Defoliation patterns in signal grass tillers with varying heights in the same pasture

The experiment was carried out to evaluate the patterns of defoliation in plants of various heights in the same pasture of Brachiaria decumbens cv. Basilisk under continuous stocking with cattle. Four plant heights were evaluated (10, 20, 30 and 40 cm) in the same managed sward, with mean height equal to 25 cm. A randomized blocks design was used, with two replications. Defoliation frequency increased linearly along with plant height in the same pasture. Defoliation intensity, number of defoliations in leaf blade and percentage of leaf blade grazed per tiller also increased linearly along with plant height. The defoliation interval decreased linearly according to plant height. The quadratic model was adequately fitted into grazing efficiency data, reaching the highest value (98%) at the sward site with 35 cm plants. The percentage variation in signal grass height showed a negative linear response with initial plant height. The structure of the pasture, characterized by the diversity in plant heights, is simultaneously the cause and consequence of the variability in defoliation patterns in individual tillers, which occur on the horizontal plane of the pasture.

CONTRIBUTION OF BASAL AND AERIAL TILLERS IN DYNAMICS OF HERBAGE PRODUCTION OF SIGNALGRASS AFTER GRAZING DEFERRED

During the spring, the understanding of regrowth in basal and aerial tillers of deferred pasture in winter it is necessary. Thus, the objective was to evaluate the morphogenesis and herbage accumulation during spring in Brachiaria decumbens cv. Basilisk (signalgrass) pasture used under deferred grazing in winter. The basal and aerial tillers in same pasture were evaluated. The signalgrass was managed with grazing cattle and with an average height of 25 cm. The randomized block design with three replications was adopted. The leaf appearance rate, phyllochron and the numbers of expanded, expanding and live leaves did not differ between basal and aerial tillers. The aerial tiller possessed lower rates of leaf senescence, of leaf elongation and of stem elongation, as well as lower number of dead leaf and stem and leaf lamina lengths, compared to basal tiller. The leaf lifespan was higher in aerial tillers than at basal. The basal tiller also contributed to higher rates of tissue growth and forage accumulation in pasture when compared to aerial tiller. After deferred grazing during the spring, the aerial tiller has low participation in forage production of signalgrass pasture.

Morphogenetic and structural characteristics of guinea grass tillers at different ages under intermittent stocking

The objective of this research was to assess morphogenetic and structural characteristics of tillers of guinea grass cv. Tanzania at different ages. The pastures of guinea grass were managed in six pasture conditions related to the combination of three frequencies (90, 95, and 99% light interception) and two post-grazing heights (25 and 50 cm). In these six pastures conditions, three tiller ages were evaluated (young, mature, and old). The design was of completely randomized block with three replications. Young tillers exhibited higher leaf appearance rate and leaf elongation rate and, consequently, higher final leaf length and number of live leaves than mature and old tillers, regardless of the pasture condition. On pastures managed with 90 or 95% light interception associated with a post-grazing height of 25 cm, old tillers presented longer leaf lifespan than young and mature ones. There is a progressive reduction in the vigor of growth of pastures of guinea grass cv. Tanzania with advancing tiller age.

Four stories about copyright law and appropriation art

This article considers copyright law and the art of appropriation in an Australian context. It tells four stories about Australian artists - Imants Tillers, Gordon Bennett, Juan Davila and Tracey Moffatt. The stories examine the postmodern critique of copyright law, indigenous copyright and self-determination, the introduction of moral rights, and copyright, photography and film. The article concludes that the work of such contemporary artists has practical implications for the reform of copyright law.

The effect of endophyte on the performance of irrigated perennial ryegrasses in subtropical Australia

