The Effect of Irrigation Period and Amount on Production Performance of Alfalfa in Haihe Plain北大核心CSCD

To explore the suitable irrigation techniques for Alfalfa in Haihe Plain, six irrigation treatments were set up to study the effects of different irrigation treatments on the yield, agronomic traits and water use efficiency of one-year and two-year Alfalfa from 2015 to 2017. The results showed that alfalfa yield increased slightly with increasing irrigation amount in Haihe Plain, but had no significant difference among six treatments. Compared with the treatment without irrigation, the cumulative increment of alfalfa yield in three years was only 6. 13 t • hm~z. The water use efficiency of Alfalfa significantly decreased gradually with the increase of irrigation amount (P相似文献   

Effects of Exogenous Glycine Betaine on the Physiological Characteristics in Medicago sativa Seedlings under Low-temperature Stress北大核心CSCD

In this study,the 'Ganong 5th' alfalfa (Medicago sativa L.) was used as experimental material,and two application methods (leaf application,root application) and six exogenous betaine concentrations (0,10,20,30,40 and 50 mmol·L-1) were used to treat the seedlings of alfalfa. Plant growth and related physiological indexes were measured after 7 days of low temperature (4?) stress,and the physiological mechanism of exogenous betaine to alleviate the low temperature stress of alfalfa was explored. The results showed that exogenous GB alleviated the loss of plant height,root length,leaf dry weight,root dry weight and chlorophyll content,and increase the content of soluble sugar (SS) and free proline (Pro),and reduced the increase in leaf relative membrane permeability and MDA content. Exogenous GB increased antioxidant enzyme activities and non-enzymatic antioxidant content. And also,exogenous GB enhanced the osmotic adjustment capacity of the plant by increasing endogenous GB accumulation and BADH activity. These results indicated that exogenous GB enhanced the resistance of Medicago sativa to low-temperature stress under low temperature adjustment. The membership function analysis indicated that spraying 30 mmol·L-1 GB on the leaves and spraying 40 mmol·L-1 GB on the roots had the best effect on alleviating the low-temperature stress of alfalfa seedlings. © 2019 Ｊｏｕｒｎａｌ ｏｆ Ｒｅｆｒｉｇｅｒａｔｉｏｎ. All rights reserved.     

Effects of plateau pika on the relationship between plant species diversity and functional diversity in alpine meadow北大核心CSCD

The relationship between plant species diversity and functional diversity in grassland will change with environmental changes. The plateau pika （Ochotona curzoniae） has an effect on the hydrothermal process of alpine meadow in its nesting area. However,it is not clear whether the disturbance of plateau pika effects the relationship between plant species diversity and functional diversity in alpine meadow. A random stratified and paired design was used to select plots in Luqu county in Gansu Province,and Qilian and Gonghe Counties in Qinghai Province and a field survey was conducted to investigate the effects of plateau pika disturbance on the relationship between plant species diversity and functional diversity of the alpine meadow. It was found that plateau pika disturbance significantly increased the plant species richness index and the species diversity index but did not significantly affect the species evenness index. Plateau pika disturbance significantly increased plant functional richness index （P< 0.05） but had no significant effect on the plant functional evenness index or the functional divergence index. With plateau pika disturbance effects,the relationship between plant functional richness index and species richness index changed from a logarithmic function to a quadratic function,and the relationship between plant functional evenness index and species evenness index changed from non-significant to significantly positive. In addition, positive correlations between functional richness index and species richness index,and functional richness index and species diversity index were significantly decreased,as were negative correlations between functional divergence index and species richness index,and functional divergence index and species diversity index were significantly decreased. The findings of this study provide basic information for understanding the mechanism of species coexistence of plant communities under plateau pika disturbance and help understanding of how plant diversity effects in an alpine meadow ecosystem function under plateau pika disturbance. © 2022 Editorial Office of Acta Prataculturae Sinica. All rights reserved.     

