民间资本参与水土保持生态建设的做法

海城市共有1 120户参与"四荒"开发,承包面积9 306.67 hm2。2000年以来,新发展治理"四荒"大户23个,总投资21 545万元,水土保持建设面积达1 322.67 hm2。采取制定优惠政策、坚持科学引导与服务支持等办法,调动民间力量参与水土流失治理的积极性。民营资本参与水土保持的主要方式为独立出资、农村合作社、股份合作和公司+农户。介绍了民间资本参与水土保持的主要做法与成效。     

毕节市民间资本参与水土保持工程建设情况探讨

2000年以来,毕节市民间资本参与水土保持工程建设项目40个,治理水土流失面积3 226.67 hm2,投入资金17 150.38万元。民间资本参与形式有农民大户、公司+农户、农民专业合作社、独立出资、股份合作等。对民间资本参与水土保持工程建设的做法和经验进行了总结,分析了存在的困难和问题,并从改善投资环境、加强宣传引导、强化服务体系建设、依法依规实施监管、加大资本集聚和增强政策资金扶持等方面提出了建议。     

邢台市推进民间资本参与水土保持工程建设的主要做法

近年来,邢台市民间资本参与水土保持工程建设的积极性迅速提高,参与形式主要有农民大户、公司+农户、农村合作社、股份合作等。对邢台市的民间资本参与水土保持工程建设的情况进行了调查,对其特点和作用进行了分析探讨。邢台市推进民间资本参与水土保持工程建设的主要做法是:制定利好政策,规范治理模式;规划引路,强化服务;科学管理,注重效益。     

关于晋陕两省民间资本参与水土流失治理的典型情况调研

对晋陕两省民间资本参与水土流失治理的典型情况调研表明,民间资本参与水土流失治理,在增加投资渠道、开发特色产业、促进群众增收致富等方面具有重要作用。鼓励和引导民间资本参与水土流失治理是新时期、新形势下水土保持工作的重要内容,也是目前在国家水保资金投入不足的情况下加快治理速度的一条重要途径。从行业及地方政府层面上看,影响民间资本参与水土流失治理的主要问题在于认识是否到位、政策是否落实、国家投资是否监管有效、机制体制是否健全、产权是否明晰等方面。建议地方政府和流域管理机构进一步加强行业引导,研究落实相关的配套政策,研究建立民间资本开展水土保持生态建设专项基金,创新深化民间资本投资的机制与体制,加强对国有资本产权的保护研究。     

引导民间资本参与水土流失治理的对策建议

泰安市是全国水土流失重点治理区，为加快水土流失治理步伐，提高生态保护质量，泰安市不断探索水土保持生态治理融资新机制，大力引导民间资本参与水土流失治理，不仅拓宽了资金投入渠道，促进了科技成果的研发应用，还加快了乡村振兴步伐。全市具有一定规模的民间投资主体共有218家，总投资达15.42亿元，治理水土流失面积256 km~2。针对目前民间投资还存在的重经济效益轻生态效益，水土资源过度开发，以及受市场影响大，后期投入不稳定等问题，提出了相应的对策和建议。     

庄浪县吸引民间资本治理水土流失模式研究

民间资本在搞好水土保持工程建设中做出了突出的贡献,对促进水土流失治理发挥着重要的作用。多年来,庄浪县以鼓励引导民间资本参与水土流失治理为突破口,按照"政府引导、业主投入、企业运作"方式,采取"个人投资、企业投资和集体投资"模式,充分调动社会各方面的力量参与水土保持生态建设,取得了显著的成效。     

甘肃省民间资本参与水土保持工程建设情况调查

为全面掌握甘肃省民间资本参与水土流失治理及开发情况,研究制定相关政策措施,进一步鼓励和引导民间资本参与水土保持工作,在对全省民间资本参与水土流失治理情况进行调查摸底的基础上,选择庆阳市环县、镇原,平凉市崆峒、庄浪,定西市临洮、陇西,天水市麦积、秦州4个市的8个县(区),采取现场察看、与有关部门及治理大户座谈等形式,专题开展了调研活动。调研组在总结各地民间资本参与水土保持工程建设模式与典型经验的基础上,分析当前面临的主要问题,提出了相关建议。     

铜仁市民间资本参与水保生态建设的做法及建议

铜仁市水土流失治理工作起步较晚,由国家实施的水保生态建设项目较少,水土流失治理速度缓慢。"十一五"以来,为了多渠道筹集治理资金,铜仁市鼓励和引导民间资本参与水保生态建设,初步取得了一些成效。民间资本参与水保生态建设是一项有利于国家、有利于社会、有利于农民的事业,要坚持政府的正确引导,使民间资本更多地参与到水保生态建设中来。     