The effect of fungal endophyte (Neotyphodium lolii) infection on the performance of perennial ryegrass (Lolium perenne) growing under irrigation in a subtropical environment was investigated. Seed of 4 cultivars, infected with standard (common toxic or wild-type) endophyte or the novel endophyte AR1, or free of endophyte (Nil), was sown in pure swards, which were fertilised with 50 kg N/ha.month. Seasonal and total yield, persistence, and rust susceptibility were assessed over 3 years, along with details of the presence of endophyte and alkaloids in plant shoots. Endophyte occurrence in tillers in both the standard and AR1 treatments was above 95% for Bronsyn and Impact throughout and rose to that level in Samson by the end of the second year. Meridian AR1 only reached 93% while, in the standard treatment, the endophyte had mostly died before sowing. Nil Zendophyte treatments carried an average of ?0.6% infection throughout. Infection of the standard endophyte was associated with increased dry matter (DM) yields in all 3 years compared with no endophyte. AR1 also significantly increased yields in the second and third years. Over the full 3 years, standard and AR1 increased yields by 18% and 11%, respectively. Infection with both endophytes was associated with increased yields in all 4 seasons, the effects increasing in intensity over time. There was 27% better persistence in standard infected plants compared with Nil at the end of the first year, increasing to 198% by the end of the experiment, while for AR1 the improvements were 20 and 134%, respectively. The effect of endophyte on crown rust (Puccinia coronata) infection was inconsistent, with endophyte increasing rust damage on one occasion and reducing it on another. Cultivar differences in rust infection were greater than endophyte effects. Plants infected with the AR1 endophyte had no detectable ergovaline or lolitrem B in leaf, pseudostem, or dead tissue. In standard infected plants, ergovaline and lolitrem B were highest in pseudostem and considerably lower in leaf. Dead tissue had very low or no detectable ergovaline but high lolitrem B concentrations. Peramine concentration was high and at similar levels in leaf and pseudostem, but not detectable in dead material. Concentration was similar in both AR1 and standard infected plants. Endophyte presence appeared to have a similar effect in the subtropics as has been demonstrated in temperate areas, in terms of improving yields and persistence and increasing tolerance of plants to stress factors.

Rice responses to soil management in a rice-based cropping system in the semi-arid tropics of southern Lombok, Eastern Indonesia

This paper is the first of a series that investigates whether new cropping systems with permanent raised beds (PRBs) or Flat land could be successfully used to increase farmers' incomes from rainfed crops in Lombok in Eastern Indonesia. This paper discusses the rice phase of the cropping system. Low grain yields of dry-seeded rice (Oryza sativa) grown on Flat land on Vertisols in the rainfed region of southern Lombok, Eastern Indonesia, are probably mainly due to (a) erratic rainfall (870-1220 mm/yr), with water often limiting at sensitive growth stages, (b) consistently high temperatures (average maximum - 31 C), and (c) low solar radiation. Farmers are therefore poor, and labour is hard and costly, as all operations are manual. Two replicated field experiments were run at Wakan (annual rainfall = 868 mm) and Kawo (1215 mm) for 3 years (2001/2002 to 2003/2004) on Vertisols in southern Lombok. Dry-seeded rice was grown in 4 treatments with or without manual tillage on (a) PRBs, 1.2 m wide, 200 mm high, separated by furrows 300 mm wide, 200 mill deep, with no rice sown in the well-graded furrows, and (b) well-graded Flat land. Excess surface water was harvested from each treatment and used for irrigation after the vegetative stage of the rice. All operations were manual. There were no differences between treatments in grain yield of rice (mean grain yield = 681 g/m(2)) which could be partly explained by total number of tillers/hill and mean panicle length, but not number of productive tillers/hill, plant height or weight of 1000 grains. When the data from both treatments on PRBs and from both treatments on Flat land, each year at each site were analysed, there were also no differences in grain yield of rice (g/m(2)). When rainfall in the wet season up to harvest was over 1000 mm (Year 2; Wakan, Kawo), or plants were water-stressed during crop establishment (Year 1; Wakan) or during grain-fill (Year 3: Kawo), there were significant differences in grain yield (g/1.5 m(2)) between treatments; generally the grain yield (g/1.5 m(2)) on PRBs with or without tillage was less than that on Flat land with or without tillage. However, when the data from both treatments on PRBs and from both treatments on Flat land, each year at each site, were analysed, the greater grain yield of dry-seeded rice on Flat land (mean yield 1 092 g/1.5 m(2)) than that on PRBs (mean 815 g/1.5 m(2)) was mainly because there were 25% more plants on Flat land. Overall when the data in the 2 outer rows and the 2 inner rows on PRBs were each combined, there was a higher number of productive tillers in the combined outer rows (mean 20.7 tillers/hill) compared with that in the combined inner rows on each PRB (mean 18.2 tillers/hill). However, there were no differences in grain yield between combined rows (mean 142 g/m row). Hence with a gap of 500 mm (the distance between the outer rows of plants on adjacent raised beds), plants did not compensate in grain yield for missing plants in furrows. This suggests that rice (a) also sown in furrows, or (b) sown in 7 rows with narrower row-spacing, or (c) sown in 6 rows with slightly wider row-spacing, and narrower gap between outer rows on adjacent beds, may further increase grain yield (g/1.5 m(2)) in this system of PRBs. The growth and the grain yield (y in g/m(2)) of rainfed rice (with rainfall on-site the only source of water for irrigation) depended mainly on the rainfall (x in mm) in the wet season up to harvest (due either to site or year) with y = 1. 1x -308; r(2) = 0.54; p < 0.005. However, 280 mm (i.e. 32%) of the rainfall was not directly used to produce grain (i.e. when y = 0 g/m(2)). Manual tillage did not affect growth and grain yield of rice (g/m(2); g/1.5 m(2)), either on PRB or on Flat land.