Characteristics of Evapotranspiration and Water Consumption of Typical Alpine Desert in the Tibetan Plateau During the Growing Season北大核心CSCD

To explore the law of water consumption in the underlying surface of a typical alpine desert on the Qinghai-Tibet Plateau, we analyzed the characteristics of ET change and water consumption on different time scales based on the raw eddy-covariance data and meteorological data measured in April to August 2019 from the observation tower on Tuotuohe weather station. The maximum hourly average ET appears at 2-3 p. m, reaching 0.46 mm·h-1; The maximum value of daily ET was 8.58 mm·d-1 on July 7, and the minimum value was 0.30 mm·d-1 on April 2; The ET increased first and then decreased during the growing season, the monthly ETmax was 120.68 mm in July and the ETmin was 64.80 mm in April; The total ET in 2019 growth season was 581.15 mm and the daily average was 4.01 mm. The total precipitation of the whole growing season was 235.70 mm, according to the difference between ET and precipitation(Pr) from April to August, water vapor exchange during the plant growth season was mainly characterized by water consumption on the land surface in 2019. © 2019 Authors. All rights reserved.     

Diurnal changes in photosynthesis and photosynthetic product partitioning in alfalfa in response to phosphorus application北大核心CSCD

This research explored the effect of different levels of phosphorus application on diurnal variation in photosynthesis and partitioning of photosynthetic products in alfalfa under drip irrigation. In particular, the relationship between photosynthetic product levels in the plant and leaf photosynthetic parameters of alfalfa was clarified. Four phosphorus（P2O5）application levels of 0（CK）,50（P1）,100（P2）and 150 kg·ha-1（P3）were used as treatments in a field experiment. Leaf photosynthetic parameters were measured with a Li-6400 portable photosynthesis instrument on sunny days from 10：00-20：00 during the early flowering stage,together with environment factors and sugar and starch content in the leaves,stems and roots. A feature of the results was a ‘photosynthetic noon-break’phenomenon across all phosphorus application treatments,and stomatal limitation was the main factor responsible for the mid-day decline of net photosynthetic rate （Pn）. Photosynthetically active radiation had the greatest impact on the Pn of alfalfa leaves,while atmospheric CO2 concentration,atmospheric temperature,and atmospheric environmental factors such as relative humidity and vapor pressure deficit based on leaf temp also affected Pn. Principal component analysis showed that alfalfa photosynthetic efficiency in the four P-treatments ranked P2>P1>P3>CK. At the 100 kg·ha-1 phosphorus level（compared to CK）,the hay yield of alfalfa was increased significantly,the soluble sugar contents of leaves,stems,and roots were increased by 11. 6%,5. 0% and 4. 6%,respectively,and the starch contents were increased by 15. 2%,9. 6% and 5. 3%,respectively. Higher overall levels of soluble sugar and starch typically manifested as greater concentration increases in leaves,and relatively smaller increases in roots and stems. The diurnal troughs in Pn,transpiration rate,leaf internal CO2 concentration and water use efficiency（WUE）of alfalfa leaves were less marked in the P treatments,compared with the control treatment. Therefore,appropriate phosphorus application can increase the photosynthetic efficiency of alfalfa leaves,thereby significantly promoting crop growth and development. At the phosphorus（P2O5）application rate of 100 kg·ha-1（P2）,the alfalfa photosynthetic enhancement effect was the most pronounced. © 2022 Editorial Office of Acta Prataculturae Sinica. All rights reserved.     

Biodiversity Characteristics and Biomass of Artificial Transplanting Leymus chinensis grassland in Soda Saline-Alkali land of Songnen Plain北大核心CSCD

In order to explore the effect of Leymus chinensis transplanting on the biodiversity and productivity of saline alkali grassland in Songnen Plain,a comparative experiment was conducted in the transplanting Leymus chinensis grassland. The results showed that the transplanting of Leymus chinensis enhanced plant species and the density of the grassland community. The total plant density under the transplanting of Leymus chinensis was 566.20 plant·m-2,6.85 times as much as that in the control (82.60 plant·m-2),and the difference between the treatments was significant (P<0.05),and the transplanting of Leymus chinensis increased the diversity index of Shannon-Wiener,the evenness index of Pielou and the richness of Margalf species. The total biomass of the community was higher than that in the control. In addition,the total biomass of the transplanting of Leymus chinensis was 357.77 g· m-2,2.14 times as much as that in the control (167.34 g·m-2),and the difference between the treatments was significant (P<0.05),which indicated that the transplanting Leymus chinensis increased the productivity of the plant community,and greatly increased the grassland output benefit, The total income was 3938.00 yuan·hm-2 for the transplanting of Leymus chinensis,7.37 times higher than that in the control (534.40 yuan·hm-2),and the difference between treatments was very significant (P<0.01).Transplanting technology of Leymus chinensis not only improved the biodiversity of the system,but also doubly increased the biomass and economic benefits,So it was a technical model which was worth of popularizing and applying in the saline alkali area of the Western Songnen Plain. © 2019 China Agricultural University. All rights reserved.     

