Screening of Drought Stress Indicators and Analysis of Drought Resistance in Cultivated Rice Germplasm Resources in Guangxi

This study aimed to screen drought stress indicators and analyze the drought resistance in 105 cultivated rice germplasm resources in Guangxi Zhuang Autonomous Region under drought stress in the whole growth period based on D value of seven morphological traits including panicle neck thickness,effective panicle number per plant,1 000-grain weight,filled grain number per panicle,total grain number,seed setting rate and yield per plant.According to the results,under drought stress,yield per plant exhibited significant positive correlation with panicle neck thickness and exhibited extremely significant positive correlation with other five morphological traits.Based on the identification and evaluation of comprehensive drought-resistance index D value,seven highly drought-resistant cultivated rice varieties were screened,accounting for 6.67％.Upland rice germplasm resources in Guangxi Zhuang Autonomous Region possess strong drought-resistance capacity,which could be used to screen highly drought-resistant rice germplasm materials.This study provided material basis and theoretical reference for breeding drought resistant rice cultivars in Guangxi Zhuang Autonomous Region.

Screening of drought resistance indices and evaluation of drought resistance in cotton(Gossypium hirsutum L.)

Sixteen cotton cultivars widely planted in China were sowed under five different drought concentrations(0,2.5,5,7.5,and 10%)using PEG6000 to screen the indices of drought resistance identification and explore the drought resistance of different cotton cultivars.Eighteen physiological indices including root,stem,and leaf water contents(RWC,SWC,and LWC),net photosynthetic rate(Pn),the maximum photochemical quantum yield(Fv/Fm),the actual photochemical quantum yield(ΦPSII),non-photochemical quenching coefficient(NPQ),leaf water potential(LWP),osmotic potential(Ψs),leaf relative conductivity(REC),leaf proline content(Pro),leaf and root soluble protein contents(LSPC and RSPC),leaf and root malondialdehyde(MDA)contents(LMDA and RMDA),root superoxide dismutase,peroxidase,and catalase activities(RSOD,RPOD,and RCAT)were measured.Results indicated the 18 physiological indices can be converted into five or six independent comprehensive indices by principal component analysis,and nine typical indices(Fv/Fm,SWC,LWP,Pro,LMDA,RSPC,RMDA,RSOD,and RCAT)screened out by a stepwise regression method could be utilized to evaluate the drought resistance.Moreover,the 16 cotton cultivars were divided into four types:drought sensitive,drought weak sensitive,moderate drought resistant,and drought resistant types.The resistance ability of two selected cotton cultivars(drought resistant cultivar,Dexiamian 1;drought sensitive cultivar,Yuzaomian 9110)with contrasting drought sensitivities were further verified by pot experiment.Results showed that the responses of final cotton biomass,yield,and yield composition to drought were significantly different between the two cultivars.In conclusion,drought resistant cultivar Dexiamian 1 and drought sensitive cultivar Yuzaomian 9110 were screened through hydroponics experiment,which can be used as ideal experimental materials to study the mechanism of different cotton cultivars with contrasting drought sensitivities in response to drought stress.

Screening and Simple Identification of Drought-resistant Lines in Sugarcane Breeding

Six sugarcane plant lines were selected from seedlings owing to good performance in agronomic characters under drought conditions.A special test with drought stress to death under groove was carried out to select the best drought tolerant clones among them. The proportion of bound water to free water content in leaves,cell cytoplasm membrane permeability in leaves,yield components,etc.,which were regarded as reasonable indexes to identify drought resistance of sugarcane,were measured. The results showed that both YT06-868 and YT05-339 were winners. The two were high-class drought-resistant clones. On some measured indexes,both of them had higher values than ROC22( the main check variety) and on the other ones,they both had the same values as ROC22. The drought resistance of YT05-291 was moderate and between ROC22 and ROC16( the secondary check variety),while the others had poor drought-resistant according to these indexes.

