共查询到20条相似文献，搜索用时 562 毫秒
1.
赣南纽荷尔脐橙叶片微量元素含量状况 总被引：10，自引：2，他引：8
为了解赣南产区纽荷尔脐橙叶片黄化原因,2008年对赣南9个县（市、区）121个脐橙园脐橙叶片微量元素进行了分析。结果表明,叶片Fe、Mn、Zn、Cu、B和Mo的含量分别为（127.90 ± 21.15）、（115.79 ± 136.72）、（16.50 ± 4.05）、（8.42 ± 9.32）、（81.88 ± 33.72）和（0.36 ± 0.14）mg · kg-1;在各脐橙园中,叶片Mo、Fe、Mn、B、Cu和Zn含量处于适量及以上水平的分别占100%、99.17%、90.91%、92.56%、62.81%和4.96%,叶片Fe、Mn、B、Cu和Zn含量处于低量水平的分别占0.83%、7.44%、7.44%、29.75%和23.97%,处于缺乏水平的仅有Mn、Cu和Zn,分别占1.65%、7.44%和71.07%。表明赣南产区脐橙叶片普遍无Mo、Fe、Mn和B缺乏问题,部分产区脐橙叶片Cu含量偏低,大多数脐橙叶片的Zn含量处于缺乏水平,生产上需要重视补充Zn肥,适量补充Cu肥。 相似文献
2.
M. Agustí V. Almela M. Juan C. Mesejo A. Martinez-Fuentes 《The Journal of Horticultural Science and Biotechnology》2013,88(4):554-558
SummaryThe influence of three rootstocks, Carrizo citrange (Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf.), Cleopatra mandarin (Citrus reshni Hort. ex Tanaka) and sour orange (Citrus aurantium L.) on the incidence and severity of rind breakdown in ‘Navelate’ sweet oranges was studied over seven years in four orchards. The proportion of affected fruit was greater in trees on Carrizo citrange (60% on an average) followed by Cleopatra mandarin (38%) and then on sour orange (9%). There were also significant differences in the severity of the disorder among rootstocks; more than 35% and 20% of fruit from trees on Carrizo citrange and Cleopatra mandarin, respectively, were rejected for commercialization, whereas only 4% of fruit on sour orange was rejected. Cryo-scanning electron microscopy (SEM) of fruit peduncles showed that average diameter of xylem vessel elements of peduncles of fruits on Carrizo citrange rootstock were 6% and 17% larger than those on Cleopatra mandarin and sour orange, respectively. Defoliation of fruit-bearing branches reduced water loss from fruit, maintained fruit peel water potential at a higher value than that of fruit on undefoliated branches and reduced the proportion and severity of affected fruit. It is concluded that fruit-tree water relationships are related to rind breakdown in ‘Navelate’ oranges and low fruit water content might be responsible for the disorder. 相似文献
3.
A GIS-based method for the reconstruction of the late eighteenth century forest vegetation in the Prignitz region (NE Germany) 总被引：1，自引：0，他引：1
Our goal was to reconstruct the late eighteenth century forest vegetation of the Prignitz region (NE Germany) at a scale of
1:50,000. We also wanted to relate the historical forest vegetation to the actual and potential natural vegetation. For these
purposes, we selected 15 woody species and transferred relevant data found in historical records from various sources together
with the recent localities of (very) old individuals belonging to these woody species into ArcView GIS. Following multi-step
data processing including the generation of a point density layer using a moving window with kernel estimation and derivation
of vegetation units applying Boolean algebra rules together with information on site conditions, we derived 17 forest communities
corresponding to the potential natural vegetation. We were able to reconstruct the historical forest vegetation for 90% of
the forest area ca. 1780. Only two of the 17 forest communities covered large parts of the forested area. The oak forest with
Agrostis capillaris covered about 44% of the total forest area, and alder forests on fenland made up about 37%. Oak-hornbeam forests with Stellaria holostea comprised slightly less than 6% of the forest area, while all other forest communities comprised less than 1%. The historical
forest vegetation is more similar to the potential forest vegetation and quite different from the actual forest vegetation
because coniferous tree species currently cover approximately two-thirds of the actual forest area. The most beneficial result
of this study is the map of high-resolution historical vegetation units that may serve as the basis for various further studies,
e.g., modelling long-term changes in biodiversity at the landscape scale. 相似文献
4.