Physiological effects of different Cd concentrations on maize root architecture and classification北大核心CSCD

In this research, a hydroponics experiment was conducted to apply different concentrations of cadmium (Cd) (0, 5, 10, 25, 50, 100, 200 μmol·L-1) to maize seedlings with two leaves and one new leaf, in order to explore the effects of the different Cd concentrations on the maize seedling growth, Cd absorption kinetics and root morphology and classification. After 5 days of Cd stress, the maize seedings were sampled, the plant height, main root length, aboveground and underground biomass, root architecture, Cd content and photosynthesis and related parameters were measured. It was found that with increasing Cd stress, the plant height, main root length, biomass and tolerance index of shoots and roots, total root length, root surface area, root volume, root forks and root tips all decreased significantly; Root average diameter and root:shoot increased significantly (P<0.05). Meanwhile root parameters (root length, root surface area and root volume) of root diameter classes designated Ⅰ-Ⅲ (0-1.5 mm) showed a decreasing trend, which had a significant (P<0.05) negative correlation with root Cd concentration. The proportion of root length, root surface area and root volume with diameter between 0-0.5 mm showed a downward trend under Cd stress. Under Cd stress, Cd concentration and accumulation in underground and aboveground parts of maize seedlings increased significantly, chlorophyll content decreased, and photosynthesis was inhibited. This study has shown that Cd affected root development mainly by inhibiting the growth and morphology of fine roots, and inhibited photosynthesis, elongation and biomass accumulation of the aboveground and underground parts of the maize seedings. © 2022, Editorial Office of Acta Prataculturae Sinica. All rights reserved.     

Dynamic Characteristics of Soil Sucrase and Amylase Activities during Vegetation Degradation in Gahai Wetland北大核心CSCD

In order to study the activities and dynamic characteristics of soil invertase and amylase during the process of vegetation degradation (Non-degradation, Light degradation,Moderate degradation, and Heavy degradation),the filed experiments were conducted in marsh meadow of Gahai wetland in Gannan state,Gansu province. The main results were as following: the average activity values of invertase and amylase activities in 0~100 cm layers varied in different stages of vegetation degradation of marsh meadow, following the order of CK (Non-degradation) > SD (Light degradation) > MD (Moderate degradation) > HD (Heavy degradation). With the increasing of soil layers,the activity of invertase significantly decreased (P<0.05),while the activity of amylase decreased fluctuantly. The activities of enzymes in the surface soil (0~20 cm) accounted for more than 60% of the total activities of each enzyme. The activities of invertase and amylase showed the obvious dynamic characteristics with time in all stages of vegetation degradation. The average activity of invertase in different months was the highest in June (47.07 mg·g-1) and the lowest in August (22.69 mg·g-1). The average activity of amylase was the highest in July,85.18 mg·g-1,while the activity values in other months were low. Correlation analysis showed that soil organic carbon was significantly correlated with invertase and amylase (P<0.01),and soil water content was only significantly correlated with invertase (P<0.01). The results showed that the vegetation degradation in Gahai wetland significantly affects soil invertase and amylase activities,reduces the efficiency of enzymatic reaction,and leads to the deterioration of wetland soil environment. © 2019 Ｊｏｕｒｎａｌ ｏｆ Ｒｅｆｒｉｇｅｒａｔｉｏｎ. All rights reserved.     

