Comprehensive assessment of growth traits and wood properties in half-sib <Emphasis Type="Italic">Pinus koraiensis</Emphasis> families

Rapid growth and high quality have always been important goals pursued for timber forests. Therefore, growth traits and wood properties are the basis of superior materials to select and breed new cultivars. In this study, 42 half-sib families of 31-year-old P. koraiensis trees were used as materials. Nine growth traits (tree height, diameter at breast height, volume, basal diameter, average annual growth of the tree height, under branch height, stem straightness degree, form quotient, and branching angle) and eight wood properties (cellulose contents, hemicellulose contents, holocellulose contents, lignin contents, ash contents, wood density, fiber length and fiber width) were measured and analyzed. The results of an analysis of variance showed that there were extremely significant differences among the families in their growth and wood properties with the exception of the form quotient and wood density; that there were significant differences among block by family for growth traits except for the tree height, basal diameter, under branch height and branching angle; and that there was no significant difference for each growth trait among the blocks. The phenotypic coefficient of variation and heritability of the growth traits ranged from 7.17 to 42.35% and from 0.13 to 0.62, respectively. The phenotypic coefficient of variation and heritability of the wood properties ranged from 10.21 to 50.26% and from 0.67 to 0.92, respectively. There were extremely significantly positive correlations between the tree height, basal diameter, diameter at breast height, volume, under branch height, average annual growth of tree height and form quotient. However, there was no significant correlation between growth traits and wood properties. The result of the principal component analysis indicated that the tree height, diameter at breast height, volume, basal diameter, and cellulose contents, holocellulose contents, and lignin contents could be selected as comprehensive evaluation indices of growth and wood properties, respectively. According to a comprehensive evaluation, when the selection rate was 10%, four families (PK 40, PK 80, PK 42, and PK 71) were selected as elite families based on growth performance; another four families (PK 70, PK 62, PK 52, and PK 44) were selected as elite families based on their wood quality; and finally, four elite families (PK 70, PK 62, PK 61, and PK 40) were selected due to a combination of growth traits and wood properties. This study will provide a theoretical basis for the genetic improvement of fast-growing and high-quality P. koraiensis families.     

Heritability Estimate for Resistance to Alternaria dauci in Carrot

An estimate of the narrow sense heritability of resistance to Alternaria dauci was obtained for the open-pollinated carrot cultivar ‘Brasília’. The estimate, based on plot means of 96 half-sib families was 0.4032 ± 0.1672, which may be considered in the medium-low range. Considering this result, it is concluded that recurrent selection based on half-sib progeny tests, will be more effective than simple phenotypic recurrent selection in increasing the resistance level of ‘Brasília’ to A. daucci.     

北方茶区茶树短穗扦插繁育技术研究

研究旨在提出适宜北方茶区茶树的扦插繁育技术,为抗寒茶树品种的选育和推广提供技术支撑。以无性系茶树品种‘中茶108’为试验材料,采用L₉(3⁴)正交试验设计,研究激素种类、插穗状态、浸蘸浓度和时间等因子对茶苗发育和扦插成活率的影响。正交试验结果显示,最优组合为A₁B₃C₃D₃,即插穗清水浸泡,扦插前浸蘸200 mg/L IBA 30 min,成活率达81.3%;4个扦插因素产生的效应由主到次依次为激素种类、插穗处理方式、激素的浸蘸时间、激素浓度。不同激素种类处理下,地上部发育指标显示IBA+NAA处理有利于叶片数量和干重增长;由茶苗根系发育情况表型观测可知,IBA+NAA处理根类组成较合理,有利于根系中一级侧根、延长根和吸收根的协同生长;由根系发育指标分析可知,IBA+NAA处理最大程度地促进了根系总根长、总表面积、根体积、根尖数和生物量的增长。由此确立最优扦插组合为插穗斜削后立即清水浸泡,扦插前用激素组合IBA(200 mg/L)+NAA(200 mg/L)浸蘸30 min后迅速插入基质。在此扦插组合下,27个茶树品种的扦插繁育特性差异较大,扦插成活率最高为91.1%,最低仅为12.17%,高于80%的有11个。研究结果在北方茶树扦插中具有较强的应用性,能够为茶树品种的选育和推广提供技术支撑。     

