Carbon isotope ratio in cotton varies with growth stage and plant

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2023年高考英语外刊时文精读专题14气候变化与珊瑚礁

2023年高考英语外刊时文精读精练 (14)Climate change and coral reefs气候变化与珊瑚礁主题语境：人与自然主题语境内容：自然生态【外刊原文】（斜体单词为超纲词汇，认识即可；下划线单词为课标词汇，需熟记。

）Human beings have been altering habitats—sometimes deliberately andsometimes accidentall y—at least since the end of the last Ice Age. Now, though, that change is happening on a grand scale. Global warming is a growing factor. Fortunately, the human wisdom that is destroying nature can also be brought to bear on trying to save it.Some interventions to save ecosystems are hard to imagine andsucceed. Consider a project to reintroducesomething similar to a mammoth(猛犸象)to Siberiaby gene-editing Asian elephants. Their feeding habits could restore the grassland habitat that was around before mammoths died out, increasing the sunlight reflected into space and helping keep carbon compounds(碳化合物)trapped in the soil. But other projects have a bigger chance of making an impact quickly. As we report, one example involves coral reefs.These are the rainforests of the ocean. They exist on vast scales: half a trillion corals line the Pacific from Indonesia to French Polynesia, roughly the same as the number of trees that fill the Amazon. They are equally important harbor of biodiversity. Rainforests cover18% of the land’s s urface and offer a home to more than half its vertebrate(脊椎动物的)species. Reefs occupy0.1% of the oceans and host a quarter of marine(海洋的)species.And corals are useful to people, too. Without the protection which reefs afford from crashing waves, low-lying islands such as the Maldives would have flooded long ago, and a billion people would lose food or income. One team of economists has estimated that coral’s global ecosystem services are worth up to $10trn a year. reefs are, however, under threat from rising sea temperatures. Heat causes the algae（海藻） with which corals co-exist, and on which they depend for food and colour, to generate toxins（毒素）that lead to those algae’s expulsion（排出）. This is known as “bleaching（白化）”, and can cause a coral’s death.As temperatures continue to rise, research groups around the world are coming up with plansof action. Their ideas include identifying naturally heat-resistant（耐热的）corals and moving themaround the world; crossbreeding（杂交）such corals to create strains that are yet-more heat-resistant; employing genetic editing to add heat resistance artificially; transplantingheat-resistant symbiotic（共生的）algae; and even repairing with the bacteria and other micro-organismswith which corals co-exist—to see if that will help.The assisted evolution of corals does not meet with universal enthusiasm. Without carbon reduction and decline in coral-killing pollution, even resistant corals will not survive the century. Some doubt whetherhumans will get its act together in time to make much difference. Few of these techniques are ready for action in the wild. Some, such as gene editing, are so controversial that it is doubtful they will be approved any time soon. scale is also an issue.But there are grounds for optimism. Carbon targets are being set and ocean pollution is being dealt with. Countries that share responsibilities for reefs are starting to act together. Scientific methods can also be found. Natural currents can be used to facilitate mass breeding. Sites of the greatest ecological and economical importance can be identified to maximise benefits.This mix of natural activity and human intervention could serve as a blueprint （蓝图）for other ecosystems. Those who think that all habitats should be kept original may not approve. But when entire ecosystems are facing destruction, the cost of doing nothing is too great to bear. For coral reefs, at least, if any are to survive at all, it will be those that humans have re-engineered to handle the future.【课标词汇精讲】1.alter （通常指轻微地）改动，修改；改变，（使）变化We've had to alter some of our plans.我们不得不对一些计划作出改动。

carbon uptake

Note A model of carbon isotopic fractionation and active carbon uptake in phytoplankton
Klaus Keller
Department of Civil Engineering and Operations Research, Princeton University, Princeton, NJ 08540, klkeller@
p
=
up + fix , diff :
1
In this equation up, fix, and diff represent the fractionation e ects of the carbon uptake processes, carbon xation, and di usive carbon loss from the cell, respectively, and is the ratio of cellular carbon loss to carbon in ux. p is well approximated by 13 CCO2 - 13COM , the di erence between the isotopic compositions of the external CO2 and the organic matter 1
Байду номын сангаас
pools Goericke et al., 1994 . Note that this stylized model neglects a host of potentially important cellular characteristics such as respiration or cellular compartments. The ratio of carbon loss to carbon in ux is a function of the di usive CO2 in ux equal to CO2 P A, where P denotes the membrane permeability and A the membrane surface area, the cellular carbon demand equal to Qc, where Qc represents the cellular carbon content, as well as the active carbon uptake uxes. To model the regulation of carbon uptake in the simplest way possible, we assume that the cells adjust their active carbon uptake in a constant ratio to their carbon xation rate. We neglect the di usive , ux of the charged HCO3 molecule across the lipid cell membrane as well as the e ects of the di usive boundary layer. The ratio of carbon loss to carbon in ux is then: C 1 + , 1 CO2QP A : 2 = C 1 + CO2QP A The fractionation e ect of the carbon uptake processes up is calculated by an isotopic mass balance of the carbon uxes into the internal CO2 pool. We assume the fractionation of the carbon uptake mechanism t to be equal to the fractionation by di usion , t = diff = 0.7 o =oo O'Leary, 1984 . Because we assume zero HCO3 e ux, all the , HCO3 actively taken up has to be completely converted into CO2. In this situation, the intracellular dehydration shows no isotopic fractionation. Finally, in the case of active , HCO3 uptake, the substrate for the carbon uptake mechanism has an isotopic composition 13 Csource which is around 9 o=oo higher than 13 CCO2 Mook et al., 1974 . up is then:

滨海盐碱地棉田盐度等级划分

山东农业科学2012，44（3）：36 39Shandong Agricultural Sciences收稿日期：2011－08－22基金项目：国家自然科学基金项目（30971720）、现代农业产业技术体系建设专项资金（CARS －18－21）和山东省重大应用技术研究项目（2010－棉花）资助。

作者简介：董合忠（1965－），男，博士，研究员，主要从事棉花生理生态研究。

E －mail ：donghz@滨海盐碱地棉田盐度等级划分董合忠，辛承松，李维江（山东棉花研究中心/山东省棉花栽培生理重点实验室，山东济南250100）摘要：我国植棉区内的滨海盐碱地主要呈带状分布在山东、河北、天津和苏北沿海低平原海岸地区，滨海盐碱地已成为我国重要的棉田生态类型。

为满足盐碱地棉花生产发展的需要，本研究在参考前人研究与实践的基础上，基于盐碱地棉田土壤盐分的季节性变化、土壤盐分对棉花出苗、成苗和产量的影响，以春季（3月中下旬）0 20cm 表层土壤全盐含量为指标，将滨海盐碱地棉田划分为脱盐非盐碱地（＜0.10%）、轻度盐碱地（0.10% 0.25%）、中度盐碱地（0.25% 0.45%）和重度盐碱地（0.45% 0.80%）。