Characteristics of Slope Runoff and Sediment of Different Vegetation Types under Individual Rainfall Events in Loess Hilly and Gully Region北大核心CSCD

The runoff plots of Anjiagou watershed were selected as the research object in Dingxi City,Gansu Province,and the characteristics of rainfall infiltration, runoff and sediment of different vegetation types were studied using the observed data of runoff and sediment under natural rainfall conditions. The results showed that: the infiltration rate of soil under different vegetation types increased linearly with the increase of rain intensity, while the relation between the infiltration rate and the rainfall duration was a power function. The runoff coefficient of pine forest (15.97%~19.88%) was the largest, the wheat field (10.91%~17.32%) and sea buckthorn forest (9.51%~17.47%) the second,the wheatgrass meadow (4.62%~8.30%) and the alfalfa land (6.82%~10.66%)were the smallest. In the meanwhile,the relation between runoff coefficient (1%~28%) and rainfall presented a power function (P<0.05). The order of average sediment concentration was as follow: wheat field (16.49~22.71 g·L-1) > alfalfa land (12.66~16.91 g·L-1) > sea buckthorn forest (7.04~11.8 g·L-1) > pine forest (6.95~7.78 g·L-1) > wheatgrass meadow(5.53~7.71 g·L-1). There was a positive correlation between sediment concentration and soil erosion rate and rainfall erosivity (P<0.01),which can be quantified separately by linear function and quadratic function. The results can provide references for optimizing configuration of water and soil conservation in Loess hilly and gully region. © 2019 China Agricultural University. All rights reserved.     

Changes of Rumen Microbiota Density and Physicochemical Properties at Different pH北大核心CSCD

The aim of this experiment was to investigate the changes of rumen microbiota density and physicochemical properties at different pH. Five Holstein cows in dry milk period were selected as rumen fluid donors. Using in vitro method, five treatments were set according to the criteria of rumen acidosis, and the pH of culture medium was 6.5, 5.8, 5.5, 5.2 and 5.0, respectively, with five replicates in each treatment. After three hours of incubation, the changes of rumen microbiota density and physicochemical properties were measured. The results showed as follows: 1) with the decrease of pH, the rumen microbiota density showed a fluctuation change of first decreasing, then increasing and then decreasing, and the microbiota density in pH 5.8 treatment was significantly lower than that in pH 6.5 treatment (P<0.05). When pH was 5.2, the rumen microbiota density was the highest, which was significantly higher than that in the other treatments (P<0.05). 2) With the decrease of pH, the intracellular H+-ATPase activity in rumen microbiota was firstly increased and then decreased, but there was no significant difference among all treatments (P>0.05). 3) The intracellular ATP content in rumen microbiota was not significantly affected by different pH treatments (P>0.05). 4) With the decrease of pH, the intracellular protein content in rumen microbiota was gradually increased (P<0.05). 5) With the decrease of pH, the intracellular pH (pHi) and cellular transmembrane pH difference (ΔpH) in rumen microbiota were firstly increased and then decreased, and the pHi and ΔpH in pH 5.5 and 5.2 treatments were significantly higher than those in the other three treatments (P<0.05). 6) With the decrease of pH, the cell membrane permeability of rumen microbiota was gradually increased, except for pH 5.8 treatment, the other treatments were significantly higher than pH 6.5 treatment (P<0.05). In conclusion, the rumen microbiota can increase the intracellular H+-ATPase activity and protein content, consume ATP, and change pHi and ΔpH in response to external pH decline. When pH decreases to 5.5, the membrane permeability and pHi of rumen microbiota increase significantly, indicating that they are running to be subjected to more serious acid stress. The density of rumen microbiota fluctuates with the decrease of pH, and when pH decreases to 5.2, the density of rumen microbiota is the highest. © 2023 Authors. All rights reserved.     

