春季低温对小麦花粉育性及粒数形成的影响

小麦拔节后遭遇春季低温,每穗粒数下降,产量降低。为探明春季低温引起每穗粒数减少的生理原因,以春性小麦扬麦16和半冬性小麦徐麦30为供试品种,研究小麦倒二叶出生期(昼夜5℃/–3℃)、孕穗期(昼夜8℃/–1℃)和开花期(昼夜12℃/4℃)分别进行低温处理对小麦花粉育性及每穗粒数形成的影响。结果表明:倒二叶出生期和孕穗期低温均导致2个小麦品种在二胞花粉期和三胞花粉期花药中的多糖物质淀粉和蛋白质的代谢异常,绒毡层解体延迟;孕穗期低温还造成花粉母细胞减数分裂中染色体配对异常、出现微核等情况,影响正常雄配子体形成;花粉败育率表现为倒二叶出生期低温处理>孕穗期低温处理>开花期低温处理,徐麦30败育率高于扬麦16;3个时期低温均显著降低了2个小麦品种结实小穗数、每小穗结实粒数和每穗粒数,以倒二叶出生期低温处理穗粒数降低的幅度最大。相关分析表明,春季低温引起花粉母细胞减数分裂异常、绒毡层延迟解体、花药营养物质供给不足导致的花粉育性下降,是春季低温导致小麦每穗粒数减少的主要原因。     

春季低温对小麦生产的影响

孕穗期低温冷害主要表现为麦穗抽出后整穗或一段穗失绿发黄或变白,小穗生长发育停止。     

小麦穗粒数形成的基因型差异及增粒途径分析

以27个穗粒性状不同的小麦品种为材料,对小麦穗粒数形成过程中的各构成因素进行了相关、通径和聚类分析。结果表明：不同穗粒性状基因型在分化小穗数、结实小穗数、分化小花数和可孕小花数上均有明显差异。特大穗型小麦的小花分化速率最快,分化持续时间最短。穗粒数对小麦产量提高的贡献最大,穗粒数与千粒重之间不存在负相     

诱变剂对棉花花粉育性的影响

本研究旨在研究诱变剂对棉花花粉育性的影响以及在对陆地棉(Gossypium hirsutum L．)两个品系的离体研究中适宜剂量的筛选。用100、200、300、400和500Gy剂量的γ-射线照射棉花的品种MCV5和MCU11的健康种子。在化学药剂处理这种情况下，将种子浸泡在10、20、     

小麦花粉育性检测和花粉致死基因携带种质的鉴定

小麦雄性不育主要是通过花粉的败育来表现,研究花粉致死基因对小麦杂种优势的利用研究具有重要意义和价值。本研究通过对组配的155个F1杂交组合成熟花药用1%KI-I2染色,显微镜观察,鉴定花粉败育情况,并对表现出花粉半不育特性的F1组合亲本进行花粉致死基因的鉴定。结果表明,在155个冬小麦F1杂交组合中有4个F1组合(西农9718/鑫农516,西农9817/周麦22,西农9817/西农509,西农261/西纯4号)的花粉表现为半不育花粉状态,一半花粉粒碘染呈深蓝色圆形,花粉粒较大;另外一半的花粉粒较小,不规则,未上色。用中国春(具有显性花粉致死基因Ki)和宁春4、宁春16小麦品种(具有隐性花粉致死基因ki)与4个F1组合亲本分别杂交获得相应F1,对其花粉染色显微镜鉴定,从中筛选出携带相应等位显性Ki基因的品种2份,携带相应等位隐性ki基因的品种4份。     

春季低温对小麦产量和光合特性的影响

黄淮麦区频发春季低温冻害, 造成小麦减产。为探讨小麦品种对春季低温胁迫响应的生理特点, 确定品种抗寒性鉴定的生理指标, 以泰山6426、泰山4033和济麦22为试验材料, 研究了起身期、拔节期和孕穗期低温处理下不同品种的产量性状、光合生理指标及叶片细胞结构差异。3个品种受低温胁迫后, 观测农艺性状的变化趋势相似, 且年度间有一定的一致性。不同低温处理对株高的影响相对较小, 尤其是起身期低温处理; 不同生育期低温处理, 小麦单株穗数均显著低于对照, 但下降幅度在年度间不完全一致; 单株穗粒数和单株产量随低温处理的推迟呈现显著降低趋势, 尤以孕穗期低温处理的降低幅度最大, 单株穗粒数比对照低90.5%~93.3% (2012—2013)和91.9%~96.6% (2013—2014), 单株产量比对照低87.9%~97.3% (2012—2013)和91.5%~97.8% (2013—2014); 拔节期是低温伤害的第二敏感期, 而起身期低温对小麦产量的影响相对最小。减产的主要原因是穗粒数降低。无论是拔节期还是孕穗期低温处理, 3个品种的叶绿素含量均呈现下降趋势, 下降的幅度因品种而异; 低温胁迫下光合速率、蒸腾速率和叶片气孔导度均显著下降, 胞间CO₂浓度均有较大幅度的升高, 3个品种中泰山6426受影响最小。低温胁迫对叶绿素荧光参数也有明显影响, 除泰山6426外, 其余2个品种的F_v/F_m均显著下降。各品种受低温伤害后表皮叶肉细胞破坏严重, 排列趋于松散, 保卫细胞和副卫细胞变形, 气孔变大。本研究结果显示, 光合速率、蒸腾速率、叶片气孔导度、胞间CO₂浓度及F_v/F_m可作为评价品种春季抗寒性的生理指标。     

