Phenotypic variation in fruit and seed morphology of Adansonia digitata L. (baobab) in five selected wild populations in Malawi

Adansonia digitata L. (Baobab) is widely distributed throughout Sub-Saharan Africa stretching from Senegal to Sudan, and from Ethiopia to Natal. Information of phenotypic and genetic variation is a prerequisite for the domestication and improvement of baobab fruits from the wild. A study was done to determine within and between provenance variability in fruit and seed characteristics of five populations selected from four silvicultural zones and assess whether morphometric traits could delineate populations from different zones into land races. Fruits were characterized from 55 trees representing a wide geographical range. Six fruit traits and three individual seed traits were assessed. Results showed highly significant differences (P????0.001) in fruit, pulp, and seed weight, fruit length and width, number of seed, individual seed weight, seed length and width within and between populations. Mean fruit weight ranged from 125.8?±?3.25 to 162.9?±?3.25?g, seed weight ranged from 38.6?±?2.5 to 66?±?2.01?g and pulp weight ranged from 28.7?±?1.33 to 41.4?±?1.33?g. Single seed weight showed pronounced evidence of divergence of populations into ecotypes. The rich diversity found between and within populations is important for domestication purposes and tree improvement through selection and breeding. All populations could be used for seed source but distribution should be consciously done recognizing existence of races.     

Variability of Baobab (Adansonia digitata L.) fruits’ physical characteristics and nutrient content in the West African Sahel

The present study was carried out to evaluate variability in fruit characteristics and nutritional quality of Baobab fruits with the aim of providing the background to select trees bearing fruit with desirable characteristics for further utilisation. Vitamin C, total sugar and ash contents were assessed in 178 Baobab fruit samples from 11 sites in Burkina Faso, Mali and Niger. Furthermore the following tree and fruit physical characteristics were recorded: tree height, bark colour, fruit size, pulp weight, seed weight, seed size and pulp colour. The content (mean?±?SD) of vitamin C was 4.78?±?1.02?g?kg^?1, sugar 514?±?72?g?kg^?1 and fruit weight 293?±?96?g. There was a significant correlation between annual precipitation of the tree population site and vitamin C content but not with sugar content. For sugar, there were significant positive correlations with latitude and longitude. Negative correlations were found between fruit size and both longitude and latitude with smaller fruits generally being found to the north/east. No relation was found between pulp or bark colour and the sugar or vitamin C content. The contents of protein, lipid, carbohydrates, ash and moisture in the seeds ranged from 156 to 159, 143 to 150, 641 to 652, 44 to 49 and 50 to 55.7?g?kg^?1 respectively. The variation for vitamin C and sugar found within populations is a first indication that valuable gains could be made by selection of superior trees.     

Provenance Variation in Seed Morphometric Traits, Germination, and Seedling Growth of Cordia africana Lam

Patterns of genetic variation in Cordia africana, a tropical timber species, were evaluated at the population level. Bulk seed samples were collected from six natural populations in Ethiopia and examined for variations in seed morphometric traits, seed germination, and seedling growth at nursery stage. Analysis of variance revealed significant differences among provenances in all studied attributes except root collar diameter after 4 months of growth. The provenance effect, as determined by broad sense heritability, was 71–98% for seed morphometric traits, 80% for germination capacity, 42% for germination energy, 57–58% for seedling height and 3–13% for root collar diameter. Seed weight showed a significant positive correlation with altitude and negative correlation with mean annual temperature of seed origin. Germination energy was significantly correlated with longitude and mean annual rainfall. Seedling parameters and geo-climatic variables of seed origin were fairly correlated. A significant intercharacter correlation was found between seed length and seed weight, between root collar diameter at the age of 4 months and seed length and weight, as well as between seedling height after 4 and 8 months of growth. It can be concluded that the observed patterns of variation will have implications for genetic resources conservation and tree improvement.     

Genetic Variance and Covariance Patterns of Growth and Survival in Northern Pinus sylvestris

The amount of additive genetic and environmental variance for tree height and field survival, and the genetic relationship between the traits were estimated using data from half-sib progenies of Swedish and Finnish Scots pine (Pinus sylvestris L.) plus-trees, assessed in 18 single-tree plot progeny trials. The progeny trials were established in northern Sweden and comprised 9-13-yr-old, Finnish polycross progenies or Swedish open-pollinated progenies. In total across the trials, 71?630 individual trees from 888 families were included in the study. At the overall level, the additive genetic coefficient of variation ranged between 3.1 and 16.3% for height and between 0 and 27.9% for survival, with averages of 9.5% and 14.2%, respectively. Narrow-sense heritabilities were moderate to low, with averages across trials of 0.11 for height and 0.06 for survival. At the within-population level, estimates of genetic correlation between height and survival were mostly large and positive, with an arithmetic mean and standard error across trials of 0.47±0.39.     