华山松半同胞子代测定遗传力分析及优良家系选择

对贵州省平坝县华山松优树半同胞子代和威宁县初级种子园自由授粉子代生长进行了调查,遗传力分析估算的结果表明:22年生华山松优树子代,胸径、树高和冠幅的家系遗传力分别为0.523、0.435、0.629,每个性状的单株遗传力则分别为0.310、0.0497、0.159;12年生种子园自由授粉半同胞子代的胸径和树高家系遗传力为0.328和0.298,单株遗传力分别为0.356、0.312。平坝试验林评选出24个优树优良半同胞家系,威宁试验林评选出15个种子园自由授粉优良半同胞家系,可供营建1.5代华山松种子园选用或进入二代遗传改良育种群体。     

恩施红椿种子发芽率及苗期特性分析

为保护湖北乡土红椿资源和良种选育提供理论基础,以恩施红椿7 个半同胞家系为研究对象,对种子发芽率、1 年生苗木成活率、苗高、地径等生长性状及叶片性状进行分析。结果表明,参试红椿种子发芽率、成活率均较低且在红椿半同胞家系间差异显著,平均发芽率为38%,平均成活率为21%,XE-4家系发芽率和成活率最高。苗高、地径、冠幅、枝数、叶片数、复叶长度、叶片鲜重等7 个指标在红椿半同胞家系间差异显著,遗传力与遗传变异系数较高,属于中高度遗传,变异丰富具有选育潜力且能稳定遗传。地径与冠幅、叶片数、叶片鲜重、叶片干重极显著相关。综合考虑,初步筛选出XE-2、XE-4、XE-5 优良家系。     

Responses to divergent selection for adventitious root growth in red clover (Trifolium pratense L.)

Summary Red clover (Trifolium pratense L.) persistence is improved by the growth of adventitious roots from the crown. The effect of one cycle of divergent phenotypic selection for adventitious roots in red clover was evaluated and root and shoot traits including degree of flowering habit correlated. Three classes of single-cross progenies were produced by crossing plants within and between the high and low root selections. Parents and progeny were grown as spaced plants. Adventitious root score and volume were significantly correlated (p<0.05); however they generally had low or nonsignificant correlations with other variables. A significant correlation (r=-0.36, p<0.01) was found between adventitious root score and flowering score (growth type) in 1988 but not in 1989. Significant variation was found among the three classes of single-cross progeny for adventitious root score and crown diameter. The effect of progeny class on score of adventitious roots was not linear, suggesting dominance effects for the absence of adventitious roots may have been present. A narrow-sense heritability estimate of 0.30 was found by midparent offspring regression of the adventitious root score. This low heritability value implies that successful selection would require progeny testing.     

黧蒴栲生长材性热值灰色关联分析及优良半同胞家系选择

为科学选择生长、材性、热值多性状优良的黧蒴栲半同胞家系,采用随机完全区组试验方法,通过对6年生家系生长测定与材性、热值分析,运用灰色关联度分析模型证实木材基本密度与生长性状关联度较高。利用木材材积、木材密度和热值三性状计算得出黧蒴栲半同胞家系综合选择指数为I=0.4480X1＋0.5395X2＋0.5762X3,指数遗传力为0.8158,均值化综合育种值选择进展△H=0.1693。以综合选择指数均值加1.25倍标准差的指数作为适用于黧蒴栲半同胞家系材积、木材密度、热值多性状综合选择的指标,有5个半同胞家系即：PG07、RS09、TD01、RS08、PG08入选,其材积、基本密度、热值增益分别为156.33%~391.78%、12.70%~25.22%、15.81%~31.80%。黧蒴栲半同胞家系初次选择效果十分显著,可为黧蒴栲种子园的营建和制定遗传改良策略提供技术依据。     

