Mutagenic Effects of Spaceflight Treatment on the Second-Generation Seeds of Alfalfa

[ Objective] To explore the effects of spaceflight on the second-generation seeds of alfalfa and provide a theoretical basis for mutation breeding. [Method] The seeds of Medicago stavia L. lines no. 1, no. 2 and no. 4 were carried into space by the Shijian-8 seed breeding satellite for a 15-d spaceflight treatment. After returning to the ground, seedlings were transplanted to field. Traits of the second-generation seeds of alfalfa were evaluated. [Result] The 1 000-grain weight of the second-generation seeds were 5% -9% significantly higher than that the control （P 〈 0.05）. The germination rate, seedling weight, shoot length and root length were significantly increased （P 〈 0.05）. The hard seed rate and the rate of moldy seeds were significantly decreased （ P 〈 0.05）. However, the rate of dead seeds was increased. [ Conclusion] Spaceflight treatment has positive mutagenic effects on the second-generation seeds of alfalfa.

Similarity between seed rain and neighbouring mature tree communities in an old-growth temperate forest

Seed distribution and deposition patterns around parent trees are strongly aff ected by functional traits and therefore infl uence the development of plant communities.To assess the limitations of seed dispersal and the extent to which diaspore and neighbouring parental traits explain seed rain,we used a 9-year seed data set based on 150 seed traps in a 25-ha area of a temperate forest in the Changbai Mountain.Among 480,598 seeds belonging to 12 families,17 genera,and 26 species were identifi ed,only 54%of the species with mature trees in the community were represented in seeds collected over the 9 years,indicating a limitation in seed dispersal.Understory species were most limited;overstory species were least limited.Species with wind-dispersed seed had the least limitation,while the lowest similarity in species richness was for animal-dispersed species followed by gravity-dispersed species;fl eshy-fruited species had stronger dispersal limitations than dry-fruited species.Generalized linear mixed models showed that relative basal area had a signifi cant positive eff ect on seed abundance in traps,while the contribution of diaspore traits was low for nearly all groups.These results suggest that tree traits had the strongest contribution to seed dispersal and deposition for all functional groups examined here.These fi ndings strengthen the knowledge that tree traits are key in explaining seed deposition patterns,at least at the primary dispersal stage.This improved knowledge of sources of seeds that are dispersed could facilitate greater understanding of seedling and community dynamics in temperate forests.

Variations in seed size and seed mass related to tree growth over 5 years for 23 provenances of Quercus acutissima from across China

The origin of a seed strongly impacts its traits, and both origin and seed traits influence seed germination and seedling development. However, in many instances, this effect on the seedling does not persist into adulthood, and little is known about how seed traits and original environment affect seedling/tree growth over time. In this study, seed size, seed mass, seedling/tree growth and origins were collected and determined for 23 provenances of Quercus acutissima from across China. Origin variables correlated well with seed size and seed mass. In stepwise multiple regressions, a longitudinal aridity index explained 49.2-68.7% of the total variation in seed size and mass, while only seed width was correlated with seedling/tree height (H) and diameter at the ground (D) from seed traits and origins. The total variance in H and D explained by the models decreased over time, for example, the R 2 value of the models for H declined from 0.477 in the first year to 0.224 in the fourth year; no models was significant in the fifth year. These results indicate that seed size, regulated by the longitudinal aridity index strongly impacted seedling and tree growth, but the strength of the influence decreased over time, and disappeared after 4 years.

Effect of thinning intensity on tree growth and temporal variation of seed and cone production in a Pinus koraiensis plantation

Thinning of Korean pine (Pinus koraiensis Sieb. et Zucc.) is used to facilitate timber and cone production. The present study in Northeast China investigated the effects of thinning intensity on individual tree growth, temporal variation in cone yield, and seed quality in Korean pine plantation. In 2005, five thinning intensity levels (none, extreme, heavy, moderate and light) were set in 15 permanent plots in a 32-year-old Korean pine plantation at Mengjiagang Forest Farm, Jiamusi City, Heilongjiang Province. We recorded tree growth and seed cone production from 2013 to 2016, i.e., from 8 to 11 years after thinning. Except for height growth, thinning increased tree growth (diameter at breast height and crown size) and improved cone yield. The extreme thinning treatment (to 300 trees per hectare) resulted in the largest tree diameter, tree volume, crown size and 4-year cone production per tree. The highest cone yield per tree in the mast year (2014) was observed when stands were thinned to 500 trees per hectare (heavy thinning). Although the best cone and seed quality and the largest cone and seed mass per tree were recorded in the heavily thinned stand, no significant differences were found between heavy and moderate thinning stands (750 trees per hectare). At the stand level, the moderately thinned stand had the highest basal area, stock volume and seed cone production per stand. Our results suggest that thinning to 750 trees per hectare will improve timber and cone productivity in 40-year-old P. koraiensis stands.

