of the individual seedlings from these two species. For P. alba, the percentage of seedlings which survived at the highest salinity level had a lower correlation (r2=0.46) with the number of seedlings which grew at that salinity level than for P. pallida (r2=0.70). The correlation between mean family growth and maximum individual growth was lower for P. alba (r2=0.24) than for P. pallida (r2=0.49) suggesting that within P. alba, with a sufficiently high number of seedlings, it would be possible to find individuals with rapid growth rates in most families. Approximately 50 of the most rapidly growing seedlings at the highest salinity level have been repotted to be multiplied by rooting of cuttings and to serve as seed orchards for salt tolerance. Given the success in identifying rapidly growing P. alba individuals from only one provenance in Argentina, more extensive germplasm collections and testing are warranted to locate individuals with superior growth rates. Due to the previously demonstrated erect form, high biomass productivity and sweet pods in these P. pallida families in Haiti, Cape Verde, India and Peru, extensive recollections and field testing of P. pallida are warranted.

Effects of the variation in male and female fertilities of clones, flowering phenology, and spatial distribution of clones on the genetic structure of progenies of three Scots pine seed orchards were investigated using isozyme gene markers. A pronounced variation of male and female gametic contributions was found. Most clones appear to be phenologically synchronized, but up to 15% of early or late flowering clones were found in all seed orchards. The presence of ramets, which do not belong to any seed orchard clone, does not affect allelic or genotypic diversity of the seed orchard crop. Gene-pool genetic distances based on allelic frequencies between the parental and the progeny generations are not very high, but there are certain loci exhibiting a considerable differentiation. On the other hand, variance effective population sizes indicate a substantial drift of gene frequencies between seed orchard itself and its offspring. The necessity of a cautious use of the reproductive material originating from seed orchards is emphasized.

Ten provenance/progeny tests of Bombacopsis quinata were established in Venezuela and Colombia using open-pollinated (OP) seed collected from throughout its natural range. In addition, two full-sib progeny tests were established in Colombia with seed from crosses made in a second-generation seed orchard. Average survival of all tests was approximately 80%, with the local source from Colombia (Atlantico) having slightly better survival in Colombia. Average growth rates at age 8 years were 6–7 m height and 12–13 cm DBH. Provenance×country interaction was highly significant between Colombia and Venezuela, although at a within-provenance level, families performed relatively consistently in the two countries (rBg=0.58). There was no important genotype×environment interaction at the provenance or family level between test sites in the same country. There were large provenance effects in both countries. In Colombia, two provenances from Nicaragua (Hacienda San Juan and Los Playones) performed as well as the local source, with 11–16% more volume than average. In Venezuela, provenances originating in areas of 1600–2100 mm of annual rainfall (Choluteca, Honduras, and Guanacaste, Costa Rica) had volumes 26% above average, while the local source performed poorly both in survival and growth. Heritabilities for growth traits are moderate and increase with age up to 0.25–0.30 at age 8 years. Dominance variance is relatively unimportant as it is approximately 1 4 or less than the size of additive variance. After the appropriate provenances have been identified, additional genetic gains of up to 50% in volume are possible from family and within family selection.

The demand for Abies amabilis (Dougl. Ex Loud) Dougl. Ex Forbes, Pacific silver fir seed has increased in British Columbia in recent years but the supply of wild seed is limited due to periodic cone crops and difficulty and high cost of cone harvest. Several clonal seed orchards have been established but cone production is very low. A study was undertaken to enhance cone production in a clonal seed orchard grafted in 1984. Five treatments were applied with 20 trees per treatment. Treatments began on 20 May 1998. Each tree was given two applications of GA4/7 at 1 week interval, 20 and 27 May (early application) or 27 May and 3 June (late application). Ramets in treatment 2 received early GA 4/7 application + fertilizer + girdling . Ramets in treatment 3 received a similar treatment but given late. Ramets in treatment 4 received early GA 4/7 application + fertilizer + girdling + tenting . Ramets in treatment 5 received a similar treatment but given late. Ramets in treatment 1 received one injection of 80% ethanol but no GA4/7 on 30 May. Each treatment had 10 trees in which vegetative bud burst was early and 10 trees in which bud burst was late. Pollen and seed cone abundance was measured in April 1999. Only 10% of control ramets produced seed cones (0.75 cones/ramet). In treatment 2, 45% of ramets produced seed cones (8.4 cones/ramet). In treatment 3, 35% of ramets produced seed cones (2.3 cones/ramet). In treatment 4, 70% of ramets produced seed cones (23.1 cones/ramet). In treatment 5, 75% of ramets produced seed cones (21.2 cones/ramet). Pollen cone enhancement was statistically significant for treatments 2–5 over controls but production was not as dramatic as for seed cones because most control ramets produced some pollen cones.