Winter hardiness in marginal populations of timothy

Summary A comprehensive collection of local fodder grass populations was carried out in the northern regions of Norway in 1972 and 1973. The main purpose was to find ecotypes with extreme winter hardiness. This paper gives results from experiments carried out with some of the timothy populations collected.After testing in dense stand a few of the most promising populations were selected for investigation of genetic variation within populations by growing in duplicate blocs of 100 clones from randomly selected plants. Twenty-two clones were selected from each of six populations and planted in separate isolated polycross fields. During 1986 to 1990 the half-sib families from these polycrosses were grown in two series of experiments laid out at two locations, Tromsø and Alta.Significant genetic variations were found for winter hardiness within all six populations tested, as well as interaction between families and locations, while the interaction effects between families and years were small and insignificant in all cases.Winter hardiness was strongly genotypically correlated in the positive direction with visually estimated general performance, but not correlated with digestibility.     

Growth patterns of Slash and Caribbean Pine and their hybrids in Queensland

Summary Seasonal height and girth growth patterns of hybrids between Slash Pine (Pinus elliottii Engelm. var elliottii L. & D.) and Caribbean Pine (Pinus caribaea Mor. var hondurensis B. & G.) were compared with those of the parental species over one year at Beerwah Forest in southern coastal Queensland, Australia. The parental growth patterns differed markedly. Slash Pine had very vigorous early season growth, the rate then declined steadily through the later part of the season until the species entered winter dormancy. Caribbean Pine grew steadily throughout the year with late summer the most active period and winter the least. The hybrids combined the parental growth patterns with a consequent vigour advantage.Slash Pine showed a high degree of stem to stem synchronization of height growth in the early season, but much less in the later part, whilst height growth of Caribbean Pine was totally asynchronous. The hybrid was intermediate in stem to stem synchronization.The number of branch whorls produced by individual trees of Slash Pine on the main stem in the season 1965–1966 were found to be directly related to the length of the growing season for the tree concerned and also to the total height of the tree. Counts on trees at various centres in Queensland showed a decrease in branch whorl number per season with movement northwards suggesting a decrease in the length of the growing season of the species at lower latitudes. Possible physiological reasons for this are discussed.     

Heritability estimates and progeny testing of phenotypic selections for soluble solids content in dehydrator onion

Soluble solids comprise most of onion bulb dry mass, and dehydrator onion cultivars are developed from breeding populations that have high dry mass content. Realized and narrow-sense heritability estimates were obtained for the soluble solids content (SSC) trait in two open-pollinated dehydrator onion breeding populations (BP) using response to selection and half-sib family analysis. Parental populations, designated as BP9335-U and BP9243-U, were derived from two-way crosses of lines advanced as open- pollinated (OP) populations to the F7 or F_6 generation, respectively. BP9335-U had one previous selection cycle for increased SSC and BP9243-U had three SSC selection cycles. In these experiments, parental populations were screened again for high SSC, and selected bulbs were intermated to form half-sib progeny groups, designated as BP9335-S and BP9243-S. Mean SSC was increased by 6.6% and a realized heritability estimate of 0.64 was obtained for BP9335-S. Mean SSC was increased by 6.3% and a realized heritability estimate of 0.36 was obtained for BP9243-S. Narrow-sense heritability estimates of 0.58 ±0.05 and 0.30 ±0.03 were obtained for parental populations BP9335-U and BP9243-U, respectively. Narrow-sense heritability estimates of 0.40 ± 0.03 and 0.63 ± 0.23 were obtained for progeny populations derived from selected high-SSC bulbs of these lines (BP9335-S and BP9243-S), respectively, indicating that there is significant additive genetic control of the SSC trait in these populations. Significant differences in half-sib family performance in the advanced groups BP9335-S and BP9243-S demonstrate that progeny testing was effective for evaluating phenotypic selections. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effects of high- vs. low-yield environments on selection for increased biomass yield in switchgrass