Genetic differentiation and diversity of Adansonia digitata L (baobab) in Malawi using microsatellite markers

Baobab (Adansonia digitata L) belonging to Bombacaceae family, is one of the most widely used indigenous priority tree species in sub-Saharan Africa, valued in the cosmetic industry for its seed oil, and powdery fruit pulp for juice making. Baobab has high potential for domestication in southern Africa, therefore understanding its genetic diversity and population structuring is warranted. The study investigated the level of genetic diversity and differentiation of five populations of A. digitata L. sampled from four diverse silvicultural zones in Malawi. Variation at nine microsatellite loci were examined in 150 individual trees. Low mean genetic diversity was expressed through genetic diversity indices: Nei’s genetic diversity (h, 0.18 ± 0.03), Shannon Information Index (I, 0.21 ± 0.07), observed number of alleles (na, 1.47 ± 0.10), effective number of alleles (ne, 1.23 ± 0.04) and percentage polymorphic loci (pp, 48 %). The low genetic variation found is attributed to the population growing in marginal areas of genetic centre of diversity of the species, anthropogenic factors and founder effects. Moderate genetic differentiation was observed among populations (Gst = 0.13) indicating the presence of a large number of common alleles resulting in a homogenisation effect. Clustering of individual trees by genetic similarity coefficients indicated that mainland trees were genetically closer than the trees on Likoma Island. Mantel’s test showed a weak positive insignificant correlation (Z = 0.12; P = 0.64) between genetic distance among populations and actual distance on the ground implying that geneflow was not directly influenced by isolation by distance. The results suggest that seed distribution and tree improvement should recognise the presence of ecotypes and conservation measures should protect all the populations due to existence of private alleles which are of adaptive importance.     

Effect of shading by baobab (Adansonia digitata) and néré (Parkia biglobosa) on yields of millet (Pennisetum glaucum) and taro (Colocasia esculenta) in parkland systems in Burkina Faso, West Africa

An experiment was conducted in Nobéré, Burkina Faso to assess the effect of shade of two indigenous fruit trees, Adansonia digitata (Baobab) and Parkia biglobosa (Néré), on a shade-tolerant crop called taro (Colocasia esculenta) in comparison with millet (Pennisetum glaucum) a shade-intolerant crop. Photosynthetically active radiation (PAR) and performance of crops under trees and in the open field were assessed during three cropping seasons. Millet performed better under baobab (806.1?±?121.48?kg?ha^?1) compared to the control plot (595.8?±?83.43?kg?ha^?1) and néré (320.2?±?59.91?kg?ha^?1). In contrast, the yield of taro was higher under néré (4124.0?±?469.05?kg?ha^?1) compared to the control plot (2336.9?±?617.04?kg?ha^?1) and baobab (2738.3?±?595.61?kg?ha^?1). There was a strong relationship between the amount of PAR intercepted by trees and crop yields under trees. As PAR decreased the yield of millet decreased whereas the yield of taro increased. Hence, it was concluded that parkland productivity could be enhanced by cropping taro under néré where light reduction was 83, 56 and 18% in zones A, B and C, respectively. An efficient association of baobab with crops could be the production of taro in zone A and millet in zones B and C where PAR reduction was 62, 38 and 15%, respectively.     

Genetic parameters of greenhouse growth and performance of 2‐year pinus contorts subsp. latifolia

Stand differentiation, heritabilities and genetic correlations in 16 growth, bud and branch traits in Pinus contorta subsp. latifolia were studied for two growth periods in the greenhouse. Data for analyses were based on 116. open‐pollinated families from 33 stands in one breeding region in central Alberta, Canada. Family effect was significant at the 1% level of probability for all traits. The narrow‐sense heritabilities (h²) from 0.43 + 0.09 to 0.71 + 0.12 for traits of absolute height and diameter were the highest reported for growth traits in this conifer. In contrast, h² varied between 0.15±0.06 and 0.33 ± 0.08 for bud, branch and growth increment traits. Except for relative branch length, all traits showed convariation with the other traits. Levels of heritability and genetic correlation suggest that selection procedures that exploit additive genetic variance and covariance might be practised, provided there would be high juvenile‐mature correlation for this sample of P. contorta subsp. latifolia.     