The species-specific properties and the environmental requirements of lodgepole pine (LP) in both its native environment and as an exotic are reviewed in order to describe the large-scale introduction of this tree to Sweden, where the planted area has reached about 600,000 ha during a 25-year period. LP is estimated to produce 36% more wood than Scots pine (SP) and survives better in the young stages, but is less stable against wind and snow load after being planted. Other species differences are discussed in terms of resource acquisition, biomass allocation and losses, as well as the resistance to abiotic and biotic stresses. The experiences of silvicultural practices are described, along with initial progress in tree breeding and seed orchard programmes. The influence of tree and stand characteristics, e.g. rotation age, stand density, species composition and stand distribution in the landscape, are discussed in order to analyze the ecological and environmental consequences of current and future management alternatives.

A ground-based estimate was made of the number of emergent female strobili carried by 74 open-grown stands (10–12 years old) of Pinus radiata growing across a range of latitudes and altitudes of the South Island and North Island of New Zealand. The intent of this study was to develop and evaluate an empirical model to describe the relationship between environmental variables and emergent female strobilus numbers. The model suggested that variability in female strobilus number was necessarily associated with climate and site factors. Temperature and to a lesser extent rainfall variables were associated with the number of seed cone-buds that achieved anthesis in the spring. The step-wise multiple regression analysis selected mean minimum February temperature, integrated soil water stress (February–March), accumulated growing degree days (weighted against spring rainfall prior to seed cone-bud initiation), in that order. The first variable was found to explain around 54% of the variance in strobilus numbers across sites, while taken together all of the variables explained 64% of among-site variability. Model evaluation was carried out across both similar eastern South Island sites and different North Island sites at which it was developed. It was found to predict strobilus counts accurately across the South Island sites, but less accurately across the warmer North Island sites. Mean minimum February temperature was still the most important predictor of strobilus production across sites, but this relationship was non-linear. Thus, a non-linear modelling approach was adopted to better fit the model across regions New Zealand-wide. Long term nation-wide data for mean minimum February temperature were then used in a climate modelling system to generate a temperature map for New Zealand, to assist with seed orchard site selection. This map illustrated that oceanic (as opposed to semi-continental) environments around the New Zealand coast are likely to be the most productive sites for seed orchard production. Contrary to a priori perceptions, the northern regions of the North Island were depicted to offer a greater number of candidate sites for seed orchard siting than the more south eastern semi-arid regions of New Zealand.

Advanced silvicultural methods in Thuringia as well as the necessity to preserve the genetic resources of endangered tree species have led to the goal of establishing seed orchards of silver fir ( Abies alba Mill.). In order to combine several economic and genetic features in constructing these seed orchards, the clones were chosen using a multistep procedure accompanied by genetic surveys at isoenzyme loci. Of the initial material consisting of 26 indigenous stands, 500 plus-trees were selected according to their vitality and growth. Based on several sampling strategies where the clone collections were stratified according to the level of gene diversity, occurrence of rare alleles and degree of homozygosity, 130 clones were finally chosen from the plus-tree collection. These clones are assumed to include all essential features attributed to a seed orchard which should produce vital and improved seed crop and preserve the gene pool of silver fir.