Effect of the seeds provenance and treatment on the germination rate and plants growth of four forest trees species of Cote d’Ivoire

The rapid rate of deforestation in Cote d’Ivoire has led to loss of plant species diversity and also threatens some commercial tree species with extinction.Some reforestation and aff orestation has been completed.However,for some species,the numbers of surviving transplants has declined.Hence,it is necessary to develop properly adapted and resilient genotypes that can eff ectively support the programs of forest restoration.In this context we evaluated the eff ects of the provenances of seeds and of various treatments on the germination rates and on plant growth of four commercial trees species(Pycnanthus angolensis,Terminalia superba,Mansonia altissima and Pterygota macrocarpa).We analyzed these parameters for seeds of three provenances(Daloa,Akoupéand Daoukro)of four species and for thirty plants aged 6 months per provenance.Time to begin germination and time to reach maximum germination were similar among species,and were not infl uenced by either treatment or provenance.Untreated seeds and those soaked for 24 and 48 h in water at room temperature yielded the highest germination rates,irrespective of species or provenance.The one exception was P.angolensis,for which no germination was recorded.Within species,some provenances produced higher germination percentages than did others.No clear relationship was computed between the germination rate and the morphometric characteristics of the seeds which varied signifi cantly between provenances.Plant growth and morphological variability also depended greatly on provenance.Genetic factors might be implicated,therefore provenance trials should be undertaken and evaluated.Furthermore,molecular analysis should be undertaken to confi rm the implications of genetic factors and allow for genetic selection.

Differential roles of seed and sprout regeneration in forest diversity and productivity after disturbance

Natural regeneration after disturbances is a key phase of forest development,which determines the trajectory of successional changes in tree species composition and diversity.Regenerating trees can originate from either seeds or sprouts produced by disturbed trees with sprouting ability.Although both regeneration strategies often develop and co-occur after a disturbance,they tend to affect forest development differently due to significant functional differences.However,the origin of tree regeneration is rarely distinguished in post-disturbance forest surveys and ecological studies,and the differential roles of seed and sprout regeneration in forest productivity and diversity remain poorly understood.To address these research gaps,we explored the role of sprout and seed regeneration in the formation of woody species diversity and above-ground biomass(AGB)productivity in early-stage forest development.Data were collected in two experimental forest stands in the Czech Republic,where trees were cut with varying intensities with the density of residual(uncut)trees ranging from 0 to 275 trees per hectare.All trees were mapped and their sizes were measured before cutting and then,either as a stump with sprouts or a residual tree,remeasured 11 years later.In addition,all tree saplings were mapped and measured 11 years after logging,and their origin(sprout or seed)was identified.To assess abundances and productivity,we estimated AGB of all2,685 sprouting stumps of 19 woody species and 504 generative(i.e.,seed origin)individuals of 16 woody species,using allometric equations.Mixed-effects models were used to analyze the effects of each regeneration strategy on woody species diversity and the total AGB under varying densities of residual trees.Nonmetric multidimensional scaling was used to evaluate the effect of regeneration strategies on species composition.AGB and diversity of sprouts were significantly higher than those of seed regeneration.Sprouts formed on average97.1%of the total regeneration AGB in H ady and 98.6%in Sobe s ice.The average species richness of sprouts was4.7 in H ady and 2.2 in Sob e sice,while the species richness of seed regeneration averaged 2.1 and 1.1 in H ady and Sob e sice,respectively.Increasing density of residual trees reduced AGB and diversity of both sprouts and seed regeneration,but seed regeneration was affected to a greater extent.Residual trees had an especially strong inhibitory effect on the establishment of seed regeneration.Consequently,seed-originated saplings were nearly absent in plots with high residual tree density,and abundant sprouts accounted for most of the AGB and diversity.However,unlike sprouts whose species composition resembled that of the original stand,seed regeneration brought in new species,enriching the stand?s overall species pool and beta diversity.Our results demonstrated differential roles of sprout and seed regeneration in the early stage of forest succession.Sprout regeneration was the main source of woody AGB productivity as well as species diversity,and its importance increased with the increasing density of standing mature trees.The results indicate the crucial yet previously underestimated role of sprout regeneration in post-disturbance forest dynamics.They suggest that the presence of residual mature trees,whether retained after partial cutting or undisturbed,can substantially suppress seed regeneration while the role of sprout regeneration in early succession becomes more distinctly evident.

