疏剪不同穗位小穗对小麦籽粒结实和粒重的影响

１９９７～１９９８年在河南省农作物品种展览中心以中大穗小麦品种温麦６号为材料,设计了去除不同穗位小穗的试验。结果表明,去除不同位小穗对结实粒数和粒重的影响不同, 除顶端小穗的粒数下降较多,穗粒重最低,却除基部小重申对结实粒数和粒重的影响较小,穗粒数和粒重下降较少;却除中部小穗对结实粒数影响较大,穗粒数量小,其穗粒重因剩余籽粒单粒重增加而得以一定程度补偿。     

小麦体细胞无性系矮秆变异体AS34株高构成和育种潜力探讨

创制和利用矮秆资源对于小麦品种改良具有重要意义。到目前为止,在小麦属中虽然已鉴定了多个矮秆资源,但多数矮秆资源在小麦中的利用价值有限。本研究对利用无性系变异途径获得的小麦矮秆材料AS34及其与模式小麦品种中国春杂交F1、F2材料进行了株高构成和主要农艺性状分析。结果发现,AS34共有4个节间,比其野生型豫麦66少了1个节间,各个节间长度按相似比例缩短,穗下节长度短于第2节长度;F1株高、节间长度指数介于2个亲本之间,节数与AS34相同,穗长、小穗数、穗粒数超过2个亲本;F2株高、穗长、穗粒数、小穗数变异范围广泛,约70%植株株高为60~89 cm,穗长6.0~9.9 cm、穗粒数50~79粒、小穗数20~24个。结果表明,AS34的矮秆变异由多基因控制,表现为数量性状,其矮秆性状对杂交后代穗长、小穗数、穗粒数等主要农艺性状有正向遗传效应,F2选择穗大、粒多、株高适中优良单株的机率较大,具有很好的育种利用价值。     

大麦赤霉病抗扩展性鉴定与评价

利用禾谷镰刀菌单花滴注接种研究了245份大麦品种对赤霉病抗扩展性。结果表明,大麦赤霉病抗性除了抗初侵染外还存在抗扩展类型。比较了接种后7d、14d和21d的病小穗数和病小穗率以覆由不同期病小穗率获得的病程曲线面积等7个指标性状,并对其进行遗传参数分析,发现21d病小穗率指标在品种间具帔大的变幅、遗传变异系数和遗传率,21d病小穗数和病程曲线面积与病小穗率呈极显著正相关。不同大麦品种抗扩展性表现不一,供试品种中以Suyin21、乌金一号、莆846193、盐97001、96AC20-30五个品种21d病小穗率最低,为高抗品种,占全部供试品种的2．04％。     

大穗多花种质B46的选育及细胞遗传学鉴定

利用普通小麦(Triticum aestivum L.)7182与华山新麦草(Psathyrostachys huashanica)杂交、回交和自交,经多代选育出能够稳定遗传的大穗多花种质B46.对B46进行形态学观察及其细胞学检测与GISH鉴定.结果表明,B46形态学特征表现大穗多花特性,穗长12 cm左右,小穗达23个,小穗粒数平均6个;其根尖细胞染色体计数为2n=44;根尖原位杂交(GISH)及减数分裂中期Ⅰ染色体的基因组原位杂交(GISH)显示,B46附加1对来自于华山新麦草的同源染色体.由此可以确定B46为小麦-华山新麦草的二体异附加系,其综合农艺性状优于小麦亲本7182,可作为培育高产小麦品种的优良种质材料.     

广西薹草属(莎草科)一新种——贺州薹草

根状茎短。秆丛生,高20～55cm,扁三棱形,纤细,平滑,基部具暗褐色的叶鞘。叶长于或短于秆,宽2．5～4mm,边缘粗糙。苞片短叶状,上部的刚毛状,短于小穗,具鞘。小穗4～5个,顶生小穗雄性,线形,长3～6cm,小穗柄长1～2．5cm;侧生小穗雌性,线状圆柱形,长1～3．5cm,直立,花疏生,小穗柄长0．6～5cm,最上一个雌小穗柄藏于苞鞘内。雄花鳞片狭倒披针形,顶端钝,淡褐色,     

