河南高速公路中的外来入侵植物调查

近年来,外来入侵植物逐渐增多,对生态构成了一定的威胁。为查清高速公路中出现的外来入侵植物对当地生态系统的影响程度,采用实地调查的方法对河南省高速公路边坡的植被进行了统计,共调查植物58种,其中外来入侵植物4种,有些入侵植物的入侵情况已经比较严重。针对入侵问题,提出了高速公路生态修复的建议。     

高速公路边坡植被重建过程中群落组成特征

[目的]对河北省西柏坡高速公路4种不同边坡类型进行调查,旨在选择合适的边坡植被恢复技术。[方法]通过随机取样调查进行不同边坡群落组成结构分析。[结果]4种边坡类型的物种多样性差异显著。自然恢复土质边坡植被盖度最低,自然恢复石质边坡的物种多样性最差,人工恢复生态袋技术边坡的物种多样性和植被盖度最高。[结论]人工恢复生态袋技术和挂网喷播技术对高速公路边坡复绿都有明显的改善,而生态袋技术对边坡复绿改善最为明显。     

高速公路边坡三种植被恢复模式的生态效果评估

边坡的生态恢复是高速公路建设的重要组成部分,但如何恢复却有诸多争论。归纳起来,我国高速公路主要有3种植被恢复模式:单纯植草、灌草结合、乔灌草结合。选取了3种植被恢复模式的代表性公路进行植被调查,进而评估生态恢复效果,结果表明:思小高速公路乔灌草结合的恢复模式较其他高速公路单纯植草和灌草结合的植被恢复模式具有更好的生态恢复效果,它具有更丰富的群落结构和物种多样性,并能够更有效地阻止外来物种入侵,在高速公路边坡的生态恢复中应予大力倡导应用。     

广西十万大山自然保护区外来植物的初步研究

十万大山地处北热带山地,有着丰富的生物多样性,但定居的外来种在不断增多,有的外来种成了入侵种,如飞机草等,给该自然保护区带来了严重威胁。通过实地调查以及查证文献,全面整理了十万大山国家级自然保护区的外来植物,并分析了外来种的类型、原产地、引种原因及引入途径,确认：①迄今为止共计99种（含亚种）外来植物,隶属于38科83属,其中菊科最多（10种）,占10．1％,其次为禾本科（6种）,占6．1％;②栽培种56种,逸生种20种,入侵种23种,分别占56．6％、20．2％和23．2％;③外来植物的原产地主要是热带美洲（有54种,占54．5％）,其次是印度（10种）、非洲（9种）和地中海地区（7种）;④人为有意引入有87种,占87．9％。最后对保护区内外来植物的危害预测和防治策略做了分析。     

四川省铁路路堑边坡植物多样性分析

通过分析四川省内成都平原及其附近4个地点的不同铁路路堑边坡的植物多样性,比较不同边坡植被自然恢复后的植物物种多样性、人工恢复后的植物物种多样性和自然边坡的植物物种多样性,得到以下结论不同的恢复时间、不同的土壤基质和不同地点的坡面的植被情况不同,恢复时间较长、土质松软且当地原生植被较好的地点植被恢复后的植物种丰富度较高.在进行人工生态恢复时,要依据当地土壤的物理化学性质和当地植物群落的演替规律选择先锋植物种,以本地乡土植物种为首选,可依据当地情况引进外来植物种.     

滨州市外来入侵农业有害生物发生及防控对策初探

经过实地调查和资料分析,初步确定滨州市外来入侵农业有害生物物种达66种,其中外来入侵有害动物12种,有害病原微生物6种,有害植物48种。在此基础上,明确了外来入侵物种的地理分布,提出了相应的防治对策。     

黄延高速公路边坡植被与土壤特性调查研究

采用现场调查、观测、试验等多种试验方法,对黄延高速公路绿化植物、边坡土壤理化性质以及植物群落组成进行了研究.通过分析,总结了中央分隔带、平台和边坡绿化植物种类以及边坡有效配置模式,分析了土壤养分贫瘠的原因和提高措施.在此基础上提出土壤肥力与植物恢复是相辅相成的,土壤肥力随人工植被建立时间的延长而逐渐恢复;随着时间序列的延长,其物种数目和比例也发生较大变化,有利于护坡植物群落最终实现结构稳定.     