羊草不同地理种群表型变异及其对根茎克隆繁殖的影响

羊草是我国重要优良牧草之一，广泛分布于欧亚草原，由于资源环境的多样性和自然选择的复杂性，羊草种群发生了丰富的表型变异。以不同地理来源的66份羊草为试验材料，采用同质园试验方法，研究了羊草种群间表型和繁殖相关性状的变异情况，用曲线拟合和偏最小二乘回归分析研究了变量性状对羊草根茎克隆无性繁殖的影响。主要结论如下：1）不同地理来源羊草的表型和繁殖性状存在显著差异，原生境条件对羊草表型和繁殖产生了深刻而长久的影响。2）羊草不同性状的变异程度有所不同，叶片性状的变异最小，根茎子株相关性状的变异大于空间扩展相关性状。3）线性函数可较好地描述羊草根茎克隆生长力与主要变量性状间的关系。4）表型性状茎长、株高、叶宽和叶片大小，分蘖能力相关性状母株分蘖增加倍数对羊草根茎克隆生长力的解释作用强。总之，叶片宽大、茎长和株高方面有优势、分蘖能力强的羊草的根茎克隆无性繁殖能力相应也强。     

补播羊草和黄花苜蓿对退化草甸植物群落特征的影响

呼伦贝尔草原区是我国北方重要的生态屏障,近年来不合理的利用方式导致该地区退化草地面积不断扩大,为了探究牧草补播时间及补播比例对呼伦贝尔退化草甸草原植物群落特征的影响,为该地区退化草地修复提供依据。本研究以羊草（Leymus chinensis（Trin.） Tzvel.）和黄花苜蓿（Medicago falcata L.）为试验材料,采用双因素随机区组试验设计,通过测定幼苗数、高度、生物量等群落指标,并综合评价补播效果,结果表明：夏播羊草和黄花苜蓿幼苗数量显著高于春播和秋播（P<0.05）,夏播和秋播植物群落总生物量呈增加趋势,春播则呈减少趋势;补播措施提高了退化草地植物群落Shannon-Weiner指数、Simpson指数和Pielou指数,豆科和禾本科植物重要值呈增加趋势,其他科植物呈下降趋势。呼伦贝尔地区夏季补播羊草和黄花苜蓿以1∶3补播效果较好,而春播由于恢复时间短,需进一步观察。     

盐碱胁迫下AMF对羊草的离子吸收和分配作用

丛枝菌根真菌（AMF）通过影响植物地上及地下离子吸收分配来增强植物耐盐碱能力的机理尚不明确，采用盆栽试验，选取松嫩草地的优势种羊草作为试验材料，研究不同盐碱梯度下接种AMF对羊草体内无机阳离子吸收、运输和分配的影响。试验结果表明：1）盐碱胁迫会增加羊草体内Na⁺含量，减少K⁺、Ca²⁺和Mg²⁺含量，增强地下到地上部分Na⁺的运输，抑制K⁺、Ca²⁺和Mg²⁺的运输，改变羊草体内地上和地下的离子分配；2）盐碱胁迫条件下，AMF抑制了羊草对Na⁺的吸收，促进了其对K⁺、Ca²⁺和Mg²⁺的吸收，同时提高了根系对Na⁺的截留能力，通过调节羊草体内的无机离子运输比和阳离子运输选择比，维持其体内的离子平衡，从而提高耐盐碱性；3）盐碱胁迫程度增加改变了AMF的盐碱适应性，使其菌丝侵染率及菌丝密度显著降低，泡囊侵染率显著升高，AMF可以利用泡囊存储更多的盐碱离子来减轻盐碱胁迫对羊草根系的破坏作用。可见，在盐碱胁迫下，AMF能够通过抑制羊草吸收Na⁺，利用泡囊结构帮助其根系截留Na⁺，以及促进K⁺、Ca²⁺和Mg²⁺的吸收来调节羊草体内地上和地下的离子分配，进而增强羊草的盐碱耐受性。由此，可以利用羊草-AMF共生体改良草地盐碱化，同时为研究AMF对其他植物的耐盐碱机理提供了有效参考。     

新疆兵团九师退化天然草地补播改良效果分析

在新疆兵团九师不同类型退化天然草地典型区域,选择豆科、禾本科牧草混播开展补播试验2年,结果表明：补播当年各播入种出苗率均达85%以上,且都能安全越冬;第2年各牧草返青达80%以上,山地草甸类杂类草＋鸭茅（Dactylis glomerata ）型、温性草原类针茅（Stipa capillata ）＋羊茅（Fes-tuca ovina ）型和温性草原类羊茅＋冷蒿（Artemisia frigida ）型草地干草产量分别比对照（未补播）显著（P 〈0.01）提高了114%,125%和109%;豆、禾牧草比例明显增加,草群结构趋于合理;各草地群落高度、盖度、密度都显著（P 〈0.01）高于对照,山地草甸区补播效果最明显,分别增加了34 cm,40.8%和265株/m2;豆、禾牧草对不同草地类型区域适应性不同,山地草甸区豆科牧草补播改良效果优于禾本科,温性草原区二者表现刚好相反。     

