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1.
Water is a limiting factor in the restoration and construction of desert steppe. Exploring plant water sources is necessary to understand soil-plant interactions and species coexistence; however, water sources of major plant communities within the desert steppe of Ningxia Hui Autonomous Region, China remain poorly understood. In this study, we analyzed the water uptake of plants in four typical communities: Agropyron mongolicum Keng.; Sophora alopecuroids Linn.; Stipa breviflora Griseb., and Achnatherum splendens (Trin.) Nevski communities. Stable isotopes δD and δ18O in the xylem of plant and soil water at different soil depths were analyzed. An IsoSource model was used to determine the soil depths from which plants obtained water. Results showed that A. mongolicum community obtained water predominantly from 0-20 and 40-80 cm depth, S. alopecuroids community from 0-20 cm depth, S. breviflora community from 0-40 cm depth, and A. splendens community from 0-20 and 80-140 cm depths. S. alopecuroides had a wider range of soil depths for water extraction, i.e., utilizing different water sources depending on habitat, and the plasticity of its water uptake pattern determined its role in different communities. Water source of plants relayed heavily on the distribution of their roots. Competition for soil water exists between different plant life forms in the sierozem habitat (A. mongolicum, S. alopecuroids, and S. breviflora communities), and in the sandy soil habitat (A. splendens community). The use of soil water by A. splendens community is more spatially differentiated, and shrubs and herbs can coexist stably. Under the pattern of extended drought period in the future, sierozem habitat may be more favorable for the formation of a dominant monoculture community type of perennial fibrous plants. In aeolian sandy soil habitat, A. splendens had a strong competitive advantage, and the growth of shallow-rooted plants was easily suppressed. 相似文献
2.
阐明斑块尺度上物种共存格局,对于深入认识荒漠草原破碎化草地生物多样性的维持机理具有重要意义。按斑块的土壤生境退化程度,选取短花针茅荒漠草原3类典型群落斑块为研究对象,对比分析不同斑块的物种构成、多样性及物种间的共存关系格局。结果表明：① 斑块A属单优种短花针茅（Stipa breviflora）群落;斑块B为短花针茅+草木樨状黄耆（Astragalus melilotoides）群落;斑块C为苦豆子（Sophora alopecuroides）+老瓜头（Cynanchum komarovii）+猪毛蒿（Artemisia scoparia）群落。② 群落结构中斑块A和斑块B多样性相近,均高于无短花针茅生长的斑块C。③ 基于零模型的分析结果显示,物种共存格局的复杂性和强度为：斑块A>斑块B>斑块C,且下降趋势明显,斑块A存在的16组显著物种对中有4组为显著竞争关系,而斑块C中的物种对减少到7组,且仅存在猪毛蒿与苦豆子组显著竞争物种对。结论：表明未沙化的土壤生境斑块是荒漠草原破碎化草地生物多样性维持的一个重要前提,土壤生境的退化显著降低了斑块内部群落组织的复杂性和物种间相互作用的强度,不利于群落的自我维持。 相似文献
3.
YANG Xinguo 《干旱区科学》2023,15(1):63-76
Maintaining the stability of exotic sand-binding shrub has become a large challenge in arid and semi-arid grassland ecosystems in northern China. We investigated two kinds of shrublands with different BSCs (biological soil crusts) cover in desert steppe in Northwest China to characterize the water sources of shrub (Caragana intermedia Kuang et H. C. Fu) and grass (Artemisia scoparia Waldst. et Kit.) by stable 18O isotopic. Our results showed that both shrublands were subject to persistent soil water deficiency from 2012 to 2017, the minimum soil depth with CV (coefficient of variation) <15% and SWC (soil water content) <6% was 1.4 m in shrubland with open areas lacking obvious BSC cover, and 0.8 m in shrubland covered by mature BSCs. For C. intermedia, a considerable proportion of water sources pointed to the surface soil. Water from BSCs contributed to averages 22.9% and 17.6% of the total for C. intermedia and A. scoparia, respectively. C. intermedia might use more water from BSCs in rainy season than dry season, in contrast to A. scoparia. The relationship between shrub (or grass) and soil water by δ18O shown significant differences in months, which partly verified the potential trends and relations covered by the high variability of the water source at seasonal scale. More fine roots at 0-5 cm soil layer could be found in the surface soil layer covered by BSCs (8000 cm/m3) than without BSCs (3200 cm/m3), which ensured the possibility of using the surface soil water by C. intermedia. The result implies that even under serious soil water deficiency, C. intermedia can use the surface soil water, leading to the coexistence between C. intermedia and A. scoparia. Different with the result from BSCs in desert areas, the natural withdrawal of artificial C. intermedia from desert steppe will be a long-term process, and the highly competitive relationship between shrubs and grasses also determines that its habitat will be maintained in serious drought state for a long time. 相似文献
4.