依靠政策创新机制积极引导民间资本参与水土流失治理

民间资本是指掌握在民营企业以及股份制企业中属于私人股份和其他形式的所有私人资本的统称。我国民间资本治理水土流失起步于20世纪80年代初的以户承包治理小流域,2000-2012年全国累计有10万多大户参与了水土保持工程建设,投入资金279亿元,高标准治理水土流失面积4．65万km^2。民间资本成为治理水土流失的重要投入力量,是新时期、新形势下水土保持工作的重要内容,是目前国家在治理资金不足情况下加快治理速度、改善生态环境、促进经济社会发展的有效途径。各级应加强对民间资本参与水土流失治理的归口管理,及时掌握参与治理情况,加快落实相关配套政策,搞好技术服务与指导,加大资金扶持力度、加强政策宣传引导,在全社会营造关心、重视、支持民间资本参与水土流失治理的良好氛围。     

新时期民间资本参与小流域水土流失综合治理的模式与经验

[目的]研究新时期民间资本参与小流域水土流失综合治理情况,为各地政府提供相关决策参考。[方法]在实地调研的基础上,对当前民间资本参与小流域水土流失综合治理情况进行分析研究。[结果]总结分析了民间资本参与小流域水土流失综合治理的特点、模式与经验。[结论]民间资本逐步成为中国水土保持生态建设领域的重要补充,加快了水土流失防治进程,提高了治理效益。要推进这项工作,还需从政策优惠、建设管理、技术服务等方面加强相关工作。     

Changes in yield and gas exchange parameters in Festulolium and alfalfa grown in pure sowing and in mixture under drought stress

Crop performance and yield are the results of genotypic expression as modulated by continuous interaction with the environment. Among environmental factors, water is globally one of the most limiting for crop production. Water resources in the world are steadily diminishing and in many areas, including Poland, more frequent periods of drought are being observed. The aim of the study was to compare the yields and gas exchange parameters of Festulolium hybrid (Festulolium braunii (K. Richt) A. Camus) and alfalfa (Medicago?×?varia T. Martyn) under different levels of soil moisture (well-watered conditions and drought stress) and cultivation method (pure stand and mixture). The study has shown that all the measured parameters were affected by drought stress. Net photosynthetic rate, transpiration rate, stomatal conductance and dry mass yield were significantly lower under drought stress than under well-watered conditions in all treatment types. Alfalfa grown in a pure sowing showed the strongest reaction to stress, while hybrid Festulolium grown in mixture showed the weakest. It was also found that under stress, grass assimilated CO₂ and evaporated water much more intensively in mixture cultivation than in pure sowing. Higher water use efficiency (WUE) was observed in alfalfa and Festulolium growing in mixture only in the first year of the study.     

Throughfall quality and quantity in polluted and damaged ecosystems in Northern Bohemia

The interaction between high concentrations of polluting gases (SO₂ and NO_x) and damaged forest ecosystems was observed by studying throughfall precipitation in the Erzegebirge Mountains, Northern Bohemia. Qualitative and quantitative data on throughfall for the period November 1989–October 1990 are presented. Weighted averages of SO ₄ ^2? and NO ₃ ^? concentrations in the throughfall were 23.05 mg L^?1 and 13.61 mg L^?1 in a beech and 34.41 mg L^?1 and 11.03 mg L^?1 in a spruce forest respectively. Three variables (the molar ratios of K/Na, N_tot/S and N-NO₃/N-NE₄) were used to compare the spruce throughfall quality to that observed in areas with similar however, less damaged spruce stands. Both K/Na and N-NO₃/N-NH₄ ratios clearly decreased with increasing tree damage, the N_tot/S ratio increased. The results suggest that the throughfall in damaged ecosystems of the Erzegebirge region becomes more like a wet precipitation as the tree canopies get sparser and the trees reduce canopy leaching.     