不同生态区小麦品种的穗发芽抗性评价

本研究对来自不同生态区的137个小麦品种进行穗发芽抗性鉴定,计算相对发芽指数,并分析这些品种穗部籽粒性状、品质指标、吸胀萌发后0～72 h α-淀粉酶活性及其基因表达量与穗发芽抗性之间的关系。结果表明: 长江中下游麦区小麦的平均发芽指数最低,抗穗发芽品种最多,其次是长江上游麦区,黄淮麦区抗穗发芽品种相对较少。红粒品种小麦的相对发芽指数低于白粒品种,相对发芽指数与籽粒长度、宽度呈极显著正相关,与小穗数呈显著正相关,与穗型、穗色、穗长、小穗密度、穗粒数、千粒重无显著相关性。相对发芽指数与容重呈极显著负相关,与面团形成时间和出粉率呈显著负相关,与蛋白质含量、湿面筋含量、吸水率、稳定时间、沉降值、拉伸面积、延展性、最大阻力无显著相关性。不同品种的α-淀粉酶活性随吸胀萌发时间的延长呈上升趋势,萌发24～72 h的相对发芽指数与α-淀粉酶活性呈极显著正相关,穗发芽中抗以上品种萌发48 h后α-淀粉酶活性聚类分析结果与穗发芽鉴定结果一致。萌发后各时段α-淀粉酶基因表达量与相对发芽指数呈极显著正相关。     

小麦-冰草衍生后代 3558-2 穗部相关性状的遗传分析和QTL定位

从普通小麦Fukuho与冰草(Agropyron cristatum,2n=4x=28,PPPP)Z559的衍生系中发现3558-2具有小穗数、小穗粒数和穗粒数多的优异性状.为了揭示衍生系3558-2优异性状的遗传特征,本研究对其与小麦品种京4841间的282个F2单株的穗长、小穗数、小穗粒数、穗粒数等穗部相关性状进行了遗传分析和QTL定位.主基因+多基因混合遗传模型分析结果显示小麦穗部相关性状都符合数量性状特征.利用单标记分析将穗部相关性状的QTL主要定位于小麦1 A染色体上,同时发现在小麦的2A、5B和5D染色体上也有QTL分布.通过加密标记重点构建了1 A染色体短臂的遗传连锁图,利用复合区间作图法解析了小麦1AS染色体上的穗部相关性状的QTL效应,发现在1A染色体上存在与穗长、小穗数、小穗粒数和穗粒数相关的重要QTL各1个,解释变异度分别为14.41%、5.15%、14.84%和10.87%.本研究发现在3558-2的1 AS染色体上成簇分布着涉及穗长、小穗教、小穗粒数和穗粒数重要性状的QTL,这一结果对指导进一步研究与利用3558-2具有重要意义.     

河北省小麦品种基于农艺性状的遗传多样性分析

为明确河北省小麦品种遗传多样性的基础和历史演变,本研究以所收集的该省近60年来审(认)定的125个小麦品种为研究材料,以8个农艺性状为基础进行了遗传多样性分析.结果表明:河北省小麦品种农艺性状变异比较丰富,以每穗不孕小穗数的变异系数最高(52.63%),其次为单株粒重和有效分蘖数,每穗小穗数的变异最小;多样性指数从20世纪70年代的1.62增加到目前的1.89,平均值为1.76,但略低于其他省份.在上述分析基础上,用最长距离法可将125份材料聚为3大类,其中80.8%(101个)的品种归入第3大类,主要为20世纪90年代以后的品种.这说明该省小麦品种遗传多样性在逐步提高的同时,其遗传基础仍需进一步拓宽.     

宽幅播种下带间距对冬小麦衰老进程及产量的影响

在大田试验条件下以多穗型品种‘百农矮抗58’和大穗型品种‘兰考矮早八’为供试材料,研究了宽幅播种(播幅8 cm)种植方式下不同带间距7 cm(KF7)、12 cm(KF12)和17 cm(KF17)对冬小麦(Triticum aestivum)衰老进程及产量的影响。结果表明:与常规条播(行距20 cm,播幅1—2 cm)相比,宽幅带播种植方式的花后旗叶叶绿素降解缓慢,丙二醛(MDA)含量降低,抗氧化酶活性增强,成穗数和产量提高。宽幅带播下不同带间距处理间差异因品种类型而异,矮抗58品种叶绿素相对含量(SPAD)、过氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性整体呈现为KF12KF17KF7,兰考矮早八品种表现为KF7KF12KF17,而MDA变化规律则相反。试验条件下,多穗型品种矮抗58以KF12处理、大穗型品种兰考矮早八以KF7处理花后叶绿素含量高,MDA含量低,抗氧化酶活性强,叶片衰老进程缓慢,产量结构协调,最终产量最高。     

