水稻孕穗期耐热种质资源的初步筛选

在人工气候室设定极端高温条件下,对来源于不同国家和地区的58份处于温度敏感期的水稻品种耐热性进行鉴定,以结实率下降的百分率为指标,通过方差分析,对水稻种质资源的耐热性进行评价。结果表明,种质间的耐热性存在显著差异,筛选出极端耐热品种2份（IRAT118和冷水白）。     

地方稻资源D43的开花期耐热特性研究

水稻在抽穗开花期对高温胁迫非常敏感,通过挖掘耐热资源,培育耐热水稻品种是应对高温热害最有效的方式。前期研究发现,地方稻资源D43在花期连续高温条件下能保持较高的结实率。本研究在大田和人工气候室不同高温处理下,分析了D43的开花时间与耐热性之间的相互关系。结果表明,高温能够使水稻的开花时间提前,D43表现出稳定的早花时特性,高温胁迫下的开花时间集中在8∶30~10∶00;在开花时间段恒定高温胁迫下,D43的结实率较低;但在大田高温和人工气候室模拟高温胁迫下,D43的开花时间避开了日高温段,从而表现出较高的结实率;花器官形态性状包括花药开裂率、柱头上的花粉附着数、花粉萌发数与结实率之间呈显著正相关,因此可用于评价水稻的花期耐热性。     

广东高州普通野生稻生殖特性的研究Ⅰ.结实率、花粉育性及其发育特点

对采自6个采样点141个编号的高州普通野生稻的结实率、花粉育性及其发育特点进行研究。结果发现,高州野生稻的结实率平均为57．23％,普遍偏低;花粉育性平均为89．3％。育性在50％以上的编号134个,占95．04％;7个编号出现不同程度的败育现象,败育类型以典败为主。其中育性最低的是GZW122,育性仅为8％;17个编号（占12,06％）的裂药性存在严重的异常现象。相关分析表明,花粉育性和裂药性与结实率存在极显著相关。不同采样点问存在一定差异,其中位于祥山镇祥山村祥山洞的编号结实率、花粉育性和裂药指数都较低,变异系数却较大,显示出较丰富的多样性。利用激光扫描共聚焦显微镜术研究发现,高州普通野生稻花粉发育过程与栽培稻一致,同样经历了8个时期,即小孢子母细胞形成期、小袍子母细胞减数分裂期、小孢子早期、小孢子中期、小孢子晚期、二孢花粉期和成熟花粉期。     

茶陵野生稻苗期耐冷性研究

以耐冷性强弱不同的栽培稻为参比,通过自然冷胁迫与(或)人工冷处理,比较了茶陵野生稻与不同类型栽培稻经冷胁迫后的秧苗成活率、净光合速率和光系统Ⅱ光化学量子效率的变化,对茶陵野生稻苗期耐冷性作出评估.结果表明:经冷胁迫后,茶陵野生稻上述指标值的变化小于典型籼稻和爪哇稻,大于典型粳稻.说明茶陵野生稻苗期耐冷性强于籼稻和爪哇稻,但弱于粳稻.     