A guide to the process of Mitchell grass recovery

In western Queensland, severe drought conditions began in late 2001 and did not generally ease until the 2008/09 summer. Despite the ability of Mitchell grass plants to become dormant during drought, a large proportion of plants appeared to be dead rather than drought-dormant by the end of the 2002/03 summer. Tillers and remaining leaves were blackened and unpalatable to livestock. The term Mitchell grass dieback was coined by producers and other observers to describe what had occurred, although most were confident that the grass would recover with the breaking of the drought. Mitchell grass plants generally failed to respond to widespread average summer rains in early 2004 (> 250 mm). Observation suggested that moisture had penetrated to a soil depth of about 60 cm and a response from plants was expected. When there was no general response, research into the reasons for this was initiated (NBP.348 'Mitchell grass death in Queensland: extent, economic impact and potential for recovery'; 2005-07). This included an investigation of discrete areas of pasture that had responded to the 2003-04 summer rain. Further declines in condition of Mitchell grasslands occurred between winter 2005 and winter 2006 and, by 2006, field surveys indicated that 53% of this pasture community was in poor (C) condition, primarily due to dieback. Measurements at some sites suggested practices such as wet season spelling and burning can pre-condition Mitchell grass pasture for greater resistance to drought-induced dieback. However, the casual mechanisms and the effective timing and frequency of these practices remained unclear.

Optimizing Hill Seeding Density for High-Yielding Hybrid Rice in a Single Rice Cropping System in South China

Mechanical hill direct seeding of hybrid rice could be the way to solve the problems of high seeding rates and uneven plant establishment now faced in direct seeded rice; however, it is not clear what the optimum hill seeding density should be for high-yielding hybrid rice in the single-season rice production system. Experiments were conducted in 2010 and 2011 to determine the effects of hill seeding density (25 cm 615 cm, 25 cm 617 cm, 25 cm 619 cm, 25 cm 621 cm, and 25 cm 623 cm; three to five seeds per hill) on plant growth and grain yield of a hybrid variety, Nei2you6, in two fields with different fertility (soil fertility 1 and 2). In addition, in 2012 and 2013, comparisons among mechanical hill seeding, broadcasting, and transplanting were conducted with three hybrid varieties to evaluate the optimum seeding density. With increases in seeding spacing from 25 cm615 cm to 25 cm623 cm, productive tillers per hill increased by 34.2% and 50.0% in soil fertility 1 and 2. Panicles per m2 declined with increases in seeding spacing in soil fertility 1. In soil fertility 2, no difference in panicles per m2 was found at spacing ranging from 25 cm617 cm to 25 cm623 cm, while decreases in the area of the top three leaves and aboveground dry weight per shoot at flowering were observed. Grain yield was the maximum at 25 cm 617 cm spacing in both soil fertility fields. Our results suggest that a seeding density of 25 cm617 cm was suitable for high-yielding hybrid rice. These results were verified through on-farm demonstration experiments, in which mechanical hill-seeded rice at this density had equal or higher grain yield than transplanted rice

Transfer of saline tolerance from one strain of rice to another by injection of DNA

Direct injection of genomic DNA from salt tolerant cv. Pokkali into developing floral tillers on IR20 produced transgenic seeds similar to Pokkali in husk colour and which germinated well in 0.2 M NaCl and had a 4-6-fold higher proline content.

Timotein (Phleum pratense ssp. pratense L.) alkuperän vaikutus kylmänkestävyyteen, vernalisaatiovaatimukseen sekä kasvuun ja kehitykseen