各类盐碱地应根据盐度等级采取针对性成苗和管理技术措施，才能实现全苗壮苗和丰产丰收。

关键词：滨海盐碱地；棉花；盐度中图分类号：S562.061文献标识号：A文章编号：1001－4942（2012）03－0036－04Soil Salinity Grading of Cotton Field in Coastal Saline AreaDONG He －zhong ，XIN Cheng －song ，LI Wei －jiang（Shandong Cotton Research Center /Key Laboratory for Cotton Cultivation and Physiology ofShandong Province ，Jinan 250100，China ）Abstract Coastal saline soil within cotton cultivating areas in China is mainly distributed in the coastallow plain of Shandong ，Hebei ，Tianjin and north of Jiangsu Province．It has become one of the most important ecotypes of cotton field in China．On the basis of previous research and practice ，the seasonal dynamics of soil salinity and its effect on cotton emergence ，seedling establishment and lint yield were analyzed．To meet the demand of developing cotton production ，the saline cotton fields were divided into four grades according to the total salt content in soil of 0 20cm in spring （the middle and later ten days of March ）．They were desali-nized non －saline soil （＜0．10%），low salinity （0．10% 0．25%），moderate salinity （0．25% 0．45%）and high salinity soil （0．45% 0．80%）．It was suggested that each type of saline cotton field should adopt pertinent and appropriate technical measures to improve the seedling establishment and cotton yield．Key wordsCoastal saline soil ；Cotton ；Salinity grading盐土、碱土和各种盐化、碱化土壤统称盐碱土、盐渍土或盐碱地［1］。

碳排放外文翻译--全球碳披露激励设置：实证研究

碳排放外文翻译--全球碳披露激励设置：实证研究中文3265字,1825单词，1.1万英文字符本科毕业论文外文资料翻译系别：经济系专业：会计学姓名：学号：2014 年 4 月 30 日外文原文CarbonDisclosure Incentives ina Global Setting:An Empirical InvestigationI. IntroductionWe investigate the country level factors that influence a firm?s decision to participate in and disclose corporate carbon emission information. Concern over climate change and its potential impact on corporate activities is garnering increased attention among company stakeholders and regulators. In response, the field of accounting is increasingly being shouldered with the responsibility of understanding the role of reporting corporate environmental performance, as well as financial performance (Hopwood, 2009). In particular companies are being confronted with the challenges of accounting for and reporting of greenhouse gas or carbon emissions.While carbon disclosure is predominately voluntary, mandatory legislation is increasingly being proposed or implemented throughout the world. For example, the U.S. Environmental Protection Agency (EPA) has proposed a mandatory greenhouse gas reporting rule to collect accurate and comprehensive corporate emissions data in order to informfuture policy decisions. Likewise, public demands for corporations and financial markets to address climate change reporting prompted the formation of the Climate Disclosure Standards Board (CDSB) at the 2007 Annual World Economic Forum. The goal of the CDSB is to advance climate changedisclosure in mainstream corporate reporting by developing a global framework and standards for carbon emission disclosures (CDSB 2007).II. Carbon Disclosure and Related Disclosure LiteratureCarbon Disclosure ProjectThe CDP has become a standard for carbon emission reduction, providing an avenue and repository for the largest corporations in the world. It is an independent not-for-profit organization, established December 4, 2002, to facilitate communication between shareholders and corporations in an effort to develop a comprehensive response to global climate change. Because firm specific responses to each questionnaire, including a decline or non-response action, are displayed on the CDP?s website, motivation increases for firms to participate in the questionnaire process and disclose results. Each year the CDP lists all firms requested to participate and discloses specific responses to a comprehensive questionnaire regarding corporate carbon emissions and climate change.Extant voluntary disclosure literature is limited with regards to studies concerning carbon reporting information. Growing more important for stakeholders, regulators, and practitioners is the need to better understand the motivation for these disclosures as firm risk of potential legal liabilities related to corporate influence on climate change increases. If they do not adequately disclose their climate change risks, shareholders cansue the company and pursue separate actions against directors and managers who might not have satisfied their fiduciary responsibility in relation to informing investors (Johnson 2007). The first of such lawsuits came in 2004, when the attorney generals from eight states and New York City filed a climate change …nuisance? lawsuit against the top five U.S. emitters of carbon dioxide (Baue 2004). In response to these fears, firms are increasing their environmental strategies and related disclosures.Environmental Disclosure LiteratureMany environmental accounting studies have attempted to determine the incentives which motivate firms to disclose environmental information. These studies are often limited to settings which involve firms within only one country or in a small set of countries. Barth et al. (1997) investigate those U.S. firms included in environmental liability intensive industries which are named as Environmental Protection Agency (EPA) potentially responsible parties (PRP) and determine that increased environmental disclosure is associated with regulatory influence, allocation uncertainty, litigation and negotiation concerns, capital market concerns, and other regulatory effects.V oluntary Disclosure LiteratureThe second stream of research supporting our study focuses more generally on voluntary disclosure incentives in an international, cross-country setting. A recent study by Cahan et al. (2005) examines how firm level variation in voluntary disclosure is affected by global diversification. Studies by Bushman et al. (2004) and La Porta et al. (1998) investigate variation in cross-country determinants of voluntary disclosure at the country level.Additionally, Jaggi and Low (2000), Hope (2003), and Francis et al. (2005) examine the influence of country leveland firm level incentives on the level of voluntary disclosure. None of these studies focus on the unique domain of environmental reporting.III. SampleAnd Empirical TestsSampleThe sample firms and disclosure data are gathered from years 1-5 of the CDP. Information pertaining to the environmental regulatory stringency of each country is determined by Esty and Porter (2005). Nationallevel corporate environmental responsiveness is from the 2002 Environmental Sustainability Index (World Economic Forum 2002). The variable for the legal system comes from La Porta et al. (1998) and the data for financial structure comes from Levine (2002). Both the size and leverage of the firm are obtained from Global Vantage. Firm-specific cross-listing is determined by the world?s top six stock exchanges as determined by domestic market capitalization.The initial sample of CDP disclosure firms represented 63 different countries. This initial sample was restricted by country-level data regarding environmental regulatory stringency in Esty and Porter (2005). Data for financial structure (Levine 2002) and legal structure (La Porta et al. 1998) further restricted the country-level data, decreasing the country level coverage to 28 distinct countries. Additional losses from the absence of Compustat data reduced the sample to a final 4799 firm-specific responses, consisting of 2140 unique firms. Appendix provides a detailed list of disclosures by country and by year,provides a summarized list of disclosure level by country. For those firms that chose to disclose, the level of CDP participation is broken down into full participation and those firms only providing areduced level of information. Non-disclosure also includes those firms choosing not to participate.Dependent Variable – Carbon Accounting DisclosureThe existence of carbon disclosure is determined by the 2002 –2006 CDPquestionnaire response results. Since its inception in 2002, the CDP has requested corporate voluntary participation in a carbon disclosure questionnaire aimed at increasing the global climate change communication among corporations, non-governmental organizations, regulators, academics, and all other interested stakeholders. Once sent a questionnaire, the firms decide whether to participate in the process in one of four actions. They can: (1) participate in the questionnaire by providing all requested information, (2) participate in the questionnaire by providing some information, but not all as requested by the CDP, (3) disclose their response or choose to have it noted otherwise as a non-disclosure, (4) choose not to participate at all by communicating such a response or by not responding.Because the methodology for carbon disclosure is so ambiguous and there is a fear of non-comparability, the uncertainty of response to this complex information, and the proprietary cost associated with the knowledge of such information by competitors and environmental advocacy groups alike, it is of interest to empirically determine which country-level characteristics are associated with this global disclosure amongst firms. The CDP setting provides a unique opportunity to test environmental disclosure across country boundaries where the request for information is ubiquitous and comparable. These advantages allow me to conduct multiple analyses. We examinethe determinants of overall disclosure which is denoted by DISC. We then disentangle the firm disclosure decision further to evaluate those firms that choose to fully participate and disclose all requested information, FULLDISC, and those firms that choose only to provide some information and disclose, PIDISC, across countries. We further examine the sample to determine what incentives drive a firm?s decision for initial disclosure (FIRSTDISC), and finally, we examine the incentives driving mere participation in the CDP questionnaire process to deduce the motivatio n to participate in such a resource intensive process, regardless of a firm?s decision to disclose (PARTIC).Concern about carbon emissions, and hence concern about disclosure of carbon emissionlevels, has been expressed by various stakeholders, including corporate executives, boards of directors, investors, creditors, standard setters, government regulators, and NGOs. Indeed, some informed observers expect that the relationship between carbon emissions and global climate change will drive a redistribution of value from firms that do notcontrol their carbon emissions successfully to firms that do (GS Sustain 2009). Using hand-collected carbon emissions data for 2006-2008 that S&P 500 firms disclosed voluntarilyto the Carbon Disclosure Project, we examine two separate, yet, related questions. The first question addresses firm-level characteristics associated with the choice to disclose carbon emissions. Consistent with economic theory, we predict and find a higher likelihood of carbon emission disclosures by firms with superiorenvironmental performance, conditional on firms taking environmentally proactive actions. However, contrary to our predictions based on socio-political theories, we find no association between inferiorenvironmental performance and thelikelihood of disclosing carbon emissions, conditional on firms taking environmentally damaging actions. Further, we predict and find that firms are more likely to voluntarily disclosetheir carbon emissions as the proportion of industrypeer firm disclosers increases. To address the second question concerning the relationship between carbon emission levels and firm value, we correct for self-selection bias caused by firm- and industry-level characteristics associated with the decision to disclose such emissions. We predict and find a negative association between carbon emission levels and firm value. On average, for every additional thousand metric tons of carbon emissions for our sample of S&P 500 firms, firm value decreases by $202,000. Our sensitivity analyses and robustness test results are similar to our main results.In conclusion, we provide evidence on the factors that affect managers? decisions to publicly disclose their carbon emissions. We alsoshow that investors in equity markets are incorporating the effects of carbon emissions intheir valuation decisions. In response to heightened concerns about climate change, proposals to reduce carbon emissions aim to internalize the costs of emitting GHG by requiring the firm to pay for its emissions –the “Polluter Pays Principle.” Although there are no U.S. regulatory penalties currently in place for carbon emissions, our findings suggest that the market finds the frequently unverified, nonfinancial disclosures of carbon emissions useful and implicitly imputes a price to carbon emissions.Environmental ResponsivenessThe 2002 Environmental Sustainability Index is a collaborative effort between YaleUniversity?s Center for Environmental Law and Policy, ColumbiaUniversity?s Center forInternational Earth Science Information Network, and the World Economic Forum (World Economic Forum 2002). This index provides analysis of 142 countries and ranks those countries based on their overall country sustainability. One area of interest in this examination is that of …Social and Institutional Capacity?, which focuses on society?s capacity to improve its environmental performance. One indicator involved in this measure is environmental responsiveness and includes five specific measures. First, it measures the number of ISO 14001 certified companies per million dollars in GDP, which is a set of environmental management standards to assists firms in minimizing how their operations might negatively affect the natural environment. A second indicator of environmental responsiveness is firm existence on the Dow Jones Sustainability Group Index.Third, the index evaluates the average Innovest EcoValue ratios of firms in each country.This rating methodology assesses each country?s strategies to improve environmental performance, reduce environmentally-related risk, and the capacity for business to develop new opportunities through environmentally-oriented investments. Fourth, they examine the level of corporate concern for environmental sustainability by determining firm membership in the World Business Council for Sustainable Development. Finally, the index evaluates the private sector environmental innovation.(From: Journal ofinternational financial management&accountingV olume 23)外文资料翻译译文全球碳披露激励设置：实证研究一、引言我们调查的国家一级因素影响着公司的决定，参加并披露企业碳排放信息。