新疆自然高温环境下玉米自交系开花期耐热性鉴定与评价

在新疆夏季自然高温环境下,以田间玉米空秆率、果穗结实率、相对结实率为主要评价指标,综合籽粒产量与穗部性状,对26份国内外玉米骨干自交系连续2年进行耐热性鉴定与评价,结合新疆当地高温干燥的气候特点,建立一套适宜玉米种质资源大田耐热性的鉴定、评价体系,为中国玉米耐热种质资源的遗传改良和新品种选育提供参考。结果表明:(1)不同基因型玉米自交系空秆率、果穗结穗率、相对结实率和耐热性差异较大,其中GW5F、GW4F、GW7F和PH6WC耐热性最强,在高温胁迫下空秆率最低,果穗结实率与相对结实率最高;其次为PHBA6、新自351等8份自交系,在高温胁迫下籽粒产量及综合表现较好;其余自交系对高温均表现敏感。(2)高温胁迫导致玉米穗部性状严重衰退,其中的穗重、穗行数和行粒数所受影响最大。(3)在年份或材料之间,玉米自交系籽粒产量与其主要农艺性状相关性差异较大,并以果穗重与籽粒产量相关性最高。(4)以相对结实率为主要指标通过层次聚类可将参试材料分为两大群,耐热性最强的GW5F、PH6WC、GW4M聚为第Ⅰ群,其余自交系聚为第Ⅱ群;第Ⅱ群中‘吉63’、Mo17等6份自交系可聚为第1亚群,PHBA6、LH82等6份自交系聚为第2亚群,郑58、新农育6390M等11份自交系聚为第3亚群。综合分析来看,该研究中表现极耐高温的4份自交系均为国外优异种质,可用于玉米耐高温基础研究和遗传改良;表现较强耐热性的8份品系多来自于新疆本地选育的材料,其遗传基础较为广泛,适应当地的高温环境,也是优异的耐热育种资源。     

盐胁迫下不同水稻种质形态指标与耐盐性的相关分析

选用中国、韩国和国际水稻研究所(IRRI)不同耐盐能力的籼、粳、爪哇稻16份为材料进行芽期和苗期试验。随着NaCl浓度增加,种子开始发芽的时间推迟、发芽过程延长、发芽率降低;品种的发芽率能有效地指示其芽期耐盐能力。NaCl浓度对许多苗期形态指标有显影响,其中叶片盐害指数能反映品种的苗期耐盐能力;随着NaCl处理时间的增长,叶片盐害指数与NaCl浓度间的相关性越来越大。同一品种在芽期的耐盐能力和苗期表现不一致,两的相关系数很低。     

广东高州普通野生稻生殖特性的研究Ⅱ.胚囊育性、胚囊发育、胚胎发生和胚乳发育

利用整体染色激光扫描共聚焦显微镜术（WCLSM）,对采自广东省高州市6个地点共141个编号的高州普通野生稻的成熟胚囊育性和胚囊形成发育特点等进行研究。结果表明,供试的绝大多数高州普通野生稻材料成熟胚囊均存在不同程度的育性异常现象,包括雌性生殖单位退化、极核位置异常、极核数目异常、胚囊退化等。这些异常结构的胚囊由于没有正常的卵细胞,不能正常受精,影响子粒结实。141个编号平均异常胚囊频率为11．11％,最高异常率为67．86％。高州普通野生稻胚囊发育过程与正常栽培稻一致,属寥型。对一些结实率偏低材料的研究,发现在胚囊发育过程的不同时期存在一些异常现象,包括功能大孢子退化,二至八核胚囊发育异常等。对柱头上的花粉量调查,发现观察的69个编号中,多数编号柱头上花粉量偏少。研究表明,花粉量偏少影响受精是导致结实率偏低的最主要原因之一。本文对导致结实率偏低的综合因素进行了讨论。     

茄子种质资源青枯病抗性鉴定及分子标记研究

利用分子标记结合人工接种鉴定评价41份茄子材料的青枯病抗性。试验结果表明,41个材料中,人工接种鉴定为抗病材料有38份,感病的3份,与分子标记鉴定结果基本吻合。综合人工接种与分子鉴定结果得出,只含有一个特异标记或不含特异标记的材料表现为感病。在3个分子标记鉴定结果中,有8份材料不完全一致,原因可能是各标记所连锁的抗性位点不同;另外,不同的材料在试验环境中基因表达很可能存在差异。因此,在茄子抗青枯病育种中,人工接种鉴定和分子标记辅助鉴定都是重要的。     

经野生稻总DNA处理的栽培稻离体胚长成植株后的某些性状变化(简报)

栽培稻离体胚（幼胚、萌动胚）以野生稻总ＤＮＡ浸泡或滴加处理后,经组织培养长成的完整植株进行盆栽的结果显示,当代与后代植株中大多数无变异,仅１株产生芒,２株抗稻瘟病。有芒种子再次种植于人工气候室内,其Ｄ_１、Ｄ_２和Ｄ_３代种子仍有芒;抗稻瘟病植株的种子收获后再次播种,后代仍有抗稻瘟病特性。     