Genetic parameters for large white pigs reared under intensive management systems in Kenya

A lack of performance parameters is one of the factors limiting the implementation of sustainable breeding strategies for the pig industry in Kenya. The objective of this study was to estimate genetic and phenotypic parameters for growth performance of Large White pigs reared under intensive management systems in Kenya. Growth performance data of 1398 pigs with 10 428 records were obtained from the Kenya Agricultural and Livestock Research Organization (KALRO)-Naivasha. Random regression models were used to estimate variance components by fitting different orders of Legendre polynomials. Phenotypic variance increased with age from 3.43±0.28 to 2449.28±392.07, while direct heritability ranged between 0.20±0.04 and 0.52±0.08. Maternal heritability increased from 0.26±0.05 to 0.79±0.04 while permanent environmental heritability was between 0±0.01 and 0.15±0.10. Genetic correlations were greater than 0.48 between all weights and decreased with an increase in age intervals. The first three eigenvalues of the coefficient matrix of the additive genetic covariance accounted for 98.62% of the sum of the eigenvalues. Growth was highly heritable at pre-weaning and influenced by maternal and common environmental effects. The prospect for selection for high sale weights based on pre-weaning growth performance is evident based on the high genetic correlations among body weight measurements.     

Genetic variation in seed and seedling traits in 12 African provenances of Faidherbia albida (del.) A. Chev. at Lodwar, Kenya

The extent of genetic variation in seed length, width, thickness, weight and germination percentage and seedling traits among and within 12 African provenances of Faidherbia albida was examined. The regional provenances showed a consistent variation in seed length, seed width and seed weight: the southern African provenances had the largest seeds and west African provenances the smallest. Seedling height, stem collar diameter and true leaf number differed (P = 0.05) among the provenances 90 days after germination. The seedlings from west Africa were shorter, had smaller stem collar diameter and fewer leaves. In contrast, the southern and east African provenances had taller seedlings with bigger seedling diameter and more leaves per seedling. Seedling traits did not show clear-cut divisions between southern and east African provenances, but the west African provenances formed a distinct group. Positive correlations were found in some of the seed characteristics and seedling height among provenances, which could be an important criterion for early provenance selection. Greater variation was observed for seed and seedling traits among than within provenances suggesting that selection among provenances might result in rapid genetic gain for the traits studied. This revised version was published online in June 2006 with corrections to the Cover Date.     

Influence of duration of storage at room temperature,pre-sowing seed treatment and fruit colour harvest index on germination and seedling growth of <Emphasis Type="Italic">Jatropha curcas</Emphasis> L.

Jatropha curcas L. is being promoted by governments for greening marginal areas for rural development and biodiesel production in sub-Saharan Africa, however large gaps in knowledge on its agronomy and yield potential exist. The effect of duration of storage at room temperature, pre-sowing seed treatment of Jatropha seed and fruit colour harvest index on germination and seedling growth parameters was investigated. There was a significant negative correlation between the duration of storage of Jatropha seed and seed oil content (P < 0.001, r = ?0.99), viability (P < 0.01, r = ?0.93), percent germination (P < 0.05, r = ?0.90) and germination index (P < 0.05, r = ?0.89). The relationship between duration of seed storage and seed oil content and seed germination parameters was best described by quadratic and exponential functions which showed rapid declines in seed oil content and germination parameters in the first 3 years of storage and a slower decline between 3 and 8 years of storage. There was a significant negative correlation between duration of storage and seedling height (P < 0.01, r = ?0.97), stem diameter (P < 0.01, r = ?0.93) and dry weight (P < 0.05, r = 0.91) that was best described by quadratic functions. Seed oil content was significantly and positively correlated to seed viability (P < 0.01, r = 0.96), germination per cent (P < 0.01, r = 0.94) and germination index (P < 0.01, r = 0.93). The relationship between seed oil content and seed germination parameters was best described by exponential functions which showed an exponential increase in seed germination parameters as oil content increased above 30% and smaller increases below 30% oil content. Progressive peroxidation of lipids as seed aged explains the loss of oil from the seed. Peroxidation of lipids produced highly reactive radicals that damaged membranes and proteins reducing seed germination and seedling growth parameters as seed aged. Pre-sowing seed treatments (seed soaking and scarification) produced marginal gains in germination and seedling growth parameters in Jatropha seed stored for 3 months to 8 years. Seeds harvested at the yellow fruit maturity index, 60 days after anthesis (DAA), showed the highest seed germination percent while seed harvested at the black fruit maturity index, 75 DAA, had the highest oil content. Harvesting of Jatropha seed for oil expression is therefore recommended at the black maturity index while harvesting for seed is recommended at the yellow maturity stage. The results of this study indicate that Jatropha seed should be stored for as short a period of time as possible to maximize seed germination, seedling growth and oil yield.     