No information is available on the effects of different biomass yield environments on selection efficiency in switchgrass (Panicum virgatum L.) breeding improvement. This study was conducted to assess the effects of high- and low-biomass yield environments (HYE and LYE, respectively) on recurrent selection for general combining ability (RSGCA) in a lowland population of switchgrass (NL-94). The top 14 of 65 NL-94 C₀ parent plants were selected based on biomass yield of half-sib (HS) progeny tested for one post-establishment year under HYE and LYE conditions. Nine of the 14 C₀ parent plants were the same based on HS performance under HYE and LYE. Selected plants were intercrossed to produce NL-94 HYE and NL-94 LYE C₁ populations. One hundred and twenty-five HS C₁ progeny families (60 NL-94 HYE and 65 NL-94 LYE) were evaluated for biomass yield for 3 years (2002–2004) under HYE and LYE conditions. The HYE produced about 2.5 times higher biomass yields than the LYE in both C₀ and C₁ HS progeny tests. Estimated additive genetic variance and predicted gains from selection (ΔG) were high in the C₁ populations indicating that RSGCA should achieve higher biomass yields. Mean biomass yields of C₁ HS families originating from the LYE protocol were significantly higher than those of families originating from the HYE protocol in both HYE and LYE performance tests, suggesting greater selection response under LYE in the C₀ population. The estimates of narrow-sense heritability ( ) and ΔG from the C₁ populations indicate that positive response to selection for biomass yield is possible in subsequent cycles of selection under either HYE or LYE, with a possible small advantage for HYE.     

Productivity under contrasting cutting regimes of perennial ryegrass selected for short and long leaves

The productivity of short-leaved and long-leaved perennial ryegrass was evaluated in 5 different sites. In each site, half-sib families, derived from the first cycle of divergent selection on leaf length, were managed both under infrequent cutting and under frequent cutting simulating grazing. Despite the importance of the effects of the site and the cutting frequency, the dry matter yield was dependent on the interaction between the morphogenetic type resulting from the selection and the cutting frequency imposed by the management. Thus, under infrequent cutting, the long-leaved families on average out-yielded the short-leaved families. Conversely, under frequent cutting the short-leaved families were on average the most productive. The use of morphogenetic traits as selection criteria in breeding for management-dependent yield is briefly discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Genetic variation for seed dormancy in Cuphea laminuligera and Cuphea lanceolata

Summary Various Cuphea species are adapted to temperate climates and characterized by caprylic, capric, and lauric acid-rich seed oils. These fatty acids are solely commercially available from palm kernel and coconut oils; thus, there is considerable interest in Cuphea as an alternative source of these fatty acids. Cuphea is a genus of undomesticated species characterized by seed dormancy and seed shedding. Our goal is to eliminate these domestication barriers in a few species with agronomic potential. Our objective was to survey existing Cuphea laminuligera and C. lanceolata germplasm for genetic variation for seed dormancy (germination percentage after a certain seed storage period). Recurrent half-sib family selection was practiced in various open-pollinated and synthetic populations. Half-sib family seed were evaluated for germination percentages at 26° C after various seed storage periods. There was significant genetic variation among families in every population. Additive genetic variance, half-sib family-mean heritability, and expected selection response magnitudes depended on the length of the seed storage period within a given population. Estimates of these parameters were significantly greater for longer seed storage periods within a population. Heritability estimates ranged from 0.00 to 0.79. Expected half-sib family selection responses ranged from 0.0 to 23.9%. Our study demonstrated there is substantial genetic variation for seed dormancy in C. laminuligera and C. lanceolata.     