呼伦贝尔草甸草原3种禾草碳水化合物季节动态研究

贮藏碳水化合物对牧草生命代谢、再生、返青及逆境的适应性等方面有重要作用。本研究于2015年7月—2016年9月,分析了呼伦贝尔草甸草原中羊草（Leymus chinensis）、无芒雀麦（Bromus inermis）和糙隐子草（Cleistogenes squarrosa）3种植物碳水化合物含量的季节变化规律,探讨牧草生长对气候环境的适应性特点,以期为草地合理利用提供指导。研究结果表明：3种禾草碳水化合物含量随季节变化显著（P<0.05）,可溶性糖含量均在8月最高,羊草与无芒雀麦的还原糖和淀粉含量在6月最高,糙隐子草则在7月最高;糙隐子草的可溶性糖与淀粉含量显著小于羊草和无芒雀麦（P<0.05）,并主要分配在地上部分,羊草茎基部与根部的各碳水化合物含量显著小于无芒雀麦（P<0.05）;碳水化合物含量年际间差异较大,干旱年份草地植物根部碳水化合物贮藏水平偏低,该区域草地宜降低载畜率或提前休牧。     

沙地生境不同播期对紫花苜蓿生产性能及其越冬率的影响

为确定科尔沁沙地种植苜蓿（Medicago sativa）的适宜播期，本研究于2017年在内蒙古阿鲁科尔沁旗，选择骑士T、公农1号、擎天柱3个紫花苜蓿品种，7月1日开始播种，每5天播种1期，共10个播期，分析播期、生产性能、越冬率之间的关系。结果表明：建植当年苜蓿播种越晚干草产量越低，骑士T干草产量在7月21日播期显著降低（P<0.05），公农1号干草产量在7月16日播期显著降低（P<0.05），擎天柱干草产量在7月11日播期显著降低（P<0.05）；随播种时期的推迟，苜蓿株高、单枝条重呈降低的变化趋势，单位面积株数和枝条数呈先增加后降低的变化趋势；苜蓿越冬率从播期7月16日开始显著降低，公农1号在7月16日以前播种越冬率显著高于骑士T和擎天柱（P<0.05）；播种翌年第1茬苜蓿干草产量和株高随着播期的推迟而逐渐降低，2，3茬则无明显变化；苜蓿单位面积株数和枝条数都随播期的推迟呈降低的变化趋势，随着刈割茬次的增加，苜蓿的株数逐渐降低。因此，在科尔沁沙地种植紫花苜蓿最佳播期为7月1日—7月16日。     

围封、浅耕翻改良技术对退化羊草草地植被恢复的影响

为探求华北农牧交错带地区退化草地适宜的改良技术,于2005年在中国农业大学河北沽源草地生态野外试验站研究了围封、浅耕翻改良处理对退化天然羊草(Leymus chinensis(Trin.)Tzvel.)草地地上植被恢复的影响。结果表明:与过度放牧相比,围封、浅耕翻改良均能有效地改善退化羊草草甸草地地上植被的物种组成结构和群落结构,显著提高退化羊草草甸草地地上植被盖度、高度和地上生物产量(P<0.05),其中以浅耕翻改良的效果最为明显;围封、浅耕翻改良导致退化羊草草地植被物种饱和度、物种均匀性指数、物种丰富度指数和物种多样性指数显著下降(P<0.05),其中以浅耕翻的影响效果最明显。从利用的角度看,围封、浅耕翻改良4年后,羊草已占绝对优势,地上植被得到一定程度的恢复,地上生产量也显著提高(P<0.05),草地可以开始有计划地加以利用,其中,浅耕翻改良对促进退化羊草草甸草地地上植被生产力的恢复,尤其是羊草种群的恢复较围封改良效果更好。     