碳墨移动比值英语

碳墨移动比值英语The Ratio of Carbon Ink MovementThe world of printing and writing has undergone a remarkable transformation in recent years, driven by the rapid advancements in technology. One of the most significant developments in this field is the emergence of carbon ink, a versatile and innovative material that has revolutionized the way we approach the printed word. In this essay, we will delve into the intriguing concept of the ratio of carbon ink movement, exploring its implications and the factors that influence this crucial aspect of modern printing and writing.At the heart of the carbon ink movement lies the fundamental principle of efficient ink transfer and distribution. The ratio of carbon ink movement refers to the precise balance between the amount of ink deposited on a surface and the distance it travels across that surface. This ratio is of paramount importance in ensuring consistent and high-quality output, whether it be in the realm of commercial printing, artistic expression, or personal writing.The ratio of carbon ink movement is influenced by a multitude of factors, each playing a crucial role in the overall performance and effectiveness of the printing or writing process. One of the primary determinants is the composition of the carbon ink itself. The precise blend of carbon-based pigments, binders, and solvents can significantly impact the ink's viscosity, surface tension, and drying characteristics, all of which directly affect the way it moves and interacts with the substrate.Another key factor is the surface characteristics of the material being printed or written upon. The porosity, smoothness, and absorbency of the paper, fabric, or other media can greatly influence the way the carbon ink behaves, affecting its ability to spread, penetrate, and adhere to the surface. The interplay between the ink and the substrate is a delicate balance that requires careful consideration and optimization.The ratio of carbon ink movement is also influenced by the printing or writing technology employed. In the realm of commercial printing, advanced digital presses and offset printing machines utilize sophisticated ink delivery systems that precisely control the amount and distribution of carbon ink on the printed page. In the case of handwriting and artistic applications, the choice of writing instrument, the angle and pressure of the pen or brush, and the technique of the user all contribute to the final ratio of inkmovement.Achieving the optimal ratio of carbon ink movement is essential for a variety of reasons. In commercial printing, a well-calibrated ratio ensures consistent color reproduction, sharp text, and vibrant imagery, ultimately enhancing the visual impact and quality of the final product. In the realm of artistic expression, the ratio of carbon ink movement can be manipulated to create unique textures, gradients, and expressive qualities, allowing artists to push the boundaries of their craft.Furthermore, the ratio of carbon ink movement plays a crucial role in the longevity and preservation of printed materials. A well-balanced ratio can help prevent issues such as smearing, bleeding, and fading, ensuring that the printed content remains legible and visually appealing over time. This is particularly important in the preservation of historical documents, archival materials, and fine art prints, where the long-term integrity of the work is of paramount concern.The ongoing research and development in the field of carbon ink technology have led to significant advancements in our understanding of the ratio of carbon ink movement. Scientists and engineers are constantly exploring new formulations, materials, and printing techniques to optimize this crucial aspect of the printing and writing process. From the development of specialized inks withenhanced flow properties to the design of innovative printing mechanisms, the quest for the perfect ratio of carbon ink movement continues to drive innovation in the industry.As we look to the future, the significance of the ratio of carbon ink movement will only continue to grow. With the increasing demand for high-quality, sustainable, and personalized printed materials, the ability to precisely control the movement and distribution of carbon ink will be essential. Furthermore, the integration of digital technologies, such as 3D printing and augmented reality, may introduce new challenges and opportunities in the management of carbon ink ratios, requiring even greater precision and adaptability.In conclusion, the ratio of carbon ink movement is a fundamental concept that underpins the world of printing and writing. By understanding and optimizing this crucial aspect, we can unlock new possibilities in the realm of commercial printing, artistic expression, and personal communication. As technology continues to evolve, the importance of the ratio of carbon ink movement will only become more pronounced, driving further advancements and innovations in this dynamic and ever-changing field.。