Heritability and genetic correlation in daylily selection

Daylily (Hemerocallis × hybrida Hort.) is a popular ornamental plant and hybrid cultivars are frequently selected for medium size, large number of flowers per stem, and flower color diversity. However, daylily selection is limited due to the lack of information on genetic parameters and their correlation to phenotypic characteristics. This study aimed at estimating genetic parameters and genetic correlations among full sib families of 13 daylily cultivars using REML/BLUP (restricted maximum likelihood/best linear unbiased prediction) and to select families with high genotypic values for plant height and number of floral buds per stem. Crosses were performed among those cultivars and 24 families were obtained. In the third year, plant height, leaf length and width, stem number, number of floral buds per stem, and number of floral buds per plant were evaluated. The estimates of average heritability of families were superior to the estimates of restrict individual heritability for all characters evaluated. High heritability estimates were obtained for plant height, leaf length, leaf width, stem number, and number of floral buds per plant. Selected families showed genetic gain of 19.80% for plant height, 32.48% for stem number, and 38.64% for number of floral buds per plant.     

生物质醋液在2种林木播种育苗上的应用

利用以芦苇为原料生产的生物质醋液,经过在西部沙樱、腺齿蔷薇2种林木播种育苗上的应用,确定醋液对其生长作用效果。结果表明：醋液对西部沙樱、腺齿蔷薇2种林木播种幼苗生长具有促进作用,以400、800倍液在种子出苗后4～6叶一心期开始灌根使用,每隔5天一次,共灌施6次,灌根处理为每穴20～30 mL,可显著促进供试幼苗高生长和根系的萌发和生长。     

Absence of a genetic relationship between salt tolerance during seed germination and vegetative growth in tomato

Two approaches were used to determine the relationship between salt tolerance during seed germination and vegetative growth in tomato. First, F₄ progeny families of a cross between a breeding line, ‘UCT5’ (salt sensitive at all developmental stages), and a primitive cultivar, ‘PI 174263’ (salt tolerant during germination and vegetative growth), were evaluated in separate experiments for salt tolerance during germination and vegetative growth. There were significant differences among the F₄ families in both the rate of seed germination and the plant growth (dry matter production) under salt stress. There was, however, no significant correlation between the ability of seeds to germinate rapidly and the ability of plants to grow under salt stress. In the second approach, selection was made for rapid germination under salt stress in an F₂ population of the same cross and the selected progeny was evaluated for salt tolerance during both germination and vegetative growth. The results indicated that selection for salt tolerance during germination significantly improved germination performance under salt stress; a realized heritability estimate of 0.73 was obtained. Selection for salt tolerance during germination, however, did not affect plant salt tolerance during vegetative growth; there was no significant difference between the selected and unselected progeny based on either absolute or relative growth under salt stress. Obviously, in these genetic materials, salt tolerance during germination and vegetative growth are controlled by different mechanisms. Thus, to develop tomato cultivars with improved salt tolerance, selection protocols that include all critical developmental stages would be desirable.     

Evaluation of Self and Polycross Progeny Testing in Birdsfoot Trefoil (Lotus corniculatus L.) for Forage and Seed Yield

Self and cross fertility, forage and seed yield of parents, self (Sl), and polycross (PX) progenies were measured in a selected and an unselected population of birdsfoot trefoil (Lotus corniculatus L.), Self fertility was significantly less than cross fertility in both populations. In a field planting S1 progenies had lower forage yield in 1979 and 1980 and seed yield (relative to the parents) was less in the selected population than the unselected in 1979. All correlation coefficients between years and progenies were non-significant for forage yield bur the parents-poly cross progeny correlation was significant for seed yield in the selected population. Percentage survival of plants after cutting in 1980 was higher in the selected population, and the parents and PX progenies survived better than S1 progenies in both populations. The better performance of the selected population may be due, in pan, to higher frequency of favorable genes resulting from four cycles of recurrent selection, S1 progeny testing does not appear to be worth while in birdsfoot trefoil because of low self fertility and the reduced vigour of the progeny.     