Land use practices since European settlement have had profound effects on the composition and structure of certain forested ecosystems in the southeastern U.S. Coastal Plain. One significant change since the turn of the century has been the invasion of upland pine forests by sand pine in the state of Florida panhandle and peninsula. This study quantified sand pine extent and expansion and examined links between sand pine distribution and environmental factors in the Florida panhandle. Geographic information system analysis using aerial photographs (1949 and 1994) showed sand pine expansion and also increased canopy cover of sand pine over time. There was a high rate of conversion of longleaf pine to sand pine from 1949 to 1994 (44%), and conversion of sparse sand pine stands to dense sand pine stands (69%). Therefore, widespread changes in the Florida landscape were evident during a relatively short time period. Adjacency analyses showed a strong negative association between longleaf pine and dense sand pine and a positive association between riparian vegetation and dense sand pine. Distribution of sand pine across elevation demonstrated that sand pine expanded inland and upland into longleaf-pine forests. In 1949, sand pine was selectively located on sites below 30 m in elevations; by 1994, sparse and moderately dense sand-pine stands were found at all elevations. Thus, any area that may receive an input of sand pine seeds, most notably from riparian areas, is vulnerable to establishment. 相似文献
5.
6.
Response of vegetation and fire to Little Ice Age climate change: regional continuity and landscape heterogeneity 总被引：1，自引：0，他引：1
Late-Holocene climatic conditions in the upper Great Lakes region have changed sufficiently to produce significant changes in vegetation and fire regimes. The objective of this study was to determine how the vegetation mosaic and fire regimes on an oak (Quercus spp.)- and pine (Pinus spp.)-dominated sand plain in northwestern Wisconsin responded to climatic changes of the past 1,200 years. We used pollen and charcoal records from a network of sites to investigate the range of natural variability of vegetation on a 1,500-km2 landscape on the southern part of the sand plain. A major vegetation shift from jack pine (Pinus banksiana) and red pine (P. resinosa) to increased abundance of white pine (P. strobus) occurred between 700 and 600 calendar years before present (cal yr BP), apparently corresponding to more mesic conditions regionally. A decrease in charcoal accumulation rate also occurred at most sites but was not synchronous with the vegetation change. At some sites there were further changes in vegetation and fire regimes occurring ～500–300 cal yr BP, but these changes were not as strong or unidirectional as those that occurred 700–600 cal yr BP. Our results suggest that both the composition and the distribution of vegetation of the southern part of the sand plain have been sensitive to relatively small climatic changes, and that the vegetation at the time of European settlement was a transitory phenomenon, rather than a long-term stable condition. 相似文献
7.
柑橘果实膳食纤维的研究 总被引：31，自引：1，他引：31
以柠檬、玉环柚、椪柑、脐橙、温州蜜柑和胡柚为试材,测定了果皮和果肉中总膳食纤维(TDF)、不溶性膳食纤维(IDF)、水溶性膳食纤维(SDF)、中性洗涤剂纤维(NDF)、酸性洗涤剂纤维(ADF)、纤维素(CEL)、半纤维素(HC)、木质素(Lignin)、总果胶(TP)、原果胶(Protopectin)和水溶解性果胶(WSP)含量。以柚和温州蜜柑为试材,分别测定了不同的发育阶段膳食纤维及其具体组分的含量,总结了不同发育阶段果实膳食纤维的变化情况。结果表明,除柠檬和脐橙果肉的SDF含量稍多于果皮中含量外,其他各组分均是果皮中的含量大于果肉。除果皮中TDF和IDF的品种间变异较小外,其它组分在品种间的变异均较大。除HC外,各组分在果肉中的变异均大于果皮。柠檬果实中TDF、SDF、NDF、ADF、CEL、木质素和WSP含量都高于其它柑橘类水果。柚和温州蜜柑TDF和IDF随着果实的成熟而有所下降,但降幅不明显;而SDF则随着发育阶段的推移而渐渐增加。 相似文献
8.