小麦-冰草衍生系3228主要产量性状的遗传分析

为了探讨小麦-冰草(Agropyron cristatum)衍生系3228的多粒(66～82粒/穗)特性在育种中的可利用性,本研究以3228与黄淮冬麦区5个主栽品种进行杂交,并将其杂种F_1分别种植于北京、陕西和四川,采用MINQUE(1)统计方法及AD模型对主要产量性状进行了遗传分析。在研究的6个产量性状中,均存在极显著的加性方差比率,普通广义遗传率在产量性状的遗传中所占比例较大,所有性状的遗传均存在加性和环境的互作。特别值得指出的是,3228在穗粒数方面具有极显著的加性和显性效应,在穗长、小穗数方面也具有极显著的加性效应,说明利用该种质对于提高小麦的穗粒数具有重要作用。     

Studies on the Germination of Cereals: I. The Germination of Wheat Grains in the Ear during Development, Ripening, and After-ripening

The ability of individual grains to germinate in the ears ofa red and a white wheat variety has been determined at differentperiods after anthesis, and at different moisture contents,before the stage of full maturity. No grains germinated while active growth was taking place, butafter desiccation during ripening, 88·5 per cent. ofthe white grains and 7 per cent. of the red grains were ableto germinate in the ear; the percentage germination of the redgrains increased to 83 per cent., when further desiccation occurredduring the first 5 weeks of after-ripening, but some grainsin the basal spikelets of the ears of both varieties failedto germinate until they had been subjected to the same desiccationfrom 13 to 23 weeks after anthesis. The ability of the grains to germinate has been correlated withtheir desiccation at different stages during maturation, andthe effect of certain factors, which inhibit the germinationof immature grains, are discussed in relation to varietal differencesin the colour of the grains and their position in the ear.     

Development and Floret Survival in Wheat Ears With Supernumerary Spikelets

In the supernumerary spikelet wheat, AUS159I0, the supernumeraryspikelet primordia appeared just after the ear reached the terminalspikelet stage. Appearance of the primordia of the multiplesessile spikelets preceded that of indeterminate rachilla spikelets.Supernumerary spikelets had a lower number of potentially fertileflorets per spikelet than normal (non-supernumerary) spikeletsin the ear and thus a smaller number of grains per spikelet.Mean weight per grain in the supernumerary spikelet wheat waslower than in the cultivar, Meering, without supernumerary spikelets.Total grain number in the supernumerary spikelet ear was greaterthan in the normal ear despite the lower spikelet fertilityin the former. Within the supernumerary spikelet ear the multiplesessile spikelets had a higher number of grains per spikeletand mean weight per grain than the indeterminate rachilla spikelets.It appears possible to improve the productivity of the supernumeraryspikelet ear by breeding for reduced expression of the indeterminaterachilla spikelets. Wheat, ear development, floret survival, supernumerary spikelets, grain number     

Effects on dry weight and nitrogen content of grains of semi-dwarf and tall varieties of winter wheat caused by decreasing the number of grains per ear

The number of grains in ears of six varieties of winter wheat growing in the field was decreased by removing the top half of the ear 6 days after anthesis (halving). In the semi-dwarf varieties Hustler, Sentry and Hobbit, and in the taller varieties Armada and Flanders, the mean dry weight per grain in the lower six spikelets of halved ears was about 23% greater than the dry weight of grains in the comparable part of intact ears. In Maris Huntsman the increase in grain size amounted to only 13%. Halving increased the number of grains in the semi-dwarf varieties but not in the others. Consequently, the increases caused by halving in the total weight of grain in the lower six spikelets ranged from 41% in Hustler and Hobbit to 7% in Maris Huntsman. Halving increased the amount of nitrogen in the grain of the lower half of the ear similarly in all varieties, and relatively more than it increased dry weight. So nitrogen per cent dry weight of grain was increased, especially in Armada, Flanders and Maris Huntsman which responded least in dry weight. The uptake of nitrogen into the stem plus ear after anthesis was unaffected by halving. Most of the nitrogen that normally moved to the upper grains accumulated in the lower grains of halved ears. More nitrogen moved into the grain of intact ears of tall than of semi-dwarf varieties after anthesis, because there was greater uptake of nitrogen into the shoot from the roots.     

