Emergence timing affects root-collar diameter and mortality in loblolly pine seedbeds

Eight half-sib families of loblolly pine (Pinus taeda L.) were sown in a nursery. Total germination, speed and uniformity of germination, root-collar diameters, mortality, and percent cull were recorded by family. Families which germinated quickest attained the greatest average diameters at the end of the growing season. Low variability in date of emergence led to correspondingly low variability in seedling diameter. When data for all families were combined, seedlings which emerged earliest experienced the lowest mortality, had the largest diameters, and produced the fewest culls.     

Detection of genetic variation among seed and seedlings ofChamaecyparis obtusa using allozyme markers

The effects of nursery practices on genetic composition and structure were studied inChamaecyparis obtusa by analyzing seeds and one-, two-, and three-year-old seedlings. Enzyme polymorphisms of the6Pgd-2, G6pd, Got, Gk, Shd-2, Pod, Dia-1, andPgm loci were used. OnlyDia-1 indicated significantly different allelic frequencies between seeds and three-year-old seedlings. Most of the genetic diversity of the parental clones in this seed orchard could be transferred to the offsprings. Genetic diversity on the basis of an average expected heterozygosity did not differ between seeds and seedlings. A slight excess of homozygotes in seeds and a significant excess of heterozygotes in seedlings of different ages to the expected panmictic proportions were found. Most of the differences in genotypic distributions among the seed and seedling stages, probably resulted from viability selection favoring outcrosses, and selective removal of inbred offsprings including self-fertilized ones prior to their transplantation in the nursery. A part of this paper was orally presented at the 107th Annual Meeting of the Japanese Forestry Society (1996).     

青海云杉自由授粉家系遗传评价与选择

[目的]通过对青海云杉1代无性系种子园自由授粉家系开展遗传评价,利用遗传测定结果提升青海云杉造林的良种化水平及提高良种使用率。[方法]本文以青海云杉初级种子园自由授粉家系测定林为研究材料,对13年生青海云杉家系树高、新梢长、保存率和11年生的主、侧梢冻害率进行了遗传评价,采用综合指数选择优良家系和最佳线性无偏预测方法预测单株育种值选择二代优树。[结果]研究结果表明:家系13年生的树高、新梢长、保存率和11年生主、侧梢冻害率的表型变异系数是24. 06%84%,遗传变异系数是3. 28%19. 31%。家系、家系和区组互作效应显著影响了13年生青海云杉树高和新梢长。树高和新梢长的家系遗传力分别是42. 5%和34. 2%,而单株遗传力是3. 00%,家系遗传力高于单株遗传力。采用综合指数选择法进行生长和抗性性状的综合选择,根据综合指数基于多样性和遗传增益进行平衡选择,有21个家系入选,入选家系的树高、保存率、主梢冻害率现实遗传增益分别为5. 66%、12. 59%和12. 96%。根据家系内单株13年生的树高育种值从1 103个单株中选择二代优树111个,单株入选率为10. 06%,入选二代优树树高的期望遗传增益是20. 10%。[结论]青海云杉13年生树高和新梢长在家系间存在显著变异,且还受家系与环境互作效应的影响,说明青海云杉家系的生长不仅受遗传的控制,还受遗传和环境的互作影响。根据各家系13年生树高和保存率和11年生主、侧梢冻害率综合指数值按35%的入选率综合选择21个家系,入选的家系不仅生长好,且抗性能力强,可用于回选优良无性系用于改扩建1代种子园或建立1. 5代种子园。     

Nursery soil cover influences germination of Thujopsis dolabrata var. hondai seeds

