甘蓝型油菜微核心种质耐旱鉴定与评价指标筛选

干旱是威胁油菜生产的重要非生物逆境，建立有效的耐旱鉴定方法，筛选鉴定耐旱油菜种质资源，对培育油菜耐旱新品种、提高油菜稳产性具有重要意义。本文以107份甘蓝型油菜微核心种质为材料，设置正常供水和干旱2个处理，采用干旱-复水-干旱-复水的处理方法，通过测定旱害指数、叶片萎蔫指数、地上部鲜重胁迫指数、地上部干重胁迫指数、根鲜重胁迫指数、根干重胁迫指数、植株总鲜重胁迫指数、植株总干重胁迫指数等指标，评价油菜种质耐旱性变异，筛选理想的耐旱评价指标。结果表明，干旱严重抑制了甘蓝型油菜的生长，8个评价指标均表现出显著差异，并呈正态分布。地上部鲜重胁迫指数、植株总鲜重胁迫指数和旱害指数3个指标之间显著相关，可作为甘蓝型油菜苗期耐旱性的主要评价指标，其中地上部鲜重胁迫指数最为简便、准确和有效；综合应用这3个评价指标，明确了107份微核心种质耐旱性，筛选出2份高耐旱种质，为耐旱相关研究及育种提供了评价方法和材料。     

干旱胁迫下热带和温带玉米种质的生理及转录组分析

通过分析热带和温带玉米自交系干旱胁迫下的苗期生理和转录组数据,阐明不同玉米种质对干旱胁迫的生理和分子响应机制。结果表明,干旱胁迫下4个自交系的过氧化物酶(POD)、超氧化物歧化酶(SOD)活性以及丙二醛(MDA)、可溶性糖和可溶性蛋白质含量上升,叶绿素含量和4个叶绿素荧光参数值(F_v/F_o、F_v/F_m、Φ_PSII和Q_P)下降,温带玉米自交系较热带自交系的变化幅度更大。4个自交系在对照(CK)和干旱处理条件下的过滤后序列数(Clean reads)变幅为44560000~52580000条,4个自交系干旱胁迫下共有20126个差异表达基因(DEGs),21个基因本体项(GO terms)的相关基因高度富集。此外,热带和温带玉米自交系对干旱存在生理和分子响应差异,热带玉米种质的耐旱性高于温带玉米种质,可在热带种质中筛选耐旱玉米种质。     

玉米耐旱鉴定研究进展

干旱是影响玉米产量最主要的非生物胁迫因子。综述玉米耐旱性评价研究进展,对目前耐旱鉴定研究过程中存在的问题进行探讨,提出玉米耐旱鉴定应采取以产量性状为评价指标的直接评价和以生理生化或形态性状为评价指标的间接评价相结合策略。     

PEG-6000胁迫下玉米品种萌发期抗旱性鉴定与评价

以收集的52个推广应用的春播玉米为供试材料,运用渗透压为0.5 MPa的PEG-6000模拟干旱胁迫,测定各品种发芽率、耐旱萌发指数等10个鉴定指标。以鉴定指标的相对值作为抗旱性评价指标,应用多种分析方法对各指标进行比较分析并对品种进行综合评价和分类。结果表明,干旱胁迫下各指标均受到不同程度的影响,其中,发芽势可用于玉米萌发期抗旱性的快速与初步鉴定。发芽势、发芽率、发芽指数与耐旱萌发指数4项指标可作为抗旱能力的主要鉴定指标,种子吸水率与胚根胚芽长、贮藏物质运转率可作为间接抗旱鉴定指标。根据供试品种隶属函数值,利用聚类分析将其分为4个不同的耐旱等级,筛选出17个抗旱型品种。     

