首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Protein synthetic activity of polysomes isolated during dehydration-rehydration cycles of black locust seedlings (Robiniapseudoacacia L.) was investigated. Polysomes of black locust seedlings were reduced by only 20% during water stress and were capable of incorporating 3H-leucine into peptide chins. RNase activity increased during stress and declined following irrigation. The presence of a protective mechanism is suggested which, if present in other drought hardy species, could help to explain the ability of these species to withstand various levels of water stress.  相似文献   

2.
为明确黄土高原丘陵区第三副区典型流域-甘肃天水罗玉沟流域刺槐生长过程及其与气候关系随海拔变化的规律。利用树木年代学方法分别建立高、中、低3个海拔刺槐的标准年表,并分析不同海拔刺槐径向生长过程以及对气候变化的响应。研究结果表明:(1)中、低海拔刺槐径向生长与温度因素多为负相关,而高海拔刺槐径向生长与温度因素多呈正相关。高海拔刺槐生长与上一年生长季(6月)、休眠期(当年3—4月)和当年生长季(6月)均温、最低温和最高温呈显著正相关,其中受最低温影响最显著;中、低海拔刺槐与上一年生长季和当年生长季的均温、最高温和最低温呈显著负相关,低海拔受均温影响显著。(2)随海拔升高,刺槐径向生长与降水和相对湿度的正相关呈降低趋势。低海拔刺槐生长与上一年生长季(7—9月)和当年生长季(6—9月)降水、相对湿度呈显著正相关,中海拔刺槐与当年生长季(6—9月)降水、相对湿度呈显著正相关,而高海拔刺槐生长与上一年生长季(6—7月)相对湿度呈显著负相关。(3)低海拔刺槐与上一年6月—当年10月帕默尔干旱指数(PDSI)呈显著正相关;中海拔刺槐与上一年6月和当年2—10月PDSI呈显著正相关;高海拔刺槐与上一年6—...  相似文献   

3.
NaCl和Na2SO4胁迫下两种刺槐叶肉细胞叶绿体超微结构   总被引:3,自引:0,他引:3  
二倍体刺槐(diploid Robinia pseudoacacia)是我国水土保持林的先锋树种,具有较强的适应性和抗逆性,对改善生态环境、防治水土流失、调节水文状况有重要作用。四倍体刺槐(tetraploid Robinia pseudoacacia)是二倍体刺槐的加倍品种,也称多倍体刺槐,由韩国引进,具有速生、耐盐碱、耐干旱和耐烟尘等特点。目前,关于四倍体刺槐的研究,主要集中于栽培技术和繁殖技术方面,而关于四倍体刺槐叶片超微结构与其耐盐性的关系尚缺乏报道。比较了二倍体刺槐和四倍体刺槐在NaCl和Na2SO4胁迫下,叶片叶绿体超微结构的变化特点,一方面可以对二者的耐盐性进行鉴定,同时也可以探讨不同盐分胁迫条件下的作用机制。利用NaCl和Na2SO4进行20d的盐胁迫处理,观察叶绿体超微结构的变化特点,发现:NaCl处理前,二者叶肉细胞叶绿体为梭形、形态饱满、结构完整,NaCl处理后10d时,二倍体刺槐的叶绿体出现变形、膜模糊、基粒片层松散、类囊体解体、脂质球增多等现象,NaCl处理后20d时,叶绿体肿胀、变形,基粒片层断裂,膜系统解体。Na2SO4处理后10d时,二倍体刺槐的叶绿体肿胀,膜模糊,基粒片层松散、类囊体解体,Na2SO4盐胁迫处理后20d时,膜系统全部解体,结构破坏更为严重。总体来说,四倍体刺槐在盐胁迫后叶绿体结构变化不明显,只是在Na2SO4处理20d时,四倍体刺槐的叶绿体出现中空、基粒片层松散、膜边缘模糊现象。在处理前,两种刺槐的叶绿体均紧贴细胞壁,分布于细胞壁边缘。在NaCl处理后10d时,二倍体刺槐的叶绿体仍呈有序排列,紧贴细胞壁,但在处理后20d时,大部分叶绿体脱离细胞壁,呈随机分布。在Na2SO4处理后10d时,二倍体刺槐部分叶绿体脱离细胞壁,位于细胞中央。在Na2SO4处理后20d时,二倍体刺槐叶绿体大部分与细胞壁脱离。四倍体刺槐在两种盐胁迫处理前后叶绿体的排列变化不明显,均分布于细胞壁边缘,紧贴细胞壁。所以在盐胁迫下,耐盐植物叶片的叶绿体表现为结构完整,基粒片层清晰,类囊体结构完整,而不耐盐植物则表现为叶绿体超微结构松散、变形,基粒片层模糊,破坏严重时基粒片层扭曲,叶绿体解体,失去完整结构。  相似文献   