Pinus caribaea var. caribaea from Cuba was introduced to southern China in 1961 with P. caribaea var. hondurensis from Guatemala and P. caribaea var. bahamensis following in 1973. However, it was not until 1983 that combined variety/provenance tests were established on several sites with a range of provenances. It was reported that significant differences existed in quantitative genetic traits such as growth rate among the three varieties and P. elliottii which was used as a control. During the period from 1973–1978, 12 seed orchards or seed production areas of P. caribaea var. caribaea were established in Guangdong and Guangxi covering a total area of about 70 ha. All trees were grafted onto root stocks of P. elliottii or P. massoniana. Seed production was very low varying between 8–50 kg/ha on an annual basis. A combined provenance/progeny trial and gene bank of P. caribaea var. bahamensis was established in Guangxi in 1990 using seed provided by Oxford Forestry Institute with 14 provenances and 121 open-pollinated families representing the whole range of the variety. A breeding seedling orchard of P. caribaea var. caribaea was established in early 1995 in Guangdong Province using a multiple population breeding strategy. The main population consists of 220 families representing the natural stands and a selected population of a seed orchard in Cuba and land races developed in Brazil and China. It will be managed as a breeding seed orchard for genetic testing, selecting and seed production. There are six sub-populations subdivided by seed origins with open pollinated families varying from 16 to 75 in each. The total area of plantations of this species in China is now estimated to be over 40 000 ha. It is foreseen that Pinus caribaea could become even more important in plantation forestry in southern China and the area of this species could be expected to reach 100–150 000 ha by the year 2010.

Atmospheric concentration profiles of pollen from jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana (Mill.) B.S.P.) were measured up to 300 m above ground level at the edge of a seed orchard in northern Ontario, Canada. Large amounts of pollen were found up to 300 m showing the occurrence of meso-scale transport of coniferous pollen and also possible long distance transport. The profile shapes were found to be a function of source characteristics and meteorological conditions. Changes in profile shape were in general agreement to those found in previous work. If meso- or synoptic-scale transport of conifer pollen occurs, then the use of isolation zones would not be useful to stop this component of the contaminant pollen cloud entering a seed orchard, especially if pollen longevity in the atmosphere is long. However, further work is required to determine if this component of the contamination pollen cloud is large and whether or not the pollen is viable.

Field-grown 4- and 9-year-old grafts of eastern white pine (Pinus strobus L.) were sprayed or injected with gibberellin A 4 7 . Treatments in May–June significantly increased pollen-cone production. Spraying produced more pollen-cone clusters per tree. Injection increased the number of clusters per branch and the number of whorls per tree producing pollen cones. Injection, but not spraying, in May–June produced more seed cones. However, spraying in August–September did not promote either pollen-cone or seed-cone production. Injection in August–September decreased the number of pollen cones per cluster and inhibited seed-cone production. Present resutls indicate that treatments for pollen- and seed-cone production are best carried out in May and June during the period of rapid shoot elongation.

The growth and survival of background pollinated progeny of northern Scots pine clones from seed orchard located in southern Finland was examined at an age of 10–15 years and compared with the respective performance of seedlings from local natural stands. The material consisted of 33 progeny tests located in northern Finland within the original areas of the clones. Although no clear difference was observed between the height growth of the two groups, the survival was significantly lower in the seed orchard material (35%) than in the local stand material (56%). The relative survival (seed orchard vs. local entries) decreased steadily along with the decrease in the effective temperature sum of the trial sites, and was relatively small in the northernmost trials. The results indicate that the totally background pollinated seed from southwards-transferred, young seed orchards even can be used for reforestation in southern and central Lapland, at least in areas located at relatively low altitudes. The decrease in background pollination levels owing to the ageing of these orchards will increase the potential use of this seed. Using only those orchards containing the northernmost clones, combined with selective harvesting of the most hardy portion of the clones, is proposed as a means of further improving the adaptedness of planting material for northern conditions.

Fertilizer and irrigation treatments (with and without) were applied in factorial combination to four seedlots of Eucalyptus grandis planted near Gympie, Queensland. Treatments aimed to ensure that growth was not limited by lack of nutrients (in fertilized plots) or water (in irrigated plots) during the first 3 years after planting. After 3 years, fertilizer treatment had significantly and substantially increased growth in mean height and basal area but there had been no response to irrigation and no interaction between fertilizer and irrigation. Over the four seedlots, trees in fertilized plots were two and a half times taller and had five times more basal area than those in unfertilized plots. More detailed growth estimates of the best seedlot (a first generation seed orchard from Coffs Harbour) showed fertilizer treatment had substantially increased leaf area, stemwood volume and all components of above-ground biomass. After 3 years, fertilizer treatment had increased stemwood mass from 6.9 to 41.4 t ha −1 . Mean annual increment in stemwood volume in fertilized plots at age 3 years had reached 34.2 m 3 ha −1 year −1 , which is the highest growth rate yet reported for any plantation in Australia at such a young age. Above-ground net primary production was directly related to leaf area index and in fertilized plots a productivity of 30 t ha −1 year −1 was associated with a leaf area index of 4.5 at 2 years of age. Tree growth rate in unfertilized plots in this study was severely inhibited by low soil nutrient supply, particularly during the period prior to canopy closure. Higher productivity following application of fertilizer resulted from more rapid expansion of leaf area during the first 12 months while tree crowns were developing, and maintenance of a higher leaf area index thereafter. The possible mechanisms responsible for increased growth and greater leaf area are discussed.