玉米花期耐高温品种的筛选与综合评价

以30个黄淮海地区主栽玉米品种为试材,研究高温对不同玉米杂交种的形态、叶片生理以及产量构成因素的影响,筛选玉米杂交种花期耐热性评价指标,对30个玉米杂交种花期耐热性进行综合评价。结果表明,高温胁迫阻碍了玉米雌雄穗的分化,造成植株生长中心转移,且不同基因型玉米间存在显著差异。高温处理后,穗位叶片变薄,其比叶重、叶绿素相对含量及净光合速率均有所下降,穗位叶片浸泡液相对电导率显著增加。高温胁迫使玉米果穗行粒数明显减少,百粒重及子粒产量显著下降。综合不同品种各性状耐热系数的相关性分析及逐步回归分析结果得出,产量、百粒重、穗长、穗粗和结实率可作为评价玉米杂交种花期耐热性的主要指标。     

玉米黄改系耐旱性材料筛选与鉴定方法研究

在正常水分、花期干旱、全生育期干旱3种水分条件下,对25份玉米黄改系材料和亲本黄早四进行耐旱性鉴定并筛选耐旱材料。结果表明,花期干旱胁迫和全生育期干旱胁迫条件均可进行耐旱性鉴定。在干旱胁迫条件下,穗部性状(单穗穗重、单穗粒重、百粒重和耐旱系数)、粒型性状(粒长)和花期性状(开花吐丝间隔,ASI)能够作为耐旱筛选性状,株型性状作为筛选的参考性状,粒型性状(粒宽和粒厚)不能作为筛选性状。根据干旱胁迫的筛选,获得9份黄改系耐旱性材料。     

不同花生基因型对干旱胁迫的适应性

以北方花生产区推广种植的29个花生品种（系）为试材,在人工控水条件下,对中度土壤水分胁迫下的植株形态、生物质累积和光合色素含量等指标变化进行研究。结果表明,干旱胁迫下,不同品种主茎高、分枝数总体上降低,根冠比、光合色素含量和比叶面积增大,且随胁迫时间延长变化趋势明显,叶绿素a增加最为明显。不同花生品种对土壤水分胁迫程度和胁迫时间的反应不同,且品种间差异明显。此外,干旱胁迫造成的同一品种或品种间生物量积累分配、根/冠和比叶面积等性状的差异,在不同生长阶段并不完全一致。苗期各指标与品种（系）抗旱性间无显著相关关系;花针期各指标与抗旱性间相关关系显著,是花生干旱胁迫的敏感期。综合分析表明,花育17号、花育25号、唐科8号、丰花1号、鲁花14、冀花4号和花育27号具有较强的耐旱抗旱能力。     

吉林省玉米骨干自交系苗期耐旱性鉴评

以78份吉林省玉米骨干自交系为试材,在温室条件下进行苗期干旱胁迫模拟,测定株高、茎粗、根鲜重、地上部分鲜重、根干重、地上部分干重等6项形态指标,估算各性状指标的耐旱系数,作为评价参数进行主成分分析和聚类分析,综合评价参试玉米自交系苗期耐旱性。结果表明,干旱胁迫组测定的形态指标数据与对照组相比均降低,变异幅度有明显差异。根鲜重耐旱系数、地上干重耐旱系数作为综合指标对玉米自交系苗期耐旱性评价的贡献率优于其他指标。聚类分析将参试玉米自交系划分出5个耐旱等级,郑58、S121、W9813、6F576为极强耐旱,丹598、8723、中128、骨马4404等18份玉米自交系为强耐旱,HCL645、四-4112、C8605-2、龙抗11等25份玉米自交系为中度耐旱。     