经野生稻总DNA处理的栽培稻离体胚长成植株后的某些性状变？…

栽培稻离体胚（幼胚、萌动胚）以野生稻总ＤＮＡ浸泡或滴加处理后,经组织培养长成的完整植株进行盆栽的结果显示,当代与后代植株中大多数无变异,仅１株产生芒,２株抗稻瘟病,有芒种子再次种植于人工气候室内,其Ｄ１、Ｄ２和Ｄ３代种子仍有芒;抗稻瘟病植株的种子收获后再次播种,后代仍有抗稻瘟病特性。     

Assessment of gene flow from a herbicide-resistant indica rice (Oryza sativa L.) to the Costa Rican weedy rice (Oryza sativa) in Tropical America: factors affecting hybridization rates and characterization of F1 hybrids

Herbicide-resistant rice cultivars allow selective weed control. A glufosinate indica rice has been developed locally. However, there is concern about weedy rice becoming herbicide resistant through gene flow. Therefore, assessment of gene flow from indica rice cultivars to weedy rice is crucial in Tropical America. A field trial mimicking crop–weed growing patterns was established to assess the rate of hybridization between a Costa Rican glufosinate-resistant rice line (PPT-R) and 58 weedy rice accessions belonging to six weedy rice morphotypes. The effects of overlapping anthesis, morphotype, weedy accession/PPT-R percentage, and the particular weedy accession on hybridization rates were evaluated. Weedy rice accessions with short overlapping anthesis (4–9 days) had lower average hybridization rates (0.1%) than long anthesis overlapping (10–14 days) accessions (0.3%). Hybridization also varied according to weedy rice morphotype and accession. Sativa-like morphotypes (WM-020, WM-120) hybridized more readily than intermediate (WM-023, WM-073, WM-121) and rufipogon-like (WM-329) morphotypes. No hybrids were identified in 11 of the 58 accessions analyzed, 21 accessions had hybridization rates from 0.01% to 0.09%, 21 had rates from 0.1% to 0.9%, and 5 had frequencies from 1% to 2.3%. Another field trial was established to compare the weedy rice-PPT-R F₁ hybrids with their parental lines under noncompetitive conditions. F₁ hybrids had a greater phenotypic variation. They had positive heterosis for vegetative trait and reproductive potential (number of spikelets and panicle length) traits, but negative heterosis for seed set. This study demonstrated the complexity of factors affecting hybridization rates in Tropical America and suggested that the phenotype of F₁ hybrids facilitate their identification in the rice fields.     

温光对稻米蛋白质及氨基酸含量的影响

研究水稻结实期的温、光条件对稻米蛋白质与氨基酸含量的影响,其结果表明：同一品种作为早季栽培时,稻米氨基酸含量比作晚季栽培时低,分期播种时,以结实期日平均气温为２４℃时蛋白质含量为最高;不同海拔高度种植时,以８００ｍ处蛋白质含量为最高;结实期人工高温处理,稻米蛋白质和氨基酸含量降低,低温（２１／２０℃）处理时,粳稻的氨基酸含量增加而籼稻则有所降低,籼稻氨基酸形成的适温在２４￣２６℃之间,弱光下,糙米     

旱作条件下水陆稻资源的生物量与结实率的差异分析

在旱作条件下对288份水陆稻种资源进行了生物量与结实率鉴定。结果表明：在旱作条件下的营养生长过程中,绝大部分的陆稻材料较水稻材料具有更好的适应性,表现在成熟期具有较大的生物量,但水稻种质资源中也存在一定数量种质成熟期具有较大的生物量。水稻和陆稻的结实率无显著差异。生物量和结实率的相关系数（r）为0．0578,表明在旱作条件下生物量的大小与结实率高低无关。     

籼稻标记性状等基因系的构建

选用涉及水稻(Oryza sativa L.)全部12条染色体的、表现简单遗传且易于识别的形态标记材料27份,以早籼品种浙辐802为轮回亲本,经10余次回交,转育成一套籼型标记等基因系.在此基础上,对同一染色体上的标记进行聚合,育成了15份双标记等基因系.该套材料除所带标记性状外,生育期、株高、分蘖力和穗子大小等主要农艺性性状与轮回亲本基本相仿.     