Effect of Seed Sizes on the Growth and Establishment of Seedlings of Sheanut Tree （Vitellaria paradoxa）

Seed size can influence germination, emergence and further development of plants to produce high yield. Therefore, pot trial was conducted to assess the effects of seed sizes on growth and establishment of sheanut tree seedlings （Vitellaria paradoxa） in tlae southern Guinea savanna of Nigeria. Seedlings produced from large sized seed had higher germination （80%） than those from medium （70%） and small （65%） sized seeds. Number of days to emergence of seedling from large-sized seed planting was 30 days, 49 days for small- and medium-sized seeds. Large sized seeds had higher N, P, K, Ca and Mg contents compared with small and medium sized seeds. Generally, seedlings from large sized seeds had about 1.5 times more leaves than medium sized seeds and about 2 times more leaves than small sized seeds at 8, 10, 12, 14 and 16 weeks after planting （WAP）. Seedlings from large sized seeds were taller and had larger stem girth （at 16WAP） than those from medium sized seeds. Variations in seedling growth from seed sizes could be of operational importance in nursery management as seeds can be sown according to size to improve uniformity. However, further studies to ascertain if the superior growth of seedlings from large sized seeds will lead to higher yield is recommended.

Variability in cone,seed and seedling characteristics of Pinus kesiya Royle ex.Gordon

Investigations were made to determine the nature and extent of variations present for 10 morphological characters of cone,seed and seedlings of 17 plus trees（PTs）of Pinus kesiya growing in eastern Himalayas（Meghalaya state） of India.The significant variations has been observed in cone weight,cone length,cone diameter,seed length,seed diameter,seed weight,number of seeds per cone,seed germination,seedling height and seedling collar diameter among different PTs of the species.Significant positive correlation（p ／ 0.01） between seed weight,cone length and cone diameter showed that seed weight in P.kesiya depend more on the cone size.Seed germination is found positively correlated（p ／ 0.01） with seed weight,seed diameter,cone size and number of seeds per cone in the study.Among geographical factors,latitude and altitude are found positively correlated（p ／ 0.05） with cone weight and seed diameter,respectively.The genetic parameters for seed,cone and seedlings of PTs of P.kesiya also showed a wide range of variability in terms of variance,coefficient of variability,broad sense heritability,genetic advance and genetic gain.Seed weight,seeds per cone and seedling diameter showed high heritability values（[75） coupled with maximum genetic gain.Traits with such values indicate the presence of good amount of heritable additive components and are under strong genetic control.The findings of the study revealed that PTs expressed both phenotypic and genotypic differences in the seed,cone and seedling characters,which may be attributed to the differences in genetic makeup of various PTs and environmental factors i.e.genotypic and environmental interaction.The presence of high variability in P.kesiya PTs for different characters provide further opportunities to improve the population in subsequent generations so as to establish this species as an important timber tree to be grown on less fertile and degraded soils in its distributional ranges.

Lipase Catalyzed Synthesis of Medium-chain Biodiesel from Cinnamonum camphora Seed Oil

The non-edible camphor tree seed oil was extracted and catalyzed by immobilized lipase for biodiesel production. The oil yield from camphor tree seeds reached 35.2% of seed weight by twice microwave-assisted extractions. Gas chromatography showed that free fatty acid content in camphor tree seed oil was 1.88%, and the main fatty acids were capric acid(53.4%) and lauric acid(38.7%). With immobilized lipase Candida sp. 99–125as catalyst, several important factors for reaction conditions were examined through orthogonal experiments.The optimum conditions were obtained: water content and enzyme loading were both 15% with a molar ratio of 1:3.5(oil/ethanol), and the process of alcoholysis was in nine steps at 40 °C for 24 h, with agitation at170 r·min-1. As a result, the medium-chain biodiesel yield was 93.5%. The immobilized lipase was stable when it was used repeatedly for 210 h.