Planting, sowing and intended natural regeneration are the main forest regeneration methods used in forest management. These methods were compared in an 11 year field trial in northern Sweden. Pinus sylvestris (L.) seeds of various origin were used. Local seeds were collected from seed-trees on site. Comparisons were made in three steps as follows. 1. (1) All three methods on the seed-tree area and with local seeds. Natural regeneration produced the greatest number of total as well as main crop plants. Planted seedlings had a height lead corresponding to 4.9 years compared with sowing and 5.6 years compared with naturally regenerated main crop plants. Planting resulted in the greatest area production (height sum) based on main crop plants. 2. (2) Sowing and planting on neighbouring clear-felled area, using local seeds. The height lead for planted seedlings corresponded to 5.6 years. The number of main crop plants decreased between the seventh and eleventh growing seasons by 18% for planting and 50% for sowing. The height sum based on main crop plants was almost three times higher for planting than for sowing. 3. (3) The local provenance was compared with seeds for other origin on the clear-felled area. The choice of seed origin had the greatest influence on survival, with seeds of northern origin giving the best production per unit area. Possible long-term effects of artificial regeneration methods, such as root deformation and lack of natural selection, are also discussed.

Pollen monitoring was conducted in 1987, 1988, and 1989 in the 2.8 ha Second Falls black spruce (Picea mariana (Mill.) B.S.P.) seedling seed orchard established in 1978. The objectives of the study were to evaluate (i) the orchard pollen-cone production, (ii) the level of orchard pollen production, and (iii) the level of pollen contamination for 3 consecutive years. Pollen traps were established around the orchard and collected on a daily basis. Pollen-cone production per tree averaged 3, 40, and 76 in 1987–1989, respectively. Pollen contamination during seed-cone receptivity was estimated to be 32%, 83%, and 58% in 1987, 1988 and 1989, respectively. The important increase in pollen contamination from 1987 to 1988 resulted, in part, from (i) the roguing of 40% of orchard trees and (ii) a 37-fold increase in pollen catch from contaminant sources from 1987 to 1988 compared to a 3.6-fold increase in pollen production by orchard trees. Supplemental mass pollination and synchronization of high orchard seed-cone and pollen-cone production with low pollen production from contaminant sources are suggested to reduce the level of pollen contamination, to increase panmixis and seed yield, and to maximize genetic gain.

Stem injections of gibberellin A 4/7 (GA 4/7 ) and girdling were tested in factorial combination on good- and poor-flowering clones of Engelmann-white spruce in two seed orchards on the same site with different levels of past cone production. A second study compared one vs. two injections of GA 4/7 (same total dosage), the latter with and without the auxin naphthaleneacetic acid (NAA). In both years and both orchards, GA 4/7 alone promoted abundant seed and pollen cones, but treatment was relatively more effective on good-flowering clones and in the more productive orchard. Still, treatment improved the orchard parental balance in that without treatment, 80% of the seed cones were produced by only 10–17% of the clones, compared to 43% of the clones with GA 4/7 . Flowering response to GA 4/7 was independent of number of injections and addition of NAA. Girdling was ineffective by itself in flowering promotion but enhanced the female response to GA 4/7 in the less-productive orchard and the male response by poor-flowering clones. Gibberellin A 4/7 treatment in 1988 had a slight adverse carry-over effect on tree condition and level of flowering in 1990, although this may be a consequence of heavy cone-bearing in 1989. Gibberellin A 4/7 stem injection is practical, but the optimal retreatment interval necessary for vegetative recovery and sustained abundant cone production remains to be established.

