水分亏缺对作物的伤害

全世界干旱、半干旱地区的总面积约占总陆地面积的1/3。中国是世界上主要的干旱国家之一,全国干旱、半干旱地区约占总国土面积的一半左右。干旱是制约我国西北和整个北方地区农业生产发展的基本自然因素,其他地区在作物生长季节也发生不同程度的干旱危害。研究作物水分胁迫及其伤害生理,不仅在理论上而且在实践中都有重要意义。     

半干旱地区抗旱作物的育种方向和策略

在半干旱地区作物生长的主要的限制因子是水分,主要包括土壤干旱和大气干旱。现有的理论和实践表明,作物育种的目标应该是培养具有中等强度抗旱能力和高产潜能的品种。由于作物的生产是在特定水、温、光和热等特定条件下进行的,而且作物的生产又是个种群过程而非个体的表现：因此,抗旱品种的选育应该遵循高产性、针对性和整体性的原则。现有的抗旱育种理论有很多引起争议且不完善的地方,总的趋势就是要选育小根系、繁殖分配优化、在低水多变环境下有较高的净光合速率并且能对干旱环境迅速作出反应的品种。     

小麦干旱诱导蛋白及相关基因研究进展

干旱胁迫条件下,小麦相关基因受到激活并表达产生干旱胁迫蛋白,主动适应干旱环境、维持个体存活和产量形成。介绍了小麦中一些干旱诱导蛋白及相关基因的研究进展,包括不同小麦品种、胁迫程度、发育阶段的差异性反应和共性特征、对主要干旱信号物质ABA和Ca²⁺的差异应答、以及新近发现的干旱诱导蛋白及相关基因的生物学特性及主要功能等。对于干旱诱导蛋白来说,研究手段和目标从过去以单向电泳技术为主、揭示蛋白条带的表达差异转到现在以双向电泳技术为主、以揭示蛋白质组中干旱诱导蛋白结构和功能的耦合。对于干旱诱导蛋白相关基因来说,研究内容主要包括功能基因和调控基因两大类,功能基因研究主要集中在LEA蛋白基因和透物质合成酶基因等几大类型上,而调控基因研究主要集中在转录因子和蛋白激酶等相关基因及其作用。对干旱诱导蛋白及相关基因在小麦栽培管理和产量育种中的应用前景展开了讨论。     

干旱胁迫对光合作用的影响

地球上干旱和半干旱地区的面积占陆地总面积的1／3以上,而且广大半湿润地区也经常出现干旱,因此全球大约有一半左右的陆生植物群落经常处于干旱胁迫状态,甚至一些处于非常潮湿的植物群落,如热带雨林,在一天之内也可能受不同程度（如轻度甚至中度）的干旱胁迫,而且往往每隔数年就会周期性遭到一次严重于旱胁迫。因此,干旱经常威胁着人们的生存和制约着植物生产力的提高,甚至限制植物的分布。干旱所造成的损失比盐碱和低温冷害所造成的损失都大,尤其严重威胁作物产量的提高。据统计,全世界每年因水分胁迫（包括旱涝）所造成粮食生产…     

盐胁迫环境下植物促生菌的作用机制研究进展

盐胁迫是限制干旱和半干旱地区作物生产的主要非生物胁迫之一,严重影响作物的生长发育,植物促生菌(Plant growth-promoting bacteria,PGPB)可有效减轻植物的盐胁迫损伤,合理施用PGPB是盐胁迫下促进作物生长的重要途径。本文从盐胁迫环境下PGPB在调节植物激素内稳态、促进养分吸收和诱导植物产生系统耐受性等方面的作用阐述了PGPB提高植物耐盐性、减轻植物胁迫损伤的作用机制。讨论了能够在植物根际稳定定殖并在盐生环境下稳定保持PGP活性的功能菌株对未来农业的可持续发展的重要意义,同时,对该研究方向的重难点和未来的发展趋势作出展望。     

半干旱区作物根系生长冗余的生态学分析

干旱是威胁农业生产的一个常见因子。在水分有限条件下,植物往往产生庞大的根系;这是自然选择的必然结果,是一个进化上稳定的生长对策（ＥＳＳ）。但作物产量是一个种群水平上的属性;个体的ＥＳＳ并不能优化整个群体的产量。我们提出在半干旱雨养农业地区作物受自然选择的影响在根系生长上往往失之于过快或过大,出现了“冗余”。通过育种或管理措施降低根系生长冗余可提高作物产量。     