桤木种源苗期生长和固N能力的变异

1996年秋采集桤木自然分布区四川盆地及其周边地区的19个产地的种子用于种源试验研究。苗期研究结果表明,在不同种源之间,种子性状（千粒质量、发芽率）、苗木生长性状（高径生长、分枝数、根茎比）、固N性状（根瘤量、固N酶活力、叶N量）和抗冻性等均存在显著或极显著的差异。不同性状变异量的相对大小和种源遗传力估计值高低顺序是：抗冻性＞生长性状＞固N性状。苗木生长性状与固N性状之间存在着较高的正向遗传相关,与抗冻性之间也有一定正相关。应用综合指数法筛选出南江、都江堰和金堂3个最优种源,可供生产单位参考应用。桤木苗木大多数性状与种子产地海拔高度呈负相关,与经度呈正相关,而与纬度关系轻微,呈现出以垂直为异为主、经向变异为次、纬向变异不明显的地理变异特点。     

Characterization of raffia palm fiber for use in polymer composites

Raffia palm fibers are potential reinforcement materials for making cost-effective polymer-based composite. This paper presents the results obtained from a study of physical, chemical, thermal and mechanical properties of raffia palm fibers (RPFs) derived from the raffia palm tree (Raphia farinifera). The as-received RPFs had their remnant binders manually removed and was subsequently cleaned in a 2% detergent solution before drying in an air oven at 70 °C for 24 h. Evaluation of the properties of the dried samples was carried out using a combination of characterization techniques including chemical composition determination, density measurement, moisture adsorption and water absorption measurements, tensile testing, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Raman spectroscopy, X-ray diffractometry, and Fourier transform infrared spectromicroscopy. The main constituents of RPFs were found to be cellulose, hemicellulose and lignin. The average diameter and average density were 1.53?±?0.29 mm and 1.50?±?0.01 g/cm³, respectively. The average breaking strength of the fibers ranged from 152?±?22 to 270?±?39 MPa; it did not vary significantly with fiber length and cross-head speed during tensile testing. The results of scanning electron microscopic investigation of the fibers showed that they comprise several elemental fibers which are tightly packed together with each having its own lumen. Synchrotron-based Fourier-transform infrared spectromicroscopy of a cross-section of the fiber showed that lignin is concentrated mostly on the outside while cellulose and pectin are concentrated in the mid-section. A two-stage water sorption behavior was observed for the fibers.     

Differentiation of seed germination and early seedling growth in ten provenances ofEucalyptus microtheca

An investigation of seed germination and early seedling growth ofEucalyptus microtheca was based on seed collection from 10 widely separated provenances in Australia. Genetic variation of seed germination and early seedling growth was observed among a series of provenances whose natural habitats range from different climatic condition. In the ten provenances, both the model of seed relative germination percentage and the model of seed total germination percentage fitted Logistic regression [y=a/(1+exp(-ex+b))]. In comparison with provenances from four high temperature (mean annual maximum temperature >30.0 °C; mean annual minimum temperature >17.0 °C) areas, six low temperature (mean annual maximum temperature <30.0 °C; mean annual minimum temperature <17.0 °C) areas showed the fast germination rate and the high total germination percentage. For each provenance we have 45 seedlings equally divided into three watering levels (100%, 50%, and 25% of field capacity), and studies on relationship between early seedling growth and climatic factors of the natural habitat of provenance. In control treatment, height growth of the seedling has been associated with intrinsically the driest quarter precipitation in the seed collection areas of provenance. In all the treatments, length growth of the biggest leaf of the seedling was related to mean annual maximum temperature and mean annual minimum temperature in origin of provenance. In contrast, basal diameter growth of the seedling was related to mean annual minimum temperature of the seed collection areas in water stress treatment. From an ecological viewpoint, the fast germination rate and the high total germination percentage of the seed and rapid early growth of the seedling appear to be favourable adaptations to the climatic conditions prevailing in the natural habitat of provenance. Responsible Editor: Chai Ruihai     