4.
Rice  Steven K.  Westerman  Bryant  Federici  Robert 《Plant Ecology》2004,174(1):97-107
We investigated the influence of the exotic nitrogen-fixing black locust (Robinia pseudoacacia) on nitrogen cycling in a pitch pine (Pinus rigida) −scrub oak (Quercus ilicifolia, Q. prinoides) ecosystem. Within paired pine-oak and adjacent black locust stands that were the result of a 20-35 year-old invasion, we evaluated soil nutrient contents, soil nitrogen transformation rates, and annual litterfall biomass and nitrogen concentrations. In the A horizon, black locust soils had 1.3-3.2 times greater nitrogen concentration relative to soils within pine-oak stands. Black locust soils also had elevated levels of P and Ca, net nitrification rates and total net N-mineralization rates. Net nitrification rates were 25-120 times greater in black locust than in pine-oak stands. Elevated net N-mineralization rates in black locust stands were associated with an abundance of high nitrogen, low lignin leaf litter, with 86 kg N ha–1 yr–1 in leaf litter returned compared with 19 kg N ha–1 yr–1 in pine-oak stands. This difference resulted from a two-fold greater litterfall mass combined with increased litter nitrogen concentration in black locust stands (1.1% and 2.6% N for scrub oak and black locust litter, respectively). Thus, black locust supplements soil nitrogen pools, increases nitrogen return in litterfall, and enhances soil nitrogen mineralization rates when it invades nutrient poor, pine-oak ecosystems. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

5.
全球气候变化导致的区域森林生长衰退和死亡普遍发生,并对森林生态系统结构和组成以及主要生态系统服务功能产生重要影响,然而相关研究在国内还显偏少。根据黄土高原延安羊圈沟小流域人工刺槐林健康和衰退个体分别构建了刺槐健康和衰退树轮年表,并对人工刺槐林健康和衰退年表特征及对气候响应敏感性进行了对比分析。结果表明刺槐衰退年表质量较低,其年表统计参量,包括平均敏感度、样芯间相关系数、信噪比和样本群体代表系数均要低于刺槐健康年表。刺槐衰退年表在生活史早期(1985-2007年)与生长健康年表的波动趋势相类似,而在生活史晚期(2008-2016年)与健康年表指数出现生长分离现象,生长速率明显偏低。年表与气候要素响应分析表明刺槐生长衰退年表对气候要素响应敏感性要低于刺槐生长健康年表,但是两者均含有干旱胁迫气候信号,主要体现在与温度呈负相关关系,与降雨和干旱指数的正相关关系。年表与极端气候年份的时序叠加分析表明,生长健康和衰退年表对极端干旱年份响应敏感性均较高,表明极端干旱胁迫条件对刺槐生长健康和衰退个体均有抑制性影响;生长健康年表对极端湿润年份响应敏感性明显高于衰退年表,表明刺槐健康个体比衰退个体更能有效利用湿润年份有利条件,而具有较高的生长速率。研究揭示出黄土高原健康和衰退刺槐个体生长趋势变化及对气候响应敏感性均存在明显差异性,将为气候变化背景下人工刺槐林生长衰退和死亡预测模型建立提供科学依据,因而对黄土高原人工刺槐林生态恢复和保护及可持续经营具有科学价值。  相似文献   