我国常用玉米自交系的耐旱性评价

2007年冬季和2008年春季分别在海南三亚和新疆乌鲁木齐对196份玉米自交系采用两种不同干旱胁迫处理,依据形态性状及产量相关性状评价其耐旱性。通过典型相关分析发现,株高、雌雄开花间隔天数(ASI)、单穗粒重和结实株数百分率4个性状可以作为玉米自交系耐旱性评价指标。采用因子分析方法,计算株高、雌雄开花间隔天数、单穗粒重和结实株数百分率4个性状的综合耐旱系数,对196份玉米自交系进行耐旱性评价,将试验材料分为耐旱、中度耐旱、中度干旱敏感和干旱敏感4种类型。两点试验耐旱级别完全一致的材料有58份,其中耐旱自交系有7份(H201、Mo113、英64、H21、早49、丹598、吉842);中度耐旱自交系有14份(丹黄02、8902、中106、郑22、中黄68、K22等),这些材料为耐旱育种提供了种质基础。     

玉米抗旱性与生理生化指标关系的研究

以目前我国主栽的14个玉米品种为试材,研究了玉米耐旱指数与生理生化指标的关系。结果表明,干旱胁迫下玉米耐旱指数与叶片相对含水量、脯氨酸含量及可溶性蛋白含量呈极显著正相关,与叶片相对电导率和可溶性糖含量呈极显著负相关,与叶片中丙二醛含量呈显著负相关。上述生理生化指标均可作为玉米抗旱性鉴定指标的参数,用于玉米品种抗旱性的评定。     

Leaf Traits and Antioxidant Defense for Drought Tolerance During Early Growth Stage in Some Popular Traditional Rice Landraces from Koraput,India

Three popular traditional rice landraces, namely Kalajeera, Machakanta and Haladichudi, from Koraput, India were used to analyse the leaf traits and antioxidant defence for drought tolerance. When rice plants were exposed to different levels of drought stress by varying concentrations of polyethylene glycol(PEG) 6000, seed germination and growth parameters were significantly declined in all the rice landraces compared to the control. Drought stress also altered the leaf phenotypic traits based on chlorophyll fluorescence parameters and chlorophyll index, with more significant differences in susceptible variety IR64 than in traditional landraces. Furthermore, activities of antioxidative enzymes and proline and protein contents overtly increased under drought stress. The traditional rice landraces showed higher relative ratios for different parameters compared to the susceptible variety IR64. Taken together,the traditional landraces had superior leaf physiological efficiency compared to the susceptible and tolerant check varieties under drought stress.     

玉米抗旱性指标研究进展

干旱作为玉米生长发育最主要的非生物逆境因子,已成为限制玉米产量形成的关键生态因素,也是我国玉米产量产生波动的重要原因,对粮食生产安全构成严重威胁。玉米抗旱性是水分胁迫条件下表现出的一种复杂综合特性,其适应干旱的形态结构是长期进化的结果,其生理指标变化也是一系列适应性改变后的综合表现。当今水资源短缺日益成为突出问题,且对玉米造成干旱的外部因素较多。本文从鉴定方法、形态指标、生理生化等方面阐述玉米抗旱机制与鉴定方法,综述玉米抗旱性最新研究进展。发展抗旱性玉米研究,为创制选育新的耐旱种质提供支撑,最终提升玉米抵御干旱胁迫的能力,这对于保障玉米可持续生产、解决粮食安全具有重要意义。     

玉米自交系耐热生理指标筛选研究

以10份具有耐热性差异的玉米自交系为材料,在田间采用高温胁迫试验,室内检测玉米自交系的主要生理指标,探讨高温胁迫下玉米自交系的主要生物学特性及其耐热胁迫的生理指标筛选。结果表明,高温胁迫下,具有不同耐热性玉米自交系的丙二醛含量、叶绿素含量和花粉粒活性差异较大,部分耐热性不同的玉米自交系间差异显著。6个叶绿素荧光参数Fm’、Fo’、Fm、Fo、Fm’/Fv’和Fm/Fv的大小能大致反映10个玉米自交系的耐热性差异。结果表明,花粉粒活性、叶绿素含量、丙二醛含量及叶绿素荧光参数可作为玉米耐热种质的筛选指标。     