Amygdalus pedunculata Pall. is a major species that is widely planted in afforested soils with different textures in the transitional zone between Mu Us Desert and Loess Plateau, China. However, the responses of A. pedunculata to increasing intensity of water stress in different textural soils are not clear. Here, we conducted a soil column experiment to evaluate the effects of different textures (sandy and loamy) on water consumption, water use efficiency (WUE), biomass accumulation and ecological adaptability of A. pedunculata under increasing water stress, i.e., 90% (±5%) FC (field capacity), 75% (±5%) FC, 60% (±5%) FC, 45% (±5%) FC and 30% (±5%) FC in 2018. A. pedunculata grown in the sandy soil with the lowest (30% FC) and highest (90% FC) water contents had respectively 21.3%-37.0% and 4.4%-20.4% less transpiration than those with other water treatments (45%-75% FC). In contrast, A. pedunculata transpiration in the loamy soil decreased with decreasing water content. The magnitude of decrease in transpiration increased with increasing level of water deficit (45% and 30% FC). Mean daily and cumulative transpirations of the plant were significantly lower in the sandy soil than in the loamy soil under good water condition (90% FC), but the reverse was noted under water deficit treatments (45% and 30% FC). Plant height, stem diameter and total biomass initially increased with decreasing water content from 90% to 75% FC and then declined under severe water deficit conditions (45% and 30% FC) in the sandy soil. However, these plant parameters decreased with decreasing water content in the loamy soil. WUE in the sandy soil was 7.8%-12.3% higher than that in the loamy soil, which initially increased with decreasing water content from 90% to 75% FC and then declined under water deficit conditions (45% and 30% FC). The study showed that plant transpiration, biomass production and WUE responded differentially to increasing intensity of water stress in the sandy and loamy soils. The contrasting responses of A. pedunculata to water stress in different textural soils can guide future revegetation programs in the northern region of Chinese Loess Plateau by considering plant adaptability to varying soil and water conditions. 相似文献
5.
Jinhu ZHANG 《干旱区科学》2018,10(6):821-832
The complex interactions in desert ecosystems between functional types and environmental conditions could be reflected by plant water use patterns. However, the mechanisms underlying the water use patterns as well as the water sources of Tamarix laxa in the mega-dunes of the Badain Jaran Desert, China, remain unclear. This study investigated the water sources and water use patterns of T. laxa using the stable oxygen isotope method. The δ18O values of xylem water, soil water in different layers (0-200 cm), rainwater, snow water, lake water, atmospheric water vapor, condensate water, and groundwater were measured. The sources of water used by T. laxa were determined using the IsoSource model. The results indicate that T. laxa mainly relies on soil water. At the beginning of the growing season (in May), the species is primarily dependent on water from the middle soil layer (60-120 cm) and deep soil layer (120-200 cm). However, it mainly absorbs water from the shallow soil layer (0-60 cm) as the rainy season commences. In September, water use of T. laxa reverts to the deep soil layer (120-200 cm). The water use patterns of T. laxa are closely linked with heavy precipitation events and soil water content. These findings reveal the drought resistance mechanisms of T. laxa and are of significance for screening species for ecological restoration. 相似文献
6.
从防风根际土壤中筛选得到1株对根腐病具有良好防治效果的拮抗菌株MR-47,基于形态学、ITS序列分析方法对菌株MR-47进行鉴定,确定该菌株为桃色顶孢霉Acremonium persicinum（GenBank No. OK287149.1）。通过对峙培养、显微镜观察,探究了菌株MR-47对木贼镰刀菌Fusarium equiseti的抑菌机理;基于盆栽试验,明确菌株MR-47的定殖能力及防病促生效果。结果表明,菌株MR-47对木贼镰刀菌抑菌率达69.26%,病原菌菌丝出现缢缩、膨大、扭曲、畸形等现象;对尖孢镰刀菌、腐皮镰刀菌等多种病原真菌表现出了良好的广谱抑菌活性;在土壤中定殖35 d内,最大定殖量为8.38×106 CFU/g,最低为5.57×106 CFU/g;MR-47对防风根腐病防效达75.05%。因此,桃色顶孢霉MR-47在防风根腐病的病害管理方面具有较好的开发价值及应用潜力。 相似文献
7.