高速公路边坡水土保持植物防护设计方案探讨

针对我国高速公路边坡水土流失防护存在形式多样、效果不一的问题 ,以洛界高速公路为例 ,介绍了边坡水土流失植物防护的设计方案 ,在采用人工模拟该区间百年一遇暴雨和径流试验对方案可行性验证的基础上 ,进行了效益分析 ,经过讨论认为该方案可供河南省及周边地区其它高速公路边坡采用植物防护时借鉴和参考 ,高速公路边坡应大力提倡采用植物进行防护 ,为保证施工质量应推行招投标制和监理制等。     

内蒙古中部高速公路边坡植被恢复研究

为探讨干旱半干旱地区的植被护坡效果,为道路边坡植被恢复与重建提供理论与技术依据,依托高速公路建设工程,遵循恢复生态学原理,研究了高速公路边坡植被恢复的生态效果.结果表明1)护坡植被覆盖度必须控制在一定范围内;2)人工建植的护坡植被群落,在经过一定时间的演替后逐渐趋向当地自然群落;3)植物种的选择一定要结合所在区域的自然环境;4)坡面植被具有明显的防治坡面水土流失的效果.     

覆土厚度和地形对废弃地植物群落的影响

适宜的土壤覆盖厚度是矿区复垦的一项关键技术,美国学者A.F.Wick等对矿业废弃地长期复垦地覆土厚度及地形对植物群落影响进行研究。评价了北达科他州以前试验土壤楔的3种不同底土上的重建植被群落(产量和多样性)、覆土厚度和边坡条件之间的关系。冠羽冬麦草和雀麦草等非乡土物种28 a后存留接近50%,而入侵性较低的物种,如俄罗斯野麦和紫苜蓿,更容易被外来入侵种侵入而形成多样性较高的植被群落。生物量对土壤厚度和坡向反应最敏感的是南向2%坡度的底土为C层土的地块。试验结果表明:覆土厚度应根据土壤稳定性和初始建设时土壤的多样性来确定,这样才能阻止有害植物种的入侵。     

Bragg soybeans grown on a southern coastal plains soil i. dry matter distribution,nodal growth analysis,and sample variability

Yields of soybean [Glycine max (L.) Merr.] are affected by the manner in which available resources are partitioned into component plant parts. Little is known about these partitioning processes and much of what has been reported describes indeterminate cultivars or comes from other than field studies. A field investigation was conducted, therefore, on a Goldsboro loamy sand (Aquic Paleudult) to characterize in detail the growth and development of a determinate soybean cultivar ‘Bragg’. Soybean were grown in well watered field plots in four replications from each of which 4 nested samples of 0.3 m² each were combined at each sampling. Leaf area, dry matter production, internode length, and sample variability were determined nodally at 10‐ to 14‐day intervals from 7 July to 17 October. Plant components at each node were separated into stems, leaf blades, pods, and petioles. Primary and secondary branches were combined in the petiole fraction.

Maximum above ground plant dry weight achieved was 1027 g/m² and maximum combined nodal dry weight was 92 g/m² (at node 8), both occurring at the R7 growth stage. Canopy dry weight distribution over time was unique for each plant part. Growth analyses showed that RGR, NAR, LAR, and LWR declined with plant age at a rate that could be described with either linear or exponential models. A maximum CGR of 16.24 g/m²/day occurred at mid‐podfill and declined thereafter due to maturity. Leaf area per node peaked between nodes 7 and 12, decreasing uniformly toward the top of the canopy. Maximum nodal LAI was 0.79 at node 7 on 31 August.

Distribution of dry weight among parts varied with plant age and node position. Maximum dry weights of stems (276 g/m²), petioles (253 g/m²), and leaves (263 g/m²) were found during mid‐podfill. During mid‐August, the dry weights of the stems, petioles, and leaves were similar and approximately 250 g/m². Stem dry weights had the lowest coefficients of variation of all plant fractions once maximum dry weight was achieved. Internode length varied along the stem with the maximum at node 12. By bloom, expansion of the internodes lower than 12 had ceased; expansion of the eight higher internodes ceased three weeks later. During vegetative growth, the ratio of stem internodal dry weight to internodal length had peak values at the lowest and highest internodes. During reproductive growth, the ratio decreased linearly with internode number. Coefficients of variation (CV) for the combined weight of plant parts, and for stems, petioles, leaves, and pods were relatively constant during the season and were 24.8, 23.4, 38.2, 25.5, and 26.8%, respectively. The CV's for the combined weight of plant parts were somewhat higher at the lowest and uppermost nodes. This variability resulted from the abscission of petioles and leaves in the lower nodes and the initiation of leaves, petioles, and pods in the upper nodes where rapid growth and development was occurring. Time from node initiation to achievement of lowest stable CV was determined for each node and plant part. Plant node position and morphological part with the lowest CV was identified for each sampling date (and growth stage).     