We examined the influence of nursery soil cover on germination of Thujopsis dolabrata var. hondai. Seeds were sown under seeding bed conditions: (1) nursery soil (andosol) without soil cover, (2) Kanuma pumice without soil cover, (3) nursery soil with nursery soil cover, and (4) nursery soil with sterilized sand cover. Germination percentages were compared between these conditions. The germination percentage (8.8%) at 10 weeks after sowing under condition 3 was significantly lower than under conditions 1, 2, and 4 (56.8%, 52.0%, and 47.2%, respectively). Of the nongerminated seeds under condition 3, 75.0% were decayed and several fungi were isolated from decayed seeds. An inoculation test of isolated fungi Cylindrocarpon tenue, Cylindrocarpon sp., Fusarium oxysporum, and Botrytis sp. to seeds showed that these fungi caused seed decay. Our results indicated that nursery soil cover may not be suitable for T. dolabrata var. hondai seeds sown in nursery soil because of seed decay by pathogens.     

Interpretation of seed-germination parameters

Traditional methods of expressing germination speed have limitations when these estimates are used to gain insights into the consequences of nursery practices on genetic diversity. Limitations result primarily from confounding of viability with vigor, as illustrated by hypothetical and computer simulated examples. Germination characteristics of seeds from 19 Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) families were then used to illustrate the advantage of a proposed approach to measuring germination speed, based on proportion of viable seeds germinating by a particular day. This measure is independent of viability. It is demonstrated that fast germination can occur in seedlots where viability is low, and slow germination can occur in seedlots where viability is high.     

Size hierarchy in conifer seedbeds. I. Time of emergence

Studies conducted at two pine nurseries in the South and one in the West empirically related the genesis of seedling size hierarchies to time of emergence (TOE). Pinus taeda seeds were operationally sown at the southern nurseries in late April and P. ponderosa in late July at the western nursery. Germinated seedlings were tagged with color-coded plastic rings (20 turn dia.) every other day until germination was complete. Emergence was complete in 16–20 days. Growth response to TOE effects was determined 8 and 15 months, respectively, after sowing.Results were strikingly similar across nurseries; TOE strongly influenced germinant mortality and shoot biomass decreased 3.5% per day elapsed from initial emergence. That is, seedlings emerging 10 days after emergence began were 35% smaller at harvest than those emerging first. Late germinants accounted for significantly more culls among harvested seedlings than early germinants. Also, TOE accountend for more than 80% of variation in harvest biomass. Findings suggest that the germination period should not exceed 5 days. Response models are proposed to elucidate TOE effects in nursery operations.New Mexico Agric. Exp. Sta. journal article no. 1280.     

Effects of acorn size and mass on seedling quality of northern red oak (<Emphasis Type="Italic">Quercus rubra</Emphasis>)

Oaks are not sustainable in many upland temperate forests because of poor recruitment resulting from natural regeneration. Artificial regeneration is an alternative to natural regeneration, but is difficult, in part, due to large variation in seedling quality. In this study, we examined the effects of acorn size and mass on nursery seedling morphological parameters commonly used to quantify seedling quality, and we determined if genetic factors affected these relationships. Acorns were collected from six open-pollinated orchard trees (i.e., six half-sib families), and were separated into six size classes based on acorn diameter (ranging from 1.3 to 2.5 cm). Samples from each size class were weighed for total fresh mass. Acorns were sown in a commercial bareroot nursery in Polk County, Tennessee, USA, and seedlings were grown for 1 year using nursery protocols to maximize growth. Seedling survival was generally not affected by acorn size class or mass, except one family had higher survival in the larger acorn size classes. Five of the six families had no discernable relationship between acorn size class and seedling size. Acorn mass was positively related to seedling morphology, but relationships were weak (R²?≤?0.11) and biologically insignificant. Neither acorn size nor mass could be used reliably to predict seedling survival or morphological indicators of seedling quality. We hypothesized that results were affected by an unusually long growing season and advanced fertilization regimes at the nursery, which may have negated acorn size/mass effects on seedling growth. Family affected relationships between acorn size/mass and seedling morphology, indicating that family selections could improve overall seedling quality.     