水稻生理特性与抗旱性的相关分析及QTL定位

利用籼稻品种IR64和粳稻品种Azucena杂交产生的包含110个加倍单倍体株系的群体,在干旱胁迫和正常水分条件下,连续在2004年和2005年于抽穗期分别测定了叶片水势、相对含水量、叶绿素含量(SPAD值)、游离脯氨酸含量、气孔导度和蒸腾速率,并于成熟期取样,计算抗旱系数。与正常水分状况下相比,干旱胁迫条件下叶片的游离脯氨酸含量的增加达极显著水平,干旱胁迫条件下叶片的相对含水量、水势、叶绿素含量和气孔导度的降低均达显著或极显著水平。相关分析表明,在干旱胁迫条件下,叶片相对含水量、叶片水势与抗旱系数呈显著或极显著正相关。 利用175个RFLP标记构建的遗传连锁图谱分析了与抗旱性相关的叶片生理指标,共检测到与抗旱性相关的6个生理指标的7个加性QTL,31对上位性QTL,其中有2个主效QTL、9对上位性QTL存在环境互作效应。在两种水分条件下检测到的QTL结果有较大差异,说明干旱胁迫对控制与抗旱性相关的叶片生理性状基因的表达有显著的影响。在6个抗旱相关生理指标中,检测到的控制叶片气孔导度和水势的QTL较多,有3个加性QTL和8对上位性QTL控制气孔导度,有8对上位性QTL控制水势。     

Performance and yield stability of maize hybrids in stress-prone environments in eastern Africa

Identification and deployment of high-yielding and stress-tolerant maize hybrids adapted to stress-prone agro-ecologies is important for improving the food security and livelihoods of smallholder farmers in eastern Africa.The objectives of this study were to(i)assess the performance of maize hybrids under well-watered and drought stress conditions;(ii)evaluate grain yield stability of 65 intermediate-maturing and 55 early-maturing hybrids in 24 well-watered locations and seven drought stress locations;and(iii)identify representative and/or discriminative testing locations for increasing genetic gains for the target traits.There were significant differences for grain yield among early-and intermediatematuring hybrids tested under well-watered and drought stress environments.Among the early-maturing hybrids,the top 10 hybrids produced 46.8%–73.9%and 31.2%–42.1%higher mean grain yields than the best commercial check under drought and well-watered conditions,respectively.Among the intermediate-maturing hybrids,the top 10 hybrids produced 25.2%–47.7%and 8.5%–13.5%higher grain yield than commercial checks under drought stress and well-watered conditions,respectively,suggesting improvement in the levels of drought tolerance in both early-and intermediate-maturing hybrids.GGE biplot analysis and a bi-segmented regression linear method identified specific early-maturing and intermediate-maturing hybrids that performed well under both well-watered and drought stress conditions.These hybrids could be recommended for commercial production in eastern Africa.Kakamega in Kenya was found to be the most representative and highly discriminating site among well-watered testing locations,while Kabuku in Tanzania was the least representative of test locations.For testing under drought stress conditions,Kiboko in Kenya was identified as the most representative location.This information could be useful for allocating resources and streamlining CIMMYT maize hybrid testing in eastern Africa.     

Genetic analysis and validation of quantitative trait loci associated with reproductive-growth traits and grain yield under drought stress in a doubled haploid line population of rice (Oryza sativa L.)