Screening of Drought Resistance Identification Indexes for Rice(Oryza sativa L.) Cultivars in Ningxia

The morphological characters, physiological characters, yield traits and yield per plant of total 49 rice cultivars from Ningxia were investigated under conditions of water stress and non-water stress so as to determine the relationship between each trait and yield per plant under water stress and the relationship between each relative character and drought resistance coefficient under water stress and non-water stress. The correlation, grey correlation, stepwise regression and path analyses showed that the tiller number per plant, plant height, grain density, effective panicle number per plant and grain number per panicle, total 5 traits, were significantly correlated with the drought resistance of rice, and they could be used to identify the drought resistance of rice in Ningxia. In addition, the drought resistance of rice was graded qualitatively according to the subordinate function value of corresponding drought resistance coefficient. The results showed that among the 49 rice cultivars from Ningxia,6 rice cultivars were highly drought resistant, and 9 rice cultivars were moderately drought resistant, suggesting that the evaluation method was feasible and effective.

Field identification of morphological and physiological traits in two special mutants with strong tolerance and high sensitivity to drought stress in upland rice(Oryza sativa L.)

The two mutants idr1-1 and 297-28, which were obtained from the radiation mutation of HD297 and IAPAR9, were used as experimental materials in this study for a 2-year(2012 and 2013) experiment about field drought resistance identification in Beijing, China. Key agronomic traits and water-related physiological indexes were observed and measured, including the leaf anti-dead level(LADL), days to heading, plant height, setting percentage, aboveground biomass, leaf water potential(LWP), net photosynthetic rate(Pn) and transpiration rate. The results showed that the mutant idr1-1 that was under drought stress(DS) conditions for 2 years had the highest LADL grades(1.3 and 2.0) among all the materials, and they were 2–3 grades stronger than the wild-type IAPAR9 with an average that was 21.4% higher for the setting percentage than the wild type. Compared with the IAPAR9 for the 2-year average delay in the days to heading and the reduction rates in the plant height, setting percentage, and aboveground biomass under DS compared with the well-watered(WW) treatment, idr1-1 showed 3.2% less delay and 19.1, 16.4, and 6.1% less reduction, respectively. The idr1-1 in the LWP always exhibited the highest performance among all the materials. The Pn of idr1-1 under severe and mild DS comparing with that under WW was slightly decreased and even slightly increased, respectively, leading to an average reduction rate of only 0.92%, which was 26.93% less than that of IAPAR9. Under the severe DS, idr1-1 still showed the highest value of 16.88 μmol CO2 m–2 s–1 among all the materials and was significantly higher than that of IAPAR9(11.66 μmol CO2 m–2 s–1). Furthermore, only idr1-1 had the increased and the highest transpiration rate values(7.6 and 6.04 mmol H2 O m–2 s–1) under both mild and severe DS compared with the values under WW, when the transpiration rate of all the other materials significantly decreased. By contrast, the 297-28 in terms of the LADL grade under DS was the lowest(7.0), and it was four grades weaker than its wildtype HD297 and even one grade weaker than the drought-sensitive paddy rice SN265. For the 2-year average reduction rates in aboveground biomass and plant heights under DS compared with those under the WW, 297-28 was 31.6 and 31.8% higher than HD297, respectively. Meanwhile, 297-28 showed the worst performance for the LWP, Pn, and transpiration rate. These results suggest that idr1-1 might be a superior drought tolerant mutant of upland rice found in China. It has a strong ability to maintain and even enhance leaf transpiration while maintaining a high plant water potential under DS, thus supporting a high Pn and alleviating the delay in agronomic trait development and yield loss effectively. 297-28 is a much more highly drought-sensitive mutant that is even more sensitive than paddy rice varieties. The two mutants could be used as drought tolerance controls for rice germplasm identification and the drought resistant mechanism studies in the future. idr1-1 is also suitable for breeding drought-tolerant and lodging-resistant high-yield rice varieties.

Rapid Identification for Drought Resistance of Wheat Using Near-infrared Diffuse Reflectance Spectroscopy