Black spruce and jack pine seed orchard programs in Ontario are compared using cost-benefit analysis. The analysis illustrates economic relationships that should be considered when developing tree improvement programs, particularly if budgets are limited. Important factors include stumpage values, potential size of the improved planting program, magnitude of the genetic gain, quality of the land-base, the discount rate and the fecundity of seed orchards through time. Optimal economic rotation ages were calculated for unimproved and improved plantations. The difference in net present value of an infinite number of unimproved and improved plantations was compared to research costs to determine if tree improvement was economically worthwhile. This approach enables each generation of tree improvement activities to be considered on its own potential merits. Jack pine tree improvement consistently outperformed black spruce tree improvement in its economic potential.

Enhancement of the genetic value of conifer seeds produced in open-pollinated conifer seed orchards by supplemental mass pollination (SMP) is affected by the timing of the application, orchard flowering phenologies, and background pollen values. Ambient pollen cloud genetic values are often only marginally different from the genetic value of the SMP pollen and the level of improvement is low. Large gains can be made by intensive applications of high genetic quality pollen during periods of low value ambient pollen. The time and expense involved with the intensive application programs needs to be weighed against the potential genetic gains prior to initiating the program.

The genetic implications of plus-tree selection were studied in Norway spruce (Picea abies) with the aid of isozyme gene markers. For this purpose, 45 phenotypically selected seed orchard clones and 60 randomly chosen trees from the same Bavarian forest districts were compared with respect to their genetic structure, gene diversity and heterozygosity at eight enzyme gene loci. In general, the gene frequency distributions, the gene multiplicity and the gene diversity did not significantly differ between the selected clone (plus-tree) collection and the random tree sample; however, the average degree of heterozygosity and the distribution of individual heterozygosity clearly differed between the two collections. The most significant differences in heterozygosity between the two collections were observed in the case of three loci controlling enzymes involved in the pentose phosphate cycle. The implications of these results for tree improvement procedures, establishment of seed orchards and programmes in gene conservation are discussed.

Reproductive bud phenology and seed-cone crop of a Sitka-spruce [Picea sitchensis (Bong.) Carr.] seed-orchard were studied to assess the validity of two seed-orchard assumptions, namely panmictic equilibrium, and parental balance. Also, the impact of supplemental mass pollination as a crop-management practice was evaluated. The study revealed significant variation in reproductive bud-development timing as well as proportion of reproductive strobili. A lack of mature male cones was observed while the majority of seed cones were in their receptive stage. It was also observed that approximately 80% of the seed-cone crop was produced by only 20% of the orchard clones. Supplemental mass pollination produced a 14-fold difference in the number of filled seeds per cone compared to that produced under wind pollination. In addition to the significant increase in seed-yield, supplemental mass pollination is proposed as a management option in Sitka-spruce seed-orchards to alleviate the effect of parental imbalance and panmictic disequilibrium.

Research reported here has evaluated interactions of factors limiting the biological potential of slash pine ( Pinus elliottii var. elliottii Engelm.) and loblolly pine ( P. Taeda L.). Water and nutrients were manipulated by irrigation, weed control, and intensive fertilization. Genetic factors were incorporated as (1) improved loblolly seedlings from a commercial clonal seed orchard and (2) slash seedlings from four fast-growing, open-pollinated seed-orchard clones. Three replications of a 2 × 2 × 2 factorial experiment were established on a Typic Haplaquod soil in northern Florida using four cultural treatments: no treatment (F0H0); weed control (F0H1); fertilizer (F1F0); and combination of weed control and fertilizer (F1H1) for each species. During the first year there were large, sustained responses to all cultural practices. Loblolly and slash pine showed similar growth responses and had a lengthened growing season (60–100 days). Slash pine growth was superior to that of loblolly. Growth responses observed during the first year continued. After 4 years, irrigation had no measurable effect on tree growth. Both pine species responded equally to F1H0 and F0H1, but slash retained a slight edge. Extra nutrients]available via fertilizer, reduced competition, or additional rooting space, increased slash-pine volume index from an average of 2.0 m 3 ha −1 (F0H0) to 11.90 and 13.59 m 3 ha −1 (F0H1 and F1H0, respectively). The F1H1 treatment produced the largest slash-pine response, diameter at breast height ( D bh ) averaged 9.84 cm, height reached 5.02 m, and volume index rose to about 22.94 m 3 ha −1 . With teh F1H1 treatment, average loblolly-pine height and volume exceeded that of the average slash pine. At age 4, the growth response due to increased nutrient supply was 13–29 times that of the best genetic response within F0H0 trees of the four slash-pine progenies. The best-growing slash-pine family (6–56) exceeded loblolly-pine growth under all four treatments and approximated the vigor shown by slash pine in the southern hemisphere.