Genetic Variation among <i>Cucurbita pepo</i>Accessions Varying in Seed Nutrition and Seed Size

Pumpkin seed (Cucurbita pepo L.) is a nutritionally valuable food and a significant source of income globally. Pumpkin seeds are rich in oil, protein, unsaturated fatty acids and tocopherols, which are associated with improved human health. Understanding the genetic diversity among pumpkin accessions varying in seed nutrition traits is necessary for designing sound breeding strategies for developing superior cultivars. In the current study, 26 simple sequence repeats (SSR) markers were used to assess genetic relatedness among 29 C. pepo accessions varying in seed oil, seed protein, seed-coat phenotype, seed size and fatty acid composition. The SSR markers revealed 102 alleles averaging 3.92 alleles per loci and mean polymorphic information content (PIC) of 0.44. Eleven of the markers had a PIC of ≥0.5. Ward dendrogram and principle component analysis based on seed traits grouped the genotypes into two major clusters corresponding to subspecies pepo and texana, with all the reduced-hull accessions grouping within the former. Collectively, this data suggests wide phenotypic (seed traits) and genotypic variation within C. pepo that may be exploited to develop superior reduced-hull cultivars.

Attributes of Naturally Fallen (Rained) <i>Melaleuca quinquenervia</i>Seeds in Two Habitat Types of South Florida Wetlands

Melaleuca quinquenervia is an Australian tree that has successfully invaded many habitats in Florida. It maintains an aerial seed bank in serotinous capsular fruits held in the tree canopies. These fruits open gradually and shed seeds that fall (rain) throughout the year. Comparative attributes (quantities and qualities) of these fallen seeds from different habitats and tree size categories are unknown. We documented these attributes of fallen M. quinquenervia seeds for 12 months among three tree size categories from each of the two hydrologically delineated habitat types. Quantities (8961 seeds m2&middot;mo-1) and the viability (8.8%) and germinability (8.4%) of fallen melaleuca seeds in the occasionally inundated habitat were significantly higher (P = 0.05) than the quantities (6716 seeds m2&middot;mo-1), and viability (5.6%) and germinability (5.3%) of melaleuca seeds in the permanently inundated habitat. Although relatively more seeds rained from larger trees, higher quality seeds were rained from the trees of smaller dimensions. Smaller trees typically inhabit at the edges of melaleuca stands and hence they may increase the potential for further spread of seeds into the adjacent areas.

Ponderosa Pine Seed Source Test in Nebraska in the Central Great Plains of the United States

Ponderosa pine (Pinus ponderosa Laws) has been planted widely in the Great Plains for wind breaks. A 1968 study recommended using material from south-central South Dakota and north-central Nebraska. A second test to further delineate seed sources (families) from numerous collection sites in this region was established in 1986. This paper reports results for survival, height, diameter, and D2H (diameter squared X height) measurements at 15 years. Results identify a wide range of suitable families within the region. A majority of the tested sources performed well, thus verifying the original recommendations.

Photoperiod and Nitrogen Supply Limit the Scope of Northward Migration and Seed Transfer of Black Spruce in a Future Climate Associated with Doubled Atmospheric CO2 Concentration

The predicated changes in precipitation and temperature associated with the continued elevation of atmospheric CO2 concentration will trigger the northward shift of the Climate Envelopes for 130 North America tree species by as much as 10 degrees. However, climate envelope models do not take into account changes in other factors that may also influence the survival and growth of plants at the predicted new locations, such as photoperiod and nutrient regimes. This study investigated how photoperiod and nitrogen supply would affect the ecophysiological traits of black spruce (Picea mariana (Mill) B. S. P.) that are critical for survival and growth at new locations predicted by climate envelope models. We exposed black spruce seedlings to the photoperiod regime at the seed origin (PS) and that 10° north of the seed origin (PNM) as predicted by climate envelope models under the current and doubled atmospheric CO2 concentration and different levels of N supply (30 vs. 300 μmol·mol-1 N). We found that the PNM and the 30 μmol·mol-1 N supply both had negative impact on the development of seedling cold hardiness in the fall, and led to earlier burst of the terminal bud and greater rate of mortality in the following growing season. While the PNM stimulated seedling growth in the first growing season, the effect was not sustained in the second growing season. Our results suggest that the photoperiod regimes and poor nutrient conditions at higher latitudes will likely constrain the scope of the northward migration or seed transfer of black spruce.

