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1.
杉木地理种源核型的研究 总被引：3，自引：0，他引：3
为研究杉木地理种源对杉木核型的影响,将20个杉木产区的种子在25℃条件下发芽,当根生长到5厘米时,用8-羟基喹啉预处理,压片观察。杉木染色体是22条,在5个种源内发现了1—2个B-染色体。杉木核型具有多态型,这种多态型表现在随体的形状、位置及上述两个方面特征的杂合性。随体形状有大随体、小随体、复和随体、线形随体和T-随体。随体不仅稳定地位于一对染色体上,而且变动在第一对和第五对染色体上。多数情况下随体位于短臂上,有时在长臂上也出现随体。多变量分析表明:四川德昌的核型是一个独特的类型,基因飘移并不明显,其余19个地区虽然地理分布广泛,但是有较为一致的核型,经纬度对随体的变异影响不大。 相似文献
2.
应用去壁低渗法对２个酸枣类型的染色体数目，核型等研究的结果表明，它们的染色体数目为２ｎ＝２ｘ＝２４，酸枣属于小梁色体植物，两者核型类型均属１Ｂ型，本研究不仅丰富了酸枣的核型资料，并且首次发现酸枣的核型中存在高等植物少见的１Ｂ核型。 相似文献
3.
4个石榴品种的染色体核型分析 总被引：1，自引：0，他引：1
采用常规根尖压片法对4个石榴品种的染色体数目进行了统计,并进行了核型分析。旨在了解品种间演化关系,为石榴品种间分类研究提供细胞学依据。结果表明:4个石榴品种的染色体数都为18,且核型不对称性类型均为2B型,说明4个品种间的染色体核型变异不大。但核型仍然存在一定的差异,芽变新品种白玉和其母本的核型公式相似,说明两者亲缘关系较近,但母本的臂比大于2的染色体占11.11%,而白玉为22.22%,说明前者较后者原始。大笨子与玉石籽的核型公式具有一定的相似性,说明两者之间亲缘关系也较近。单就臂比大于2的比例来看,芽变新品种白玉较其它3个品种进化。从核型来看,白玉及其母本比另2个品种的核型不对称性强。4个石榴品种的染色体都具有随体,且随体位置相同,但是随体大小稍有不同。4个石榴品种的染色体总体积亦不相同。 相似文献
4.
青海产四种沙棘的核型分析 总被引：6，自引：0，他引：6
对青海产4种沙棘的染色体数目和核型通过可比性研究,结果表明:4个种的染色体数目均为2n=24,所有的染色体具中部着丝粒,核型归属于2A;棱果沙棘(H.goniocarpa Lian,X.L.Chen et K.Sun)的核型不对称系数As.k％=54.2％,随体在第四对染色体上;肋果沙棘(H.neurocarpa)的随体在第三对染色体上,As.k％=51.8％;西藏沙棘(H.tibetana)的随体在第三对染色体上,As.k％=50.5％;而中国沙棘(H.rhamnoidessubsp.sinensis)的随体分别在第一、第二、第三对染色体上,As.k％=50.4％.其中棱果沙棘的核型尚属首次报道。 相似文献
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核型分析在四种落叶松种子鉴别中的研究 总被引：1，自引：0，他引：1
一个物种恒定的、具有其特点的单倍体敷的染色体组,称为这个物种的核型。染色体是遗传基因的载体,它体现着遗传特性和变异现象。染色体的形态和效目依不同物种而异,而且色体的形态和数目,对于鉴别种是非常重要的.四种落叶松(兴安落叶松、长自落叶松、华北落叶松、日本落叶松)种子的鉴别在林业生产上一直是个难题.本文力求利用核型比较稳定、具有可重复性的特点,对四种落叶松的核型进行比较研究,以确定各种落叶松的特征染色体及其核型的差异,作为不同种鉴 相似文献
7.
八个杉木地理种源的核型分析 总被引：2，自引：0，他引：2
对八个杉木不同地理种源进行核型分析,结果表明,其染色体数目均为2n=12,其中广西融水杉木的核型公式为2n=22=22m(2SATs),其他种源第7对染色体为近中着丝粒,核型公式为2n=22=20m(2SATs)+2sm。核型类型为1B,第4对染色体短臂上有一对随体。融水杉木少数分裂相发现有一条B染色体,在研究中发现,同源染色体两成员长度差异对数多(核型杂合程度高)的种源,均系属于优良种源。而差异对数少的种源为一般种源(会同杉木除外),核型杂合程度的高低。可作为判定种源优劣的一种标志。 相似文献
8.