HUANG Laiming 《干旱区科学》2021,13(7):688-698
Soil water deficit is increasingly threatening the sustainable vegetation restoration and ecological construction on the Loess Plateau of China due to the climate warming and human activities. To determine the response thresholds of Amygdalus pedunculata (AP) and Salix psammophila (SP) to soil water availability under different textural soils, we measured the changes in net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci), leaf water potential (ψw), water use efficiency (WUE) and daily transpiration rate (Td) of the two plant species during soil water content (SWC) decreased from 100% field capacity (FC) to 20% FC in the sandy and loamy soils on the Loess Plateau in the growing season from June to August in 2018. Results showed that Pn, Gs, WUE and Td of AP and SP remained relatively constant at the beginning of soil water deficit but decreased rapidly as plant available soil water content (PASWC) fell below the threshold values in both the sandy and loamy soils. The PASWC thresholds corresponding to Pn, Gs and Ci of AP in the loamy soil (0.61, 0.62 and 0.70, respectively) were lower than those in the sandy soil (0.70, 0.63 and 0.75, respectively), whereas the PASWC thresholds corresponding to Pn, Gs and Ci of SP in the loamy soil (0.63, 0.68 and 0.78, respectively) were higher than those in the sandy soil (0.58, 0.62 and 0.66, respectively). In addition, the PASWC thresholds in relation to Td and WUE of AP (0.60 and 0.58, respectively) and SP (0.62 and 0.60, respectively) in the loamy soil were higher than the corresponding PASWC thresholds of AP (0.58 and 0.52, respectively) and SP (0.55 and 0.56, respectively) in the sandy soil. Furthermore, the PASWC thresholds for the instantaneous gas exchange parameters (e.g., Pn and Gs) at the transient scale were higher than the thresholds for the parameters (e.g., Td) at the daily scale. Our study demonstrates that different plant species and/or different physiological parameters exhibit different thresholds of PASWC and that the thresholds are affected by soil texture. The result can provide guidance for the rational allocation and sustainable management of reforestation species under different soil conditions in the loess regions. 相似文献
8.
HU Xiaoxing 《干旱区科学》2019,11(6):824-836
In the arid and semi-arid areas of China, rainfall and drought affect the growth and photosynthetic activities of plants. Gross primary productivity (GPP) is one of the most important indices that measure the photosynthetic ability of plants. This paper focused on the GPP of two representative grassland species (Stipa krylovii Roshev. and Allium polyrhizum Turcz. ex Regel) to demonstrate the effect of a temporal rainfall on the two species. Our research was conducted in a temperate grassland in New Barag Right Banner, Hulun Buir City, Inner Mongolia Autonomous Region of China, in a dry year 2015. We measured net ecosystem productivity (NEP) and ecosystem respiration flux (ER) using a transparent chamber system and monitored the photosynthetically active radiation (PAR), air and soil temperature and humidity simultaneously. Based on the measured values of NEP and ER, we calculated the GPP of the two species before and after the rainfall. The saturated GPP per aboveground biomass (GPPAGB) of A. polyrhizum remarkably increased from 0.033 (±0.018) to 0.185 (±0.055) μmol CO2/(gdw?s) by 5.6-fold and that of S. krylovii decreased from 0.068 (±0.021) to 0.034 (±0.011) μmol CO2/(gdw?s) by 0.5-fold on the 1st and 2nd d after a 9.1 mm rainfall event compared to the values before the rainfall at low temperatures below 35°C. However, on the 1st and 2nd d after the rainfall, both of the saturated GPPAGB values of S. krylovii and A. polyrhizum were significantly lower at high temperatures above 35°C (0.018 (±0.007) and 0.110 (±0.061) μmol CO2/(gdw?s), respectively) than at low temperatures below 35°C (0.034 (±0.011) and 0.185 (±0.055) μmol CO2/(gdw?s), respectively). The results showed that the GPP responses to the temporal rainfall differed between S. krylovii and A. polyrhizum and strongly negative influenced by temperature. The temporal rainfall seems to be more effective on the GPP of A. polyrhizum than S. krylovii. These differences might be related to the different physiological and structural features, the coexistence of the species and their species-specific survival strategies. 相似文献
9.