野生毛冬青的驯化繁育研究

毛冬青(Ilex pubescens) 是我国南方常用中药,药材来源主要为野生资源。文章通过引种野生 毛冬青,开展繁育方面的初步研究。结果表明,毛冬青种子具休眠性,导致出苗不齐;采种时间为 10— 12 月,可用随采随播方式播种,播种后约 67 d 开始出土,春季发芽率约 20%,采用低温沙藏略可提高种 子发芽率。毛冬青当年苗平均苗高 33.24 cm,平均地径 4.08 mm,速生期为 5—10 月,苗高 Logistic 拟合 曲线为 y=34.710/(1+66.416exp-0.638× 月份)。毛冬青苗期采用搭棚遮荫（50% 光照）对苗木的生长有利,平均 苗高、地径、苗木存活率、合格苗率比全光照增加 5.81 cm、0.7 mm、16 及 26 个百分点。     

Effect of water-spray cooling treatment in a Douglas-fir seed orchard on seed germination

Overhead-cooling treatment used to delay flowering produced non-significant effects on germination capacity, germination rate, germination value, and abnormal germination of seeds from a 13-year-old Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] seedling seed orchard. The percentage of variation accounted for by cooling treatment ranged from 0.0 to 1.0%. In contrast, variation among trees within treatments ranged from 28 to 46%. These effects were significant, indicating that each tree has an individual germination pattern. The temporal delay of reproductive phenology caused by temperature manipulation as a result of the cooling treatment was judged to be within the species' biological limits.     

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。     

木荷优树子代苗期生长遗传和变异研究

利用设置在福建建瓯、浙江龙泉和淳安3个试验点的96～141个木荷优树自由授粉家系苗期测定材料,以研究和揭示其苗木生长和叶片形态性状的家系遗传变异规律.方差分析结果显示,木荷苗高、地径、叶片数、叶片长和叶片宽等在家系间的遗传差异皆达到极显著水平.性状遗传力估算值显示,苗高和叶片长分别受中等和较强的家系与加性遗传控制,而地径、叶片数和叶片宽等则受弱度至中等的家系和加性遗传控制.试验观测到,与来自较北部和较高海拔地区的家系比较,来自较南部和低海拔地区的家系在各区试点的苗木生长量大、叶片宽大、叶片数多,说明木荷苗木生长和叶片形态的家系效应中还存在明显的产地效应.木荷苗高和地径等不仅立地效应显著,而且存在显著的家系与立地互作效应.基于家系苗期测定结果,以苗高为标准,分别为水热条件较好的中心产区(福建建瓯)、一般产区(浙江龙泉)和水热资源较差的北缘区(浙江淳安)初选出20个速生的优良家系.     

核桃楸不同种源苗期试验初报

从6个核桃楸优良种源地采集种子进行播种育苗,调查出苗率、苗高、地径生长量,进行核桃楸种源试验。结果表明:出苗率较高的两个种源为上庄种源(77%)、大南坪(69%),各种源间在苗高、地径生长方面差异不显著,变化幅度较小,说明核桃楸种源种子遗传特性较好。     

湿地松半双列子代遗传分析

根据 10年生湿地松 6× 6半双列子代在两个试验地点的生长量、木材基本密度、树干通直度和抗风性数据 ,研究了该树种目的性状的遗传变异规律。结果表明 ,地点间存在着显著的生长差异和通直度差异 ,但两点的木材基本密度非常一致 ;所有研究性状均存在着一定程度的地点与基因型互作 ,其中胸径、基本密度均达到了显著以上水平 ;在一般配合力 (GCA)均方差显著地大于特殊配合力 (SCA)均方差的前提下 ,胸径、材积、基本密度、通直度、抗风性的加性方差占总遗传方差的 96 .4 1%～ 10 0 %。但是 ,树高性状以非加性方差居优。决定子代表现的遗传因素 ,主要是亲本的GCA,SCA和反交效应也有影响 ,但程度较低 ;两块测定林中 ,树高、胸径、材积、基本密度、通直度、抗风性的单株狭义遗传力分别为 0 .0 0 1和 0 .0 74、0 .0 80和 0 .144、0 .0 6 8和 0 .137、0 .10 8和 0 .6 0 9、0 .0 5 2和 0 .2 5 2、0 .0 5 8(单地点 )。     

香樟16个优良半同胞家系子代苗期性状遗传测定

以香樟16个半同胞家系子代为研究对象,在四川省大邑县进行苗期试验,测定1 a龄苗期苗高、地径、冠幅3个性状。采用方差分析、遗传力估算、相关分析等方法对测定数据进行统计分析。结果表明:香樟家系间苗高、地径达到极显著差异,表明香樟半同胞家系苗期存在较为丰富的变异,进行苗期选择潜力较大;苗高、地径遗传力较高,属强度遗传;苗高、地径、冠幅三个性状之间呈显著正相关,尤以苗高与地径相关密切;以苗高、地径2个主要苗期生长性状,初步筛选4个苗期生长较快的家系。