对８个不同杉木地理种源的Ｎ－带带型进行分析，结果表明，Ｎ－显带染色体随体及其相对应的短臂末端均为深着色．着丝粒区域多数有两个明显的小点，其大小、形状和位置与ｃｄ（ｃｅｈｔｒｏｍｅｒｅｄｏｔ）带相同．Ｎ－带显带难度不大，重现性好．易于检出随体染色体、随体的形状和大小，以及着丝位位置．对提高核型分析水平有一定的意义． 相似文献
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本文对山茶属金花茶组植物的核型特征进行了初步探讨。该组植物的核型特征为:染色体数目2n=30,染色体属于中等大小染色体,染色体组主要由中部和近中部着丝点染色体组成,随体数目为0—1对。核型属于“2A”、“1B”和“2B”类型,为对称性较强的核型类型。本文还研究了四种金花茶的核型。弄岗金花茶2n=30=26m(2SAT)+4sm;陇瑞金花茶2n=30=26m(2SAT)+4sm;武鸣金花茶2n=30=26m+4sm;凹脉金花茶2n=30=20m+10sm(2SAT)。其中陇瑞、弄岗和武鸣金花茶的核型为首次报道。 相似文献
11.
The foliar chemistry of diseased and healthy trees was studied one growing season after severe reduction in living crown caused by Gremmeniella abietina in four young Scots pine (Pinus sylvestris) stands. Sample trees were chosen pairwise on the basis of the living crown length: a diseased tree with about 50% live crown reduction and a healthy tree in each pair. Fifteen elements were determined in the youngest healthy needles on the lateral top shoots of each sample tree. Diseased trees had higher foliar boron, manganese and sodium concentrations and lower magnesium, iron, zinc, copper, potassium, nitrogen and sulphur concentrations compared to the healthy trees. Foliar calcium, aluminium, phosphorus, carbon and hydrogen concentrations did not differ between the diseased and healthy trees, except for P and A1 in two of the stands when the stands were analysed separately. Significant correlations between the needle element concentrations and crown ratio (length of the living crown/tree height) were found especially for B (increasing B with decreasing crown ratio) and for Mg, Fe and Zn (decreasing concentrations with decreasing crown ratio). The effect of G. abietina-induced living crown reduction on tree nutrient status and the role of these mineral nutrients in the susceptibility are discussed. 相似文献
12.
对无人机遥感影像中单木树冠进行检测与分割并获取树冠冠幅与树冠面积参数,可以为城市中不同场景下的林业资源调查提供高效快捷的途径。以银杏树为研究对象,创建基于无人机遥感影像的银杏单木树冠数据集,并使用卷积神经网络Mask R-CNN算法结合正射影像图对城市中不同场景下的树冠进行检测和树冠边界勾绘以获取相关树冠参数。结果表明,加入无人机银杏树冠影像数据集训练后的网络模型,可以较好地适用于城市不同场景下的银杏单木树冠检测与分割。在4个测试场景下的86棵银杏单木树冠目标总体查准率达到93.90%,召回率达到89.53%,F1-score为91.66%,平均精度均值为90.86%,且可以提取到较为准确的银杏单木树冠的冠幅值与树冠面积,预测冠幅的平均相对误差与均方根误差分别为7.50%和0.55,预测树冠面积的平均相对误差与均方根误差分别为11.15%和2.48。将无人机影像与深度学习算法结合应用到城市林业资源调查中,可以得到较为准确的树冠检测与轮廓分割结果,有效地提高城市林业资源调查效率。 相似文献
13.