Lucerne(Medicago sativa L.) is a deep-rooted perennial leguminous forage with high evapo-transpiration rate exceeding the annual precipitation in semi-arid areas of Northwest China.Groundwater might be the potential water sources of lucerne in the area with shallow groundwater table.In this study,stable isotopic compositions of oxygen and hydrogen(δ18O and δD) of different water sources and xylem sap were analyzed to determine the seasonal(April,June,July and August) and topographic(three slope positions) variations in water sources for lucerne growing in Ningxia eastern semi-arid area adjacent to Mu Us Desert characterized by shallow groundwater table.Iso Source software was used to calculate the probable contribution of different water sources to the total plant water uptake.Stomatal conductance,stem water potential,carbon isotope discrimination(?~(13)C) of whole plant were also determined for evaluating the water status of lucerne growing at different slope positions.The results showed that soil water content increased as the elevation decreased.Oxygen compositions of soil water in the 0–40 cm profile fluctuated considerably.Soil water δ~(18)O values in deep profile(3.5 m) were similar to those in groundwater,implying the recharge of groundwater to this soil layer.Highest water utilization rate from deep soil profile(below 350 cm) was recorded for lucerne grown at the slope position 1(groundwater table depth of 3.5–3.9 m) in April,June and July.The lucernes at slope position 2(groundwater table depth of 5.8–6.4 m) and slope position 3(groundwater table depth 7.1–8.3 m) mostly used water from deep soil layers(below 350 cm) during dry period,and turned to use water from superficial soil layer in wet period.Higher yield,?~(13)C value of whole plant and stomatal conductance were observed for lucerne grown at the slope position 1 than those at other slope positions.These results indicated that groundwater is a significant water source for transpiration of lucerne grown in Ningxia semi-arid area with shallow groundwater table where lucerne grassland is suggested to be established so as to obtain better yield performance. 相似文献
10.
2016—2017年，利用扫网法系统调查了北疆棉田周边的非作物生境中9科13种常见植物上的食蚜蝇种群发生情况。研究发现，食蚜蝇种群密度在不同植物上有显著差异，种群发生高峰主要集中在各种植物开花期，种群消长还与这些植物上的蚜虫发生有明显跟随关系。5—6月，食蚜蝇在大部分植物上都有发生，但主要集中于新疆大蒜芥和罗布麻等；7—8月，在碱蓬、大麻、顶羽菊等上种群密度高；9月，主要在甘草、顶羽菊、罗布麻等上。本研究为今后充分利用棉田周边非作物生境，提升对食蚜蝇种群保育功能及棉花害虫生态控制水平提供了科学依据。 相似文献
11.
Caragana korshinskii Kom. and Tamarix ramosissima Ledeb. are pioneer shrubs for water and soil conservation, and for windbreak and sand fixation in arid and semi-arid areas. Understanding the water use characteristics of different pioneer shrubs at different ages is of great importance for their survival when extreme rainfall occurs. In recent years, the stable isotope tracing technique has been used in exploring the water use strategies of plants. However, the widespread δ2H offsets of stem water from its potential sources result in conflicting interpretations of water utilization of plants in arid and semi-arid areas. In this study, we used three sets of hydrogen and oxygen stable isotope data (δ2H and δ18O, corrected δ2H_c1 based on SW-excess and δ18O, and corrected δ2H_c2 based on -8.1‰ and δ18O) as inputs for the MixSIAR model to explore the water use characteristics of C. korshinskii and T. ramosissima at different ages and in response to rainfall. The results showed that δ2H_c1 and δ18O have the best performance, and the contribution rate of deep soil water was underestimated because of δ2H offset. During the dry periods, C. korshinskii and T. ramosissima at different ages both obtained mostly water from deeper soil layers. After rainfall, the proportions of surface (0-10 cm) and shallow (10-40 cm) soil water for C. korshinskii and T. ramosissima at different ages both increased. Nevertheless, there were different response mechanisms of these two plants for rainfall. In addition, C. korshinskii absorbed various potential water sources, while T. ramosissima only used deep water. These flexible water use characteristics of C. korshinskii and T. ramosissima might facilitate the coexistence of plants once extreme rainfall occurs. Thus, reasonable allocation of different plants may be a good vegetation restoration program in western Chinese Loess Plateau. 相似文献
12.