[Objective] This study aimed to establish an identification system for drought-resistance in wheat by using near-infrared diffuse reflectance spectroscopy. [Method] In 2006-2007, 36 wheat varieties with different drought resistance were selected and were classified according to their drought resistance grades determined by the Technical Specification of Identification and Evaluation for Drought Resistance in Wheat （GB/T 21127-2007）. In addition, the harvested wheat seed samples were spectrally analyzed with FOSS NIRSystems5000 near-infrared spectrum analyzer for grain quality （full spectrum analyzer） and then the forecasted regression equations were established. [Result] After the establishment of a database and validation, dis- criminated functions were obtained. The determination coefficient （RSQ） and coeffi- cients of determination for cross validation （1-VR） in the discriminant function built with seed samples from water stress area were 0.846 0 and 0.781 8, respectively, which indicated that the consistency between drought resistance and spectral charac- teristics in wheat varieties was good, and there was high correlation between the near-infrared diffuse reflectance spectra of seeds and the drought resistance in wheat. [Conclusiou] Under water stress condition, it is feasible to establish a conve- nient, rapid and no-damage identification system for the drought resistance in wheat by using the near-infrared diffuse reflectance spectrum technique to scan wheat seeds.

Advances and Developing Tendency of Water Use Efficiency in Plant Biology

Biological water saving is one of the major fields of water saving agriculture in the future and has an enormous potential in agricultural production. In this paper, the necessity and urgency of developing high water use efficiency in plant biology were dissertated firstly, and the research progresses at home and abroad were reviewed as following aspects： mechanisms of drought resistance and high water use efficiency, criterions for identifying and evaluating drought resistance and water use efficiency, genetic improvement for drought resistance and water use efficiency, water saving irrigation technology based on the physiological regulation and control in crop plants. Major problems in the research field at present were put forward, and development tendency of water use efficiency in plant biology in the future were also discussed.

In vitro Screening of Fusarium Wilt-resistant Germplasm Resources of Red Edible Seed Watermelon( Citrullus lanatus ssp. vulgaris var. megalaspermus Lin et Chao)

[ Objective] This study aimed to establish an appropriate technology system for in vitro screening of Fuzarium wilt-resistant germplasm resources of red edible seed watermelon and obtain variants resistant to fusaric acid, thus providing resistant materials for breeding Fusarium wilt-resistant red edible seed watermel- on. [ Method] Using Zhongxin No. 1 red edible seed watermelon advemitious buds as screening materials and fusaric acid （FA） as a stress agent, in vitro screen- ing of Fusarium wilt-resistant red edible seed watermelon clonal variants and identification of Fusarium wilt-resistance of the germplasm resources of red edible seed watermelon were performed. [ Result] The results showed that the appropriate FA for in vitro screening of Fusarium wilt-resistant red edible seed watermelon vari- ants was 15 mg/L. In vitro screening system for Fusarium wilt-resistant red edible seed watermelon variants was established preliminarily and FA-resistant regenera- ted plants were obtained. Among the 36 germplasm resources of red edible seed watermelon, there were 2 highly resistant materials, 6 moderately resistant materi- als, 11 slightly resistant materials and 17 highly susceptible materials. [ Conclusion] This study confirmed preliminarily that in vitro screening method is effective for obtaining resistant materials of red edible seed watermelon.

Advances in Research on Drought Resistance in Rice

Rice is the main grain crop in China. With global warming, drought and water shortage have become one of the important factors limiting rice production. Improving the drought resistance of rice can effectively alleviate the loss of rice yield caused by drought. In this paper, the research progress on rice drought resistance and its evaluation methods, mapping of QTLs for drought resistance-related traits, and mining for drought resistance genes were reviewed, and molecular breeding for drought resistance in rice was prospected.

不同大豆品种萌发期抗旱性鉴定方法研究

为筛选出大豆萌发期抗旱性鉴定的适宜试验条件,以大豆品种陇中黄601、恳鉴豆15、九农29、长农16为供试材料,采用蛭石法和滤纸法进行发芽试验,运用内源转录间隔区(Internally Transcribed Spacer,ITS)序列分析法进行发芽床筛选,测定各供试大豆品种的发芽率、硬实豆数、发霉豆数,并进行了蛭石湿度和PEG-6000浓度筛选。结果表明,蛭石法发芽试验能明显减少大豆发芽试验中产生霉菌的种类与数量,适宜在大豆萌发期抗旱性鉴定中应用。且在蛭石湿度为170%、PEG-6000浓度为22%的条件下,不同大豆品种间的发芽率差异比较明显,硬实豆数和发霉豆数少,试验数据可靠,可作为大豆萌发期抗旱性鉴定试验的适宜条件。且在此条件下,4个供试大豆品种的抗旱性表现由强到弱依次为陇中黄601、九农29、长农16、恳鉴豆15。