6.
刺槐是广泛分布于黄土高原的典型水土保持植物。以黄土丘陵区甘肃天水吕二沟小流域为研究区,分析了刺槐径向生长过程及其对气候因子的响应,并开展了利用刺槐年轮估算小流域年径流量、年输沙量的适用性评估。研究表明:(1)吕二沟刺槐人工林的径向生长随林龄呈明显的下降趋势,在幼龄林阶段(1—10 a)刺槐处于快速径向生长期((4.17±0.74)mm/a),之后逐渐下降,中龄林、成熟林、过熟林阶段(11—40 a)平均生长速率为(2.31±0.41)mm/a,较前期下降了44.60%。刺槐胸高断面积增量(BAI)在1—10 a平均以(5.46±2.13)cm2/a的速度生长,在11—40 a仍保持上升趋势但年际间生长波动较大,生长速率平均为(10.80±1.95)cm2/a,流域刺槐生长并未发生明显衰退。(2)刺槐的径向生长与温度多呈负相关,与降水、相对湿度及帕默尔干旱指数(PDSI)多呈正相关。其中刺槐径向生长与上年8月、9月(P<0.05)及当年7月均温、最高温呈显著负相关(P<0.01),与当年5月最低温呈显著正相关(P<0.05);...  相似文献   

7.
根据黄土高原南北样带尺度的人工刺槐林(Robinia pseudoacacia)的年轮宽度资料,分析了该地区刺槐树木生长趋势,以及刺槐年表对气候响应随降雨梯度变化规律。研究结果表明延安以北的刺槐样点(绥德、神木)年轮指数近期趋于下降,树木有生长衰退现象;而延安以南刺槐样点(延安、富县、宜君、永寿)年轮指数近期趋于上升,树木无生长衰退现象。气候响应结果表明,刺槐年表对气候响应均以延安样点最为敏感,表现年表与温度的负相关关系,以及年表与降雨和干旱指数的正相关关系,而延安以北和以南刺槐样点对气候响应敏感性均较低。黄土高原中部延安地区地处森林草原过渡带,刺槐生长对外界环境变化最为敏感,年表中气候信号也较强;延安以南地区地处森林植被带,气候条件较为适宜刺槐林生长,因而年表中气候信号较弱;延安以北地区地处草原植被带,气候条件比较恶劣,刺槐生长对干旱气候已有一定适应性特征,因而年表中气候信号也较弱。  相似文献   

8.
A harmonious interspecies relationship is the key to the success of mixed afforestation. This study was conducted to assess the responses of afforestation species to their neighboring trees. We examined five types of stands—monocultures of Chinese pine (Pinus tabuliformis), black locust (Robinia pseudoacacia), sea‐buckthorn (Hippophae rhamnoides), and two mixtures (Chinese pine × black locust mixture and Chinese pine × sea‐buckthorn mixture)—in the Loess Plateau, northwestern China. The height and diameter at breast height of each tree species were measured, and rhizosphere soil, shoot, and root were sampled. In monocultures, black locust was taller than Chinese pine and sea‐buckthorn, while the height of Chinese pine and sea‐buckthorn was similar. In mixtures, Chinese pine grew better with sea‐buckthorn than alone as a result of modified soil properties and plant nutrition, but not with black locust. When Chinese pine was used as neighbors, it affected the level of arbuscular mycorrhizal (AM) colonization of black locust, soil properties and AM fungal spore density of black locust and sea‐buckthorn, but did not significantly affect their growth. Our results suggest that the reciprocal effects between tree species in mixture are not symmetric, and thus planning for efficient mixed afforestation requires knowledge of species‐specific growth rate, nutrient requirements, and species interactions.  相似文献   