纺织专业英语课文翻译

第二课Cotton Properties and Uses棉纤维的特性和用途吸湿性和良好的吸湿排汗性能使棉纤维的一个更舒适的一个比较高的水平。

因为在纤维素的羟基基团，棉花对水有很强的吸引力。

当水进入纤维棉，膨胀，其截面变得更圆。

水分和膨胀时湿让棉花吸收水的重量约四分之一的高亲和力的能力。

这意味着，在炎热的天气里，身体的汗会吸收棉织品，沿运纱布的外表面和蒸发到空气中。

因此，身体会帮助维持其温度。

不幸的是，棉花的亲水性使得它容易受到水渍。

如在咖啡或葡萄汁的水溶性色素会渗入纤维随着水；当水分蒸发，着色剂是困在纤维。

也许主要的缺点，棉织品是他们的倾向，皱纹和去除皱纹的困难。

棉纤维的刚度降低纱线抗起皱能力。

当纤维弯曲的一种新的配置，氢债券持有的纤维素链在一起破裂和分子滑动以减少纤维中的应力。

在新的位置的氢键的改革，所以当破碎力去除纤维保持在新的位置。

这是氢键，有助于保持皱纹的断裂和改革，使棉织品要熨。

棉花是具有良好的耐磨性和尺寸稳定性好，中等强度的纤维。

这是抵抗酸，碱和有机溶剂，通常提供给消费者。

但由于它是一种天然物质，它是受攻击的昆虫，霉菌和真菌。

最突出的是棉花霉烂的倾向，如果允许存在潮湿。

棉花抗太阳光和热，虽然直接暴露于恒定的强烈的阳光会引起黄的最终降解纤维。

变黄时也可能出现在气干燥器干燥棉织品。

颜色的变化是一种化学反应的纤维素和氧或氮氧化物之间在热空气中干燥的结果。

棉花将保留其白度较长时，线干或在电干燥器中干燥。

主要感兴趣的是事实，棉纱时干时湿比。

此属性的宏观和微观结构特征的纤维的结果。

当水被吸收，纤维膨胀，其截面变得更圆。

通常这种大量的外来物质的吸收会导致内部应力较高，导致纤维弱化。

然而，棉花，水的吸收导致的内部应力减少。

因此，减少内部应力来克服，肿胀的纤维变得更强。

同时，在纱线溶胀纤维按对彼此更强烈。

的内部摩擦增强纱线。

此外，所吸收的水作为一个内部润滑剂，赋予纤维较高水平的灵活性。

这说明棉花衣服更容易熨潮湿时。

“东西成垄，一垄一行，弓背朝南”栽培对草莓生长与品质的影响

山东农业大学学报(自然科学版),2024,55(2):146-152Journal of Shandong Agricultural University ( Natural Science Edition )VOL.55 NO.2 2024 doi:10.3969/j.issn.1000-2324.2024.02.002“东西成垄，一垄一行，弓背朝南”栽培对草莓生长与品质的影响孙楠1，2，张一诺1，2，柏尧非1，2，薛俊龙3，宫明永3，赵林3，李玲1，2*，肖伟1，2*1. 山东农业大学园艺科学与工程学院，山东泰安 2710182. 山东省果蔬优质高效生产协同创新中心，山东泰安 2710183. 山东省创新发展研究院，山东济南 250012摘要：为了确定东西垄单行栽植模式在草莓生产中应用的可能性，以草莓品种‘雪里香’和‘雪沁香’为试材，研究了东西垄单行和南北垄双行两种栽培模式对草莓植株表型、光合特性、果实品质及产量的影响。

结果表明：东西垄单行栽植叶面积、根系活力、根直径显著优于南北垄双行栽植，而株高和叶柄长则相反；叶绿素含量、光合速率、蒸腾速率、气孔导度、二氧化碳（CO2）浓度均在不同程度上高于南北垄双行栽植，且表现稳定；东西垄单行栽植显著提升了草莓果实可溶性糖、可溶性固形物及可溶性蛋白的含量，并在一定程度上降低了可滴定酸含量。

综合来看，东西垄单行栽植显著促进了草莓植株生长，提高了产量和品质。

本研究对关键词：草莓；东西垄单行；生长发育；品质；产量中图法分类号：S668.4文献标识码： A文章编号：1000-2324（2024）02-0146-07 Cultivation of "East-west Ridge, One-row Row, Bow-back Facing South" on Growth and Quality of StrawberrySUN Nan1,2, ZHANG Yi-nuo1,2, BAI Y ao-fei1,2, XUE Jun-long3, GONG Ming-yong3, ZHAO Lin3, LI Ling1,2*, XIAO Wei1,2*1. College of Horticulture Science and Engineering/Shandong Agricultural University, Tai'an 271018, China2. Shandong Collaborative Innovation Center for High-quality and Efficient Production of Fruits and Vegetables, Tai 'an Shandong 271018, China3. Shandong Institute of Innovation and Development, Jinan 250012, ChinaAbstract: In order to determine the application possibility of the east and west ridge single row planting model in strawberry production, we studied the effects of single row planting model in east and west ridge and double row planting model innorth and south ridge on plant phenotype, photosynthetic characteristics, fruit quality and yield of strawberry using 'Xuelixiang' and 'Xueqinxiang' as experimental materials. The results showed that the leaf area, root activity and root diameter of east-west row planting were significantly better than those of north-south row planting, but the plant height and petiole length were opposite. The chlorophyll content, photosynthetic rate, transpiration rate, stomatal conductance andcarbon dioxide (CO2) concentration were higher than those of the two-row planting in north and south rows, and the results were stable. The contents of soluble sugar, soluble solid matter and soluble protein of strawberry fruit were significantly increased, and the titrable acid content was decreased to some extent. east and west ridge single row planting model promote the growth of strawberry plants, and improve the yield and quality of strawberry, our study has significant effect on improving quality and efficiency, changing planting concept, promoting strawberry intensive production and reducing production cost.Keywords: Strawberry; east-west ridge single line; growth and development; quality; yield草莓（Fragaria×ananassa Duch.）为蔷薇科多年生草本植物。