小麦抗旱机理研究进展

干旱是影响小麦产量和品质的重要环境因素,而小麦在干旱胁迫下的抗旱机理非常复杂,不同程度以及不同发育时期的干旱胁迫对不同品种的影响各异。对近年来有关干旱胁迫下小麦的形态结构与渗透调节物质的变化,特别是基因和蛋白表达量的改变进行了综述,对小麦在干旱胁迫下如何提高品质及产量等问题提出建议。     

耐旱性和耐盐性:认识及应用

不利环境是限制农作物生产力的最重要因素,其中尤以干旱最为严重.盐度也是一个主要的逆境因素,这些重要问题影响着美国一些高产农业区,其中包括加利福尼亚州30%的灌溉田.因此,提高作物的耐旱和耐盐性已成为一些地区进行作物育种的主要目的,这些地区包括降水量或灌溉量受到限制、土壤盐度高或水质差的地区.虽然常规的育种方法已获得一些可喜的进步,但总的进展是缓慢的.这使人们把注意力集中到利用遗传工程提高耐旱和耐盐     

春小麦竞争能力与产量的关系

采用deWit替代系列实验确定了4个春小麦品种混播时的竞争能力与单播产量之间的关系。4个春小麦品种竞争能力由强到弱的排序依次为定西-24、和尚头、陇春-8139和高原-602。各品种单播时产量由高到低的排序依次为现代品种定西-24、陇春-8139、高原-602与地方品种和尚头。该结果表明,以优化个体适合度为目标的自然选择,导致个体竞争能力提高、繁殖分配下降,因而产生‘生长冗余’及群体表现下降。现代小麦育种通过降低竞争能力,剔除生长冗余,可以提高小麦单位面积产量(如地方品种和尚头与现代品种高原-602和陇春-8139的比较)。然而,如果现代小麦育种可以同时提高收获指数和地上生物量(如现代品种定西-24与陇春-8139和高原-602的比较),那么具有相对较高竞争能力的品种仍然可望获得较高产量,其前提是具有较高竞争能力的育成品种有着较高的收获指数。因此,春小麦品种的个体竞争能力并不必然地与产量相关,当选育的品种可以使竞争能力与收获指数同步提高,或者伴随着竞争能力的提高,收获指数具有更大幅度的提高,仍然可以获得高产。半干旱地区作物育种应集中于收获指数和地上生物量的同时提高。     

水稻非生物胁迫相关QTL研究进展

培育优质高产水稻品种是水稻育种工作者的首要目标。近年来,不断恶化的环境条件使水稻生长面,临更多的逆境胁迫。其中,非生物胁迫严重影响水稻产量提高和品质改善。从QTL角度研究水稻对非生物胁迫的适应机理,对于提高水稻产量、品质和抗逆性等方面具有重要的意义。本文综述了近年来水稻非生物胁迫相关QTL的研究进展,以及通过分子辅助育种手段创制多目标性状聚合的优良水稻品种的主要策略,为实现水稻优质高产和广适性的综合改良提供思路。     

半干旱区春小麦生长系统的人工神经网络模型与产量预测

以半干旱区春小麦生长系统为研究对象。探讨了作物生长系统中水分、土壤养分等生态因子的时空变化特征及春小麦产量形成机制,应用人工神经网络方法建立了半干旱区春小麦生长系统的产量随环境因子变化的神经网络模型,并与传统的CTM模型进行了比较。模拟结果表明,人工神经网络模型可适用于半干旱区春小麦生长系统产量随环境因子变化规律描述,且优于传统模型,从而为春小麦产量预测提供了新的途径,也为作物生态系统的人工调控提供了新的模式与定量依据。     

中国食用向日葵育种国产化历程及研究进展

中国食用向日葵育种近40年来取得了巨大成就,实现了从自留农家种、选育常规品种、引进国外杂交种以及培育国产杂交种4 次品种更新。中国向日葵种植面积基本保持在59万hm²左右,种植区主要集中在北方10个省区,其中内蒙古自治区种植面积约占全国总面积的四分之三,其次是新疆。中国以食用向日葵种植为主,约占总面积的95%以上,是世界上食用向日葵主要生产国。食用向日葵主要用于休闲嗑食,除高产外,商品外观品质(粒型、色泽、口感等)仍将是当今主要育种目标。另外,向日葵生产区因长期连作种植,病原菌、列当等生物逆境因素与向日葵发生协同进化,加之食用向日葵遗传背景狭窄,病虫草害日趋严重。该文通过对中国食用向日葵育种历程进行回顾,尤其对国内外有关向日葵抗病育种研究进展进行综述,为解析食用向日葵抗性育种机制以及前瞻性抗性品种储备提供重要的理论与技术支持,以推动食用向日葵产业的高效优质发展。     