不同年份对小麦穗数穗粒数的影响及其对策

通过多年的小区高产栽培试验和高产攻关，对小麦的穗数、穗粒数进行了研究。结果表明，在相似栽培条件下，有的年份间穗教相差较多，有的年份间穗粒教相差较多。年后幼苗阶段积温，是决定穗数多少的主要因子；小麦返青后5d平均滑动气温首次≥4℃至拔节前的天数，是决定穗粒数多少的主要因素。但只要采取相应的技术措施，不论什么年份，均可获得足够的穗数和较多穗粒数。     

三系杂交棉花粉育性对高温和低温胁迫的反应

为研究在高温和低温胁迫条件下的三系杂交棉花粉育性稳定性问题,利用棉花细胞质雄性不育系和恢复系,配制2个三系杂交棉组合,抗A×浙大强恢(记作：强恢F₁)和抗A×DES-HMF277(记作：弱恢F₁),并以保持系(抗B)为对照,分别进行温室控温试验和田间自然温度试验,分析三系杂交棉对高温和低温胁迫的反应和花粉育性转换(可育至不育)的临界温度。试验表明,一般三系杂交棉的花粉育性对胁迫温度的反应比保持系敏感,常常花粉散粉少和花粉活力较低。不同三系杂交棉组合对胁迫温度的抗性存在明显差异,强恢F₁明显高于弱恢F₁,与保持系的育性相似,可育花粉率和自交结铃率较高,不孕籽率较低。经可育花粉率(Y)与温度(T)的回归分析,花粉育性转换的临界温度符合Y = a (T–T_opt)²+b模型。强恢F₁育性转换的上限和下限温度分别为38.0℃和13.0℃,弱恢F₁为36.0℃和14.0℃,保持系为38.5℃和10.0℃。与低温胁迫比较,高温胁迫在我国大部分棉区更普遍,持续时间更长,对产量影响更大。提高三系杂交棉在胁迫气温条件下的花粉育性的稳定性是近期育种的重要目标。     

黑暗对冬小麦花粉育性和结实率的影响

在冬小麦雄蕊造孢细胞开始增大到花粉母细胞形成期间,给整株小麦以72小时的黑暗处理,可导致花粉的全部败育,给麦穗套袋后的空粒率达到100%。然而,在人工授粉后的结实率可以达到90%以上。在被黑暗处理的花粉的双核阶段,不具有淀粉粒,并失去了过氧化物酶的活性。与小麦雄性不育系的表现相同。因此,可以在杂交育种中应用这种小麦     

染色体加倍对茄属杂种育性的恢复作用和对花粉育性的影响

埃塞俄比亚茄子[Solanum aethiopicum L．Gilo Group(S．gilo Raddi)]是与茄子S．melongena L．间有很高亲缘性的物种。在非洲广泛栽培。已知该物种具有几种可以用来改良茄子的有用性状，比如串果习性和镰刀菌萎蔫病抗性。Singh等人已获得了这两个物种间的杂种。但它们是不育的。     

Selection and genetic improvement of pollen fertility restorer lines with Triticum timopheevii cytoplasm in common wheat

The paper summarizes the selection and improvement of pollen fertility restoration in cytoplasmic male-sterile lines during the past 30 years at Jiangsu Province, China. A fertility restorer line (R16) with a good history of strong and stable restoring ability to different sterile lines was bred by accumulating fertility-restoring genes from derivatives of T797 and other restorer lines such as Primepi. A series of well-performing restorer lines with similar fertility-restoring ability has been bred by improving agronomic characters, disease-resistance and kernel size of R16. The restoring ability of these restorer lines using different male-sterile lines demonstrates that fertility restoration is no longer an obstacle for commercial utilization of hybrid wheat with the Triticum timopheeviii cytoplasmic male-sterile system. Line 2114 is a restorer with a single restoring gene transferred from Aegilops umbellulata. Its restoring ability, using both difficult and easily restored lines was 82% and 93.3% respectively. Maiyou No. 5, one hybrid variety, showed 13.2% yield advantage over the control variety in the Jiangsu Province registration test in 1997-1998 and was superior to nine other varieties adapted to the Jiangsu Province.     