碳平衡趋势英文

碳平衡趋势英文In the era of industrialization and urbanization, the increasing emission of greenhouse gases, primarily carbon dioxide, has become a significant concern for global environmental sustainability. Carbon balance, a critical aspect of climate change mitigation, refers to the equilibrium between carbon emissions and carbon sequestration, ensuring that the amount of carbon released into the atmosphere is balanced by the amount removed or stored. This balance is essential for maintaining a stable climate and preventing the adverse impacts of climate change.The current trend in carbon balance is highly alarming. With the rising demand for energy and the continuedreliance on fossil fuels, carbon emissions are increasing exponentially. This unchecked emission is leading to a disruption in the natural carbon cycle, resulting in abuild-up of carbon dioxide in the atmosphere and subsequent global warming. The impact of this warming is already being felt across the globe, from melting ice caps to extreme weather events.To address this dire situation, it is imperative to adopt a carbon balance perspective in our approach to sustainable development. This involves a shift from acarbon-intensive economy to a low-carbon or carbon-neutral economy. This transition requires a concerted effort fromall stakeholders, including governments, businesses, and individuals.Governments play a pivotal role in shaping carbon balance trends. They can adopt policies that encourage the use of renewable energy sources, promote sustainable transport systems, and enforce carbon emissions regulations. Additionally, they can invest in research and developmentto promote innovative technologies that can reduce carbon emissions and enhance carbon sequestration.Businesses, on the other hand, can adopt sustainable practices that reduce their carbon footprint. This includes adopting energy-efficient technologies, promoting circular economy models, and investing in carbon offsetting projects. By doing so, businesses can not only contribute to carbon balance but also enhance their brand image and attractconsumers who are increasingly concerned about environmental sustainability.Individual actions, although seemingly small, can also contribute significantly to carbon balance. Simplelifestyle changes, such as reducing meat consumption, using public transportation, and recycling, can help reduce carbon emissions. Additionally, individuals can support organizations that are working towards carbon neutrality and encourage their friends and family to do the same.The importance of carbon balance is not just limited to environmental sustainability. It also has significant economic implications. A low-carbon economy can create new job opportunities, drive innovation, and enhance competitiveness. Additionally, it can reduce the costs associated with climate change adaptation and mitigation, saving valuable resources for other development priorities. However, achieving carbon balance is not without challenges. It requires a significant investment in infrastructure, technology, and human resources. It also necessitates a change in mindset and behavior, which can be difficult to achieve. Nevertheless, the benefits of acarbon-balanced world far outweigh the costs, making it a worthwhile pursuit for all.In conclusion, carbon balance trends are a crucial perspective for sustainable development. By adopting a carbon balance approach, we can mitigate the adverseimpacts of climate change, promote economic growth, and ensure a sustainable future for all. It is a collective responsibility that requires the concerted effort of governments, businesses, and individuals. Only by working together can we achieve the goal of carbon balance and protect our planet for future generations.**碳平衡趋势：可持续发展的关键视角**在工业化与城市化时代，温室气体——尤其是二氧化碳——排放量的不断增加，已成为全球环境可持续性的重大关切。