Combining top-down and bottom-up dynamics in land use modeling: exploring the future of abandoned farmlands in Europe with the Dyna-CLUE model 总被引：9，自引：0，他引：9
Land use change is the result of interactions between processes operating at different scales. Simulation models at regional
to global scales are often incapable of including locally determined processes of land use change. This paper introduces a
modeling approach that integrates demand-driven changes in land area with locally determined conversion processes. The model
is illustrated with an application for European land use. Interactions between changing demands for agricultural land and
vegetation processes leading to the re-growth of (semi-) natural vegetation on abandoned farmland are explicitly addressed.
Succession of natural vegetation is simulated based on the spatial variation in biophysical and management related conditions,
while the dynamics of the agricultural area are determined by a global multi-sector model. The results allow an exploration
of the future dynamics of European land use and landscapes. The model approach is similarly suitable for other regions and
processes where large scale processes interact with local dynamics. 相似文献
9.
Variations in landscape patterns and vegetation cover between 1957 and 1994 in a semiarid Mediterranean ecosystem 总被引：9，自引：2，他引：9
Alodos C.L. Pueyo Y. Barrantes O. Escós J. Giner L. Robles A.B. 《Landscape Ecology》2004,19(5):543-559
The aim of this study was to analyze the main processes that determine changes in landscape patterns and vegetation cover from 1957-1994 to develop a model for land cover dynamics. Land cover and landscape patterns were assessed and compared using aerial photographs taken in 1957, 1985, and 1994. Over this period, tall grass steppe and arid garrigues increased by 6% and 4%, respectively, while crop fields decreased by 15% and tall arid brush remained the same. Over the same period, tall grass steppes and arid garrigues became less fragmented.Changes in land use were triggered by socioeconomic forces, which were constrained by the underlying structure of the physical landscape. The best preserved vegetation (tall arid brushes) was concentrated at higher elevations, with a pronounced slope, not oriented towards the sea, and in volcanic substrate. Communities tended to be better preserved further away from towns and at lower house densities. Tall grass steppe was present on more gradual sea-oriented slope and in calcareous substrate, and increased at higher elevations, although not far from the town but away from high anthropogenic influence. Previous studies have revealed that traditional land uses of this landscape, particularly grazing, favoured the transition from tall arid brush to tall grass steppe. In this study, we analyzed to what extent the underlying structure of the physical landscape imposes limitations to the vulnerability to human activity of the main vegetation types. According to the data on the probability of vegetation transition over the 37-year period, the shift from tall arid brush to tall grass steppe appeared to be favoured by gradual slopes. Tall arid brush recovered from either arid garrigues or tall grass steppes at steeper slopes. Thus, steep terrain had a favourable effect on the formation of brushwood and more gradual terrain favoured tall grass steppe. The prevalent trends were confirmed by a projection of a transition matrix over 100 years.This revised version was published online in May 2005 with corrections to the Cover Date. 相似文献
10.