Effect of inoculum density of Macrophomina phaseolina on seedling susceptibility of six conifer species

The severity of charcoal root disease of conifer seedlings (Abies concolor, A. magnified, Pinus jeffreyi, P. lambertiana, and Pseudotsuga menziesii) was a power function of the sclerotial density of the fungus (Macrophomina phaseolina) in nursery soil.     

思茅松自由授粉家系遗传参数与早期选择分析

[目的]通过对思茅松自由授粉子代测试林的生长与形质性状遗传参数的估计,进行优良家系选择,为建立思茅松高世代种子园及培育优良无性系苗木提供种质资源。[方法]采用随机区组试验设计,在214个思茅松自由授粉家系子代测试林中选择胸径、地径、树高、枝下高、冠幅、通直度、树干圆满度、树冠圆满度、材积及地上生物量等生长与形质性状,利用线性混合模型进行遗传参数的估计,进行优良家系筛选。[结果]思茅松自由授粉子代测试林生长与形质性状的遗传参数在家系间差异极显著。各性状的家系遗传力较高,其中,地径的家系遗传力最大(1.105)。材积的预期遗传增益高于地上生物量,利用家系/家系内选择方法进行优良家系的筛选,材积的预期遗传增益为60.75%,入选家系为60个;地上生物量的预期遗传增益为44.22%,入选家系为66个。轮盘数、通直度和树干圆满度对材积和地上生物量都有显著影响。[结论]在早期选择中,形质性状的遗传变异对思茅松自由授粉优良家系的选择有重要参考作用,4年生思茅松自由授粉家系子代测试林中各性状存在着丰富的遗传变异,在早期选择中可以筛选出适合不同培育目标的优良家系,最大限度挖掘其遗传潜力。     

Occurrence of dark septate endophytes in Nothofagus seedlings from Patagonia,Argentina

Temperate forests of southern Argentina and Chile cover a wide latitudinal and altitudinal range on both sides of the Andes, with Nothofagus species being one of the main tree species. Most of the larger remnants are protected within the limits of national parks and forest reserves. However, some of these are invaded by exotic conifers such as Pseudotsuga menziesii. In order to better understand the mycorrhizal condition within the Nothofagus–P. menziesii interaction, transects were established at six study sites along the effective recruitment area. Three treatments were established: Nothofagus forest without P. menziesii invasion (Forest), Nothofagus–P. menziesii matrix (Interface) and P. menziesii plantation lacking Nothofagus specimens (Plantation). A 2 kg mixed soil sample was taken at each treatment site and kept in brand-new plastic bags. A soil bioassay with Nothofagus seedlings acting as baits was set to evaluate the mycorrhizal inoculum potential and soil-fungi composition at each sampling treatment. Forty percent of the evaluated seedlings were found to be colonised by dark septate endophytes (DSE) fungi. Ectomycorrhizal colonisation percentage was significantly higher in plants growing in Forest soils (mean = 57.77%) when compared with Interface (mean = 42.53%) and Plantation (mean = 44.65%). The high incidence of DSE in young roots of Nothofagus seedlings in this study supports the hypothesis that DSE might be pioneering colonisers of young tree seedlings in secondary successional environments. For future interventions in the forest, either with productive or protective intentions, it should be taken into account the incidence of these fungi, which may have an important positive role in Nothofagus forest post-invasion recovery.     

Effects of length of seed chilling period and sowing date on family performance and genetic variances of Douglas-fir seedlings in the nursery

