芦笋种植对冷凉沙化区土壤改良的效果研究

为探索芦笋种植对冷凉沙化区土壤的改良效果,在山西省朔州市右玉县,以未种植芦笋裸沙地为对照（CK）,设置种植芦笋1、2、3和4年共4个处理,通过田间试验测定不同种植年限芦笋田土壤理化特性和芦笋生长发育情况。结果表明,与CK相比,随种植年限增加,土壤黏粒和粉砂粒含量递增,砂粒含量递减,土壤容重递减,土壤田间持水量递增;土壤pH和可溶性盐浓度（EC）递减;土壤有机质、全氮、有效磷和速效钾含量逐年递增。种植芦笋3年的土壤粒级、土壤容重、田间持水量、pH、EC值、土壤肥力发生显著变化;连续种植芦笋4年的土壤黏粒含量较CK增加到29.8%,粉砂粒含量增加到12.6%,砂粒含量降低到57.6%,田间土壤持水量显著提高,土壤容重显著降低,土壤由砂质壤土向砂质黏土转变;土壤pH降低0.75,EC值降低0.08mS/cm;土壤有机质含量增加28.89%,全氮、有效磷和速效钾含量分别增加95.12%、94.92%和45.40%;芦笋产量达6 037.5kg/hm ²。综合分析,连续种植芦笋4年可改善沙化土壤的物理结构,提高土壤养分,降低盐碱程度。芦笋是冷凉沙化区土壤改良的先锋作物之一,可实现生态效益与经济效益并举。     

NaCl胁迫对2种柑橘砧木生长及盐离子分布的影响

以耐盐性不同的柑橘砧木枳和枸头橙为材料，分析NaCl胁迫后植株生长表现以及盐离子（Na+和Cl-）在叶片、茎和根中的含量。结果表明：NaCl胁迫降低了植株的株高和干重，而枳的下降幅度高于枸头橙。NaCl胁迫导致2种砧木叶片相对电导率升高，枳高于枸头橙。此外，NaCl处理后2种砧木叶片、茎和根中的Na+和Cl-含量均上升。除了处理21天内枳叶片Cl-含量低于枸头橙外，其他时间枳叶片和茎中的盐离子含量均高于枸头橙。在根中，NaCl处理15天内枳中的Na+和Cl-含量高于枸头橙，其后则是枸头橙高于枳。     

Fertilizer-induced Changes in Rhizosphere Electrical Conductivity: Relation to Forest Tree Seedling Root System Growth and Function

Fertilization is standard practice in forest tree seedling nursery culture. Additionally, fertilization at outplanting has potential to facilitate nutrient uptake and reduce transplant shock. Fertilization, however, may dramatically alter rhizosphere chemical properties such as pH, ion availability, and electrical conductivity (EC). These changes may inhibit root system growth and function by reducing soil osmotic potential and creating specific ion toxicities. The risk of root damage associated with high EC levels appears to be dependent on species, age of root system, and soil moisture availability. Root inhibition in container nursery culture of conifers is likely to occur above 2.5 dS m⁻¹, though threshold EC levels for bareroot culture and field plantings are largely unavailable. Fertilization at outplanting has the added risk that drought conditions may prevent leaching of excess fertilizer salts, which can increase rhizosphere EC beyond safe levels and ultimately impair root uptake of water or nutrients. For fertilization programs to be successful, a critical threshold balance must be maintained between optimizing seedling nutrient availability in the rhizosphere, while minimizing potential for root damage. Future research is needed to identify optimal EC levels for a range of species across all stages of the reforestation process, from nursery culture through plantation establishment.     

八个竹种海涂引种试验报告

本文从土壤含盐量着手对八个竹种在引种成活率、新竹抽发数及其质量、角竹笋产量等方面进行了较系统的研究。结果表明,土壤盐分影响竹子的生长发育,此影响一般随含盐量的增加而增加;不同竹种对土壤盐分的适应能力不同;角竹笋能获得高产,单产达20800kg/ha。参照产地母竹和引种地新竹的生长情况,我们建议:海涂地区发展竹子时可选用角竹、桂竹和红竹。     

Evaluating a multi-level subsurface drainage system for improved drainage water quality

This paper describes a multi-level drainage system, designed to improve drainage water quality. Results are presented from a field scale land reclamation experiment implemented in the Murrumbidgee Irrigation Area of New South Wales, Australia. A traditional single level drainage system and a multi-level drainage system were compared in the experiment in an irrigated field setting. The single level drainage system consisted of 1.8 m deep drains at 20 m spacing. This configuration is typical of subsurface drainage system design used in the area. The multi-level drainage system consisted of shallow closely spaced drains (3.3 m spacing at 0.75 m depth) underlain by deeper widely spaced drains (20 m spacing at 1.8 m depth). Data on drainage flows and salinity, water table regime and soil salinity were collected over a 2-year period.     