Mapping quantitative trait loci associated with grain filling duration and grain number under terminal heat stress in bread wheat (Triticum aestivum L.)

Terminal heat stress has the potential negative impact on wheat production across the world, especially in South Asia. Under the threat of terminal heat stress, wheat genotypes with stay green trait would suffer from high temperature stress during their long grain filling duration (GFD). The genotypes with short GFD would be advantageous. To identify quantitative trait loci (QTL) for heat tolerance, a RIL population of K 7903 (heat tolerant) and RAJ 4014 (heat sensitive) wheat genotypes was investigated under timely and late‐sown conditions. Heat susceptibility index of GFD, yield components and traits under late‐sown condition were used as phenotypic data for QTL identification. Stable QTLs associated with these traits were identified on chromosomes 1B, 2B, 3B, 5A and 6B. The LOD value ranged from 2.9 to 5.0 and the corresponding phenotyping variation explained ranged from 12.0–22%. QTL for heat susceptibility index for the grain filling duration were colocalized with QTL for productive tillers under late sown and GFD under late‐sown condition on chromosomes 1B and 5A, respectively. These genomic regions could be exploited for molecular wheat breeding programmes targeting heat tolerance.     

乙烯对小麦小花发育和结实的影响

该试验测定了高、矮秆品种及不同密度处理麦穗开花前乙烯释放量的变化,并利用穗培养方法研究了乙烯利处理对穗粒数的影响。结果表明,增加抽穗前幼穗乙烯释放水平导致穗粒数降低,但开花期穗大量释放乙烯对小花结实并无明显抑制作用。     

Cytology and pollen grain fertility in populations of Astragalus adsurgens Pall. indigenous to Yunwu Mountain in the Loess Plateau,north-west China

Summary The wild type populations of Astragalus adsurgens Pall. growing on the northern slopes of Yunwu Mountain were investigated as a part of the program on the reclamation of the Loess Plateau, north-west China.In 1990, plants were sampled from two populations indigenous to Yunwu Mountain and Liupan Mountain, and two populations cultivated in experimental plots. Pollen grain fertility of the plants showed a wide variation from 20 to 99%. In 1991, cytological analysis of chromosome behaviour during meiosis was carried out in order to clarify the causal factors of pollen grain sterility. In anaphase-1, a chromatid bridge and an acentric fragment as well as two chromatid bridges were observed in high frequencies. In addition, more than two chromatid bridges per nucleus existed in considerably high frequencies.These observations clearly indicate that inversions are dominant in populations of wild A. adsurgens indigenous to Yunwu Mountain. xxThis study was supported by a Grant-in-Aid for scientific research from the Ministry of Education, Science and Culture, Japan (No. 01102023).     

Estimating pollen fertility in Solanum species and haploids

Summary Three staining methods (acetocarmine, fuchsin and oxidation of benzidine) and germination in vitro and in vivo were applied to estimate pollen fertility in Solanum species and dihaploids. Pollen was divided into six classes based on shape and contents of the grains. With acetocarmine, fuchsin, peroxidase and germination in vitro 4, 3, 2 and 1 classes, respectively, are supposed to be included in the percentage of good pollen as measured by these methods. This percentage therefore, in more than 96% of the cases studied, shows a decrease in the order indicated. Neither aging of pollen at room conditions nor collecting pollen from flowers on 1–9 days after anthesis does influence the percentage of good pollen with acetocarmine and fuchsin, whereas this percentage drops sharply to zero with peroxidase and germination in vitro. The latter two methods apparently measure as good pollen only the grains with living cytoplasm. When pollen is collected at three successive dates from the same flowers the percentage of good pollen drops sharply with all methods used. There is a relation between quantity of pollen per flower and pollen quality (% good), low-quantity pollen containing significantly lower percentages of good pollen than medium- and high-quantity pollen. The latter two are not significantly different in this respect.From calculations of correlation coefficients it is concluded that only germination of pollen in vitro is significantly correlated with berry and seed set and thus gives a reliable estimate of male fertility. This does not hold true for the two staining methods without due reserve. The peroxidase method is not useful for the Solanum material studied.After standardized pollination the average number of haploid pollen grains on diploid stigmata was found to be 1625±127, that of diploid pollen on tetraploid stigmata 2863±98.A. W. B. Janssen 1975.     