9.
Plants growing under natural conditions are constantly exposed to various stress factors, which can restrain their productivity and limit yields. This paper deals with the effect of long- and short-term osmotic stress followed by recovery on the formation of polysomes and their stability during germination of pea (Pisum sativum L.) seeds. By isolating polysomes, it is possible to obtain an index which evidences the ability of tissues to synthesize proteins. Changes in the distribution of polysomes often precede measurable changes in amounts of proteins. Under osmotic stress, the dominant population of polysomes was the population of free polysomes (FP). The share of membrane-bound polysomes (MBP) and cytoskeleton-bound polysomes (CBP) and cytoskeleton-membrane-bound polysomes (CMBP) in the total fraction of ribosomes increased under intensive (−1.0 and −1.5 MPa) osmotic stress. These results can suggest that the bound forms of polysomes play an important role in the synthesis of stress proteins. In addition, the stability of polysomes isolated from pea early seedlings growing under unstressed control and osmotic stress conditions was tested. It turned out that polysomes formed under osmotic stress conditions (especially the CMBP) were more resistant to the activity of exogenous ribonucleases than the polysomes in the control samples. Under stress conditions it is highly likely that ribosomes become more densely packed on mRNA thus making it more resistant to ribonuclease. This is just one of the many mechanisms regulating stability of mRNA.  相似文献   

10.
In Japan the black locust (Robinia pseudoacacia L.) is undergoing rapid habitat expansion, which has an adverse effect on native vegetation. It is therefore a priority to clarify the regeneration characteristics of the black locust and establish adequate management of this invasive species in Japan. To determine the germination characteristics of physically dormant black locust seeds, we observed anatomical features of the seed coat and identified the water gap that acts as a signal detector. Our microscopic observations showed that seed coats of this species had hilum, micropyle and strophiole. The anatomical features of these regions correspond to the general characteristics of papilionoid legume seeds. Based on our microscopic observations, water absorption blocking experiments and a dye tracking experiment, we identified the strophiole as a water gap in black locust seeds. Our results suggest that the opening of the strophiole is important for water uptake to the embryo and subsequent germination of black locust seeds under natural conditions.  相似文献   

11.
记述了采自北京刺槐上的1种中国的记录外来蚜虫——刺槐附毛斑蚜,它原产于北美,寄主为刺槐,在当地一些地区较为常见,并已扩散到欧洲等地。描述了有翅孤雌蚜、无翅雌性蚜和有翅雄性蚜的鉴别特征,并提供了生态图片。最后讨论了它的潜在危害性及蚜虫寄主植物、蚜群生活状及生态照片在蚜虫识别上的重要性。  相似文献   

12.
Soil nitrogen mineralisation and nitrification potentials, and soil solution chemistry were measured in black locust (Robinia pseudo-acacia L.), in pine-mixed hardwood stands on an early successional watershed (WS6), and in an older growth oak-hickory forest located on an adjacent, mixed hardwood watershed (WS14) at Coweeta Hydrologic laboratory, in the southern Appalachian mountains, U.S.A. Nitrification potentials were higher in black locust and pine-mixed hardwood early successional stands than in the oak-hickory forest of the older growth watershed. Ammonification rates were the main factor controlling nitrification in the early successional stands. There was no evidence of inhibition of nitrification in soils from the older growth oak-hickory forest site.Within the early successional watershed, black locust sites had net mineralisation and nitrification rates at least twice as high as those in the pine mixed-hardwood stands. Concentrations of exchangeable nitrate in the soil of black locust stands were higher than in pine-mixed hardwoods at 0–15 cm in March and they were also higher at 0–15, 16–30 and 31–45 cm depth in the black locust dominated sites in July. Soil solution nitrate concentrations were higher under black locust than under pine-mixed hardwoods. Areas dominated by the nitrogen fixing black locust had greater nitrogen mineralisation and nitrification rates, resulting in higher potential for leaching losses of nitrate from the soil column in the early successional watershed.  相似文献   

13.
A living wood fiber (LWF) is one that retains the living protoplast. LWFs store numerous starch grains during the dormant period. In black locust (Robinia pseudoacacia), almost all wood fibers in the outer part of the annual ring are LWFs. In the outermost ring, starch is accumulated during the summer, retained in winter, and metabolized during spring. We determined the starch content of LWFs, ray parenchyma, and axial parenchyma using image analysis. More than 70% of the starch grains in the outermost ring were stored in LWFs during winter. After the breakdown of starch in spring, LWFs resulted in cell death. These results indicate that LWFs in black locust function as “single-use” large-capacity starch storage.  相似文献   