耐寒、抗旱、优质中晚熟甘蓝品种筛选试验

为筛选出适宜在六盘山区种植的耐寒、抗旱的优质甘蓝品种,对13个甘蓝品种开展了比较试验,结果表明:所有参试品种均未发生抽薹开花和茎秆升高现象,圆球型甘蓝品种京甘103在品质方面除硝酸盐含量较高外,其他品质表现优异,可溶性固形物含量、可溶性糖含量、净菜率分别达9.17%、5.92%、65.07%,均显著高于其他圆球型甘蓝品种,MDA(丙二醛)含量较低,为0.43μmol/g,虽然产量低,但品质较优、口感脆嫩、外形美观,深受消费者喜欢;平头型甘蓝品种中甘107生长势强,不易裂球,可溶性糖含量、维生素C含量高,分别达5.32%、9.68 mg/kg,显著高于其他平头型甘蓝品种,且MDA和POD(过氧化物酶)含量较低,SOD(超氧化物歧化酶)和CAT(过氧化氢酶)的活性较高,整体抗逆性优于其他品种;平头型甘蓝品种晚丰光合能力较强,SPAD值最高为60.18,显著高于其他圆球型甘蓝品种,抗病性强,可溶性固形物、净菜率、脯氨酸含量高,分别为9.2%、61.14%、0.123%,667 m^(2)产量最高,为3518.43 kg。综上所述,京甘103、中甘107和晚丰适宜在六盘山区大面积示范推广种植。虽然紫甘蓝欧梅罗和普来米罗的长势较其他品种差,但是品质优异,营养价值高,可作为鲜食品种进行推广种植。

棉花抗旱性综合评价及其相关性分析

为综合评价棉花种质资源的抗旱性,筛选优异抗旱品种(品系),并建立成株期产量抗旱预测模型。对50份棉花种质资源在苗期进行干旱处理,调查其表型性状并测定其生理指标,根据各性状/指标差异的显著性筛选抗旱指标,并计算抗旱系数和抗旱指数,利用主成分分析法和隶属函数法计算综合抗旱系数、综合抗旱指数、综合抗旱隶属函数值、加权抗旱性系数和抗旱性综合度量值,对棉花抗旱性进行综合评价和分级。进一步将苗期评价分级结果与成株期干旱胁迫下产量和纤维品质性状进行比较,以分析苗期抗旱鉴定模型对成株期预测的精度。苗期生理性状在提高抗旱鉴定模型精度上具有重要作用,基于苗期生理指标建立的抗旱鉴定模型能够很好地预测成株期的抗旱性。

66个紫花苜蓿品种无性系苗期抗旱性评价

为筛选出紫花苜蓿(Medicago sativa)最精准的评价指标和抗旱性较强的紫花苜蓿品种,本研究对来自不同国家的66个紫花苜蓿品种的无性系进行了温室干旱胁迫试验。通过测定株高、鲜重、干重、根长及叶片相对含水量,分析不同紫花苜蓿品种幼苗对干旱胁迫的敏感程度,结合抗旱系数、鲜重抗旱指数、综合抗旱系数以及隶属函数法综合评比其抗旱性。结果表明:株高、鲜重、干重、根长及叶片相对含水量可作为干旱条件下紫花苜蓿抗旱性评价指标。综合比较筛选出‘Dryland’‘比佛’‘陇东’‘杂20’及‘巨能7’为抗旱性强的紫花苜蓿品种,适宜在干旱地区推广种植。

PEG胁迫下小麦新品系萌发期抗旱性鉴定

干旱胁迫严重影响小麦种子萌发速度和成苗质量。为鉴定9个自选小麦新品系的抗旱性强弱,本试验以洛旱7号为对照,用20%PEG-6000模拟干旱胁迫环境,测定种子萌发期相关形态指标,并利用隶属函数分析法对供试小麦材料的抗旱性进行综合评价。结果表明,干旱胁迫下,小麦发芽势、发芽率、发芽指数及胚根长、胚芽鞘长、胚芽长的平均降低幅度分别为32.9%、6.1%、27.3%、47.1%、15.4%、66.6%。由隶属函数综合评价结果可知,洛旱7号、KD7020-2为强抗旱型,KDG07-6、KD7034-8、KD7053-9、KD7043-8为中抗旱型,KD7047-2、KD6055-6、KD701为弱抗旱型,KDG03-1为不抗旱型。由相关性分析结果得出,相对发芽势和相对发芽指数对D值影响最大,可用作小麦萌发期抗旱性鉴定的快速评价指标。