The effect of pollen load and pollen grain competition on fertilization success and progeny performance inFagopyrum esculentum

Summary Flowers of cultivated buckwheat (Fagopyrum esculentum Moench) often receive natural pollen loads of fewer than 10 pollen grains. The cultivated varieties also have high genetic variability. These observations raise the question of whether seed production in buckwheat is often limited by pollen delivery, and whether small increases in pollen load could result in gametophytic selection through pollen grain competition. In greenhouse-grown buckwheat plants, embryo sac penetration by pollen tubes was universal with 10 or more pollen grains. However, seed production increased with pollen load up to 30 grains per flower. Larger pollen loads, which intensify selection among gametophytes, resulted in more vigorous progeny. Seedlings produced from high pollen load (15–20 pollen grains) were larger (40% by weight) than those from low pollen load (5 pollen grains). These results are evidence that pollen grain competition can occur in buckwheat with benefits for progeny performance.     

Comparison of different pollen viability assays to evaluate pollen fertility of potato dihaploids

Summary The main obstacle in breeding potato (Solanum tuberosum L.) dihaploids is the severe limitation of male fertility. To determine pollen viability assays that correlate well to fertility in crosses, results of five different pollen viability assays were compared by correlation analysis with fruit and seed set characters in test crosses, and to pollen tube growth in situ (PL-test). The methods used were: staining the pollen cells with carmino acetic acid (CAA-test); in vitro pollen germination (PG-test); and detection of pollen staining rates after incubation with fluoresceine diacetate (FDA-test), 2-3-5-triphenyle tetrazolium chloride (TTC-test), and 5-bromo-4-chloro-3-indolyle--galactoside (X-Gal-test).The results of test crosses and pollen tube growth in situ correlated with the results of all other assays with the following ranking, from highest to lowest: enzyme activity assays (X-Gal-test, FDA-test, TTC-test), in vitro pollen germination (PG-test), and pollen staining by CAA. The newly developed X-Gal-test for monitoring -galactosidase activity showed the least variation of all assays investigated. Thus, this highly reproducible simple procedure is recommended for male fertility screening.Abbreviations B/F Berries obtained per 100 flowers - CAA Carmino acetic acid - FDA Fluoresceine diacetate - PG Pollen germination rate in vitro - PL Pollen tube growth in situ - S/B Seeds per berry - S/F Seeds per pollinated flower - TTC 2-3-5-triphenyle tetrazolium chloride - X-Gal 5-bromo-4-chloro-3-indolyle--galactoside     

Flag leaf area in five spring wheat crosses and the relationship to grain yield

Summary Five spring wheat crosses were evaluated over a 6-year period using comparisons between F₂ and F₃ data and between near-isogenic F₄ populations selected for flag leaf area. Nonsignificant r values for F₂ vs. F₃ flag leaf measurements may be due to the effect of environment on flag leaf area, but are probably also an indication of low heritability for this plant character. Near-isogenic populations selected on the basis of flag leaf area showed little difference in grain yield, an indication that other plant parts must be more influential in determining grain yield. Flag leaf area, by itself, appears not to be a good index to plant performance.Joint contribution of ARS/USDA and the Montana Agricultural Experiment Station. Published with approval of the Director of the Montana Agricultural Experiment Station as Paper No. 725. Journal Series. Use of data from Research Centers at Moccasin. Havre. Huntley, and Kalispell is gratefully acknowledged.     

Factors affecting haploid production in wheat using the Hordeum bulbosum system. 1. Genotypic and environmental effects on pollen grain germination,pollen tube growth and the frequency of fertilization

Summary A quantitative examination of pollen grain germination and pollen tube growth within the overy wall was made in selected wheat × tetraploid H. bulbosum hybridizations, to investigate the effect of the wheat and the H. bulbosum genotype on these characters. As expected, variation at the known crossability loci had no effect on pollen grain germination. The frequency of pollen tube penetration of the ovary wall was, however, severely reduced when the dominant alleles were present. Pollen tube penetration was nevertheless observed in 3 of the 110 ovaries examined of the non-crossable cultivar Highbury. The H. bulbosum genotype had a much smaller effect on these characters, but significant differences between the clones were observed in the numbers of pollen tubes initially penetrating the ovary wall. Although two H. bulbosum genotypes showed no significant differences in the number of ovaries with pollen tubes at the base of the ovule, significant differences in the frequency of fertilization were observed. The possible cause of this discrepancy is discussed.The frequency of fertilization in crossable wheat × H. bulbosum hybridizations was improved by the application of gibberellic acid within 10 minutes of pollination, and reduced by an increase in the ambient temperature from 20°C to 26°C. Fertilization following the pollination of non-crossable wheat genotypes was not affected by either of these factors.