Effect of Tungsten on the Growth,Dry-Matter Production,and Biochemical Constituents of Cowpea

The effects of various concentrations (0, 5, 10, 15, 20, and 25 μg g^?1) of tungsten (W) as sodium tungstate were observed on growth performance, dry-matter production, and selected biochemical constituents of cowpea. Lower applied doses of W promoted root–shoot length whereas greater doses retarded it. Chlorophyll contents and soluble sugars increased with lower applied doses of W. Greater applied doses of W resulted in an increase in the chlorophyll a/b ratio. A significant gradual decrease in proline contents was observed with lower applied doses of tungsten. Tungsten contents in plant material showed a very highly significant (P < 0.001) correlation with soil-applied tungsten.     

大豆抗逆基因GmDREB3启动子的克隆及调控区段分析

GmDREB3基因能提高转基因烟草和拟南芥的抗逆性。利用SiteFinding-PCR技术, 从大豆品种铁丰8号基因组中分离到大豆抗逆基因GmDREB3启动子片段, 长度1 648 bp。该片段富含A/T碱基, 还含有TATA-box、低温响应元件MYC及其他顺式元件MYB、CAAT-box等。将该启动子分区段与GUS报告基因连接构建表达载体, 利用基因枪法转化小麦愈伤组织, 并进行干旱、高盐、低温等处理, 通过组织化学染色和GUS荧光定量测定分析各区段调控元件的活性。结果表明, 在干旱和低温的诱导下, 该启动子能激活下游GUS基因的表达, 在–285 ~ –1 117区域存在与低温和干旱应答有关的重要调控元件, 在–1 464 ~ –1 648区域内存在抑制启动子活性的调控元件。由此推断, 在逆境条件下通过启动子区域正、负调控元件的共同作用, 使GmDREB3基因的表达维持在一个恰当的水平。     

5-氨基乙酰丙酸和乙烯利对东北春玉米功能叶光合生理特性和产量的影响

以中单909为材料,设置5-氨基乙酰丙酸（5-ALA）和乙烯利（ETH）不同浓度复配组合,于拔节期（V6）进行叶面喷施。研究5-ALA-ETH复配剂对缓解东北春玉米冠层郁闭效应、提高叶片净光合效率（P_n）、增强叶片的光合产物供给能力、保障春玉米稳产增产的调控效应。结果表明,A2E1（22.5g/hm² 5-ALA+450mL/hm² ETH）处理能够增强叶片的光合生理活性,调控效果最佳,其中V7期叶片叶绿素含量相比对照（CK）显著提高8.9%,V12期叶片RuBP羧化酶（RuBPCase）和PEP羧化酶（PEPCase）活性比CK分别显著提高65.2%和87.1%,V8和V12期叶片P_n比CK分别显著提高14.8%和24.5%。同时,该处理提高了叶片蔗糖的合成能力,其中V12期叶片蔗糖合酶（SS）活性比CK显著提高85.0%,V11期蔗糖磷酸合酶（SPS）活性比CK显著提高33.1%,V7、V9和V12期叶片蔗糖含量比CK分别显著提高69.2%、16.8%和78.6%。在玉米收获期,A2E1处理显著增加了玉米穗长、穗粒数和产量,相比CK分别提高了5.4%、6.2%和5.4%,玉米秃尖长显著缩短50.4%。综上所述,5-ALA（22.5g/hm²）和ETH（450mL/hm²）复配能够改善东北春玉米生育期内光合生理特性,提高收获穗粒数和产量,增强其抵抗冠层郁闭效应胁迫的能力。     

Glyphosate accumulation,translocation, and biological effects in Coffea arabica after single and multiple exposures

In perennial crops like coffee, glyphosate drift exposure can occur multiple times during its commercial life span. Due to limited glyphosate degradation in higher plants, a potential accumulation of glyphosate could lead to increased biological effects with increased exposure frequency. In this study, we investigated glyphosate translocation over time, and its concentration and biological effects after single and multiple simulated spray-drift exposures. Additionally, shikimic acid/glyphosate ratios were used as biomarkers for glyphosate binding to its target enzyme.Four weeks after the exposure, glyphosate was continuously translocated. Shikimic acid levels were linear correlated with glyphosate levels. After two months, however, glyphosate appeared to have reduced activity. In the greenhouse, multiple applications resulted in higher internal glyphosate concentrations. The time of application, however, was more important regarding biological effects than the number of applications both in the greenhouse and in the field. In the field, berry yield, the most important biological response variable, was reduced 26% by the first out of four sequential applications of glyphosate at 64 g a.e. ha⁻¹ each. The three subsequent applications did not reduce yield any further.     