Rice (Oryza sativa L.) plant protection using dual biological control and plant growth-promoting agents: Current scenarios and future prospects

Various microorganisms live in association with different parts of plants and can be harmful, neutral, or beneficial to plant health. Some microbial inhabitants of plants can control plant diseases by contesting with, predating on, or antagonizing plant pathogens and by inducing systems for plant defense. A range of methods, including plant growth-promoting microorganisms(PGPMs) as biological control agents(BCAs)(BCA-PGPMs) are used for the biological management and control of plant pathogens. S...     

The influence of carbon dioxide on the growth,pigment, protein,carbohydrate, and mineral status of lettuce

Lettuce plants (Lactuca sativa L. cv. Grand Rapids) were grown in nutrient solution in controlled environment plant growth chambers to characterize certain qualitative responses to above ambient levels of CO₂. Increased plant material produced under high CO₂ levels did not differ nutritionally from plants grown under ambient levels. No differences were found in chloroplast pigment content, protein content, or in carbohydrate content on a weight basis. Sequential harvests did reveal, however, that there is a greater accumulation of carbohydrate, under high CO₂ conditions, prior to an increased growth rate as the plants reach maturity.     

Optimum N and P rates for greenhouse production of vegetative coleus using constant liquid feed

Many new coleus (C. hybridus cv.) cultivars are vegetatively propagated and require different fertilization practices from seed propagated cultivars. Two experiments were conducted to evaluate growth responses of Henna, Indian Summer, Mint Mocha, New Orleans Red, Red Head, and Trusty Rusty to 0, 70, 140, 280 and 420 mg·L^?1 nitrogen (N), and Henna, Mint Mocha, Red Head, and Trusty Rusty to 0, 6.2, 12.4, 24.8, or 49.6 mg·L^?1 phosphorus (P) to determine optimum constant liquid feed rates to produce marketable size plants from rooted cuttings. Positive growth responses in terms of biomass were found with increasing N rates but not P rates. For medium-sized cultivars such as Henna, Indian Summer, and New Orleans Red, quadratic responses were found in aboveground biomass, and N at 280 mg·L^?1 resulted in similar plant size and dry weight as those fertilized at 140 and 420 mg·L^?1 N. For large-sized cultivars such as Mint Mocha, Red Head and Trusty Rusty, plant dry weight responded linearly within the N range tested and were greatest at 420 mg·L^?1. However, plant visual quality was negatively affected by N rates at 280 and 420 mg·L^?1 in that, leaf color became less intense at these high N rates. Plants fertilized at 70 mg·L^?1 were smaller than those fertilized at 140 mg·L^?1, however, they received similar visual quality ratings because of more intense leaf color. Therefore, N at 70 to 140 mg·L^?1 can be used to grow most vegetative coleus for similar marketable quality. Mint Mocha and Henna were the only cultivars responded to P treatments that, 12.4 mg·L^?1 P rate resulted in greater biomass than the no-P control. All other cultivars had no response to supplemental P except a linear response in tissue P%. Therefore, supplemental P is not required during the 8 week production period when there is an initial P charge in the substrate. We found that substrate pH decreases with higher P rates, therefore supplemental P fertilizer can be used for adjusting pH. Both N and P rates found optimum in this study are lower than current industry practices (N at 150 to 250 mg·L^?1 and P at 24 mg·L^?1) and can significantly lower production cost and potential leaching of excessive nutrient into waterway. Nutrient treatments in further study on postharvest performance of vegetative coleus will be selected based on this study.     

Fruit Quality and Nitrogen,Potassium, and Calcium Content of Apple as Influenced by Nitrate: Ammonium Ratios in Tree Nutrition

Evaluations of fruit quality and nitrogen, potassium, and calcium concentration of apple (Malus domestica Borkh. cvs. Gala and Golab) grown with five treatments of NO₃^?:NH₄⁺ ratios were made in pot culture. The concentrations of NO₃^?:NH₄⁺ ratios were 2.5:0.1, 6:1, 6:0.7, 6:0.5, 6:0.3 meq L^?1. Fruit size, percent dry matter, total dissolved solids, total acidity, or juice pH was not affected by increased ammonium in the ratio. Firmness decreased as the proportion of NH₄⁺ increased. Gala and Golab differed in some of these parameters. Concentrations of N and K increased as NH₄⁺ increased, whereas Ca had no trend or decreased. Generally, the treatment of 2.5:0.1 produced fruits with lower N but higher K and Ca concentrations than the other treatments. This research showed that some parameters such as fruit weight, length, and diameter, juice pH, and dry matter were not affected significantly by NH₄⁺ concentration whereas composition was affected.     