多异瓢虫是新疆地区的优势捕食性天敌,可取食蚜虫、粉蚧、木虱等多种害虫。开展多异瓢虫的大规模扩繁对于推进害虫的绿色防控具有重要意义,选择适合多异瓢虫生长发育和繁殖的食物,是保证其人工扩繁的重要基础。本研究通过室内比较饲喂6种蚜虫（麦长管蚜、棉黑蚜、棉蚜、玉米蚜、豌豆蚜、桃蚜）后多异瓢虫的生命参数,筛选适合用于其人工扩繁的活体饲料。结果表明：多异瓢虫取食6种蚜虫显著影响幼虫的发育历期、存活率、成虫寿命、繁殖力以及世代历期。其中,多异瓢虫幼虫取食麦长管蚜（7.70d）和玉米蚜（7.67d）的发育历期明显短于取食其他4种蚜虫的;取食麦长管蚜发育成的雌、雄成虫均较重（雌11.02mg、雄8.54mg）;取食棉黑蚜时蛹期（3.80d）和卵期（2.52d）均较短;多异瓢虫取食麦长管蚜（20.02d）、棉黑蚜（21.14d）、棉蚜（20.07d）和玉米蚜（20.37d）的世代历期均较短;多异瓢虫幼虫取食麦长管蚜（96.33%）、棉黑蚜（96.50%）和棉蚜（90.67%）的存活率均明显高于取食其他3种蚜虫的。同时,多异瓢虫雌、雄成虫分别在取食棉黑蚜（44.67d）和麦长管蚜（59.13d）时寿命最长。在繁殖力方面,多异瓢虫成虫取食麦长管蚜（3.53d）和棉蚜（3.68d）时产卵前期均较短;取食棉黑蚜（1044.02粒）和棉蚜（1084.45粒）时单雌产卵量较高。综合来看,在6种蚜虫中,麦长管蚜、棉黑蚜和棉蚜均相对适合多异瓢虫的生长发育和繁殖,是饲养与人工扩繁多异瓢虫较为理想的活体饲料。 相似文献
13.
榕管蓟马和香蕉花蓟马分别归属于管蓟马科和蓟马科,目前这2种蓟马对寄主为害重且相应的生防菌资源较少。为丰富这2种蓟马的生防菌资源,本研究尝试从受虫生真菌感染死亡的昆虫上分离生防菌株,确定其分类地位,测定其对这2种蓟马的致病力。结果表明,从自然罹病死亡的马尾松毛虫幼虫上分离到1株编号为BB-T02的虫生真菌,经形态观察和分子鉴定确认为球孢白僵菌。针对榕管蓟马和香蕉花蓟马的2龄若虫,菌株BB-T02侵染7 d后的LC50分别为1.89×105孢子/mL和9.90×104孢子/mL,1.00×108孢子/mL处理的累计校正死亡率分别为94.12%和98.81%、LT50分别为3.48 d和3.14 d;针对它们的成虫,侵染8 d后的LC50分别为4.45×105孢子/mL和2.13×105孢子/mL,1.00×108孢子/mL处理的累计校正死亡率分别为87.21%和95.29%、LT50分别为4.20 d和3.69 d。综上,球孢白僵菌BB-T02对这2种蓟马致病力强,生防潜力和应用前景良好。 相似文献
14.
Maryam MOSLEHI JOUYBARI 《干旱区科学》2022,14(10):1099-1108
Biological invasions can alter soil properties within the range of their introduced, leading to impacts on ecosystem services, ecosystem functions, and biodiversity. To better understand the impacts of biological invasions on soil, we compared topsoil physiochemical properties at sites with invasive alien tree species (Prosopis juliflora), native tree species (Prosopis cineraria, Acacia tortilis, and Acacia ehrenbergiana), and mixed tree species in Hormozgan Province of Iran in May 2018. In this study, we collected 40 soil samples at a depth of 10 cm under single tree species, including P. juliflora, P. cineraria, A. tortilis, and A. ehrenbergiana, as well as under mixed tree species. The results showed that organic matter, moisture, potassium, calcium, nitrogen, and magnesium in topsoil at sites with A. tortilis and A. ehrenbergiana growing in combination with P. cineraria were higher than that at sites where P. juliflora was present (P<0.05). Sodium at sites with A. tortilis and A. ehrenbergiana growing in combination with P. cineraria and P. juliflora was lower as compared to that at sites with just A. tortilis and A. ehrenbergiana. Electrical conductivity was lower at sites with A. tortilis and A. ehrenbergiana growing in combination with P. cineraria, and it was higher at sites with mixed Acacia and P. juliflora trees. Based on the generally more positive effect of native Acacia and P. cineraria on topsoil physiochemical properties as compared to the P. julifora, afforestation with native tree species is preferable for soil restoration. In addition, due to the negative effects of P. julifora on soil properties, P. julifora spread should be better managed. 相似文献
15.