Not a load of rubbish: simulated field trials in large‐scale containers

Assessment of yield performance under fluctuating environmental conditions is a major aim of crop breeders. Unfortunately, results from controlled‐environment evaluations of complex agronomic traits rarely translate to field performance. A major cause is that crops grown over their complete lifecycle in a greenhouse or growth chamber are generally constricted in their root growth, which influences their response to important abiotic constraints like water or nutrient availability. To overcome this poor transferability, we established a plant growth system comprising large refuse containers (120 L ‘wheelie bins’) that allow detailed phenotyping of small field‐crop populations under semi‐controlled growth conditions. Diverse winter oilseed rape cultivars were grown at field densities throughout the crop lifecycle, in different experiments over 2 years, to compare seed yields from individual containers to plot yields from multi‐environment field trials. We found that we were able to predict yields in the field with high accuracy from container‐grown plants. The container system proved suitable for detailed studies of stress response physiology and performance in pre‐breeding populations. Investment in automated large‐container systems may help breeders improve field transferability of greenhouse experiments, enabling screening of pre‐breeding materials for abiotic stress response traits with a positive influence on yield.     

Inducing drought tolerance in plants: Recent advances

Undoubtedly, drought is one of the prime abiotic stresses in the world. Crop yield losses due to drought stress are considerable. Although a variety of approaches have been used to alleviate the problem of drought, plant breeding, either conventional breeding or genetic engineering, seems to be an efficient and economic means of tailoring crops to enable them to grow successfully in drought-prone environments. During the last century, although plant breeders have made ample progress through conventional breeding in developing drought tolerant lines/cultivars of some selected crops, the approach is, in fact, highly time-consuming and labor- and cost-intensive. Alternatively, marker-assisted breeding (MAB) is a more efficient approach, which identifies the usefulness of thousands of genomic regions of a crop under stress conditions, which was, in reality, previously not possible. Quantitative trait loci (QTL) for drought tolerance have been identified for a variety of traits in different crops. With the development of comprehensive molecular linkage maps, marker-assisted selection procedures have led to pyramiding desirable traits to achieve improvements in crop drought tolerance. However, the accuracy and preciseness in QTL identification are problematic. Furthermore, significant genetic × environment interaction, large number of genes encoding yield, and use of wrong mapping populations, have all harmed programs involved in mapping of QTL for high growth and yield under water limited conditions. Under such circumstances, a transgenic approach to the problem seems more convincing and practicable, and it is being pursued vigorously to improve qualitative and quantitative traits including tolerance to biotic and abiotic stresses in different crops. Rapid advance in knowledge on genomics and proteomics will certainly be beneficial to fine-tune the molecular breeding and transformation approaches so as to achieve a significant progress in crop improvement in future. Knowledge of gene regulation and signal transduction to generate drought tolerant crop cultivars/lines has been discussed in the present review. In addition, the advantages and disadvantages as well as future prospects of each breeding approach have also been discussed.     

赤霉素调控玉米种子活力的研究进展

玉米是我国总产与平均单产最高的主要农作物,对于保障国家粮食安全具有举足轻重的作用。种子活力是衡量种子质量和应用价值的关键指标,高活力种子是确保作物高产、稳产的基础。赤霉素是重要的植物生长调节物质,具有解除种子休眠、促进萌发的作用,外源赤霉素的喷施已被广泛应用于农业生产以提高作物产量。目前赤霉素对玉米种子活力的影响研究多侧重于施加外源GA影响种子活力的相关生理指标上,而赤霉素调控玉米种子活力的作用机理尚需深入研究。本文综述了赤霉素的生物合成、信号转导、作用机制以及对玉米和其他作物种子活力影响的研究进展,旨为深入探究GA对于玉米种子活力的调控机制乃至玉米育种实践中高活力玉米新种质的创制提供参考。     