Landscape history of a calcareous (alvar) grassland in Hanila,western Estonia,during the last three hundred years 总被引：10，自引：4，他引：6
The landscape history of the largest calcareous seminatural alvar site (ca. 700 ha) in Estonia, is described with the help of a historical map from 1705 and aerial photographs from 1951, and recent vegetation mapping from 1994–1996. The seminatural, species rich alvar grasslands originate and are maintained by grazing of domestic animals. Three hundred years ago the area was mainly open grassland with sparse shrubs and some fields. Forty years ago the vegetation pattern was similar, with some smaller forests and forest clear-cut areas present. Now, since grazing has ceased for ca. 40 years, only 30% of the area remains as open grassland and 70% as forest. Identification of clusters of field layer vegetation using the program TABORD resulted in 8 clusters, which agreed with the empirically determined community types. The field layer within the young pine forest (up to 20 year old pines) is similar to the open alvar grassland. In older forests, the field layer has already changed. There were no phytosociological differences found between ancient grasslands and grasslands on former arable fields or forest clear-cut areas. Decrease in species richness, compared to open grassland, was most drastic in forests of age 20–40 years where the canopy was most closed. Forests have spread more extensively in areas with deeper soil. The continuation of traditional management (grazing and tree cutting) in alvar grasslands is urgently needed in order to keep seminatural alvar grasslands open. The possibility to restore open grasslands remains as long as there is a pool of grassland species available, especially in younger forests. 相似文献
11.
蕉柑起源与分类地位的研究 总被引：4，自引：0，他引：4
从植物学形态特征、孢粉学、核型、过氧化物酶（ＰＯＸ）同工酶等方面综合比较分析了蕉柑与两个甜橙品种（雪柑、柳橙）、两个桔类品种（红桔、碰柑）的异同。结果表明，蕉柑的多数性状表现为橙、桔的中间状态，有些性状表现倾向甜橙或桔类。多项遗传指标分析说明，蕉柑系起源于甜检和桔类的杂种，并为蕉柑的分类地位提供了科学证据。 相似文献
12.
宽皮柑橘单核苷酸多态性的高分辨率熔解曲线分型 总被引：4，自引：1，他引：3
高分辨率熔解曲线分析（High resolution melting analysis,HRM）可以检测单碱基改变引起的DNA双链熔解温度（Tm）值变化,从而可以对样本在单核苷酸多态性分子标记（Single nucleotide polymor- phism,SNP）上进行基因分型。通过分析NCBI数据库中宽皮柑橘的表达序列标签（Expressed sequence tag,EST）数据鉴别SNP位点,并用小片段扩增法高分辨率熔解曲线分型技术（High resolution melting analysis of small amplicons）分析11个宽皮柑橘（Citrus reticulata）品种以及柳橙（Citrus sinensis Osbeck var.‘Liucheng’）的5个SNP位点的基因型。结果显示,小片段扩增法高分辨率熔解曲线分型可以快速、清楚地分辨纯合与杂合基因型,在校正温度差异后也可以很好地分辨同一个SNP位点不同的纯合型。统计分析表明样本在所有SNP位点上均存在多态性,5个SNP位点的平均多态性信息含量（PIC）为0.3190,显示样本在这组SNP位点上具有较高的杂合率。 相似文献
13.
粤引红脐橙品种树形呈自然圆头形,树势中等,成枝力强,枝梢较开张。成花能力强,与枳、枳橙、温州蜜柑和甜橙嫁接表现亲和。果个中等,单果质量180g左右,近球形;闭脐或露脐;果皮橙色,果肉紫红色。可溶性固形物含量15.0%,可滴定酸含量0.876%,维生素C594.0mg/L,总糖116g/L,固酸比17.12:1,肉质脆嫩化渣,风味清甜,有独特芳香味,无核,品质优。成熟期为翌年1月份,耐贮,留树挂果可贮至2月份,常温下常规贮藏,能保存至3月底,品质风味优良。 相似文献
14.
不同柑橘砧木对锦橙果实品质的影响 总被引：5，自引：0，他引：5
2006—2008年连续3年研究11种砧木对铜水72-1锦橙果实品质的影响。结果表明：不同砧木对果实颜色和内在品质均有影响,其中以卡里佐枳橙为砧的果实亮度最好,黄色度值最高,果实最大,果皮最薄;以路比枳为砧的果实红色度值和固酸比（TSS/TA）最高,果皮最厚;以沃尔卡姆为砧的亮度最差,黄色度值、单果质量和可食率最低,中心柱最小;以C35枳橙为砧的中心柱最大且维生素C含量最低;以光皮酸橙为砧的果实红色度最低而可食率最高;以里其16-6枳为砧的果实可溶性固形物（TSS）含量最高;以孙楚沙橘为砧的果实可滴定酸（TA）和维生素C含量最高,而TSS/TA最低;果实TSS和TA最低的砧木为枸头橙。品质综合评价,性状表现较好的为孙楚沙橘、卡里佐枳橙和C35枳橙,而表现较差的为兰普莱檬和沃尔卡姆柠檬。 相似文献
15.