The diagnosis of nitrogen deficiency in wheat by means of a critical nitrate concentration in stem bases

Abstract

Stem bases from wheat plants in a glasshouse pot experiment conducted under varying nitrogen and two water regimes, were analysed for nitrate (NO₃) concentration. The concentration of NO₃ at three stages of growth i.e. tillering, jointing and anthesis were related both to rates of applied nitrogen and to shoot dry matter yield at time of sampling. Plotted against rate of increasing nitrogen application, the response curve of NO₃ concentration in wheat stem bases was sigmoidal. The level of nitrogen application at which NO₃ began to accumulate in the plants was the supply at which plants reached maximum dry matter yield. The concentration of NO₃ at which plant yield was 90% of maximum dry matter was taken as the critical level. This concentration was around 1000 ppm NO₃‐N at all stages. Compared with plants supplied with unlimited water, plants under moderate water stress accumulated relatively more NO₃ but had a similar critical NO₃ concentration.

Maximum grain yield was obtained from plants which stayed above the critical level throughout the growing season.     

Nutrient deficiencies and toxicities in plants: Nitrogen

Current literature review and discussion of the N status of plants as related to their growth and yield and quality of produced product.     

Rapid and simple leaf tissue test for nitrate

Abstract

A simple and rapid procedure for the determination of nitrate in fresh leaf tissue, suitable for use by relatively untrained operators is presented. The method requires only 4 reagents and can be carried out in less than 20 min from start to finish. A 400 mg sample of fresh leaf tissue is macerated briefly with 5 drops of 10 N sulphuric acid, diluted with 10.0 ml of water and filtered. Nitrate‐N is estimated on an aliquot of the filtered extract by reducing the nitrate to nitrite by shaking with powdered zinc in ammonium hydroxide solution for 3 min. The reduced mixture is allowed to settle (5 min) and an aliquot is withdrawn through a cotton‐wool plug thus removing any particles of the zinc. The filtered aliquot is then reacted with a single colour reagent to yield a pink azo‐dye, the intensity of which is directly proportional to the amount of nitrate.

The method was found to have a coefficient of variation of about 4%. When compared with the phenoldisulphonic acid method for nitrate, on aliquots of the some plant extract, it yielded values which were on average 94.6% of those obtained with the former method. The coefficient of variation between the methods was 7%.     

A simplified method for determining acetic acid soluble phosphorus in plant tissue

Abstract

The proposed procedure greatly simplifies the determination of 2% HOAc soluble P in plant tissue. Extraction with Darco G 60 eliminates the need for the H₂O₂ oxidation of the extract. The use of vanadomolybdic acid as the chromogen results in a high degree of color stability eliminating the need for careful timing of the period between color development and transmission readings.     

植物营养生物学研究方向探讨

植物营养生物学是重点研究植物活化、吸收、转运与利用养分的生理、分子及遗传机制的科学。在过去的30年,我国植物营养生物学研究取得了长足的发展,但从国家自然科学基金资助情况分析,与相关学科相比,近10多年来植物营养生物学总体研究力量相对薄弱,缺乏新一代领军人才。一些研究更接近于“纯”植物生物学,与植物营养应用研究出现脱节,对农业绿色发展及化肥产业升级的支撑不够。植物营养生物学研究者应该重视与作物育种、耕作栽培、生态环境、植物保护及化肥产业的合作,跟踪这些领域的研究现状及生产中面临的技术需求,围绕这些领域的技术“瓶颈”开展植物营养基础研究,在提供解决途径的同时创新植物营养生物学机理,从而丰富植物营养学理论。在研究内容上,建议重视控制养分响应度的生理与遗传机制,养分信号与环境信号互作,养分×土壤×管理互作及其对根系生长的影响,养分供应与抗生物胁迫,高产高效的植物营养生理学基础,特种作物的营养机理,化肥产品升级的生物学途径等方向的研究。