为了解不同盐生植物生物炭特性的种间差异,特选用盐地碱蓬(Suaeda salsa)、盐角草(Salicornia europaea)、高碱蓬(Suaeda altissima)、野榆钱菠菜(Atriplex aucheri)、盐穗木(Halostachys caspica) 5种黎科盐生植物为研究对象,于500℃温度下炭化制备生物炭,通过理化性质分析,并结合主成分分析来探讨盐生植物原材料对生物炭特性差异的影响。结果表明:生物炭的产率受盐生植物原材料灰分含量影响。此外,生物炭灰分、养分及阳离子含量受盐生植物原材料物质成分的影响。炭化能显著增加生物质灰分含量,5种生物炭灰分含量与原材料相比增加了67. 22%～169. 24%,同时伴随着灰分增加,水溶性Na~+、K~+等低价离子富集,pH、电导率(EC)增大,碱性增强。本研究为盐生植物生物炭在改良酸性土壤、炭化原材料选择等方面提供基础数据及理论参考。 相似文献
16.
Stipagrostis ciliata (Desf.) De Winter is a pastoral C4 grass grown in arid regions. This research work focused on assessing the growth of S. ciliata accessions derived from two different climate regions (a wet arid region in the Bou Hedma National Park in the central and southern part of Tunisia (coded as WA), and a dry arid region from the Matmata Mountain in the south of Tunisia (coded as DA)) under water stress conditions. Specifically, the study aimed to investigate the phenological and physiological responses of potted S. ciliata seedlings under different water treatments: T1 (200 mm/a), T2 (150 mm/a), T3 (100 mm/a) and T4 (50 mm/a). Growth phenology, net photosynthesis (Pn), stomatal conductance (gs), midday leaf water potential (Ψmd), predawn leaf water potential (Ψpd), soil water content (SWC) and soil water potential (Ψs) were observed during the water stress cycle (from December 2016 to November 2017). The obtained results showed that the highest growth potential of the two accessions (WA and DA) was recorded under treatment T1. The two accessions responded differently and significantly to water stress. Photosynthetic parameters, such as Pn and gs, decreased sharply under treatments T2, T3 and T4 compared to treatment T1. The higher water stress increased the R/S ratio (the ratio of root dry biomass to shoot dry biomass), with values of 1.29 and 2.74 under treatment T4 for accessions WA and DA, respectively. Principal component analysis (PCA) was applied, and the separation of S. ciliata accessions on the first two axes of PCA (PC1 and PC2) suggested that accession DA was detected in the negative extremity of PC1 and PC2 under treatments T1 and T2. This accession was characterized by a high number of spikes. For treatments T3 and T4, both accessions were detected in the negative extremity of PC1 and PC2. They were characterized by a high root dry biomass. Therefore, S. ciliata accessions responded to water stress by displaying significant changes in their behaviours. Accession WA from the Bou Hedma National Park (wet arid region) showed higher drought tolerance than accession DA from the Matmata Mountain (dry arid region). S. ciliata exhibits a significant adaptation capacity for water limitation and may be an important species for ecosystem restoration. 相似文献
17.