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Plant Science142(1999)47–56Carbon isotope ratio in cotton varies with growth stage and plantorganYehoshua Saranga a,*,Igal Flash a,Andrew H.Paterson b,1,Dan Yakir ca The Hebrew Uni6ersity of Jerusalem,Faculty of Agricultural,Food and En6ironmental Quality Sciences,Department of Field Crops,Vegetables and Genetics,P.O.Box12,Reho6ot,76100,Israelb Texas A&M Uni6ersity,Department of Soil and Crop Sciences,College Station,TX77843-2474,USAc Weizmann Institute of Science,Department of En6ironmental Sciences and Energy Research,P.O.Box26,Reho6ot,76100,IsraelReceived5August1998;received in revised form28December1998;accepted28December1998AbstractCarbon isotope ratio(13C/12C,expressed with a differential notation as d13C)has been proposed as an indirect selection criterion for plant water-use efﬁciency(WUE=total dry matter produced or yield harvested/water used).For efﬁcient modiﬁcation of WUE in breeding programs,it is essential to determine a sampling strategy,which will provide consistent genotypic ranking for d13C and maximum differentiation between genotypes.The effects of growth stages and plant organs on d13C values and their genotypic variations were studied in cotton cultivars grown in theﬁeld under two irrigation regimes.Values of d13C in leaf remained stable during peakﬂowering and boll development stages and signiﬁcantly increased at boll ripening stage,which could result from the effect of late-season water stress on WUE.d13C varied signiﬁcantly between plant organs,with lower values obtained in assimilating organs,leaf and bur,and higher values in non-assimilating organs,stem andﬁber.This could possibly have resulted from carbon discrimination during secondary metabolism.A non-crossover interaction was found between growth stage and cultivar,whereas plant-organ effect did not interact with cultivars,indicating that a similar ranking of cultivars can be expected with d13C at various growth stages and plant te season leaf samples and bur of the last boll revealed maximal differentiation among genotypes and water regimes,both among other growth stages as well as among other plant organs.These samples have also revealed the highest correlations between d13C and WUE estimates.It is concluded that leaf sampling during boll ripening stage may be most effective for the assessment of d13C as an indicator of WUE.©1999Elsevier Science Ireland Ltd.All rights reserved.Keywords:Drought stress;Gossypium spp.;Water use efﬁciency1.IntroductionA key factor determining plant productivity un-der limited water supply is water-use efﬁciency(WUE),deﬁned in physiological terms as the ratiobetween the rate of carbonﬁxed and the rate ofwater transpired,or alternatively in agronomicterms as the ratio between total dry matter pro-duced(or yield harvested)and water used(orapplied).The existence of genetic variation inWUE has been known since the pioneering studiesof Briggs and Shantz in1914[1](for review see[2]).However,its exploitation for breeding hasbeen limited for many years due to difﬁcultiesinvolved in an accurate evaluation of WUE.The demonstration that carbon isotope ratio(13C/12C,expressed with differential notation as *Corresponding author.Tel.:+972-8-9481040;fax:+972-8-9468265.E-mail address:saranga@agri.huji.ac.il(Y.Saranga)1Current address:Plant Genome Mapping Laboratory,110River-bend Road,University of Georgia,Athens,GA30602,USA.0168-9452/99/$-see front matter©1999Elsevier Science Ireland Ltd.All rights reserved.PII:S0168-9452(99)00004-7Y.Saranga et al./Plant Science142(1999)47–56 48d13C)2could provide an indirect measure of plant WUE[3,4]stimulated considerable research on the possible use of d13C as a selection criterion in plant breeding programs.Experimental evidence of the correlation between WUE and d13C has been pro-vided for several crops[5,6].This approach,there-fore,provides a powerful tool for improving WUE in breeding programs.Cotton(Gossypium hirsutum and Gossypium barbadense)is usually grown during the summer in arid and semiarid regions,and it is often exposed to drought,which adversely affects both yield and quality.Increasing the WUE of cotton plants could reduce the adverse effects of drought and improve productivity also under non-stressful con-ditions.Genetic variation in WUE,both between the two cotton species and among G.hirsutum cultivars,has been reported previously[7,8].This variation was positively correlated with d13C and associated with variation in photosynthetic capac-ity.In other studies with cotton,d13C have also been correlated with stomatal conductance[9]and with lint yield[10].In a study of interspeciﬁc segregating cotton populations,McDaniel[11] suggested that the variance in d13C could be uti-lized as means of selection in advanced progeny. Therefore,the application of the carbon isotope approach to indirectly select cotton cultivars for improved WUE seems feasible.Efﬁcient modiﬁcation of WUE requires a sam-pling strategy that will provide a consistent geno-typic ranking and maximum differentiation for d13C among genotypes.Values of d13C can be greatly inﬂuenced by genotype×environment in-teractions[12,13],the plant part that is sampled [14–17],plant growth stage[12,15,17]and time of day[18]at which samples are taken.Therefore,a better understanding of these factors,their interac-tions with genotype,and their inﬂuence on d13C is essential to determine sampling strategy for d13C of a speciﬁc crop.In this paper,we report about the effects of growth stages and plant organs on d13C values and their genotypic variations in cotton cultivars grown in theﬁeld under two irrigation regimes.2.Materials and methods2.1.Plant materials,management,and water use efﬁciencyField trial was conducted in1995in Be’eri, located in the western Negev desert in Israel(31°25%N,34°30%E).A total of six cotton cultivars,G. hirsutum,cv.Siv’on,Vered,and G-414,G.bar-badense,cv.F-177and S-7,and an interspeciﬁc F1 hybrid(ISH)G.hirsutum×G.barbadense,cv. 195×8,were examined,and two irrigation regimes,well-watered(‘wet’)and water-stressed (‘dry’),were applied.A factorial design(irrigation regime×cultivar)was used with a randomized block layout andﬁve replicates.The wet irrigation treatment corresponded with the irrigation regime normally used for commer-cial cotton crop,with a total amount of373mm, whereas the dry treatment received205mm.Water was applied twice a week via a drip system.Soil characteristics,climatic conditions and manage-ment practices were as previously described[8]. Water-use efﬁciency was estimated based on the crop’s water consumption(water application+ soil water depletion),total dry matter(DM),and seed cotton(SC,lint+seed)production[8].Total DM and SC yield were divided by the amount of water consumed to calculate DM-based WUE and SC-based WUE,respectively.2.2.Carbon isotope ratioTwo of the cultivars,G.hirsutum cv.Vered and G.barbadense cv.F-177(each being most com-monly cultivated among its species in the semi-arid southern part of Israel)were used to study d13C at various growth stages.In every plot of these culti-vars under both irrigation treatments,three plants were selected and the youngest fully expanded leaf of each plant was tagged three times during the season,at85,109and123days after sowing, corresponding with peakﬂowering,boll develop-ment and boll ripening,respectively.A total of six 5-mm diameter disks were sampled from each of these leaves4weeks after the tagging.Disks of each plot were pooled and subjected to carbon isotope determinations.Samples for the determination of d13C in vari-ous plant organs were taken from each of the six cultivars,under the two irrigation treatments soon2The term carbon isotope discrimination(D),expressing the difference between d13C of the plant and that of the air [D=d13C air−d13C plant)/(1000+d13C plant)]is often used alter-natively to d13C.Since d13C air is assumed constant for experi-mental time-scale,D is directly related to d13C plant.The term d13C is used throughout this paper,also when citing publica-tions where D was originally used.Y.Saranga et al./Plant Science142(1999)47–5649before the end of the season.Leaf samples were taken from three plants at the30–50%boll ripen-ing stage;the youngest fully expanded leaf and the two leaves below it were sampled with three5-mm diameter disks taken from each of these leaves.All leaf samples for d13C determination were taken during morning time.At the end of boll ripening, theﬁrst boll(ﬁrst boll onﬁrst fruiting branch), mid boll(ﬁrst boll on a mid fruiting branch),last boll(the youngest fully developed boll)and the hypocotyl section of the stem were sampled from three plants of each plot.All plant samples were oven-dried,powdered (ﬁbers were cut with scissors into1–2-mm sec-tions)and combusted in an elemental analyzer (Carlo Erba EA1108,Fison,Milan,Italy).The CO2generated was passed with helium carrier gas directly into the inlet of an isotope ratio mass spectrometer(Opti,Micromass,Manchester,UK). The ratio of13C/12C was measured and expressed in the d13C notation relative to the standard PDB (d13C=(R sample/R std−1)1000;where R sample and R std are