Seed and Wasp Production in the Mutualism of Figs and Fig Wasps

Figs (Moracea: Ficus) and fig wasps (Hymenoptera: Chlocloids: Agaonideae) depend on each other to complete their reproduction. Monoecious fig species and their pollinating wasps are in conflict over the use of fig ovaries which can either produce one seed or one wasp. From observation on Ficus virens Ait., we showed that female flowers with outer layer of ovaries (near to the wall of syconium) had no significant difference from that with inner and interval layer of ovaries (near to the syconium cavity), in which most seeds and wasps were produced. This meant that fig tree provided the same potential resource for seed and wasps production. Observation indicated that there was usually only one foundress in syconium at female flower phase and no com- petition pollinators. Measurement of the style length of female flowers and the ovipositor of pollinators indicated that most ovaries could be reached by pollinator’s ovipositor. However, at the male flower phase, production of seeds was significantly more than that of wasps including non-pollinating wasps but there was no significant difference between seed and pollinating wasp production when without non-pollinating wasps produced. This result indicated that non-pollinating wasps competed ovaries not with seeds but with pollinating wasps for ovipositing. Bagged experiment showed that the sampling fig species was not self-sterile which was important for figs and wasps to survive bad season. Seed production in self-pollinated figs was not significantly different from total wasps in- cluding non-pollinating ones. This might be related with the weaker competition among wasps since bagged figs were not easy to reach by wasps from outside.

Soil Seed Bank Characteristics in Congolese Rainforests and Implications for Post-Logging Plots Reforestation

The soil seed bank is considered as an important mechanism for the natural regeneration, resilience and conservation of the forests after disturbances. This study evaluates the characteristics of the soil seed bank in two post-logging plots of Loundoungou-Toukoulaka Forest Management Unit: one plot exploited in 2008 and another exploited in 2021. In each study plot, 40 samples were collected per soil layer (0 - 5 cm, 5 - 10 cm, 10 - 15 cm, 15 - 20 cm and 20 - 25 cm depth). The species diversity and abundance of the soil seed bank were estimated after soil samples were brought to germination. The results demonstrated that 347 seedlings belonging to 37 species in the plot exploited in 2008 and 418 seedlings belonging to 27 species in that exploited in 2021 germinated during 20 weeks of monitoring. The total densities of the seedlings identified were respectively 1446 seedlings/m2 and 1742 seedlings/m2. The plot exploited in 2021 presented a higher proportion of herbaceous species (93.78%) compared to that exploited in 2008 (82.71%). Two pioneer species were recorded in the plot exploited in 2008. These are Macaranga barteri (0.29%) in the 0 - 5 cm layer and Musanga cecropioides (2.31%) up to 20 cm deep. On the other hand, in the plot exploited in 2021, Macaranga spinosa (0.96%) in the 0 - 5 cm layer and M. cecropioides (0.96%) up to 20 cm deep were identified. In the plot exploited in 2008, the 20 - 25 cm layer demonstrated important proportions in woody species (9%), these are in particular Rubiaceae sp.4 and Nauclea diderrichii. While that exploited in 2021, presented 19% of woody species, namely the species of Rubiaceae sp.4, Rubiaceae sp.5 and N. diderrichii, greatly exceeding the proportions obtained in the 15 - 20 cm layer of the two plots. Nonetheless, N. diderrichii was the only commercial species recorded with densities of 108 seedlings/m2 and 4 seedlings/m2, respectively in the plot exploited in 2008 and that exploited in 2021. Commercial tree species are poorly represented in the soil seed bank. Consequently, the study suggests that to improve the natural regeneration of the commercial species, silvicultural interventions based on planting techniques in the exploited plots should be more effective in order to sustainably manage these production forests.