14.
The role of gibberellin in the development of cold hardiness in black locust (Robinia pseudoacacia L.) seedlings was investigated. Free and bound gibberellin activities were followed during induction of cold hardiness using ethyl acetate partitioning and pH variation, with subsequent paper chromatographic fractionation and gibberellin bioassay. While total gibberellin activity decreased during the induction of cold hardiness in black locust seedlings, no convincing evidence was found to support conversion of free gibberellin to a bound form. However, bound gibberellin activity did appear to be more stable than did free gibberellin activity during the final stages of cold hardening at freezing temperatures. Gibberellin synthesis was followed using 14C-mevalonate conversion to ent-kaurene in a cell-free extract of the tissue. Ent-kaurene synthesis decreased during cold hardening with no detectable synthesis in fully hardened seedlings. However, since growth cessation precedes development of cold hardiness, decreased gibberellin synthesis and corresponding trends in free and bound fractions might have been expected, and a cause and effect relationship is difficult to establish. Even so, a decline in one step in gibberellin synthesis and a greater stability of bound than free gibberelin activity are associated with induction of cold hardiness in black locust seedlings.  相似文献   

15.
The black locust (Robinia pseudoacacia Linn.) is the dominant tree species in the “grain for green” project on the Loess Plateau (LP) of China, and brings many ecological benefits to this planted region. However, there are concerns regarding its suitability as a plantation forest species in different regions of the LP. We used a dendroclimatological approach to investigate the radial growth response of black locust to varying climate in two sites on the LP with differing precipitation gradients. We took tree-ring samples from black locust in Yongshou County (in the semi-humid southern LP) and Shenmu County (in the semi-arid northern LP), and developed tree-ring width (TRW) chronologies for each. We performed moving correlation analyses between TRW chronologies and aggregated thermal (maximum temperature (TMX), minimum temperature (TMN), mean temperature (TMP)) and hydroclimatic factors (precipitation, self-calibrated Drought Severity Index (scPDSI), and humidity). The results demonstrated the increased influence of thermal factors during autumn, and the generally decreased influence of hydroclimatic factors on black locust radial growth in Yongshou, compared with the decreasing influence of thermal factors (during all seasons) and increasing influence of hydroclimatic factors (precipitation during summer, scPDSI and humidity during autumn) on black locust radial growth in Shenmu. The results indicated that black locust radial growth might benefit from the current climatic conditions in the southern LP. However, black locust radial growth stressed by water availability in the northern LP, which may reduce its vitality and productivity as climate warms in the future. These results have implications for regional forestry planning and ecological restoration strategies on the LP.  相似文献   

16.
To identify why tree growth differs by afforestation type is a matter of prime concern in forestry. A study was conducted to determine why oriental arborvitae (Platycladus orientalis) grows better in the presence of black locust (Robinia pseudoacacia) than in monoculture. Different types of stands (i.e., monocultures and mixture of black locust and oriental arborvitae, and native grassland as a control) were selected in the Loess Plateau, China. The height and diameter at breast height of each tree species were measured, and soil, shoot, and root samples were sampled. The arbuscular mycorrhizal (AM) attributes, shoot and root nutrient status, height and diameter of black locust were not influenced by the presence of oriental arborvitae. For oriental arborvitae, however, growing in mixture increased height and diameter and reduced shoot Mn, Ca, and Mg contents, AM fungal spore density, and colonization rate. Major changes in soil properties also occurred, primarily in soil water, NO3‐N, and available K levels and in soil enzyme activity. The increase in soil water, N, and K availability in the presence of black locust stimulated oriental arborvitae growth, and black locust in the mixed stand seems to suppress the development of AM symbiosis in oriental arborvitae roots, especially the production of AM fungal spores and vesicles, through improving soil water and N levels, thus freeing up carbon to fuel plant growth. Overall, the presence of black locust favored oriental arborvitae growth directly by improving soil water and fertility and indirectly by repressing AM symbiosis in oriental arborvitae roots.  相似文献   