Sorghum grain yield,forage biomass production and revenue as affected by intercropping time

Sorghum is an excellent alternative to other grains in poor soil where corn does not develop very well, as well as in regions with warm and dry winters. Intercropping sorghum [Sorghum bicolor (L.) Moench] with forage crops, such as palisade grass [Brachiaria brizantha (Hochst. ex A. Rich) Stapf] or guinea grass (Panicum maximum Jacq.), provides large amounts of biomass for use as straw in no-tillage systems or as pasture. However, it is important to determine the appropriate time at which these forage crops have to be sown into sorghum systems to avoid reductions in both sorghum and forage production and to maximize the revenue of the cropping system. This study, conducted for three growing seasons at Botucatu in the State of São Paulo in Brazil, evaluated how nutrient concentration, yield components, sorghum grain yield, revenue, and forage crop dry matter production were affected by the timing of forage intercropping. The experimental design was a randomized complete block design. Intercropping systems were not found to cause reductions in the nutrient concentration in sorghum plants. The number of panicles per unit area of sorghum alone (133,600), intercropped sorghum and palisade grass (133,300) and intercropped sorghum and guinea grass (134,300) corresponded to sorghum grain yields of 5439, 5436 and 5566 kg ha⁻¹, respectively. However, the number of panicles per unit area of intercropped sorghum and palisade grass (144,700) and intercropped sorghum and guinea grass (145,000) with topdressing of fertilizers for the sorghum resulted in the highest sorghum grain yields (6238 and 6127 kg ha⁻¹ for intercropping with palisade grass and guinea grass, respectively). Forage production (8112, 10,972 and 13,193 Mg ha⁻¹ for the first, second and third cuts, respectively) was highest when sorghum and guinea grass were intercropped. The timing of intercropping is an important factor in sorghum grain yield and forage production. Palisade grass or guinea grass must be intercropped with sorghum with topdressing fertilization to achieve the highest sorghum grain yield, but this significantly reduces the forage production. Intercropping sorghum with guinea grass sown simultaneously yielded the highest revenue per ha (€ 1074.4), which was 2.4 times greater than the revenue achieved by sowing sorghum only.     

Arbuscular mycorrhizal fungal hyphae enhance transport of the allelochemical juglone in the field

Allelopathy is a biological phenomenon where plants have harmful effects on growth of surrounding plants through the production of chemical substances. Here we focus on allelochemical processes which operate belowground, can influence plant interactions and therefore potentially affect plant community structure. Soil hyphae of arbuscular mycorrhizal fungi (AMF) may enhance transport processes in the soil matrix by providing direct connections between plants facilitating infochemical exchange.In a two-component field study we showed that soil hyphae likely play a crucial role in movement of allelochemicals in natural soils and greatly expand bioactive zones by providing effective transport pathways for chemical compounds. First, we tested the effects of Juglans regia leaf litter extract addition in intact or disrupted hyphal networks and simultaneously determined growth reducing effects on sensitive Lycopersicon lycopersicum plants. Second, we analyzed the effect of juglone on tomato by directly adding leaf litter. In both approaches we found an increase of juglone transport if a hyphal network was present, resulting in reduced growth of target plants.Our results, together with previous work, add to the body of evidence for hyphae of soil fungi playing an important role in the transfer of allelochemicals and effectively acting as transport highways in the field. We suggest that hyphal connections, mostly formed by AMF, increase the effectiveness of allelochemicals in natural systems and can play a crucial role in chemical interaction processes in the soil.     

Reclamation of a coastal reclaimed tidal land soil by gypsum and rice straw

This study was to evaluate the application effect of gypsum and rice straw on the saline–sodic soils of coastal reclaimed tidal lands during newly reclamation process by leaching method. Soil used in the lysimeter experiment is classified as Greyic Hydragric Anthrosols (Sodic Arenic). The experiment was carried out over a period of 1 year from May 2014 to July 2015 inside a plastic film house. Saturated electrical conductivity (EC_e) and exchangeable sodium percentage (ESP) values of soils in gypsum treatment and gypsum with rice straw treatment then reached the desalinization criteria (EC_e = 4.0 dS m^?1, ESP = 15%) after the five or six pore volumes leaching cycles. However, in spite the 10 pore volumes leaching cycles in control and rice straw alone treatment, the values did not reach the desalinization criteria. The results showed that effectiveness of improvement of sodicity and salinity in coastal reclaimed tidal land soils was in the order of gypsum = gypsum + rice straw > rice straw = control. Our study has shown that gypsum alone treatment or gypsum with rice straw treatment in a coastal reclaimed tidal land soils improves their physicochemical characteristics.     