Genetic diversity within the species Arachis duranensis Krapov. &W.C. Gregory, a possible progenitor of cultivated peanut.

Eighteen accessions of a diploid wild peanut species (Arachis duranensis) were analyzed using morphological, intercrossing, cytological, and RFLP data. Abundant variation was found for morphological characters and for RFLP patterns both between and within accessions, and each accession could be uniquely identified by RFLP pattern. Several plants were found to be F1 hybrids between different accessions, indicating that intercrossing had occurred when these were planted for seed increase. Patterns of RFLP diversity were found to correspond with geographic distribution. Analysis of the number of RFLP fragments observed per accession indicates that additional field collections of this complex of taxa will yield additional genetic variability.     

Increases in the longevity of desiccation-phase developing rice seeds: response to high-temperature drying depends on harvest moisture content

Background and Aims Previous studies have suggested that the drying conditions routinely used by genebanks may not be optimal for subsequent seed longevity. The aim of this study was to compare the effect of hot-air drying and low-temperature drying on subsequent seed longevity for 20 diverse rice accessions and to consider how factors related to seed production history might influence the results.Methods Seeds of rice, Oryza sativa, were produced according to normal regeneration procedures at IRRI. They were harvested at different times [harvest date and days after anthesis (DAA), once for each accession] and dried either in a drying room (DR; 15 % relative humidity, 15 °C) or in a flat-bed heated-air batch dryer (BD; 45 °C, 8 h d^–1) for up to six daily cycles followed by drying in the DR. Relative longevity was assessed by storage at 10·9 % moisture content and 45 °C.Key Results Initial drying in the BD resulted in significantly greater longevity compared with the DR for 14 accessions (seed lots): the period of time for viability to fall to 50 % for seeds dried in the BD as a percentage of that for seeds dried throughout in the DR varied between 1.3 and 372·2 % for these accessions. The seed lots that responded the most were those that were harvested earlier in the season and at higher moisture content. Drying in the BD did not reduce subsequent longevity compared with DR drying for any of the remaining accessions.Conclusions Seeds harvested at a moisture content where, according to the moisture desorption isotherm, they could still be metabolically active (>16·2 %) may be in the first stage of the post-mass maturity, desiccation phase of seed development and thus able to increase longevity in response to hot-air drying. The genebank standards regarding seed drying for rice and, perhaps, for other tropical species should therefore be reconsidered.     

Identification and analysis of QTLs controlling cold tolerance at the reproductive stage and validation of effective QTLs in cold-tolerant genotypes of rice (Oryza sativa L.)

Low temperature or cold stress is one of the major constraints of rice production and productivity in temperate rice-growing countries and high-altitude areas in the tropics. Even though low temperature affects the rice plant in all stages of growth, the percent seed set is damaged severely by cold and this reduces the yield potential of cultivars significantly. In this study, a new source of cold-tolerant line, IR66160-121-4-4-2, was used as a donor parent with a cold-sensitive cultivar, Geumobyeo, to produce 153 F₈ recombinant inbred lines (RILs) for quantitative trait locus (QTL) analysis. QTL analysis with 175 polymorphic simple sequence repeat (SSR) markers and composite interval mapping identified three main-effect QTLs (qPSST-3, qPSST-7, and qPSST-9) on chromosomes 3, 7, and 9. The SSR markers RM569, RM1377, and RM24545 were linked to the identified QTLs for cold tolerance with respect to percent seed set using cold-water (18–19°C) irrigation in the field and controlled air temperature (17°C) in the greenhouse. The total phenotypic variation for cold tolerance contributed by the three QTLs was 27.4%. RILs with high percent seed set under cold stress were validated with linked DNA markers and by haplotype analysis that revealed the contribution of progenitor genomes from the tropical japonica cultivar Jimbrug (Javanica) and temperate japonica cultivar Shen-Nung89-366. Three QTLs contributed by the cold-tolerant parent were identified which showed additive effect on percent seed set under cold treatment. This study demonstrated the utility of a new phenotyping method as well as the identification of SSR markers associated with QTLs for selection of cold-tolerant genotypes to improve temperate rice production.     