Drought is a major constraint for rice production and yield stability in rainfed ecosystems, especially when it occurs during the reproductive stage. Combined genetic and physiological analysis of reproductive-growth traits and their effects on yield and yield components under drought stress is important for dissecting the biological bases of drought resistance and for rice yield improvement in water-limited environments. A subset of a doubled haploid (DH) line population of CT9993-5-10-1-M/IR62266-42-6-2 was evaluated for variation in plant water status, phenology, reproductive-growth traits, yield and yield components under reproductive-stage drought stress and irrigated (non-stress) conditions in the field. Since this DH line population was previously used in extensive quantitative trait loci (QTLs) mapping of various drought resistance component traits, we aimed at identifying QTLs for specific reproductive-growth and yield traits and also to validate the consensus QTLs identified earlier in these DH lines using meta-analysis. DH lines showed significant variation for plant water status, reproductive-growth traits, yield and yield components under drought stress. Total dry matter, number of panicles per plant, harvest index, panicle harvest index, panicle fertility, pollen fertility, spikelet fertility and hundred grain weight had significant positive correlations with grain yield under drought stress. A total of 46 QTLs were identified for the various traits under stress and non-stress conditions with phenotypic effect ranging from 9.5 to 35.6% in this study. QTLs for panicle exsertion, peduncle length and pollen fertility, identified for the first time in this study, could be useful in marker-assisted breeding (MAB) for drought resistance in rice. A total of 97 QTLs linked to plant growth, phenology, reproductive-growth traits, yield and its components under non-stress and drought stress, identified in this study as well as from earlier published information, were subjected to meta-analysis. Meta-analysis identified 23 MQTLs linked to plant phenology and production traits under stress conditions. Among them, four MQTLs viz., 1.3 for plant height, 3.1 for days to flowering, 8.1 for days to flowering or delay in flowering and 9.1 for days to flowering are true QTLs. Consensus QTLs for reproductive-growth traits and grain yield under drought stress have been identified on chromosomes 1 and 9 using meta-QTL analysis in these DH lines. These MQTLs associated with reproductive-growth, grain yield and its component traits under drought stress could be useful targets for drought resistance improvement in rice through MAB and/or map-based positional analysis of candidate genes.     

The study of seed yield and seed yield components of lentil (Lens culinaris Medik) under normal and drought stress conditions

In this study yield and seed yield components of twenty lentil (Lens culinaris Medik) genotypes were compared in a split plot RCBD based design with 3 replications at the Zanjan University Research Farmland in 2004. The main plots were lentil planted under drought stress and non stress (irrigation) condition and subplots were twenty of genotype lentil. There were significant differences between traits in lentil genotypes. The seed yield per plant was sensitive to drought stress but 100 seed weight was more tolerance and stable trait in drought condition. As correlation analysis of traits in various stress condition, the harvest index, seed yield per plant, pods per plant and biological yield were correlated with grain yield. In addition harvest index, seed yield per plant, pods/plant and biological yield were the most important traits that have a relationship with grain yield.     

Large-scale screening for maize drought resistance using multiple selection criteria evaluated under water-stressed and well-watered environments

A total of 550 maize inbred lines collected from global breeding programs were evaluated for drought resistance under both well-watered and water-stressed environments. The evaluation was based on multiple measurements of biomass taken before and after the drought stress was applied using the normalized difference vegetation index (NDVI), along with other selection criteria including anthesis-silking interval, leaf senescence, chlorophyll content, root capacitance, final grain yield, and grain yield components. Kernel weight was the most stable trait under drought stress. Correlations between the primary trait (grain yield) and the secondary traits, except the root capacitance and ASI under water-stressed condition, were all significant. Root capacitance had relatively low heritability and low genetic correlation with other drought resistance criteria, and is not recommended as a drought resistance criterion. Significant reduction of NDVI values measured in the afternoon when the leaves became rolling, compared to those measured in the morning when the leaves were open, provides a reliable index for leaf rolling, which however was not significantly correlated with grain yield. NDVIs measured across different developmental stages were highly correlated with each other and with most of the secondary traits as well as, grain yield, indicating that NDVI can be used as a secondary trait for large-scale drought resistance screening. Regression models built based on non-yield drought criteria and yield components explained about 40% and 95% of the variation for the grain yield, respectively. Some maize lines developed in China for temperate regions showed strong drought resistance comparable to tropical maize lines when tested under tropical condition, indicating that temperate lines with a wide adaptability can be used in drought resistance breeding for both temperate and tropical environments.