【目的】对Kozak方程进行修正,采用树木易测因子为预测变量,构建人工樟子松树冠外部轮廓预估模型,为研究树木生理和树木竞争提供依据,为模拟单木树冠表面积和树冠体积奠定基础。【方法】基于黑龙江省14块固定样地70株人工樟子松解析木907个最大枝条数据,以Kozak方程基本形式为基础并对其进行修正,选出构建人工樟子松树冠外部轮廓基础模型的最优模型形式。在最优模型基础上,建立分别考虑样地效应、样木效应及同时考虑样地和样木效应两水平的非线性混合效应模型。利用R软件的nlme软件包求解非线性混合效应模型参数,采用AIC、BIC、-2LL对混合效应模型中不同随机效应参数组合形式、不同随机效应矩阵、方差-协方差矩阵和方差函数进行比较,选出最优模型形式,并对人工樟子松外部轮廓随树木因子的变化规律进行探讨。以林分密度为哑变量,构建不同密度的人工樟子松树冠外部轮廓预估模型。【结果】人工樟子松树冠外部轮廓预估模型因子包含胸径(DBH)、冠长率(CR)和高径比(HD)。与基础模型相比,分别考虑样地效应、样木效应的混合模型能够显著提高模型拟合效果,外部轮廓模型差异主要来源于样木效应。以样木为单水平的混合效应模型中,a2、a6为随机参数,对角矩阵为方差-协方差矩阵形式,ARMA(1,1)为解释组内方差的矩阵,采用幂函数消除异方差的模型形式为最优模型。同时考虑样地和样木效应两水平混合模型的拟合效果较单水平混合模型有所提高。以两水平混合模型的固定效应部分模拟外部轮廓与树木因子之间的关系,在分别固定另外2个变量的情况下,树冠半径随着DBH、CR增大均逐渐增大,树冠上半部分半径随着HD增大而增大,下半部分半径随着HD增大而减小。外部轮廓拐点的变化范围为0.6250~0.9170,拐点平均位置为0.8413,随着林木在林分中被压强度增大,拐点位置向树冠基部移动。密度小于1000株·hm^-2林分中单木的冠形与1000~2000株·hm^-2和大于2000株·hm^-2林分中单木的冠形区别很大。【结论】修正后的Kozak模型满足梢头处半径为0、在整个树冠范围内存在拐点且拐点唯一的特性,能够对人工樟子松树冠外部轮廓进行合理模拟及预测。两水平非线性混合效应模型可显著提高模型拟合效果,能够在树冠外部轮廓模型中应用。 相似文献
14.
[目的]以湖南省黄丰桥国有林场杉木纯林为研究对象,进行树木竞争指数的研究,基于Hegyi简单竞争指数的形式,提出包含反映树冠特征因子的树冠竞争指数。[方法]将树冠竞争指数和Hegyi简单竞争指数分别与胸径增长量进行相关分析。[结果]Kendall's tau-b系数、Spearman's rho系数和相关系数R2均显示树冠竞争指数与林木生长量的相关性高于Hegyi简单竞争指数。[结论]该结果表明树冠竞争指数与林木生长量有更强的相关性,可以更好地体现树冠在树木生长中的作用,能作为模拟林分生长量的依据。 相似文献
15.
以湖南攸县黄丰桥国有林场为试验区,以1块林分边界规整的典型杉木人工同龄纯林为研究对象,测定林木胸径、树高、冠幅、冠高与活枝下高等测树因子及林木位置信息。研究冠形曲线函数,利用Direct 3D技术,实现冠形控制下的参数化林木模拟。研究林木模型格式转换方法,为林分场景构建提供模型数据,结合MOGRE技术,研究林分场景模拟技术方法,实现林分场景可视化模拟。结果表明：参数化林木个体建模算法简单适用,测树因子信息可直接用于林木个体可视化模拟,所建模型可体现林木个体差异,形态逼真;利用MOGRE技术可快速、有效模拟林分场景,所建场景真实感较强。此方法所需数据易于获取,适用性强,可对林木个体及林分场景进行逼真模拟,可为研究林木竞争关系、林分生长、林分结构与林分经营提供新思路。 相似文献
16.
Inherited narrow crown form, harvest index and stem biomass production in Norway spruce, Picea abies
The effect of crown form on stem biomass production was investigated in an 18-19-year-old Norway spruce stand (Picea abies (L.) Karst.). The harvest index was 0.271 in pendula trees, which have a heritable narrow crown form, and 0.235 in normal-crowned trees and the dry weights of stem biomass were 2.57 kg and 3.37 kg, respectively. However, the production of stem biomass per crown projected area was more than twice as much in pendula trees as in normal-crowned trees. Results indicate that the crown form of pendula spruce is less plastic than that of normal-crowned spruce suggesting that such trees might maintain a high stemwood yield per unit ground area with increasing stand density. Because pendula spruce has a higher harvest index and a less flexible crown than normal-crowned spruce, it might be useful for crop tree ideotype breeding. 相似文献
17.