高粱抗旱性研究进展

干旱是限制植物生产力和威胁粮食安全的重要因素之一。高粱(Sorghum bicolor L. Moench)是全球主粮和饲料作物,因其具有较强的抗旱性和能够在恶劣的环境条件下生存而广泛种植于干旱半干旱地区,在作物抗旱领域中具有重要的研究价值。深入解析干旱胁迫下高粱的形态和生理特性、鉴定和筛选抗旱品种、挖掘相关抗旱基因,对推动高粱抗旱育种进程、提高品种抗旱性、提高产量具有重要意义。本文从干旱胁迫对高粱生长的影响、高粱对干旱胁迫的生理响应、高粱耐旱性鉴定方法和鉴定指标、高粱抗旱性分子生物学和提高高粱抗旱性方法5个方面对高粱抗旱性研究进展进行综述,并对高粱抗旱性研究方向进行展望,以期为进一步研究高粱抗旱的形态、生理特性及分子机制奠定基础。

两株内生真菌对多年生黑麦草及早熟禾抗旱性的影响

以内生真菌JG2和JJ12,多年生黑麦草(Lolium perenne)和草地早熟禾(Poa pratensis)为试材,采用生物学鉴定及形态学观察2种方法对内生真菌JG2和JJ12进行鉴定;以总体抗氧化能力(T-AOC)测定法和自由基清除能力(DPPH)测定法综合测定菌株JG2和JJ12的抗氧化能力;通过温室盆栽试验,测定菌液浇灌处理后,重度干旱胁迫条件下多年生黑麦草和草地早熟禾的生理生化指标;研究了重度干旱胁迫条件下内生真菌JG2和JJ12对多年生黑麦草和草地早熟禾生理生化指标的影响,以期为多年生黑麦草及草地早熟禾的抗旱菌剂开发利用提供参考依据。结果表明:经鉴定,菌株JG2为Talaromyces erythromellis,菌株JJ12为蚤褐炭团菌(Hypoxylon pulicicidum);JG2和JJ12均有良好的抗氧化活性;在21 d重度干旱胁迫下,2株内生真菌发酵物处理均能提升多年生黑麦草及草地早熟禾的干旱耐受力,显著提升植株的叶绿素、可溶性蛋白质、脯氨酸(Pro)含量以及超氧化物歧化酶(SOD)活性等(P<0.05),且菌株JG2对多年生黑麦草及草地早熟禾的干旱耐受力的提升强于菌株JJ12。说明菌株JG2与JJ12均有作为抗旱菌剂开发利用的良好潜力,且菌株JG2的开发利用潜力优于菌株JJ12。

水稻抗旱性研究进展

水稻(Oryza sativa L.)是全世界1/3以上人口的主粮,是人类赖以生存的重要物质基础和保障。然而,多数水稻主产区面临的淡水资源匮乏问题严重制约水稻生长,导致水稻产量骤减,威胁粮食安全。深入探究水稻抗旱机理、选育推广节水抗旱稻,不仅有利于合理利用淡水资源,还对保障粮食安全具有重要意义。育种家利用形态、生理生化和产量指标,筛选和培育出强抗旱性的节水抗旱稻品种,并推广应用。研究人员利用关联作图、GWAS、表达谱及多组学联合分析等方法,挖掘出很多与水稻抗旱性相关转录因子、转运蛋白、泛素化酶、蛋白酶及蛋白激酶等,证明水稻抗旱性是受多基因控制的数量性状,并解析了激素含量调节、活性氧清除、渗透调节、角质蜡沉积和根结构改善等一系列水稻抗旱机制。然而,培育的节水抗旱稻数量仍不能满足我国的需求,抗旱基因仍有待于进一步挖掘解析。该文通过搜集、查阅国内外近20年水稻抗旱性相关文献,归纳总结3类水稻抗旱性常规鉴定指标,综合分析水稻抗旱性重要机制和抗旱性关键基因/QTL的最新进展。