不同生境中紫茎泽兰幼苗的动态特征

为了研究入侵植物紫茎泽兰生长瓶颈阶段幼苗在不同生境中的适应性动态变化,在四川省德昌县比较研究了非农作的林区、农林交错带及撂荒地3种生境下紫茎泽兰幼苗适应各自不同环境的生长特征。结果表明：（1）幼苗的增长有2个高峰：第1个阶段为7月中旬到9月中旬,第2个阶段为翌年春季进入3月份以后,2个高峰之间为平缓增长期。（2）林区内幼苗的生物量增速均显著低于其余2个生境;而撂荒地和农林带生境增速在第2个生长高峰前相近,之后农林带的生物量增速显著高于撂荒地。（3）越冬生长1年后农林带幼苗密度显著高于其余2个生境。从而说明农林交错带是最适合紫茎泽兰幼苗生长的,也是最容易被入侵的生境。     

Half-sib progeny evaluation and selection of potatoes resistant to the US8 genotype of Phytophthora infestans from crosses between resistant and susceptible parents

The objectives of this study were to evaluate the use of potato (Solanum tuberosum L.) late blight (Phytophthora infestans (Mont.) de Bary) resistant parents in cultivar development and identify superior clones possessing moderate to high late blight resistance combined with acceptable maturity and tuber quality. Ninety-five crosses were made between eight unadapted parents with reported late blight resistance (B0718-3, Bertita, Bzura, Greta, Libertas, Stobrawa, Tollocan and Zarevo) and susceptible parents (cultivars or advanced breeding clones) adapted to North American growing conditions. A total of 408 field selected clones were assessed for late blight resistance in the greenhouse and in the field using a mixture of US8 P. infestans isolates (A2 mating type, metalaxyl resistant) that overcame all known R-genes except R8 and R9. Clones with ≤ 10% infected foliar area in the greenhouse test or ≤ 0.30 RAUDPC (relative area under the disease progress curve) value in the field in 1998 were re-tested in 1999. A total of 118 (29% of 408) putative late blight resistant clones were selected. The eight late blight resistant parents differed in both the ability to transmit late blight resistance and in the level of resistance transmitted to the progeny. The Tollocan and B0718-3 families (half-sib progeny) had the greatest degree of resistance and frequency of resistant clones. Scott-Knott cluster analysis ranked 79 clones (67% of 118) in the high and moderate late blight resistant groups. Among these 79 clones, 19 clones had vine maturity equal to or earlier than mid-season combined with acceptable tuber quality. Further selection in 2000 resulted in eight advanced selected clones (six from Tollocan and two from B0718-3 families) with the same level of resistance as the parent combined with vine maturity and tuber quality equivalent to Atlantic, a standard cultivar for chip processing in North America. The results indicate that this breeding approach can be used to select parents for late blight resistance breeding and to identify superior clones with high levels of late blight resistance and marketable vine maturity and tuber quality. This revised version was published online in July 2006 with corrections to the Cover Date.     

Heritabilities of nutritive quality factors and interrelationships with yield in selected progenies of tall fescue

Nine polycross (PX) and nine different self (S₁) progenies were randomly chosen from 43 selected tall fescue genotypes and evaluated for in vitro digestible organic matter (IVDOM), crude protein, neutral detergent fibre, acid detergent fibre and acid detergent lignin of whole plants, leaf blades and stems (stem plus leaf sheath) at each of four harvest dates in 1991 and 1992. Significant variation for all whole‐plant and leaf quality traits occurred among the PX progenies at the May harvest. Variation among S₁ progenies was significant for almost all of the stem traits. Genetic variance components for both progeny groups were significant for almost all of the traits, confirming the presence of additive genetic variation. Heritability estimates on a progeny‐mean basis ranged from medium to high for almost all the traits of the whole‐plant and the leaf and stem fractions. The results suggest that spring would be the time at which direct selection for high IVDOM or low fibre content would be successful and that selection for leaf or stem quality traits improves whole‐plant quality. Selection for quality traits in the summer or in the autumn would be difficult since no significant genetic variability was found.