在江西省赣州市章贡区蟠龙镇一个集中连片面积达32hm2且管理粗放的11年生"纽荷尔"脐橙园调查发现,脐橙园蜘蛛分属13科38种。脐橙园树冠层蜘蛛优势种有3种:草间钻头蛛Hylyphantes graminicola全年以5—6月及9—10月的发生数量最大;斑管巢蛛Clubiona deletrix在7—9月发生量较大,2—3月的数量明显减少;鳞纹蟏蛸Tetragnatha squamata在4月和11—12月的种群数量较多,6—9月较少见到。脐橙园地面层蜘蛛优势种有2种:草间钻头蛛的季节消长同样具有两个高峰期,但时间跨度较短,仅在6月和10月出现;拟水狼蛛Pirata subpiraticus种群数量在3月达到最高峰,在12月处于低谷。脐橙园树冠层草间钻头蛛和斑管巢蛛的发生数量都与平均气温和日照时数呈显著或极显著正相关,鳞纹蟏蛸的发生数量则与平均气温间呈显著负相关;地面层拟水狼蛛的发生数量与相对湿度和降雨量间表现出极显著的正相关性。 相似文献
16.
Romaike S. Middendorp Alvaro J. Pérez Armando Molina Eric F. Lambin 《Landscape Ecology》2016,31(7):1581-1599
Context
Natural regenerating forests are rapidly expanding in the tropics. Forest transitions have the potential to restore biodiversity. Spatial targeting of land use policies could improve the biodiversity benefits of reforesting landscapes.Objective
We explored the relative importance of landscape attributes in influencing the potential of tree cover increase to restore native woody plant biodiversity at the landscape scale.Methods
We developed land use scenarios that differed in spatial patterns of reforestation, using the Pangor watershed in the Ecuadorian Andes as a case study. We distinguished between reforestation through natural regeneration of woody vegetation in abandoned fallows and planted forests through managed plantations of exotic species on previously cultivated land. We simulated the restoration of woody plant biodiversity for each scenario using LANDIS-II, a process-based model of forest dynamics. A pair-case comparison of simulated woody plant biodiversity for each scenario was conducted against a random scenario.Results
Species richness in natural regenerating fallows was considerably higher when occurring in: (i) close proximity to remnant forests; (ii) areas with a high percentage of surrounding forest cover; and (iii) compositional heterogeneous landscapes. Reforestation at intermediate altitudes also positively affected restoration of woody plant species. Planted exotic pine forests negatively affected species restoration.Conclusions
Our research contributes to a better understanding of the recolonization processes of regenerating forests. We provide guidelines for reforestation policies that aim to conserve and restore woody plant biodiversity by accounting for landscape attributes.17.
Silviculturally-managed pine plantations within southern Ohio are chronically disturbed patches of introduced vegetation distinct from the surrounding matrix of hardwood forest. To determine the successional pathways by which such pine stands might blend back into the hardwood forest matrix under different types of silvicultural management, we determined the current status of hardwood regeneration under 24 pine stands. Stands of Pinus virginiana (Virginia pine) had the highest density of hardwood seedlings and saplings (20,560 stems ha-1) whereas P. strobus (white pine) stands averaged only 7090 hardwood stems ha-1; P. resinosa (red pine) stands were intermediate. The most abundant hardwood seedling and sapling species under pine canopies were Acer rubrum and Cornus florida. DCA ordination of the seedling + sapling assemblages clustered most of the P. resinosa and P. strobus stands in the center of the ordination along with a group of species which are common in second-growth forests of the area. P. virginiana stands, in contrast, were scattered throughout the ordination space. Most of the woody species common in second-growth forests of the region were also common in the pine understory. Multiple regression indicated that large plantations with deeper litter, higher soil pH and lower total hardwood density had the greatest abundance of mesic-site species in the understory. This relationship did not hold for P. resinosa stands, however, due to more frequent and intense silvicultural intervention. The seed bank was not an important source of woody seedlings to the understory assemblage under intact pine plantations. The vegetation of 1–4 yr old clear-cut sites was dominated by wind and bird dispersed species which were generally absent from the understory of intact plantations. We conclude these chronically disturbed planted patches will revert to matrix vegetation faster if the disturbance is allowed to end in a gradual manner through stand senescence than if it is abruptly ended by clear-cutting. 相似文献
18.