东乡普通野生稻与栽培稻苗期抗旱性的比较

干旱影响水稻生长发育,不论什么时期发生最终都导致产量损失。研究水稻资源抗旱性有助于水稻抗旱改良和稳定干旱胁迫下水稻的产量。东乡普通野生稻被公认为是栽培稻的祖先,对增强水稻抗旱性可能十分重要。对4份来自3个仅存的居群的东乡野生稻与15份栽培稻进行苗期抗旱性比较,考察了3次重复的盆栽土培试验中8个抗旱指标。表明东乡普通野生稻比栽培稻更为抗旱,表现在最大根长、茎长、根干重、根鲜重、根干鲜重比及抗旱指数等6个性状,而不表现在根数及根茎长比;其中茎长、最长根长、根干重、根鲜重及根系相对含水量对水稻苗期抗旱性影响更大。采用抗旱指数和抗旱总级别值法对水稻抗旱性进行评定,结果表明4份东乡野生稻材料间的抗旱性存在很大差异,且来水桃树下居群的抗性最高,东乡野生稻抗旱性可能与其原生境状况有关。结果认为东乡普通野生稻可作为栽培稻抗旱改良的遗传资源。     

Morphological and Seed Set characteristics of Centipedegrass accessions collected in China

Greater than two-fold differences were observed between the lowest and highest means for stolon number and length characteristics. A 60% difference in total length was observed between the longest stolon of accessions. There was a 42% difference between the accessions with the fastest and slowest growing stolons. Accession with the longest and shortest internode differed by 28%. Small differences were observed for leaf length and width. Seed set under selfing was less than 7% indicating high self-incompatibility. Open-pollinated seed set ranged from 37% to 87%. Coefficients of variation for the various characteristics measured indicate that the Chinese accessions should provide more variation for genetic improvement in this species. Data showed that measuring total stolon length at five weeks after transplanting was adequate for evaluating all of the stolon length and number characteristics in this study. The Chinese accession appear to be a valuable source of new germplasm for this species.     

Variability in reproductive traits in Jatropha curcas L. accessions during early developmental stages under warm subtropical conditions

Variability in floral, fruit, and seed characteristics, and oil content of 15 accession of Jatropha curcas during early development were assessed during two flowering periods in south Florida subtropical climate. The two flowering periods had leaf flushing in March. Field evaluation using 18 quantitative traits showed significant variation among accessions. The number of female flowers and female : male flower ratio ranged from 1 to 15 and 1 : 8.8 to 1 : 67.8, respectively. Fruit set by natural pollination was 89 and 66% during the first (1st) and second (2nd) flowering periods, respectively. A higher number of female‐type inflorescences were observed during summer. There were significant differences in seed traits, except for number of seeds per fruit. Accession TREC 31 had the highest individual seed dry weight and 100‐seed weight (0.83 g and 79.7 g, respectively). The oil content varied from 19.30% to 35.62%. Seed dry weight had positive correlation with seed fresh weight, seed length, seed thickness, seed width, and 100‐seed weight, but negative correlation with oil content. Based on the cluster analysis using 15 morphological traits, jatropha accessions were grouped into five main clusters and accessions from different geographic regions grouped together in a cluster. Principal component analyses (PCA) revealed morphological variation. The first three components explained 73.5% of the total variation and seed dry weight, 100‐seed weight, total flowers per inflorescence, male flowers per inflorescence and fruit set can be used to distinguish accessions. The PCA also indicated that flowering traits were more influenced by seed origin while seed traits were affected by flowering spans. Although evaluations were performed in plants during the juvenile phase, accessions TREC 31 and TREC 55 had superior averages for almost all characters evaluated. These results provide a preliminary assessment of the high variability in jatropha accessions evaluated and their potential for use in breeding and genetic improvement programs.