Seeds of four full-sibling Douglas-fir families (F) were moist chilled (C) for 14, 33, and 77 days and sown (S) March 29, April 26, and May 24 at two densities (D=111 and 200 seeds/m²), grown for 2 years in nursery beds and phenology and size traits recorded. The study was analyzed in two parts: part I evaluated seed treatment effects and their interactions with families; and part II investigated the effect of treatments on genetic variances, particularly among-family (_F ²) and within-plot ( ²) components and the intraclass correlation for families (t_{% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOqaaGqaa0Gaa8NKba% aa!3886!\[f\]}). In part I there were large and highly significant differences associated with C and S and among F for all traits. Early S combined with long C resulted in early emergence and gave large seedlings with little loss and damage. Many interactions between C and F, and S and F, were significant. Interactions involved rank changes for size but not for phenology traits, and were larger for C×F than for S×F. Seedling density affected seedling size but not phenology, did not interact with seed treatments, and interacted significantly but weakly with families. In part II, C and S, but not D, had significant effects on _F ², ², and t_{% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOqaaGqaa0Gaa8NKba% aa!3886!\[f\]}, but not in a predictable manner. Because of significant interactions, it is recommended that standardized seed treatments be used in family nursery tests. This should aid in keeping the results from these tests as repeatable as possible. Long chilling and sowing as early as practicable are recommended to minimize disease losses and winter damages and to provide good nursery stock.     

The effects of test environments on estimation of genetic parameters for seedling traits in 2‐year‐old Douglas‐fir

The effects of test environments (dry versus wet) on estimation of genetic parameters in seedling traits were studied in 160 open‐pollinated families of Douglas‐fir (Pseudotsuga menziesii (Mirb.) Franco) from southwestern Oregon. Seedlings from four populations were grown in two test environments for two growing seasons. Between test environments, ‐9 bars of water potential difference were created in both growing seasons. Estimated genetic variances in most growth and phenology traits were considerably higher for seedlings grown in the wet environment than for those in the dry. Estimated genetic correlations between the same traits measured in different test environments indicated that most seedling traits studied for two growing seasons are genetically stable in both environments—i.e., suggesting that genotype by environment interaction in these traits are weak. However, the effect of test environment on estimation of genetic parameters in seedling traits, especially in adaptive seedling traits, should be evaluated very carefully when early evaluation of genetic entries is practiced in Douglas‐fir since these traits (budburst timing, lammas growth and free growth) appear to be plastic traits.     

山苍子家系幼林生长性状遗传变异及稳定性分析

[目的]对山苍子不同家系幼林生长性状进行遗传变异及稳定性分析,为山苍子优良家系选择及推广提供参考。[方法]以13个半同胞山苍子家系为材料,采用随机区组设计,分别在重庆万州、湖北京山和福建清流3个试验点营建家系试验林。对23年生山苍子幼林的树高和地径性状进行测定和多点联合分析,并采用AMMI模型对山苍子各家系的生长稳定性进行评价。[结果](1)山苍子家系的树高和地径在家系和地点效应上均达到显著(0. 01 P0. 05)或极显著(P 0. 01)水平,地径的家系和地点交互作用达到显著水平(0. 01 P 0. 05); 3个试验点树高和地径的表型变异系数为20. 98%～29. 27%,遗传变异系数为0. 62%～20. 35%,其中,地径的表型和遗传变异系数普遍大于树高;树高的家系遗传力为0. 003～0. 578,地径的家系遗传力为0. 455～ 0. 806。(2)综合双标图和稳定性参数得出:家系JY2和GX4地径表现较好且稳定性较高。[结论]山苍子家系的树高和地径在家系和地点间的差异均达到极显著水平(P 0. 01),存在丰富的遗传变异。在家系水平上,树高受低等到中等强度的遗传控制,地径受中等到高等强度的遗传控制。各家系在福建清流试点生长表现最好,湖北京山试点居次,重庆万州试点最差,其中家系JY2和GX4在3个试验点地径均表现较好且稳定性较高。     

Soil water stress: Its effects on phenology, physiology, and morphology of containerized Douglas-fir seedlings

Containerized Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) seedlings were subjected to six moisture-stress treatments (ranging from 7 to 65% soil water content by volume) for 12 weeks. At the end of this period, there were significant differences in phenological, physiological, and morphological responses among the seedlings in the various moisture-stress treatments. In general, seedlings grown under very high or very low soil moisture conditions were adversely affected, while those grown under moderate conditions (29 to 53% soil water content) exhibited optimum growth, bud development, and nutrient and starch reserves. The use of vector analysis was found to be helpful in data interpretation. The results indicate the importance of closely monitoring nursery moisture regimes in order to achieve the best seedling quality.     