Supplemental saline drip irrigation applied at different growth stages of two bell pepper cultivars grown with or without mulch in non-saline soil

The effect of supplemental saline (2.5 dS m⁻¹) drip irrigation and black polyethylene mulch on two cultivars of bell peppers (Capsicum annuum L.) was investigated under field conditions using a randomized complete block design with split-split plot restriction. The research included six irrigation treatments (main plots): (i) non-saline irrigation control applied throughout growth (None), (ii) saline irrigation from transplanting until formation of the first fruit set (S1S2), (iii) saline irrigation from transplanting until appearance of the first flower and from first harvest to final harvest (S1S4), (iv) saline irrigation from appearance of the first flower to first harvest (S2S3), (v) saline irrigation from fruit set to final harvest (S3S4), and (vi) saline irrigation throughout growth (All); two mulch treatments (subplots): (i) black mulch and (ii) bare soil; and two bell pepper cultivars (sub-subplots): (i) Early Sunsation and (ii) Red Knight. Production of fully ripened fruits was higher in mulched plants regardless of saline irrigation treatments. In humid areas with non-saline soil, supplemental saline drip irrigation could be used with black polyethylene mulch to save water while maintaining fruit production.     

Over-canopy saline sprinkler irrigation of grapevines during different growth stages

Wetting plant foliage with saline irrigation increases the uptake of toxic ions Na⁺ and Cl⁻. Over three consecutive seasons, Colombard vines grafted on Ramsey rootstock were irrigated with saline water (EC 3.5 dS/m) by over-canopy sprinklers during any one of the first three of the four annual growth stages: bud burst to full bloom (treatment BB-FB), full bloom to veraison (treatment FB-V), and veraison to harvest (treatment V-H). At other times, vines received non-saline water (EC 0.5 dS/m) as did the control. Seasonal average soil salinities remained relatively constant over the trial. In contrast, the concentrations of Na⁺ and Cl⁻ in one-year old wood and grape juice more than doubled. In treatments FB-V and V-H the average yield over the three seasons was reduced by up to 15%. Results were compared with those obtained in an earlier study which was undertaken in the same vineyard with the same treatments applied via dripper. With drippers, the maximum reduction in the average yield over three seasons was 2%. Saline sprinkling caused rises in Na⁺ and Cl⁻ concentrations of fruit, leaf lamina and one-year-old wood that were at least 7-fold, 5-fold and 2-fold greater, respectively, than the rises caused by application of the same treatments with drip. Progressive seasonal rises in the concentrations of Na⁺ and Cl⁻ in these tissues were due in part to carryover of salt added in previous seasons; with saline sprinkling the magnitude of these carryovers was 4-fold greater than those with saline drip irrigation. With saline water, vignerons can reduce losses by using irrigation systems which do not wet the foliage.     

Exogenously applied hexaconazole ameliorates salinity stress by inducing an antioxidant defense system in Brassica napus L. plants

The ability of hexaconazole (HEX) to ameliorate salinity stress was studied in canola plants (Brassica napus L.). Canola seedlings were subjected to sodium chloride (NaCl) treatment. A treatment with 200 mM NaCl reduced growth parameters, chlorophyll content and protein content as well as increased the proline (Pro) content in canola plants. In addition, NaCl stress increased the endogenous, nonenzymatic antioxidants and the activity of antioxidant enzymes, such as peroxidase (POX; EC 1.11.1.7), superoxide dismutase (SOD; EC 1.15.1.1) and catalase (CAT; EC 1.11.1.6). When these plants were treated with a combination of NaCl and 50 mg L⁻¹ HEX, the inhibitory effects of NaCl stress were decreased by increasing the root growth, shoot growth, dry weight (DW), chlorophyll content, protein content and antioxidant enzyme activity by ameliorating the salinity injury. These results suggested that HEX has an important role in the enhancement of plant antioxidant systems and resistance to salinity in canola plants.     

7种园林地被植物耐盐性研究

应用不同NaCI水溶液处理法,比较研究了华南地区栽培的7种常见地被植物幼苗在盐胁迫条件下的存活率、盐害指数、叶绿素荧光参数、根和叶的K＋浓度、Na＋浓度、K＋／Na＋值、叶片相对电导率和相对含水量等指标,并运用隶属函数值对其植物耐盐性进行综合评定。结果表明：在7种参试植物中,小蚌兰Rhoeospathacea和鸢尾Ir...     

Tillage and the environment in sub-tropical Australia—Tradeoffs and challenges

Tillage is defined here in a broad sense, including disturbance of the soil and crop residues, wheel traffic and sowing opportunities. In sub-tropical, semi-arid cropping areas in Australia, tillage systems have evolved from intensively tilled bare fallow systems, with high soil losses, to reduced and no tillage systems. In recent years, the use of controlled traffic has also increased. These conservation tillage systems are successful in reducing water erosion of soil and sediment-bound chemicals. Control of runoff of dissolved nutrients and weakly sorbed chemicals is less certain. Adoption of new practices appears to have been related to practical and economic considerations, and proved to be more profitable after a considerable period of research and development. However there are still challenges. One challenge is to ensure that systems that reduce soil erosion, which may involve greater use of chemicals, do not degrade water quality in streams. Another challenge is to ensure that systems that improve water entry do not increase drainage below the crop root zone, which would increase the risk of salinity. Better understanding of how tillage practices influence soil hydrology, runoff and erosion processes should lead to better tillage systems and enable better management of risks to water quality and soil health. Finally, the need to determine the effectiveness of in-field management practices in achieving stream water quality targets in large, multi-land use catchments will challenge our current knowledge base and the tools available.