Water is a restrictive factor for plant growth and ecosystem stability in arid and semiarid areas. The dynamics of water availability in soils and water use by plants are consequently critical to ecosystem functions, e.g. maintaining a high resistance to the changing climate. Plant water use strategies, including water-use efficiency(WUE) and the main water source that a plant species utilizes, play an important role in the evaluation of stability and sustainability of a plantation. The water use strategies of desert plants(Tamarix chinensis, Alhagi sparsifolia, Elaeagnus angustifolia, Sophora alopecuroides, Bassia dasyphylla and Nitraria sphaerocarpa) in three different habitats(saline land, sandy land and Gobi) in Dunhuang(located in the typical arid area of northwestern China) were studied. The stable isotope of oxygen was used to determine the main water source and leaf carbon isotope discrimination was used to estimate the long-term WUE of plant species in the summer of 2010. The results suggest that: 1) the studied desert plants took up soil water below the depth of 80 cm; 2) T. chinensis in the three habitats used deeper soil water and T. chinensis in the Gobi site had higher WUE than those in the saline land and the sandy land. The results indicated that desert plants in Dunhuang depended on stable water source and maintained high WUE to survive in water limited environments. 相似文献
18.
褐梗天牛Arhopalus rusticus（L.）是松柏类等林木的重要害虫,近年来在山东泰安、威海等地发生严重。本文利用引诱剂诱杀、饵木诱杀和释放管氏肿腿蜂Sclerodermus guani Xiao et Wu与花绒寄甲Dastarcus helophoroides Fairmaire等无公害技术对褐梗天牛进行了室内外防治研究。Ⅱ号引诱剂诱捕效果最好,30 d平均诱捕量为69头。饵木诱杀每个样木平均诱捕量为63头。管氏肿腿蜂防治褐梗天牛幼虫的室内效果最高达71.00%,不同蜂虫比之间的防治效果差异不显著;林间释放管氏肿腿蜂对直径为10～15 cm被害木中的天牛幼虫的寄生率最高,为8.43%。利用花绒寄甲防治效果较好,室内当花绒寄甲成虫和天牛幼虫量为5:1时的寄生率最高,为80.02%;林间每株树释放20头花绒寄甲成虫的寄生率最高,达58.80%。结果表明,这几种防治技术都对褐梗天牛有良好的防治效果,可在防治中综合应用。 相似文献
19.
刺吸式口器昆虫常发生严重且抗药性强。本文室内测定了玫烟色棒束孢Isaria fumosorosea Ifu13a对梨冠网蝽、小绿叶蝉和温室白粉虱等多种刺吸式口器害虫的控制潜力。在1.0×108、1.0×107和1.0×106孢子/mL接种浓度下,在处理后初始2 d保持RH（95±5）%,随后8 d保持RH（78±5）%的条件下,小绿叶蝉和温室白粉虱成虫的累积死亡率均达到100%,其致死中时LT50分别为4.12、4.11、5.43和4.77、5.55、5.32 d,而梨冠网蝽的致死中时为7.32、8.22、9.79 d。在1.0×108和1.0×107孢子/mL浓度下,小绿叶蝉和温室白粉虱累计死亡率均在5 d内即达到100%,2种害虫的致死中浓度LC50分别为3.90×103和3.03×104孢子/mL;而梨冠网蝽第10 d在2种浓度下的累计死亡率分别达到了81.25%、77.5%,其LC50为6.88×105孢子/mL。菌株Ifu13a显示出一定的寄主专化性,菌株Ifu13a显现了对多种刺吸式口器害虫的高控制潜力。 相似文献
20.
丛枝菌根真菌与大豆胞囊线虫相互作用研究初报 总被引：9，自引：0，他引：9
在温室盆栽条件下对大豆‘开育10’品种接种了丛枝菌根(AM)真菌:Gigaspora margarita Becker&Hall、Glomus fasiculatum(Thaxt) Gerd.&Trappe、G.intraradices Schenck&Smith、G.mosseae Nicolson&Gedermann及G.versiforme Berch和/或大豆胞囊线虫(SCN,Heterodera glycines)4号生理小种。供试AM真菌可不同程度地促进大豆植株的生长发育,增加植株高度、地上部和地下部干重及单株产量,减轻感病大豆品种‘开育10’SCN的危害,降低病情指数、根上和根围土壤中胞囊数量、2龄幼虫和胞囊内卵数。其中,G.fasiculatum、Gi.margarita和G.intraradices的效应大于G.mosseae和G.versiforme的处理。接种SCN显著降低了G.intraradices和G.versiforme对大豆根系的侵染率、G.fasiculatum的产孢数量及G.intraradices的侵入点数量,增加了G.mosseae的产孢数量。认为部分AM真菌能有效地抑制SCN对大豆根系的侵染、胞囊发育和2龄幼虫的形成。 相似文献