Sources of sulphate and acidity in wetlands and lakes in Nova Scotia

There is a declining gradient of wet SO₄ deposition from south to north in Nova Scotia with the highest values being in the south, along with a localized increase around the Halifax metropolitan area, due to local SO₄ emission. Edaphic conditions such as drainage from soils containing gypsum or drainage on disturbed rocks containing pyrite, provide additional SO₄ to surface waters.Acidity is usually absent in the former (pH > 7.0) and very high in the latter (as low as pH 3.6). By contrast peaty, organic drainages release water low in SO₄ during the growing season but they release high amounts of organic anions (A?), consequently, these waters maintain decreased pH values, usually < 4.5. A study of over 80 wetlands and lakes during the ice free period in Nova Scotia showed that sea salt corrected SO₄ concentrations range from 45 ueq L^?1 in the south end of the province, ～30 ueq L^?1 in the Kejimkujik area and < 17 ueq L^?1 in the northern areas with values > 85 ueq L^?1 in the Halifax area, reflecting the atmospheric deposition pattern of SO₄ The SO₄ concentrations may be > 2000 ueq L^?1 in drainages containing gypsum, > 700 ueq L^?1 in drainages over pyrite bearing socks but < 20 ueq/L^?1 in streams draining bogs. The SO₄ concentrations change considerably during the non-growing season when the ground is saturated with water or frozen, and the runoff is high (snow and rain often alternate in winter). Under such conditions SO₄ concentration drops in the two former cases and increases in bog drainages, accompanied with a considerable drop in (A?) concentrations. Care should be taken when interpreting SO₄ concentrations in surface waters in Nova Scotia with respect to atmospheric SO₄ deposition.     

Changes in amino acid and organic acid composition in tomato and cucumber plants in relation to salinity and nitrogen nutrition

Under conditions of salt stress, plants show qualitative and quantitative alterations in various organic compounds, such as nitrogen (N) compounds and organic acids. In this work, the effect of different saline levels as well as various N levels, supplied as nitrate (NO₃) or as ammonium (NH₄)+NO₃ on the concentration of amino acids and organic acids in the leaves of tomato and cucumber plants has been studied. The effect of the source of N on individual amino acid contents varied with plant species. Most of the amino acids increased when the concentration of N in the nutrient solution was increased, except when N was added as NH₄+NO₃ for tomato. The effect of salt stress depended on which amino acid was considered. The data also indicate that the effect of salinity on each particular amino acid was greatly dependent on the plant species and N source. Organic acids were differently affected by salinity and by the N source, depending on the plant species. In tomato, the concentrations of short‐chain organic acids were 2–3 times higher in NO₃‐supplied plants than in those grown with NH₄+NO₃. Finally, in cucumber, malic acid concentration increased as a function of the saline level in the medium.     

Fungal abundance and diversity in earthworm casts and in uningested soil

Earthworm casts and adjacent uningested soil from 30 different locations were compared to determine the abundance and diversity of fungal species. The casts contained larger fungal populations (g^-1 dry soil weight) and numbers of fungal species than the soil. Variations in these parameters between casts and soil were statistically significant (P=0.05). Fungal populations and the number of fungal species in casts and soil also varied significantly (P=0.05) between samples from different locations. A total of 27 fungal species were recorded from the casts and soil. Indices of dominance (0.084 casts; 0.14 soil) and general diversity (2.53 casts; 2.02 soil) demonstrated that the casts displayed more diverse fungal flora than the soil. The diversity of fungal species increased in earthworm casts after passing through the earthworm gut.     

Presence and dispersal of infective Frankia in peat and meadow soils in Sweden

Summary Use of the N₂-fixing grey alder, Alnus incana (L.) Moench, as a short-rotation crop for energy production is currently being explored. To evaluate the need for inoculation of alders, the distribution of infective propagules of Frankia in the soil at potential sites for alder plantations was examined. Uninoculated grey alder seedlings were grown in three types of soil. Frequent nodulation was found in a meadow soil which had been free from actinorhizal plants for nearly 60 years, but the alder seedlings failed to nodulate in peat soil from two different bog sites. One of these bogs had been exploited for peat and the surface layer of the peat had been removed, so that the soil samples were taken from deep layers of the peat. At the other site, an area of cultivated peat, there were no infective propagules of Frankia in plots without alders; the infective Frankia was present in plots only where it had been introduced by inoculated alders. There was no detectable air-borne dispersal of Frankia. Instead, water movement might account for the dispersal of Frankia in peat. Although the apparent absence of Frankia in these peat soils necessitates inoculation of alder seedlings before planting out, this makes it possible to introduce and maintain Frankia strains with selected beneficial characteristics, since there is no competition from an indigenous Frankia flora.     