Cholecaliferol (Vitamin D3) was evaluated as a field rodenticide for controlling pocket gophers (Thomomys spp.) under forest and seed orchard conditions by monitoring radio-equipped pocket gophers following the application of 0.0%, 0.003%, 0.04%, 0.075% and 0.15% cholecalciferol oat baits. In one trial, the difference in mortality of the three lower concentrations was not significantly greater than the control group. In two subsequent trials with the higher concentration (0.15%), mortality between the treatments was significantly greater than in the control groups. We recommend that primary and secondary hazards of cholecaliferol to nontarget species and predators be investigated.

An experiment has been carried out in the seed orchard of Scots pine in the Forest Research Station at Siemianice, Poland. Three 17-year-old clones were studied. Spraying with gibberellin GA 4 7 (200 mg/l + Aromox 0.05%) was done on 7 June 1983. Buds for analysis of endogenous gibberellins were collected four times. Spraying with GA 4 7 significantly increased the number of male flowers and to some extent also of female flowers in all clones studied as well as the content of endogenous gibberellins of the lowest polarity (Rf 0.8–1.0) in buds collected 24 h after treatment.

Apart from genetic gains, the feasibility of seed orchards is influenced by cost factors, management decisions and rates of propagation. The authors investigate the establishment, rogueing and lifespan of seed orchards, with emphasis on investment and operating costs, optimal assessment age and expected seed yields. Expenditures for establishment of seed orchards are compared to present values of savings on reduced regeneration areas, due to gains from improved stock. Lambeth's selection efficiency and age correlation formulae are used for optimizing the timing of rogueing. For the decision as to the economic lifespan of the seed orchards, the costs of investment and operation were distributed over the cone yield produced. The case studies presented refer to operational conditions in Canada and Europe.

We can distinguish essentially two methods to stimulate flower induction: firstly, methods that stimulate flowering as a consequence of each treatment; and secondly, methods with persistent effect, where a treatment increases flowering in the long run. Certain rootstocks and the movement of grafts southward show such persistent effects upon various provenanances of Norway spruce. Results presented here indicate, on the hand, a higher number of flowering grafts in wine-growing regions of southern Germany than in northern Germany. On the other hand, at least one clonal rootstock, a dwarf-growing ornamental Picea glauca ‘Conica’ increased the number of flowering grafts considerably. This increase is greater under warmer conditions. Other rootstocks seem to have a similar effect and show broad variation in normal growing and dwarf stocks. It is hoped that early, abundant and continuous flower-stimulating rootstocks such as clonal material of P. abies ‘Acrocona Hesse’ might increase flower formation further.

The temporal sequence and causes of seed and cone loss was investigated at a Pinus resinosa seed orchard and a widely-spaced planting of the same tree species. Damage was converted to seed loss for each of several designated intervals after flower emergence: 0–4 months, 4–11 months, 11–15 months, and within surviving cones ( sc ). The 0–4-month interval was the major period of loss in the seed orchard, and conelet abortion the major mortality factor. Cone-destroying insects, interval 11–15, were very damaging in 1985, when the cone crop was relatively small, but relatively unimportant in 1986. Empty seed in sc accounted for the second greatest overall seed loss. Seed-bugs were implicated in some seed damage using X-ray analysis. In the plantation the major seed loss occurred in sc . The major damaging agent was Cydia toreuta . Strobili and conelet mortalities were much lower at the plantation site than at the seed-orchard site. Cone survival was high in all three years studied.

A total of 100 millicures of 32 P was injected in a single yellow-poplar tree over a three-day period for incorporation in pollen. The number of flower samples with a count per minute significantly higher than background decreased rapidly with distance from the source tree. There was no difference in pollen movement associated with direction and no indication of wind as a vector. Bees carrying out pollination did not come from a hive placed in the orchard but rather from hives some distance away. Hand-pollination resulted in four times as many filled seed as open-pollination.

In the years 1981–1983 fertilizers were applied in three seed orchards of Scots pine aged 6, 9 and 15 years. Fertilization was done in the two periods end of May or the beginning of June, and in mid-August. Significant effects of the fertilization applied on female flowering was observed in the 2nd year after treatment. There was no difference between the two periods of fertilization tested. Better effects were observed when lower doses of fertilizer were applied twice than when single high dose fertilizer was applied.