Effect of Frankia inoculation on the growth of Alnus sieboldiana on unsterilized soil

The effect of inoculation with Frankia, a N-fixing actinomycete, on the growth of Alnus sieboldiana seedlings was studied on unsterilized soil from a nursery and an alder stand (forest of Alnus firma). The seedlings of A. sieboldiana were inoculated with Frankia before or after a 2-month culture on sterilized vermiculite, during which they nodulated, and transplanted to unsterilized soil from the nursery and the alder stand. The control seedlings were also cultured on sterilized vermiculite for about 2 months and transplanted to unsterilized soil without Frankia inoculation. The seedling growth, nodulation and N-fixing activity were measured 3, 10 and 16 weeks after the transplantation. Growth and nodule biomass of the seedlings inoculated with Frankia and those grown on the alder soil were better than those without inoculation with Frankia and grown on the nursery soil, respectively. The seedlings inoculated before spontaneous nodulation grew better than those inoculated at the transplantation. Nitrogen-fixing activity measured by acetylene reduction assay at 16 weeks after the transplantation was higher in the seedlings grown on the soil from the nursery than on the soil from the alder stand.     

红豆树优树子代遗传多样性及与生长相关性分析

[目的]研究红豆树优树自由授粉子代遗传多样性及其对生长的影响,比较天然居群子代和孤立木子代遗传多样性差异,揭示子代遗传多样性的变化规律及天然居群在子代遗传多样性维持中的作用,为红豆树遗传保育和优异种质挖掘提供科学依据。[方法]以来自浙、闽、赣、川等26个红豆树优树自由授粉家系为研究对象,利用11对SSR引物对765个子代群体进行遗传多样性评价,同时分析子代遗传多样性参数与种子、生长性状的相关性。[结果](1)红豆树优树子代群体具有较高的遗传多样性,有效等位基因数为7.766个,观测杂合度(H_O)和期望杂合度(H_E)分别为0.469和0.865。(2)除SSR8外,其余位点的观测杂合度均小于期望杂合度,表明子代群体绝大多数位点处于杂合子缺失状态。(3)红豆树不同家系的遗传多样性存在明显差异,12号家系的遗传多样性水平最高,8号家系则最低。(4)比较发现,天然居群子代的遗传多样性显著或极显著地高于孤立木子代。(5)F统计量和分子方差分析(AMOVA)均表明,红豆树优树子代群体的遗传变异主要存在于家系内,家系间的遗传分化相对较小。(6)相关性分析发现,子代遗传多样性参数与种子性状、子代年高生长量呈显著正相关(r=0.378~0.527)。[结论]较大的红豆树天然居群在维持其子代较高遗传多样性中发挥了重要作用,子代遗传多样性显著影响苗木生长,这为红豆树遗传保育和优良家系选择提供了理论依据。     

湿地松种子园自由授粉子代幼年期测定及选择

根据湿地松初级种子园14个自由授粉家系苗期和童期的材料,分析了高、径、材积及高径比等主要性状的遗传变异与遗传相关.结果表明:在苗期和童期各生长性状在家系间都有极显著差异,且呈中度至强度遗传;各家系高、径生长年度间呈正向紧密相关,各生长性状间的遗传相关也显著;家系×地点的交互作用不显著.运用指数选择法,就生长和形质两方面综合评选出三个速生且形质较优的湿地松家系.     