两种不同生境羊草根际土壤细菌群落多样性与环境因子的研究

本试验以羊草（Leymus chinensis）为优势种的草甸草原为研究对象,旨在探讨两种不同样地（样地1为原生态未扰动处理,样地2为重度退化后人工补播扰动处理）土壤条件下土壤微生物群落结构、微生物多样性及微生物间互作效应的差异。结果表明：变形菌门（Proteobacteria）、酸杆菌（Acidobacteria）、放线菌门（Actinobacteria）这3个门是该地区羊草根际土壤细菌优势群落;速效氮、速效钾对细菌群落结构影响较大;土壤pH在一定阈值范围内与羊草根际土壤细菌多样性极显著相关（P<0.01）;土壤有机质与羊草根际土壤细菌群落相对丰度、多样性、菌间互作显著正相关;土壤交换性钠离子含量与羊草根际土壤细菌群落多样性显著负相关;人工补播后的羊草根际土壤微生物间互作与未干扰生境下相比明显减弱。     

不同物候期刈割对羊草再生和根形态及产量的影响北大核心CSCD

刈割是羊草草地一种常见的利用方式,为探究不同物候期刈割对羊草再生和产量的影响程度,分别设置了对照组(CON)和刈割组。刈割组包括拔节期刈割(ES)、抽穗期刈割(HS)和开花期刈割(FS)。对照组不刈割,8月15日收获;刈割组起始刈割后,8月15日收获。结果表明,与对照相比,HS和FS刈割处理增加了(P<0.05)羊草干物质(DM)总产量而ES刈割处理则降低了(P<0.05)DM总产量。此外,所有处理均提高了(P<0.05)羊草的粗蛋白总产量。不同物候期刈割羊草的再生过程是不同的,ES处理羊草细根长、根表面积和体积最低。FS处理羊草再生后期净光合速率高于其余处理(P<0.05),导致其后期再生效率较高,但根中水溶性碳水化合物(WSC)含量最低(P<0.05)。HS和CON处理在羊草根形态和WSC含量上则无显著差异。尽管不同物候期刈割后羊草的再生过程不同,但其再生产量是接近的,特别是ES和HS处理,这是因为较长的再生周期被较低的再生效率所抵消,因此,总DM累积量主要由刈割前的DM来决定。综上所述,应在抽穗期进行刈割,能提高羊草产量并保持其持久性。     

五爪金龙两种化感作用途径释放的化学成分分析及其效应研究北大核心CSCD

五爪金龙是我国华南地区具有强入侵性的外来植物,其入侵机制与化感作用间的关系备受学者关注。通过模拟自然条件下五爪金龙挥发和淋溶两种途径的作用,发现这两种途径对三叶鬼针草和生菜种子发芽率、发芽速率表现出不同程度的抑制。继而采取顶空固相微萃取及树脂洗脱法分别收集这两种途径释放的物质,并用气相色谱与质谱联用法分析各自成分。结果表明,五爪金龙叶片挥发物被检测出18种萜烯类化合物,其中石竹烯(28.17%),β-罗勒烯(16.59%),α-蒎烯(13.65%)和β-柏木烯(9.43%)相对含量较多。淋溶水主要为酚酸类,肉桂酸(39.21%),琥珀酸(15.15%),丙酸(11.12%)及月桂酸(9.38%)相对含量居于前四。在定量得出上述主要物质实际浓度后,进一步处理受试植物发现,淋溶途径释放的肉桂酸和月桂酸显著抑制两种受体植物的种子发芽率和发芽速率,丙酸和琥珀酸则对两种受体植物大部分指标无显著影响。此外,4种主要叶片挥发物对受体植物种子萌发的影响也有明显差异,β-柏木烯和石竹烯的作用明显强于α-蒎烯和β-罗勒烯。综上所述,挥发与淋溶是五爪金龙重要的化感效应作用途径,它们分别产生以萜烯及酚酸类为代表的物质,且这两类物质对受体植物种子萌发能形成抑制,但不同物质对受体植物的抑制程度显著不同。由此可见外来植物五爪金龙产生的化感物质可以通过多种途径释放并发挥作用,其中的关键物质则对其化感作用效果产生决定性影响。