17.
An improved salt tolerance black locust (Robinia pseudoacacia L. ) seedlings can be obtained after seed soakes in 250 ppm multi-effect triazole(MET),through which plant growth is inhibited, relative water content(RWC) of plants is increased , and permeability of plasmic membrane is reduced. The contents of the free prolines in the seedlings under the saline stress of the black locust through the treatment either the seeds being soaked in MET or in water may be increased . However, the content of putrescine of black locust seedlings after seed soaked in MET was reduced under stress,showing the accumulation of putrescine was related to water state of plants.  相似文献   

18.
Fixation of river flow passages and riverbed degradation may facilitate the development of higher floodplains with the establishment of exotic species such as black locust (Robinia pseudoacacia L.). We quantitatively evaluated the relationship between nitrogen (N) levels in black locust trees and in sediments under different flood disturbance regimes in a riparian area of the Chikuma River. In this study, allometric equations were developed for relating leaf N content to diameter at breast height of black locust. The amount of leaf N in black locust increased with distance from the river, reaching 159 kg N ha−1 at 180 m from the river. There was a small difference in N content between green and fallen leaves (0.2%), and so the leaf N was almost equivalent to N input to riparian sediments. Fine sediments accumulated on the riparian area, where the amount of sediments N increased with distance from the river, ranging from 1091 ± 767 to 4953 ± 2953 kg N ha−1. The N accumulation rates also increased with distance from the river, corresponding with the amount of leaf N in black locust per unit area, but the former exceeded the latter. The sediment N accumulation might be accelerated by sediment trapping effect due to riparian vegetation itself. A large input of N provided by invaded black locust might alter nutrient dynamics and native plant community structure in the riparian area.  相似文献   

19.
Robinia pseudoacacia, a nitrogen-fixing, clonal tree species native to the central Appalachian and Ozark Mountains, is considered to be one of the top 100 worldwide woody plant invaders. We initiated this project to determine the impact of black locust (Robinia pseudoacacia) on an upland coastal ecosystem and to estimate the spread of this species within Cape Cod National Seashore (CCNS). We censused 20 × 20 m plots for vegetation cover and environmental characteristics in the center of twenty randomly-selected Robinia pseudoacacia stands. Additionally, paired plots were surveyed under native overstory stands, comprised largely of pitch pine (Pinus rigida) and mixed pitch pine–oak (Quercus velutina and Quercus alba) communities. These native stands were located 20 m from the edge of the sampled locust stand and had similar land use histories. To determine the historical distribution of black locust in CCNS, we digitized and georeferenced historical and current aerial photographs of randomly-selected stands. Ordination analyses revealed striking community-level differences between locust and pine–oak stands in their immediate vicinity. Understory nonnative species richness and abundance values were significantly higher under Robinia stands than under the paired native stands. Additionally, animal-dispersed plant species tended to occur in closer stands, suggesting their spread between locust stands. Robinia stand area significantly decreased from the 1970’s to 2002, prompting us to recommend no management action of black locust and a monitoring program and possible removal of associated animal-dispersed species. The introduction of a novel functional type (nitrogen-fixing tree) into this xeric, nutrient-poor, upland forested ecosystem resulted in ‘islands of invasion’ within this resistant system.  相似文献   

20.
盐胁迫下刺槐无性系生长和矿质营养平衡研究   总被引:7,自引:1,他引:7  
以一年生盆栽刺槐无性系BH327和B56为材料,对盐胁迫下刺槐无性系生长和矿质营养平衡进行了研究。结果表明:盐胁迫下BH56生长受抑不明显,组织水平上K^+、Ca^2+、Mg^2+保持较高水平,尤其是在高盐下上部叶片足Ca^2+、Mg^2+的选择性吸收增强;而BH327,的生长受盐胁迫明显的抑制,组织水平上K^+、Ca^2+、Mg^2-水平相对较低,在高盐下上部叶片对Ca^2-、Mg^2+的选择性吸收能力低于BH56。同时,从体内离子分配及选择性运输角度讨论了各无性系盐伤害或耐盐的原因。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号