基于不同生育时期干旱对花生抗旱性的综合评定

在防雨棚人工控水条件下,采用盆栽试验模拟花生不同生育时期干旱胁迫,调查产量和农艺性状等抗旱性指标,利用抗旱系数法和多性状隶属函数方法分析、鉴定9个商花系列花生品种的抗旱性。结果表明,在苗期、花针期及全生育期干旱条件下,花生产量的下降幅度分别为9.91%~46.86%、16.80%~86.62%和63.99%~97.29%。干旱时期不同,通过抗旱系数法和抗旱性综合评价值(D)筛选出的抗旱品种存在差异。综合不同生育时期干旱,利用平均抗旱系数和平均综合D值筛选出强抗旱品种为商花21号、商花33号和商花43号。不同生育时期干旱条件下,去根生物量、结果枝数和单株果质量的隶属函数值均与抗旱系数呈显著或极显著相关关系,可作为鉴定花生品种抗旱性的指标。研究结果可为区域推广商花系列抗旱新品种及筛选优异抗旱种质资源提供理论参考。

番茄种质资源萌发期抗旱性综合评价及筛选

番茄作为重要的蔬菜作物之一,鉴定番茄种质资源的抗旱性及筛选抗旱番茄种质资源对番茄育种具有重要意义。本研究利用12.5%PEG-6000溶液对92份番茄种质资源进行干旱胁迫处理,测定发芽势、发芽率、发芽指数、活力指数、根长、芽长等6个抗旱性相关指标,运用相关性分析、主成分分析、隶属函数法和聚类分析进行番茄萌发期抗旱性评价及筛选。结果表明,干旱胁迫下6个指标均显著降低,其中活力指数和发芽势降低最大。通过主成分分析将6个指标转化为2个新指标,累计贡献率达86.657%。基于相关性和主成分分析,筛选出发芽势、发芽率、发芽指数、活力指数作为萌发期抗旱性鉴定的主要指标,利用隶属函数法结合聚类分析将番茄种质资源分为4类,其中抗旱型19份、较抗旱型41份、较敏感型18份、敏感型14份;通过增大、减小PEG-6000溶液浓度,进一步筛选出抗旱性强的密植红番茄和锦农矮秧两个品种,敏感性强的北京早红和大红袍两个品种。本研究结果可为番茄种质资源的抗旱性研究提供理论基础。

引进ICARDA的小麦苗期抗旱性鉴定及SNP关联分析

以引进国际干旱地区农业研究中心(ICARDA)的160份小麦为研究对象,在苗期用20%PEG-6000模拟干旱条件进行处理,以正常营养液作为对照,分析干旱环境对7个苗期相关性状(苗高、最长根长、根数、茎叶鲜质量、茎叶干质量、根鲜质量和根干质量)的影响,利用综合评价值进行抗旱评价及抗旱分级,并结合55K SNP芯片对159份小麦的苗期抗旱相关性状的抗旱系数进行关联分析。抗旱鉴定结果表明:干旱处理下的各个苗期相关性状均低于正常处理水平,按照综合评价值及系统聚类,将160份小麦分为高抗旱(5份)、中等抗旱(53份)、低抗旱(97份)和干旱敏感(5份)四类;在苗期筛选出5份高抗旱品种,包括ICARDA69、ICARDA51、ICARDA49、ICARDA83、ICARDA84,其D值分别为0.823、0.813、0.765、0.722、0.711。关联分析结果显示:利用24151个SNP标记位点结合苗期相关性状的抗旱系数在P≤0.001水平下共定位到227个抗旱相关标记,分布在除1B、2D、4D和6D外的17条染色体上,可解释7.13%~14.68%的表型变异。检测到3个多效应位点,分别位于4B、5B和6A染色体上,可解释9.31%~13.28%的表型变异。其中,位于4B染色体上的AX-108789337与茎叶干质量和根干质量显著关联,可解释10.44%~13.28%的表型变异;位于5B染色体上的AX-109353092与苗高和根鲜质量显著关联,可解释9.31%~10.93%的表型变异;位于6A染色体上的AX-110432128与苗高和根鲜质量显著关联,可解释9.95%~9.99%的表型变异。