Branching Shoots and Spikes from Lateral Meristems in Bread Wheat

Wheat grain yield consists of three components: spikes per plant, grains per spike (i.e. head or ear), and grain weight; and the grains per spike can be dissected into two subcomponents: spikelets per spike and grains per spikelet. An increase in any of these components will directly contribute to grain yield. Wheat morphology biology tells that a wheat plant has no lateral meristem that forms any branching shoot or spike. In this study, we report two novel shoot and spike traits that were produced from lateral meristems in bread wheat. One is supernumerary shoot that was developed from an axillary bud at the axil of leaves on the elongated internodes of the main stem. The other is supernumerary spike that was generated from a spikelet meristem on a spike. In addition, supernumerary spikelets were generated on the same rachis node of the spike in the plant that had supernumerary shoot and spikes. All of these supernumerary shoots/spikes/spikelets found in the super wheat plants produced normal fertility and seeds, displaying huge yield potential in bread wheat.     

Homeotic Sexual Translocations and the Origin of Maize (Zea Mays, Poaceae): A New look at an old problem

In the Origin of Maize Controversy, the Orthodox Teosinte Hypothesis (OTH; Beadle 1939, 1972; Iltis 1971), five key mutations change 2-ranked (distichous) ears of teosinte (wild Zea) with a single row of grains per rank to 4- to many-ranked (polystichous) maize ears with a double row of grains per rank. BUT teosinte ears are lateral to the 1° branch axes, maize ears, like their male homologues, the teosinte I° branch tassel spikes, terminal, an enigma long unrecognized, hence ignored. In the Catastrophic Sexual Transmutation Theory (CSTT; Iltis 1983b, 1987), now abandoned, the I° branch tassel (male) of teosinte (spikelets soft-glumed, paired, i.e., double-rowed per rank, as in maize ears), when brought under female hormonal control by branch condensation, becomes feminized into a maize proto-ear. BUT lateral ears should then have remained teosintoid (2-ranked, each rank with a single row of grains), yet are in fact double-rowed. Combining OTH and CSTT, the new Sexual Translocation Theory (STLT) is based on: first, the branching pattern of teosinte ear clusters (Cámara-H. & Gambino 1990), sequentially maturing, sympodially branching, typically Andropogonoid systems, called rhipidia (sing, rhipidium), where each higher order (younger) ear originates as a lateral branch of its lower order, earlier maturing predecessor; and second, on 3 or 4 key mutations [cupule reduction, softening of glumes, doubling of female spikelets], which, by projecting outward the grains, invited human domestication by making them accessible. Within each ear cluster, the earliest maturing, hence nutrient-monopolizing and largest ear would be selected, all younger ears, already nutrientinhibited, suppressed. As fewer, larger ears evolved, and branch internode condensation moved male tassels into female hormonal zones, homeotic conversions translocated female morphology to terminal male positions: first replacing each of the II° branch tassels, and ultimately the 1° branch tassel (male), with an ear (female). With this, now female structure in the apically dominant, hence most nutrient-demanding terminal position gradually suppressing all subsidiary ears on the 1° branch beneath it, mutations for polystichy (contingent on nutrient overload) were finally allowed to become expressed, and the multi-rowed maize ear (at first with an atavistic male tail) evolved. Favored by human selection, these increases in apical dominance by stepwise homeotic sexual conversions explain both archeological and morphological realities, but need to be harmonized with recent results of developmental genetics. Current evidence suggests that teosinte was first tended for its green ears and sugary pith by hunter-gatherers as an occasional rainy-season food in small “garden” populations away from its homeland, and not for its abundant grain-containing, hard fruitcases, which easily mass-collected but useless as food, are as yet unknown from the archeological record. A rare grain-liberating teosinte mutation (probably expressed in only one “founder” plant, a mazoid “Eve”), which exposed the encased grain for easy harvest, was soon recognized as useful, collected and planted (or self-planted). Thus maize was started on its way to a unique horticultural domestication that is not comparable to that of the temperate Old World mass-selected agricultural grains.     