We studied the relationships among 5-year radial (diameter and basal area) growth of red oak (genus Quercus, subgenus Erythrobalanus) crop trees and predictor variables representing individual tree vigor, distance-dependant competition measures, and distance-independent competition measures. The red oaks we examined are representative of the commercially and ecologically important oak species of the bottomland hardwood forests of the southeastern US. The crown class score, a quantitative measure of crown class and tree vigor, performed best in accounting for the variability in tree diameter growth. Plot-level variables failed to account for a significant proportion of the variability in tree radial growth. The basal area of the first-order neighbors that were taller than the crop trees and located within 2.4 times the mean overstory crown radius had the highest negative correlation with crop tree 5-year radial growth. Red oaks were a major part of these competitors and likely exerted the greatest competitive pressure. However, crop tree radial growth was positively associated with the basal area of the red oaks which were indirect (second order) neighbors and which were taller than the crop trees. It is possible that indirect neighbors do not compete with the crop trees, but they likely compete with the direct competitors of the crop trees, thus having an indirect positive influence on crop tree growth. Such reasoning is consistent with previously observed spatial dependence up to four times the mean overstory crown radius. The findings may have implications for thinning hardwoods stands and crop tree management in that foresters need to take into account (1) oak intra-genus competition, (2) the negative competitive effect of direct neighbors, and (3) the potentially positive effect of the indirect neighbors, the competitors’ competitors. 相似文献
18.
MODELS FOR CROWN STRUCTURE OF LARCH PLANTATION 总被引：1，自引：0，他引：1
INTRODUCTIONToreflecttree'sgrowthactivityandcompetitioneffectsoftree'sdevelopment,someofcrownvariablescanbeusedtode-velopcompetitionindexes(Mitchelll975,BigingandWensell99O,BigingandDobbertin,l992).Thecrownsizedirectlyinfluencestree'sassimilationanditisoneofthebasicvariableforpredictingincrementoftree.TherefOre,inmanygrowthandyieldmod-els,treecrowndimensionsareoftenusedasanimportantcomponent.Crownvariablesintroducedingrowthmodelsasameanstoimprovethepredictiveabilityandaccuracyoftreeors… 相似文献
19.
As a tree management tool, three treatments of crown pruning (total-pruning, half-pruning and no-pruning) were applied to
Vitellaria paradoxa (karité) and Parkia biglobosa (néré) in agroforestry parkland systems in Burkina Faso. The area under each tree was divided into four concentric tree influence
zones (Zones A: up to 2 m from the tree trunk, B: up to half of the radius of the tree crown, C: up to the edge of the tree
crown and D: up to 2 m away from the edge of the tree crown). Millet production under these zones and outside was assessed
during two cropping seasons over the study period of three years and the results showed that tree crown pruning had significant
effect on millet production and the highest millet grain yield and total dry matter were produced under total-pruned trees
(507 ± 49 and 2033 ± 236 kg ha−1 year−1, respectively). Light transmission, transpiration and soil nutrient status under the trees were also analysed in relation
to millet production. The results of the analysis showed that total-pruned trees gave the highest millet production due to
the reduction by crown pruning of the effects of large tree crowns on PAR transmission below crowns and rates of transpiration
by trees. Soil was more fertile closer to the tree trunks than outside tree crowns. This may also be one of the reasons why
millet overall performed better under Zone B than outside tree crowns. The higher production of millet under Zone B than under
Zone A, the zone closer to the tree trunk, may be due to lower light intensity and more intense competition for water between
trees and crops under Zone A. It was concluded that at least in the short term millet production could be improved by crown
pruning of both karité and néré, but long term effects may depend on the ability of the trees to maintain the amelioration
of soil fertility and on how quickly the trees recover from pruning.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
20.
There is a lack of knowledge to identify and classify forest structures according to the risk of crown fires, especially in
Mediterranean regions. In this study, for the first time, we use real information, obtained after a wildfire that burnt under
extreme meteorological conditions, to classify forest structures of Pinus halepensis into fuel types as a function of crown fire potential. We identified fourteen forest structures which characterize many forest
types in Western Mediterranean areas depending on canopy closure, number of tree layers, percent of each tree layer and overall
tree density. By using the pattern of fire types that burnt the most numerous forest structures, we have identified four fire
hazard groups of forest structures which are considered different fuel types. The first two had the lowest risk of active
crown fires and they differed in the proportion of surface fires and passive crown fires. The third fuel type was the threshold
between structures with low and high extreme fire behavior; while the fourth had a high risk of active crown fires. Firefighters
and forest managers who are demanding this kind of schema, will test and upgrade this classification of fuel types in function
of crown fire potential during future wildfires. 相似文献