the isotope ratios of the sample and standard,respectively).The precision of the iso-topic determination for repeated analysis of the same sample was90.1‰.2.3.Statistical analysesThe JMP®software was used for statistical analyses[19].A randomized factorial model was employed for the analysis of variance,with con-trast analyses used for mean separation at P= 0.05.Homogeneity tests were applied to conﬁrm the adequacy of pooling data across irrigation regimes,and the pooled data were subjected to correlation analyses.3.ResultsAnalysis of variance for the effects of growth stage,irrigation,and cultivar on d13C in leaves of two cotton cultivars revealed a signiﬁcant effect of each of these factors as well as signiﬁcant culti-var×growth stage interaction and irrigation×growth stage interaction(Table1).Cultivar ranking,however,did not change with growth stages,indicating a non-cross-over interaction be-tween cultivars and growth stages.The G.hirsu-tum cultivar always exhibited higher d13C values than the G.barbadense cultivar,with high signiﬁ-Table1Carbon isotope ratio at various growth stages in leaves ofﬁeld-grown cotton,G.hirsutum cv.Vered and G.barbadense cv.F-177, under two irrigation regimes+Growth stage d13C,‰d13C,‰G.h.,Vered G.b.,F-177Wet Dry−27.1++,xPeakﬂowering−27.0++,x−27.3++,y−26.8++−27.0++,x−27.3++,yBoll development−27.2++,x−27.1++,xBoll ripening−25.6+,x−26.8+,y−26.5+,y−25.9+,xdf Mean squareSource of variation1Cultivar(C)0.68*6.89***1Irrigation(I)Growth stage(GS)2 5.79***Replications0.1240.021C×IC×GS20.53*2I×GS 1.35***I×C×GS0.2320.1644Experimental error+Data are averaged across irrigation regimes for the cultivar and growth stage effects,and averaged across cultivars for the irrigation and growth stage effects.++Mean separation at the0.05probability level by contrast analysis between growth stages within a cultivar or within an irrigation regime(a,b,c,d)and between cultivars or between irrigation regimes within a growth stage(x,y).*Signiﬁcant at the0.05probability level.***Signiﬁcant at the0.001probability level.Y.Saranga et al./Plant Science142(1999)47–5650Table2Analyses of variance for the effect of cultivar and irrigation regime at various growth stages on carbon isotope ratio in leaves of ﬁeld grown cotton,G.hirsutum cv.Vered and G.barbadense cv.F-177dfSource of variation Mean squarePeakﬂowering Boll development Boll ripeningCultivar(C)1 1.00*0.498.09***Irrigation(I)0.0110.06 1.66**0.120.7840.17Replications1C×I0.050.190.180.110.11Experimental error0.1012*Signiﬁcant at the0.05probability level.**Signiﬁcant at the0.01probability level.***Signiﬁcant at the0.001probability level.cance levels at peakﬂowering(P=0.004)and boll ripening((P B0.001),and lower level at boll devel-opment(P=0.042).The two irrigation regimes, however,revealed different d13C only at boll ripen-ing stage with higher values obtained under the dry treatment.In both cultivars and under both irrigation regimes d13C remained stable during peakﬂowering and boll development and signiﬁ-cantly increased at the boll ripening stage. Separate analyses of variance for each of the growth stages(Table2)revealed a signiﬁcant ef-fect of cultivar at peakﬂowering and boll ripening, and a signiﬁcant effect of irrigation only at boll ripening stage.The interaction between irrigation and cultivar was not signiﬁcant in any of the growth stages.Coefﬁcients of the correlation among d13C val-ues at the various growth stages were positive but not signiﬁcant(Table3).Correlation between d13C in leaf and WUE estimates were also positive,with the highest coefﬁcients obtained at boll ripening stage(signiﬁcant only with DM-based WUE). Analysis of variance for the effects of plant organ,irrigation,and cultivar on d13C revealed a signiﬁcant effect of each of these factors(Table4). The interaction between irrigation and cultivar was also signiﬁcant;however,the interactions be-tween plant organs and each of the other factors or both factors together were not signiﬁcant. Mean separation of d13C revealed signiﬁcant dif-ferences between each of the plant organs(with burs andﬁbers of the three boll positions grouped together).The lowest d13C values were obtained in the leaf,slightly higher values in burs,even higher in stem,and considerably higher values,the highest of all organs,were measured inﬁbers.Values of d13C in either burs orﬁbers of the last boll were signiﬁcantly higher then those of theﬁrst and mid boll,which did not differ from one another.Both irrigation and cultivar affected d13C signiﬁ-cantly in most plant organs,with the exception of the last boll’sﬁber,on which cultivar effect was not signiﬁcant,and the stem,on which no effect was signiﬁcant(Table5).In burs of theﬁrst and mid bolls,irrigation×cultivar interaction was also signiﬁcant.Mean squares of the experimental er-ror were lowest(0.18–0.38)in leaf,stem and burs ofﬁrst and mid bolls,highest(0.89–1.07)inﬁbers of either boll sampled,and intermediate in the bur of the last boll.Therefore,the effects of irrigation and cultivar on d13C usually revealed lower signiﬁ-cance level inﬁbers than in burs,despite the similar magnitude of the mean squares of these effects.The highest signiﬁcance levels for the effect of cultivar and irrigation were obtained with d13C of leaf,bur of mid boll and bur of last boll.In most cultivars and plant organs,values of d13C were higher under the dry treatment than in the wet treatment(Fig.1).The G.hirsutum cultivars and the ISH obtained the highest d13C values in most plant organs,while the G.barbadense cv.S-7 exhibited the lowest values.Coefﬁcients of the correlation among d13C val-ues in the various plant organs were always posi-tive,and,in most cases,they were also signiﬁcant (Table6).As could be expected,the correlation between d13C values in bur andﬁber of the same boll was always signiﬁcant.Correlation between d13C in various organs and WUE estimates were also positive;however,signiﬁcant coefﬁcients were obtained only with d13C in the bur of the last bollY.Saranga et al./Plant Science142(1999)47–5651 Table3Correlation coefﬁcients among leaf carbon isotope ratios at various growth stages and between them and dry matter-based water-use efﬁciency(DM-based WUE)and seed cotton-based water-use efﬁciency(SC-based WUE)inﬁeld-grown cotton,G. hirsutum cv.Vered and G.barbadense cv.F-177,under two irrigation regimes(n=4)SC-basedLeaf d13C at DM-basedLeaf d13C atboll development WUEWUEboll ripening0.80Leaf d13C at peakﬂowering0.840.870.910.780.74Leaf d13C at boll development0.710.99*0.92Leaf d13C at boll ripening*Signiﬁcant at the0.05probability level.(with both WUE estimates),leaf(with SC-basedWUE),and stem(with DM-based WUE).4.DiscussionSeveral studies in which d13C or WUE weremeasured have indicated that extended droughtcan substantially increase WUE,whereas otherstudies have not detected such an effect(for reviewsee[2]).Differences in the effect of drought onWUE may arise due to genetic differences in stom-atal response to water limitation,or differences inthe duration and intensity of drought.In cotton,WUE under a limited water supply was higherthan in plants grown under well-watered condi-tions[7,8].Similarly,in this study,higher d13Cvalues(higher WUE)were usually obtained in thedry treatment relative to the wet treatment(Table1,Fig.1).Values of leaf d13C were signiﬁcantly higher atboll ripening stage than at peakﬂowering and bolldevelopment stages(Table1).This result,basedon data of only two cultivars,gains further sup-port from data of the various bolls examined.Each of the three bolls sampled for d13C assess-ment represents a different growth stage at whichits major carbon accumulated.Since a cotton bollaccumulates most of its DM between10and45days post anthesis[20],theﬁrst,mid and last bollscorrespond with midﬂowering,boll developmentand boll ripening stages,respectively.The higher d13C in both bur andﬁber of the last boll relative to theﬁrst and mid bolls(Table4)is,therefore,inagreement with the variation between growthstages in leaf d13C(Table1).Under conventionaldrip irrigation practices,cotton plants would un-dergo a relatively stable non-stressful water status duringﬂowering and boll development,at which time most water is applied,followed by a gradu-ally intensiﬁed water stress during boll ripening [21].Therefore,the lower d13C values at late-sea-son,as reﬂected by leaf samples taken at boll ripening as well as by bur andﬁber of the last boll correspond with the changes in water status of Table4Carbon isotope ratio in various plant organs(averaged across irrigation regimes and cultivars)ofﬁeld-grown cotton,G. hirsutum,G.barbadense and interspeciﬁc hybrid(G.hirsu-tum×G.barbadense)Plant organ d13C,‰Leaf−26.9†dStem−25.2bBurFirst boll−26.7yMid boll−26.6y cLast boll−26.2xFiberFirst boll−24.2yMid boll−24.0y a−23.3xLast bolldfSource of variation Mean square512.76*** Cultivar(C)1Irrigation(I)43.29***Organ(O)7115.63*** Replications0.9445C×I 2.58***C×O350.84I×O70.58350.58I×C×O356‡Experimental error0.59†Mean separation at the0.05probability level by con-trast analysis between major plant organs(a,b,c,d)and be-tween burs orﬁbers of different bolls(x,y).