南方红豆杉2年生容器苗多点试验的生长节律家系变异

[目的]对南方红豆杉家系进行了生长节律变异研究,以选育优良速生的南方红豆杉家系.[方法]在江西分宜、湖北京山、浙江淳安和浙江龙泉4个地点对2年生南方红豆杉家系容器苗进行了苗期遗传测定和苗高生长节律观测,分析了其性状变异的家系效应、地点效应及家系×地点的互作效应.[结果]表明参试的南方红豆杉苗高、地径和苗高生长节律参数在家系间、地点间和家系×地点间均表现出极显著差异.南方红豆杉家系间苗高最大值分别高出最小值76.20%(江西分宜)、52.98%(湖北京山)、55.42%(浙江淳安)和78.10%(浙江龙泉);地径最大值分别高出最小值126.67%、23.68%、37.02%和26.48%.南方红豆杉家系间苗高和地径变异系数在11.81%~26.50%之间.对南方红豆杉2年生容器苗各性状进行遗传力估算,遗传力在0.80~0.97之间.相关性分析认为不同测试点间苗高与苗高生长节律参数具有不同相互关系,江西分宜点苗高与线性生长速率呈负相关,而浙江龙泉点苗高与线性生长速率则呈显著正相关.以苗高作为主要性状指标,从4个测试点中筛选出7个南方红豆杉优良家系.[结论]南方红豆杉家系间,苗高、地径与苗高生长节律具有较丰富的遗传差异,遗传改良潜力较大,家系各性状遗传力较大,受较强的遗传控制,早期选择有一定的可靠性.家系与地点的互作效应显著说明部分家系生长受环境因素影响较强,遗传稳定性较弱;其中闽11和三元06两个优良家系在4个测试点中均被选中,遗传稳定性较强,可在多点进行推广.     

Range-Wide Genetic Variation in Port-Orford-Cedar (Cupressaceae,Chamaecyparis lawsoniana)

Abstract

Timing of height growth was determined for 54 families of seedlings of Chamaecyparis lawsoniana, Port-Orford-cedar, which represented most of its natural range. Seedlings were grown in plant beds in inland and coastal nurseries. The proportion of early-season growth declined and the proportion of late-season growth increased with changes in seed source location from high to low elevations, from south to north, and from east to west. This pattern was parallel to that of seedling height and of actual elongation in each of three periods during the growing season. The tallest trees (from the Oregon coast near the species' northern range limit) grew more in each period but had the greatest proportion of late-season height growth. Planting such genotypes where late summer drought or early fall frost are common may threaten their survival. Use of breeding zones that limit genotype transfer distance may avoid such damage. Within breeding zones, height growth of families was not related to their prior screening for disease resistance; selection for disease resistance should not affect growth rate or pattern. Seedlings grown at the coastal nursery had a lower proportion of early-season growth and more in late season than seedlings grown inland.     

Growth and herbage productivity of Gliricidia in Panicum maximum pasture as influenced by seedbed preparation,planting and weed control techniques

Interplanting Gliricidia (Gliricidia sepium [Jacq.] Walp.) into poor quality native grass can improve the quality of pasture. But information on methods to establish the tree legume into existing pasture is scarce. This study was designed to compare the effects of disc-ploughing, hoeing, or rotary tillage operations, and direct seeding or planting out potted seedlings on growth and dry matter yields of Gliricidia in grass pasture. The Guinea grass (Panicum maximum) pasture was first mowed to a height of 10 cm. Then the seedbed was prepared by either hoeing 0.5 m strip or rototilling 0.5 m strip with a 2-wheel tractor or disc-ploughing 1.0 m strip with a 4-wheel tractor. Eight weeks old potted seedlings were planted or seeds were sown direct. At 6 months after planting (MAP), trees in disc-ploughed strips averaged 81 cm in height, about 35% taller than trees in hoed- or rotary-tilled strips. Potted seedlings (average height 77 cm) grew 37% taller than direct-seeded trees. At 12 MAP trees in disc-ploughed strips yielded 95% more leaf DM (1170 vs. 600 kg/ha) than trees in hoed- or rotary-tilled strips. In order to intercrop Gliricidia into existing Guinea grass pasture, it is necessary to plant potted seedlings previously raised in nursery into 1.0 m wide strips disc-ploughed with 4-wheel tractor. Weed control is necessary.