气候变化背景下中国南方地区季节性干旱特征与适应Ⅵ.防旱避灾种植模式优化布局

南方地区是我国重要的农业种植区,季节性干旱严重影响该地区的农业生产.本文基于南方地区不同干旱分区中选取的13个典型地区1981-2007年气象资料和作物生育期、产量等资料,依据各地逐年降水量将其分为干旱年、正常年和丰水年3种不同降水年型,利用作物水分临界期需水量与降水量的耦合度、气象产量、单位面积产值以及全生育期的水分利用效率和降水量5个指标,对典型地区种植模式的综合效益进行评价,得到南方不同区域不同降水年型下的优化种植模式.结果表明: 半干旱区在干旱年型下,宜采取2种抗旱种植模式：马铃-玉米-甘薯和冬小麦-中稻-甘薯.半湿润区在干旱年型下,种植模式以冬小麦-中稻-甘薯最优,油菜-中稻-甘薯次之.在温润区(即典型的季节性干旱区),江南地区在3种年型下均以马铃薯-双季稻最优;西南地区宜搭配抗旱作物进行三熟制种植,如冬小麦-中稻-甘薯、冬小麦-玉米-甘薯、马铃薯-双季稻等.从最大程度利用水热资源角度考虑,三熟种植模式最优,以水旱轮作为主,丰水年型宜搭配水稻.     

Genetic Engineering of Energy Crops: A Strategy for Biofuel Production in China Free Access

Biomass utilization is increasingly considered as a practical way for sustainable energy supply and long‐term environment care around the world. In concerns with food security in China, starch or sugar‐based bioethanol and edible‐oil‐derived biodiesel are harshly restricted for large scale production. However, conversion of lignocellulosic residues from food crops is a potential alternative. Because of its recalcitrance, current biomass process is unacceptably expensive, but genetic breeding of energy crops is a promising solution. To meet the need, energy crops are defined with a high yield for both food and biofuel purposes. In this review, main grasses (rice, wheat, maize, sorghum and miscanthus) are evaluated for high biomass production, the principles are discussed on modification of plant cell walls that lead to efficient biomass degradation and conversion, and the related biotechnologies are proposed in terms of energy crop selection.     

半干旱黄土高原退化生态系统的修复与生态农业发展

首先分析了半干旱黄土高原区域生态系统的特点,指出：这里地带性植被极度退化,土壤质量严重恶化,治理难度大,可持续发展受到严重威胁。然后,进行生态系统退化关键驱动力的分析,认为,在不同时期,农民的利益驱动始终是土地利用格局和生态系统演化／退化的关键驱动力。在寻求分析退化生态系统修复的突破口时,认为提高作物产量和经济效益,解决农民的需求是具有可操作性的途径。而实现这一途径必须提高单产,以减轻更广大土地面积上的生产力需求压力。通过集水、覆盖等措施改善农田水分条件,再配合地膜、化肥,在对农田进行合理管理的情况下,粮食单产可获得持续大幅度的提高。在此基础上,提出了实现区域可持续发展的途径——集水型生态农业及其景观配置模式。在这一模式中,经济作物、粮食作物、人工草地和天然草地在一个完整的景观单元内合理配置,形成完整的景观复合生态系统。对这一模式的深人研究和正确实施将推动半干旱黄土高原退化生态系统的修复,并为西部开发中经济建设和生态建设并举提供理论与实践指导。     

Global agricultural intensification during climate change: a role for genomics

Agriculture is now facing the ‘perfect storm’ of climate change, increasing costs of fertilizer and rising food demands from a larger and wealthier human population. These factors point to a global food deficit unless the efficiency and resilience of crop production is increased. The intensification of agriculture has focused on improving production under optimized conditions, with significant agronomic inputs. Furthermore, the intensive cultivation of a limited number of crops has drastically narrowed the number of plant species humans rely on. A new agricultural paradigm is required, reducing dependence on high inputs and increasing crop diversity, yield stability and environmental resilience. Genomics offers unprecedented opportunities to increase crop yield, quality and stability of production through advanced breeding strategies, enhancing the resilience of major crops to climate variability, and increasing the productivity and range of minor crops to diversify the food supply. Here we review the state of the art of genomic‐assisted breeding for the most important staples that feed the world, and how to use and adapt such genomic tools to accelerate development of both major and minor crops with desired traits that enhance adaptation to, or mitigate the effects of climate change.