Calibration of Hargreaves–Samani and Priestley–Taylor equations in estimating reference evapotranspiration in the Northwest of Iran

Accurate estimation of reference evapotranspiration (ET_o) is essential for water resources management and irrigation systems scheduling, especially in arid and semiarid regions such as Iran. In the present research, constant coefficients of Hargreaves–Samani (C_H–S) and Priestley–Taylor (C_P–T) equations were locally calibrated to estimate the ET_o based on the FAO–Penmen–Monteith (PM) method as standard method. For this purpose, meteorological data of eight synoptic stations located in the northwest of Iran were used during the period of 1997–2008. The outcomes showed that the values of C_H–S and C_P–T were 0.0026 (instead of 0.0023) and 1.68 (instead of 1.26), respectively. Also, at stations with high wind speed, the values of calibrated coefficients of C_H–S and C_P–T were maximum. Then, the estimated ET_o values using adjusted C_H–S and C_P–T coefficients were compared to the obtained actual ET_o values by PM method using root mean square error and mean bias error indices. The results indicated that the new calibrated H–S and P–T equations have good agreement with the PM method for estimation of the ET_o. Moreover, the equation of Ravazzani et al. was calibrated in the studied region. It was concluded that in general, the mentioned equation was shown better performance than original H–S equation.     

Potassium Fixation and Release Characteristics of Some Benchmark Soil Series under Rice–Wheat Cropping System in the Indo‐Gangetic Plains of Northwestern India

Abstract

Potassium (K) fixation and release in soil are important issues in long‐term sustainability of a cropping system. Fixation and release behavior of potassium were studied in the surface and subsurface horizons in five benchmark soil series, viz. Dhar, Gurdaspur, Naura, Ladowal, and Nabha, under rice–wheat cropping system in the Indo‐Gangetic plains of India. Potassium fixation was noted by adding six rates of K varying from 0 to 500 mg kg^?1 soil in plastic beakers while K release characteristics were studied by repeated extractions with 1 M HNO₃ and 1 M NH₄OAc extractants. The initial status of K was satisfactory to adequate. Potassium fixation of added K increased with the rate of added K irrespective of soil mineralogy and soil depth. Soils rich in K (Ladowal and Nabha) fixed lower amounts (18–42%) of added K as compared to Gurdaspur, Dhar, and Naura (44.6–86.4%) soils low in K. The unit fertilizer requirement for unit increase in available K was more in low‐K soils. The study highlights the need for more studies on K fixation in relation to the associated minerals in a particular soil. Potassium‐release parameters such as total extractable K, total step K, and CR‐K varied widely in different soil series, indicating wide variation in the K‐supplying capacity of these soils. K released with 1 M NH₄OAc extractant was 20–33% of that obtained with 1 M HNO₃. Total extractable K using 1 M HNO₃ varied from 213 to 528 mg kg^?1 and NH₄OAc‐extractable K ranged from 71 to 312 mg kg^?1 soil in surface and subsurface layers of different soil series. The Ladowal and Nabha series showed higher rates of K release than Gurdaspur, Dhar, and Naura series, indicating their greater K‐supplying capacity.     

Marine ecosystem science and the media: Exploring ways to improve news coverage through journalist–scientist working relations

1. The ocean's remoteness, ecological complexities, lengthy ecosystem processes, and vulnerability to multiple and cumulative anthropogenic threats make marine conservation communication particularly difficult. Both scientists and journalists face unique challenges in explaining the science of these often out-of-sight ecosystems. Given the inadequacies of marine news, improvement appeared necessary. However, the experiences and views of journalists and scientists have hardly been examined within marine news contexts. Thus, this study sought the perspectives of these two professional groups to provide a discussion on ways to improve news coverage of complex ocean issues through enhanced journalist–scientist working relations.
2. Both journalists and scientists rated the quantity, breadth and quality of marine news as average and were receptive to alternative ways for reporting ecosystem complexities. Although some frustrations remain, both valued impactful news stories resulting from their working relations and preferred direct contact with each other over indirect methods such as press releases and science news platforms. Both groups generally agreed on what to include in marine news, but scientists favoured a collaborative approach to news content decision-making more strongly than journalists.
3. Journalists' and scientists' commonly shared views and goals concerning marine news identified in this study could serve as a common ground for uniting the two professions. Institutional policies that permit one-on-one journalist–scientist interactions could lead to mutual understandings about the contexts of their relationship challenges. More trustful and mutually beneficial relationships, in turn, could be a basis for a more collaborative news generation process. Compiling and making marine visuals readily accessible to journalists; training programmes that enhance journalists' and scientists' understanding of the influence of media message framing on conservation actions; media appreciation of marine ecosystem complexities' newsworthiness; and the notion of media's social responsibility in reporting marine conservation issues could contribute to more impactful coverage.