Pleiotropic effects of gibberellin-sensitive and giberrellin-insensitive dwarfing genes in bread wheat of the southern step region of the Black Sea

Investigation of the pleiotropic effects of GA-sensitive (Rht8) and GA-insensitive (Rht-B1 and Rht-D1) winter bread wheat dwarfing genes and the gene that determines the response of plants to photoperiod—Ppd-D1—were carried out for 3 years in the southern step region of the Black Sea bank on five different genetic backgrounds. It is shown that, in addition to direct effects on plant height, GA-sensitive and GA-insensitive dwarfing genes have pleiotropic effects on all studied traits except the number of fertile spikelets. Presence of the dwarfing genes in the genotype of tall forms led to the decrease of stem and ear length, and, at the same time, to the increase of ear density. The number of spikelets per spike decreased due to sterile spikelets, whereas the number of fertile spikelets did not change. There was a significant increase in the number of grains per ear as a result of increasing of spikelets in ears. The number and weight of grains did not decrease, even though the plants were characterized by a smaller number of productive tillers. The presence of Rht8x allele on genetic background of variety Stepnyak resulted in a significant decrease of plants productivity. However, in combination with Ppd-D1a allele, plants with Rht8x increased the potential productivity and surpassed the parental form (Rht8x Ppd-D1a). The presence of Rht-Ble allele resulted in reduction of weight of kernels from the main ear and 1000-kernels weight, increase of l/h, and left the number of seeds per spikelet stable in comparison with Rht8x.     

Effect of awns and drought on the supply of photosynthate and its distribution within wheat ears

The presence of awns doubled the net photosynthetic rate of wheat ears and also increased the proportion of ¹⁴CO₂ assimilated by the ear that moved to the grain. The effect of water supply on photosynthesis and movement of assimilates was greater for leaves than ears, so that drought increased the proportion of assimilate contributed by ear photosynthesis to grain filling from 13% to 24% in the awnless ears, and from 34% to 43% in the awned ears. ¹⁴C assimilated by the ears was most important to the economy of the upper spikelets and to the distal florets in each spikelet, whereas flag leaf assimilate went mainly to the spikelets in the lower half of the ear, and to the proximal florets. Awns increased grain yield in the dry but not in the irrigated treatment, despite the large contribution of awned ears to grain filling. Either the supply of assimilate did not limit grain yield when water supply was not limiting, or there were compensating disadvantages to awns. However, they did not seem to have any adverse effect on the development of the upper florets, nor did they reduce grain number per ear.     

Visual assessment of grain yield and its components in single plants and ears of spring barley

Visual assessments of yield/plant and tillers/plant were more effective than unaided assessments of grains/ear and 1000-grain weight on a per plant basis. Assessments of the latter yield components were generally improved by the use of specially developed keys described by Ismail & Valentine (1983). Gains in efficiency were associated with the amount of extra time spent on making these assessments. Assessments of yield/ear were not more effective than assessments of yield/plant. This was attributed to the ease of assessment of tillers/plant which was strongly associated with yield/plant. Assessments of grains/ear and 1000-grain weight in single ears were clearly more effective than corresponding assessments in single plants in which there is high variability between ears. Apart from using keys, further improvements in the assessments of grains/ear and 1000-grain weight are necessary in order to increase the effectiveness of single plant selection in the F₂ generation which is the first opportunity of increasing yield in later generations.     

Effects of crop thinning and reduced grain numbers per ear on grain size in two winter wheat varieties given different amounts of nitrogen

To study the importance for final grain size in wheat (Triticum aestivum, L.) of assimilate supply and the storage capacity of the grain, two field experiments were done. In 1976 nitrogen was applied in the range from none to 180 kg ha^-1, part of the crop was thinned, and the top halves of some ears of the short variety Hobbit and of the tall variety Maris Huntsman were removed soon after anthesis. In 1977 ears of Maris Huntsman were halved 5 days after anthesis or at 30 days after anthesis when grain volume was maximum. Thinning the crop from 360 to 180 ear-bearing shoots m^-2 30 days before anthesis increased the number of grains per ear, except in the absence of nitrogen fertiliser, but did not increase grain size, grain dry weight per ear or total dry weight per culm. Removing the upper half of ears of Hobbit 5 days after anthesis increased dry weight per grain, but when this treatment was applied to Maris Huntsman either 5 days after anthesis in 1976 and 1977, or when grain volume was maximal in 1977, the grains failed to increase in dry weight. Non-grain dry weight of both varieties was increased by halving the ear. In both varieties the maximum volume of grains in halved ears was larger than in intact ears. Grain dry weight increased relatively less than volume after halving the ear of Hobbit, and the decrease in volume up to maturity was greater in halved than intact ears of both varieties. The larger grain volume in halved ears of Maris Huntsman in 1977 was associated with more endosperm cells.