‡Experimental error df is reduced due to missing values. ***Signiﬁcant at the0.001probability level.Y.Saranga et al./Plant Science142(1999)47–5652Table5Analyses of variance for the effect of cultivar and irrigation regime on carbon isotope ratio in various plant organs ofﬁeld-grown cotton,G.hirsutum,G.barbadense and interspeciﬁc hybrid(G.hirsutum×G.barbadense)dfSource of variation Mean squareLeaf Stem Bur FiberFirst boll Mid boll Last boll First boll Mid boll Last boll2.76***0.57 1.40** 1.65***Cultivar(C) 4.09***5 3.36** 3.41** 1.693.07*** 1.23 2.94**8.46***Irrigation(I)11.07***1 5.37* 5.04*11.08**0.400.610.340.1140.62Replications0.420.69 1.280.380.360.79* 1.21***0.330.56C×I 1.135 1.880.230.380.300.180.70440.89Error0.91 1.07*Signiﬁcant at the0.05probability level.**Signiﬁcant at the0.01probability level.***Signiﬁcant at the0.001probability level.drip-irrigated cotton and could result from the effects late-season water stress on WUE. Previous reports regarding the effect of growth stage on genotypic ranking for d13C are not con-clusive.Some studies have shown no such effect in cowpea[22],common bean[23],lentil,wheat,or canola[17].However,in other studies,genotypic ranking has been shown to change with growth stage in cowpea[12,24]and wheat[25].In this study,a non-crossover interaction between growth stage and cultivar in d13C(Table1)indicated that genotypic ranking did not change with growth stage.This was further supported by a consistent genotypic ranking obtained with bur andﬁber of different bolls as indicated by the non-signiﬁcant interaction between plant organs and cultivars (Table4).The biggest difference between geno-types(highest mean squares)was obtained at boll ripening stage both with leaf samples(Table2) and with bur of the last boll(Table5).Further-more,the highest correlation coefﬁcients between WUE estimates and d13C were obtained with leaf samples taken at boll ripening(Table3)and with burr of last boll(Table6).Therefore,the boll ripening stage should be preferred for the assess-ment of d13C in cotton.It is worth noting,how-ever,that the changes in d13C with growth stage are highly dependent on the irrigation regime,as discussed earlier,and therefore the conclusions derived from this pattern should be limited to irrigation regimes similar to those used in this study.Non-assimilating organs,stem andﬁber,exhib-ited higher d13C values than the assimilating or-gans,leaf and bur.Similar trends have also been found in other plant species;heads and roots of barley had higher d13C values than leaves[14];the peduncle,rachis and grain of wheat had higher values than leaves[15]and seeds had higher values than leaves in cowpea[16],lentil,spring wheat and canola[17].The reason for these differences has not been clearly established.Condon et al.[25] have suggested that increases in d13C of grain could be associated with progressive soil drying and stomatal closure.This possibility does not match our results,where even theﬁrst boll’sﬁber that had developed under well-watered conditions had higher d13C than leaves that had developed at a later stage under less favorable water conditions (Table4).Lipid fraction has lower d13C values than sugars,starch,proteins,and amino acids[26]. Cotton seeds contain about20%lipids[27], whereasﬁbers contain over90%cellulose[28].It can be hypothesized that if a seed and theﬁbers attached to it act as a close system,then discrimi-nation against13C during lipid synthesis in the seed enriches the assimilates allocated to theﬁbers with13C and thus increases their d13C.Plant organ effect on d13C did not interact with either cultivars or irrigation regimes(Table4),and positive correlation coefﬁcients were obtained be-tween d13C values of the various plant organs (Table6).These results indicate that a similar ranking of cultivars can be expected for d13C in various plant organs.The difference between culti-Y.Saranga et al./Plant Science142(1999)47–56 54vars in d13C values was,however,considerably affected by plant organs.The lowest cultivar and irrigation mean squares were obtained in d13C of stem.Fibers,on the other hand,revealed the highest error mean squares among all the plant organs examined.The effect of secondary discrim-Fig.1.Carbon isotope ratio in various plant organs of six cotton cultivars,G.hirsutum(G.h.),G.barbadense(G.b.)and an interspeciﬁc hybrid(G.hirsutum×G.barbadense;ISH),grown in theﬁeld under two irrigation regimes.Means separated at the 0.05level,for cultivar main effects(A,B,C,D)in organs where cultivar×irrigation interaction was not signiﬁcant,and for cultivars within each irrigation regime(a,b,c,d)where this interaction was signiﬁcant.Note the different scale used for carbon isotope ratio inﬁbers.Y.Saranga et al./Plant Science142(1999)47–5655ination,which caused the high d13C values instems andﬁbers,could have been affected byvarious environmental or metabolic factors andthereby increased the experimental error.There-fore,an assimilating organ,leaf or bur,in which d13C is determined primarily by stomatal behavior, may be the most effective for sampling whenattempting to relate d13C to WUE[2].In thisstudy,highest mean squares of cultivar effect werefound with samples of leaf and bur of the last boll,whereas mean squares of experimental error werelow in both cases;these organs,therefore,pro-vided the maximum difference between cultivars in d13C.The variation in WUE among the same sixgenotypes was examined underﬁeld conditionsover2years[8],the second of which was also usedfor the current study.The analyses of variancerevealed highly signiﬁcant effects of cultivar andyear on DM-based and SC-based WUE estimates,a signiﬁcant effect of irrigation on DM-basedWUE,and no signiﬁcant interactions.In terms ofDM-based WUE,two of the G.hirsutum cultivars,Siv’on and Vered,and the ISH produced about2.5g DM l–1H2O,whereas the two G.barbadensecultivars and the G.hirsutum cultivar G-414pro-duced about 2.1g DM l–1H2O.In terms ofSC-based WUE,however,the highest values wereattained by Siv’on and Vered(about1.1g SC l–1H2O),the lowest values by the G.barbadensecultivars(about0.8g SC l–1H2O),and intermedi-ate values by G-414and the ISH.Among thevarious plant organs examined for d13C in thisstudy,leaf and burr samples revealed genotypicrankings(Fig.1a,c,e,g)most similar to the rankingby WUE.This is further supported by the correla-tion coefﬁcients between d13C and WUE estimates,with the highest correlations occurring with d13Cin leaf and in bur of the last boll(Table6).Thecorrelation between d13C in stem and DM-basedWUE was also signiﬁcant,however,genotypicrankings by these traits were not similar.Leaf sample taken at boll ripening stage and burof the last boll revealed maximal differentiationamong genotypes and water regimes,both amongother growth stages(Table2)as well as amongother plant organs(Table5),and have been mosthighly correlated with WUE estimates(Tables3and6).Is there any reason to prefer one or theother of these two plant samples?When compar-ing d13C values of various genotypes,it is most effective to sample carbon that has been assimi-lated during the same period of the season,when the plants are subjected to similar soil and atmo-spheric conditions[2].In several studies,grain tissue has been used as a source of carbon.This procedure can yield results that are difﬁcult to interpret,especially when determinate cotton culti-vars,whichﬂower at different times,are used[29]. From a botanical point of view,the growth of a cotton plant is indeterminate,but there are varia-tions in growth behavior which have led to the classiﬁcation of some cultivars as‘determinate’[30,31].Determinate cotton cultivars fruit heavily during the early season,after which growth and ﬂowering decline,and all or most of the late ﬂowers are shed.Soil,insects and climatic factors affect the genetic expression of determinacy.Such a determinacy was not observed in our experi-ment;however,when it occurs,the burs from the last boll will contain carbon that was assimilated at different times in different cultivars.Since leaf development also stops with determinacy,leaf samples should be taken as soon as a cutout is observed in any of the examined germplasms.It is therefore concluded that under irrigated dry sum-mer conditions,leaf sampling during boll ripening stage may be the most effective strategy for the assessment of d13C as an indirect selection crite-rion for WUE.AcknowledgementsThis research was supported by Research Grant Award -2506-94R from BARD—The United States-Israel Binational Agricultural Re-search and Development Fund.References[1]L.J.Briggs,H.L.Shantz,Relative water requirement ofplants,J.Agric.Res.(Washington,DC)3(1914)1–63.[2]A.E.Hall,R.A.Richards,A.G.Condon,G.C.Wright,G.D.Farquhar,Carbon isotope discrimination and plantbreeding,Plant Breeding Rev.12(1994)81–113.[3]G.D.Farquhar,M.H.O’Leary,J.A.Berry,On the rela-tionship between carbon isotope discrimination and in-tercellular carbon dioxide concentration in leaves,Aust.J.Plant Physiol.9(1982)121–137.[4]G.D.Farquhar,R.A.Richards,Isotopic composition ofplant carbon correlates with water-use efﬁciency of wheat genotypes,Aust.J.Plant Physiol.11(1984)539–552.。