假植大苗定植对脐橙树体生长和产量的影响 总被引：1，自引：0，他引：1
在我国传统的柑橘建园中,种植裸根苗比较普遍,然而,这种种植方式的成活率较低,树体生长缓慢,投产较晚。多年来,在江西赣南脐橙产区建园中,大力推广假植大苗带土定植,即将脐橙苗假植于装有营养土的袋或篓(直径25cm×高30cm),集中管理并提供合适的环境条件,于第2年春梢老熟后(6月份)定植。这一改进,显著提高了成活率。对45个使用该方法的纽荷尔脐橙(Citrussinensiscv.Newhall)园共900株树进行了调查,同时,以传统的裸根苗直接定植作为对照。结果表明,假植大苗定植的树体生长各项指标(干周、树高、冠径和末级梢数量、质量)均明显优于对照;1-5年生幼树各项指标平均值相对于同龄对照有明显增加;4年生树干周、树高、冠径和末级梢数量比对照分别增加42.1%、42.6%、34.1%和31.7%。假植大苗定植第4年、第5年平均株产分别为19.4kg和42.5kg,显著高于同龄对照的5.1kg和27.5kg。假植大苗定植的植株树势一致,树冠形成快,投产早,经济效益显著,值得在生产上推广应用。 相似文献
19.
枳砧椪柑叶片营养元素适宜含量的研究 总被引：1，自引：0，他引：1
对枳砧椪柑叶片营养元素含量适宜范围的统计分析表明:采样地点及年份间的差异对叶片元素含量有重要的影响;叶片各元素含量的变异系数差异较大,且微量元素含量的变异系数多显著高于大量元素。初步提出丰产枳砧椪柑叶片元素含量的适宜范围:氮2.90%～3.50%,磷0.12%～0.16%,钾1.00%～1.70%,钙2.50%～3.70%,镁0.25%～0.50%,铜4.0～16.0×10~(-6),锌20.0～50.0×10~(-6),锰20.0～150.0×10~(-6),铁50.0～140.0×10~(-6),硼20.0～60.0×10~(-6).上列标准可作为营养诊断之参考。 相似文献
20.
基于柑橘多胚性品种存在珠心细胞自然加倍的特点，建立了基于种子催芽、生长室实生播种、幼苗“观根辨叶看油胞”形态初选和流式细胞仪倍性鉴定的发掘柑橘四倍体的快速方法。采用该方法，分别从无酸甜橙、红江橙、贡柑、年橘、新会柑、滑皮金柑的432、506、1 356、1 870、2 749和685株实生苗中，发掘出疑似四倍体5、6、5、17、45、7株；通过倍性检测，从上述6个品种分别获得四倍体4、5、5、14、39、5株，形态初选准确率分别为80.0%、83.3%、100.0%、82.4%、86.7%和71.4%。与之前的四倍体发掘方法相比，本方法四倍体初选准确率高，并且从种子播种到获得四倍体植株耗时不超过40 d。SSR分子鉴定表明，所鉴定的四倍体均来自其二倍体品种珠心细胞自然加倍形成的双二倍体，为柑橘三倍体无核育种提供了珍贵的四倍体亲本资源。 相似文献