Expression and inheritance of isozymes in Brassica species and in their interspecific hybrids

Abstract

Gene expression was analysed by means of isozyme electrophoresis for three diploid species Brassica rapa (genome AA), B. nigra (BB), and B. oleracea/ B. oleracea var. alboglabra (CC), three amphidiploids B. juncea (AABB), B. napus (AACC) and B. carinata (BBCC), and in 15 interspecific hybrids from crosses within and between the diploids and the amphidiploids. Five enzyme systems were assessed: glucosephosphate isomerase, leucine aminopeptidase, phosphoglucomutase, 6-phosphogluconate dehydrogenase and malate dehydrogenase. Alleles descending from the diploid species were found both in natural and artificially produced amphidiploids. No effect of reciprocal crosses was observed. i.e., the Brassica isozymes were under nuclear gene control. Mendelian segregation in the F₂ generation from crossing two resynthesized B. napus was observed for the loci glucosephosphate isomerase-2 and phosphoglucomutase-3. Genome-specific alleles were identified for several loci. No alteration in the allelic expression of isozymes was found when assembling all three Brassica genomes in the trigenomic interspecific hybrids. Moreover, trigenomic hybrids were capable of disclosing a silent allele of leucine aminopeptidase from B. carinata, and thus in this study the capability of isozyme analysis for detecting hidden variation was demonstrated.     

Carbon mineralization in response to nitrogen and litter addition in surface and subsoils in an agroecosystem

More than 50% of global soil organic carbon stocks are stored below 20 cm of soil depth capable of massively altering global C cycle and climate. However, subsoil C dynamics are largely overlooked implicitly assuming that surface and subsoil C dynamics are similar. Here, we compared the soil C dynamics in surface and subsurface soil layers in response to nitrogen and maize leaf litter additions. Soils, sampled from 0 to 5, 15 to 35, 35 to 55 and 55 to 75 cm depths, were incubated at 25°C after adding litter, nitrogen (NH₄NO₃) or litter plus nitrogen. Soil respiration (C mineralization) was measured throughout the incubation period. Litter addition significantly increased C mineralization in all the soil layers. However, the soil CO₂ release relative to control was more than twofold higher in 15–35 and 35–55 cm soil layers than the surface layer. Nitrogen additions significantly decreased C mineralization in 0–15 cm soil, increased in 35–55 cm and had minimal effects in the 15–35 and 55–75 cm layers. Different soil C dynamics in surface and subsurface soil layers found in our study contradict the general assumption that soil C dynamics may be treated similarly along different soil depths.     

Nitrogen to sulphur ratio in rapeseed and in rapeseed protein and its use in diagnosing sulphur deficiency

This study investigated the variation of nitrogen to sulphur ratios in rapeseed (N/S)_t and in rapeseed protein (N/S). Under S‐sufficient conditions the (N/ S)_t ratios varied considerably between different varieties, with low glucosinolate varieties having higher ratios than high glucosinolate varieties. In contrast, (N/S)_p remained relatively constant at about 11.5 for all varieties tested, though significant effects of N and S nutrition on the (N/S) ratio were present. The ratio increased in the S‐deficient samples. Results of yield responses to S fertilizer and (N/S)₍from six field experiments were used to see if (N/S)_t could indicate the S status of the crop. Although yield losses due to S shortage tended to occur when (N/S)_t was greater than 10, the relationship was not sufficiently reliable for use in diagnosis.     

Role of Phenolics and Organic Acids in Phosphorus Mobilization in Calcareous and Acidic Soils

Abstract

Phenolic acids (caffeic, CAF; protocatechuic, PCA; p-coumaric, COU; and vanillic, VAN), catechol (CAT), poly-galacturonic acid (PGA), and citric acid (CIT) were compared for their effectiveness in phosphorus (P) mobilization in three soils differing in chemical properties. The addition of organic ligands at 100 μmol g^{? 1} soil increased the concentrations of resin P (P_r), water-extractable P (P_w), and bicarbonate-extractable inorganic P (P_bi), thus improving the phosphorus availability. The magnitude of P mobilization in the calcareous soil can be expressed in the following order: CAF > CAT > PCA = CIT > VAN > COU > PGA, which was consistent with the number of phenolic hydroxyl groups they contained and the position of carboxyl on the benzoic ring. In the two acid soils tested, the order of P mobilization was CIT > CAT > PCA > CAF after 24 h incubation, and CIT > PCA > CAF > CAT after a 14 d incubation. The mobilized P originated partly from the organic P fractions, which could be extracted by 0.5 M NaHCO₃. In addition, P_r decreased and P_w increased during incubation. The exceptions were that the CAF treatment increased P_r and the CIT treatment did not affect P_w. Calcium extraction from the soils after a 1 d or 14 d incubation could not fully account for the P mobilization. The results suggest that the inorganic P dissolution by the organic ligands was not the only mechanism of P mobilization in the calcareous soil, while in acid soils the chelation of metal cations by organic ligands is likely an important factor in P mobilization.