日本落叶松种子园和人工林优树自由授粉家系苗期选择

探究日本落叶松种子园和人工林优树自由授粉家系苗期生长性状遗传变异规律,为优良家系造林和后期遗传改良提供参考。以沙坝国家落叶松/云杉良种基地日本落叶松初级无性系种子园25个自由授粉家系和30个人工林优树自由授粉家系为试验材料,种子园混合种子苗作为对照,田间试验采用随机完全区组试验设计,在沙坝国家落叶松云杉良种基地苗木培育圃进行苗期生长试验。数据采用SPSS 16.0进行方差分析、多重比较,并估算遗传力和遗传增益,以2年生苗地径、苗高、新梢生长量为指标,采用Brykin多性状综合评定法进行家系评价和选择。种子园、人工林优树自由授粉家系1年生苗和2年生苗生长性状(地径、苗高、2年生苗新梢生长量)具有丰富的遗传变异,生长性状间具有显著(P<0.05)或极显著(P<0.01)正相关关系,家系选择潜力大。种子园自由授粉家系2年生苗地径、苗高、新梢生长量的表型变异系数分别是27.61%、36.82%、44.28%,家系遗传力依次为0.76、0.79、0.79,人工林优树自由授粉家系地径、苗高、新梢生长量的表型变异系数分别是25.57%、32.94%、38.83%,家系遗传力依次为0.90、0.92、0.92,属较高遗传力。家系生长性状受强的遗传控制,具有一定的稳定遗传能力,家系选择的遗传增益显著。按照50%的入选率初步选择苗期表现好的优良家系,种子园有种1、种25、种8、种34、种26、种12、种16、种20、种2、种100、种7、种21、种101共13个家系入选,入选家系地径、苗高、新梢生长量的遗传增益达到1.89%、6.18%、7.65%;人工林优树自由授粉家系有优19、优8、优2、优28、优30、优3、优7、优1、优18、优6、优15、优26、优25、优24、优13共15个家系入选,入选家系的地径、苗高、新梢生长量的遗传增益分别是3.73%、9.31%、11.19%。不论种子园还是人工林优树自由授粉家系,采用Brykin综合评价法选择的优良家系恰好是将苗高最大的家系入选。因此,建议日本落叶松自由授粉家系苗期采用单一性状——苗高作为评价和选择指标,会更加直观、经济、有效。在50%的入选率下,种子园、人工林优树自由授粉家系苗期分别有13个和15个家系入选,苗期初选家系为造林试验和后期遗传改良提供参考,有效减小田间试验规模,提高选择效率。苗高作为评价和选择指标,在生产中更加直观、方便、实用。

檀香紫檀优树及其嫁接无性系间种子形态和萌发特征变异

檀香紫檀是世界上最为名贵的红木树种之一,其在我国的规模发展受制于种子生产。最近中国林业科学研究院热带林业研究所利用优树材料在海南岛尖峰岭营建了檀香紫檀嫁接无性系采种园,目前已开花结实,其种子品质及其与优树间差异尚待研究。以海南岛尖峰岭中国林业科学研究院热带林业研究所试验站引种园檀香紫檀6株优树及其在采种园内的嫁接无性系为对象,采集种子测定其形态性状,并采用双层滤纸法开展种子萌发试验。结果表明:(1)无论是优树还是其嫁接无性系,其种子形态性状的变异系数远小于芽苗生长性状,种子千粒重的变异系数最小,说明其芽苗生长变异较种子形态变异更丰富;(2)檀香紫檀优树间种子长度差异显著(P<0.05),以7号优树为最大,嫁接无性系间种子长度、宽度和厚度均差异显著,其长度和宽度以9^(#)号无性系为最大,厚度以7^(#)号无性系为最大;(3)优树间和无性系间种子发芽率、发芽势差异显著,优树中发芽率和发芽势分别以3号和9号为最高,无性系则均以5^(#)号为最高,优树间上胚轴、下胚轴和胚根长度以及芽苗总长度均差异显著,均以3号优树为最大,无性系间胚根长度和芽苗总长度差异显著,均以7^(#)号无性系为最大,说明优树间和无性系间种子萌发和芽苗生长均存在丰富变异;(4)优树与其对应无性系间种子形态、萌发和芽苗生长性状差异显著性因基因型而异,整体而言,无性系的种子长度和宽度大于其对应优树,其种子发芽和芽苗生长表现优于其对应优树;(5)相关性分析表明,种子千粒重与发芽率极显著(P<0.01),种子越饱满,发芽率越高。总而言之,檀香紫檀采种园的种子在形态和萌发上整体优于引种园的优树;而且种子千粒重在优树间、嫁接无性系间以及优树与其对应无性系间均差异不显著(P≥0.05),采种园种子较为饱满,其总体均值接近100 g,超过早期散生嫁接植株(92.9 g)。研究结果为檀香紫檀良种选育、种子园营建和壮苗培育提供科学依据。