Over 50 years of seed orchard experience has clearly shown the importance of choosing the correct site. Climate plays a major and often a decisive part in producing regular and abundant seed crops of high physiological quality. This paper discusses the criteria for selecting orchard sites within and outside the natural range of the species and emphasises the influence of climatic factors on flowering and seed production. Climatic factors which can be modified and so influence the quantity and quality of the seed crop are reviewed.

In Spring 1976 a series of fertilization and chemical weed control experiments was established in three clonal seed orchards of Scots pine ( Pinus sylvestris L.) in southern Finland. The objective was to elucidate the effects of customary techniques of practical seed orchard management. Four treatments were used: fertilization, herbicide application, combined fertilizer and herbicide application, and control. The experiments comprised some 3000 grafts in total. Their growth and cone production were observed up to 1984. The height growth of grafts was not affected by the cultural treatments, but diameter growth was slightly improved. The fertilized and herbicide-treated plots generally produced more cones than the control plots. Especially the repetition of cultural measures in 1980 had a beneficial effect on cone production. Since then, plots treated with both fertilizer and herbicide gave the best crops every year in all experiments, with an average superiority of 60% over the control. With a few exceptions, herbicide application alone resulted in a higher cone production than fertilization alone. The treatment effects were fairly slight, however, as compared to the variation caused by natural site heterogeneity within each orchard, and to the year-to-year variation in overall cone productivity.

Seed procurement is a major problem associated with the establishment of pine plantations in the tropics. Apart from the difficulties found in seed collection from natural stands, non-synchronous flowering and poor pollen production also seriously limit the usefulness of pine seed orchards; this is found especially when the seed orchards are managed outside the natural range of the pine species in question. The success of hormone treatments on a number of pine species and other Pinaceae conifers in the temperate zone has encouraged the present authors to initiate a research programme on the effects of gibberellins in tropical pines. Field experiments on Pinus merkusii and P. kesiya already preliminarily indicate that effects similar to those observed in temperate pines may also occur in the two pines native to Thailand. However, since many workers have earlier found that the proper timing of the gibberellin treatment is of crucial importance, the present work is also aimed at clarifying this particular problem. An outline of the research strategy for gibberellin studies in connection with seed orchard management in Thailand is also presented.

White spruce [ Picea glauca (Moench) Voss] grafts growing in a seed orchard were sprayed with gibberellin A 4/7 (GA 4/7 ), either at different periods of time during the growing season or in different concentrations, for a 3-year period. Whole-tree spraying in May through July 1983 significantly increased cone production in 1984, while spraying in June through August of the same year was not effective. The best treatment in branch spraying was at the highest concentration (800 mg/L GA 4/7 ). The spray was effective in a good, but not a poor, crop year. Vegetative budburst occurred in the first half of May and shoot elongation ended in late June. Needle primordia in a newly formed bud were not discernible until the end of June. Application of GA 4/7 during the period of bud scale initiation and shoot elongation, and before needle primordial initiation, could have influenced the course of bud differentiation to increase the formation of reproductive buds.

Short- and long-term effects of subsoiling four soils were closely related to variations in soil structure and consistence. Penetration resistance decreased when shear failure was accomplished by fracturing. Plastic failure in a near saturated, clayey subsoil did not affect penetration resistance. Penetration resistance of a firm, clayey subsoil with weak to moderately strong structure was lower than presubsoiling levels 2 years after subsoiling. In soils with strong structure, fracturing may occur between peds, which in time settle back to their approximate original configuration. More intra-pedal fracturing probably occurs in soils with weaker structure, thus reducing average ped size and increasing interpedal macropore volume, even after settling. Subsoiling of a loose, sandy soil decreased penetration resistance for at least 4 months, but after 4 years no residual effect was found. Only in the sandy soil did subsoiling have any noticeable effect on soil moisture content. Vertical filling of the blade and mole channels with A1 horizon material resulted in increased moisture content in the mole channel 4 months after subsoiling. After 4 years, moisture content in the A1 horizon remained higher in the vicinity of the channel. This may be due to increased upward movement of water through the more highly organic A1 horizon material that had infiltrated along the blade channel.