蔷薇科果树种子休眠特性及化学处理方法的研究进展

蔷薇科果树种子具有特有的休眠特性,种子在常规条件下萌发较困难,为通过杂交选育优良品种带来了很大局限性。本文较系统地综述了蔷薇科果树种子的结构特点、生理休眠和种皮因素限制种子萌发的特性,并重点阐述了利用化学药剂处理提高不同亚科种子萌发率的研究进展,旨在揭示其在种子萌发处理技术探究方面的共性和差异,为今后蔷薇科种子高效萌发技术研发提供线索依据。

日本落叶松种子园和优树自由授粉家系选择与利用研究

在甘肃小陇山沙坝落叶松/云杉良种基地,采用完全随机区组试验设计,对25个种子园的自由授粉家系和30个优树自由授粉家系在日本落叶松采伐迹地进行了更新造林试验,应用SPSS16.0和ASReml v3.0对造林9年生数据进行了统计分析。结果表明:不论是种子园自由授粉家系还是优树自由授粉家系试验林,树高、胸径、材积等性状家系间具有丰富的遗传变异,家系不同性状间具有显著的相关性,表型变异系数和遗传变异系数最大的是材积。种子园自由授粉家系试验林树高、胸径、材积的家系遗传力和单株遗传力为0.492、0.680、0.694和0.093、0.162、0.171,优树自由授粉家系试验林树高、胸径、材积的家系遗传力和单株遗传力为0.560、0.544、0.496和0.128、0.109、0.096,家系性状遗传力大于单株遗传力,家系性状受到中等以上的遗传控制,家系选择潜力大。根据种子园自由授粉家系亲本育种值指导初级无性系种子园去劣疏伐、改建1.5代种子园。以材积为主要选择指标,兼顾胸径、树高,在家系择基础上配合单株选择,从种子园自由授粉家系和优树自由授粉家系各选择20个优良单株构建高阶生产群体,高阶生产群体的预期遗传增益和现实增益分别达到25.74%、22.85%和122.59%、154.22%。从种子园自由授粉家系选择的50个单株作为构建遗传改良群体的应用材料,将优树自由授粉家系选择的45个单株作为育种群体的补充材料,构建遗传品质不断提高和遗传基础不断拓展的改良群体应用材料。

基于分层叠加的机载LiDAR点云单木分割

【目的】提出一种基于分层叠加的单木分割算法,以充分利用高密度激光雷达点云信息,提高林分中下层单木分割精度。【方法】区别于传统将冠顶点作为聚类种子点的单木分割算法,基于分层叠加的单木分割算法以点云水平切片后各层的局部最大值为种子点进行分层聚类,并通过分层叠加与迭代优化,减少枝杈等因素导致的过分割现象,在保证上层树单木分割精度的同时提高对中下层单木的提取能力。【结果】基于分层叠加的单木分割算法在不同密度落叶松林分均有较高单木分割精度,提取单木与实测单木总体匹配成功率最高达94%,在中高密度林分匹配成功率最高达92%,相较其他算法,对中下层单木的匹配率可提高20%~40%;在单木树高提取精度方面,单木提取树高与实测树高相关系数为0.8,相对均方根误差为8.45%,提取冠幅与实测冠幅相关系数最高为0.83,相对均方根误差为16.5%。【结论】通过分层聚类、聚类种子点优化选取,充分利用林分各层次点云信息,可提高单木分割精度,为森林经营管理提供高精度数据支持。