Nurmiheinien merkitys maailmanlaajuisesti on merkittävä, sillä noin 69 % maapallon peltopinta-alasta on pysyvää laidunmaata tai niittyä. Suomessa nurmien osuus on noin 29 %, ja tuotanto perustuu pääosin intensiiviseen säilörehuntuotantoon. Yleisin nurmiheinälaji Suomessa on timotei (Phleum pratense ssp. pratense L.). Timotei on talvenkestävä ja soveltuu siksi pohjoisiin kasvuoloihin. Timoteilajikkeita jalostettaessa pohjoista alkuperää olevia vanhempaislinjoja käytetään hyvän talvenkestävyyden varmistamiseksi, eteläisiä tavoiteltaessa nopeaa kasvurytmiä. Ilmaston muutoksen ennustetaan lisäävän erilaisia äärioloja kuten myrskyjä ja sateita. Vuorokauden keskilämpötila nousee ja kasvukausi pidentyy. Lisäksi talvet muuttuvat sateisemmiksi. Muutokset näkyvät erityisesti pohjoisissa kasvuympäristöissä. Tutkimuksessa haluttiinkin selvittää eri alkuperää edustavien timoteilajikkeiden ja linjojen kylmänkestävyyttä, kasvu-, ja kehitysnopeutta sekä vernalisaation vaikutusta. Lisäksi tutkittiin syysviljojen vernalisaatiovasteen mittaamiseen käytettyjen menetelmien soveltuvuutta nurmille. Tutkimukseen kuului kaksivuotinen peltokoe sekä kasvatuskaappikoe. Vernalisaatio nopeutti timotein kasvua ja kehitystä. Tutkimuksen perusteella eteläistä alkuperää olevilla lajikkeilla kasvu- ja kukintavalmius oli olemassa ilman vernalisaatiota. Pohjoisilla lajikkeilla oli suurempi vernalisaatiovaste ja niiden kukkiminen ja kasvu nopeutui vernalisaation myötä. Vernalisaatiolla oli vaikutusta myös kasvuston rakenteeseen. Generatiivisten versojen määrä lisääntyi vernalisaation myötä, kun taas vegetatiivisten versojen määrä väheni. Kylmänkestävyys oli tutkimuksen perusteella riippuvainen syksyn karaistumisjakson pituudesta sekä jakson lämpösummasta (FH-COLD). Korkea keskilämpötila ja lyhyt karaistumisjakso heikensivät kylmänkestävyyttä. Vastaavasti karaistumiskauden lämpötilan ollessa välillä 0 °C:ta ja + 5 °C:ta ja jakson pituuden kasvaessa kylmänkestävyys lisääntyi. Tutkimuksen perusteella vernalisaatiolla oli selvä vaikutus timotein kasvuun ja kehitykseen. Pohjoista alkuperää olevat timoteit reagoivat vernalisaatioon eteläisiä enemmän. Osa pohjoisista linjoista vaati vernalisaation generatiivisten versojen muodostumiseen. Syysviljojen vernalisaatiovasteen mittausmenetelmät soveltuvat osin myös puhtaiden timoteilajikkeiden vernalisaation seurantaan.

Functions for rice RFL in vegetative axillary meristem specification and outgrowth

Roles for the transcription factor RFL in rice axillary meristem development were studied. Its regulatory effects on LAX1, CUC1, and OsPIN3 reveal its functions in axillary meristem specification and outgrowth.Axillary meristems (AMs) are secondary shoot meristems whose outgrowth determines plant architecture. In rice, AMs form tillers, and tillering mutants reveal an interplay between transcription factors and the phytohormones auxin and strigolactone as some factors that underpin this developmental process. Previous studies showed that knockdown of the transcription factor gene RFL reduced tillering and caused a very large decrease in panicle branching. Here, the relationship between RFL, AM initiation, and outgrowth was examined. We show that RFL promotes AM specification through its effects on LAX1 and CUC genes, as their expression was modulated on RFL knockdown, on induction of RFL:GR fusion protein, and by a repressive RFL-EAR fusion protein. Further, we report reduced expression of auxin transporter genes OsPIN1 and OsPIN3 in the culm of RFL knockdown transgenic plants. Additionally, subtle change in the spatial pattern of IR4 DR5:GFP auxin reporter was observed, which hints at compromised auxin transport on RFL knockdown. The relationship between RFL, strigolactone signalling, and bud outgrowth was studied by transcript analyses and by the tillering phenotype of transgenic plants knocked down for both RFL and D3. These data suggest indirect RFL-strigolactone links that may affect tillering. Further, we show expression modulation of the auxin transporter gene OsPIN3 upon RFL:GR protein induction and by the repressive RFL-EAR protein. These modified forms of RFL had only indirect effects on OsPIN1. Together, we have found that RFL regulates the LAX1 and CUC genes during AM specification, and positively influences the outgrowth of AMs though its effects on auxin transport.

不同环境紫茎泽兰幼苗动态和特征

紫茎泽兰（Eupatorium adenophorum Spreng.）入侵我国已有70余年的时间，目前已经对我国西南地区造成了严重危害，却缺少有效的防治方法加以控制。本研究着眼于紫茎泽兰治理效果，在两片大面积综合防治样地的基础上，针对综合防治后样地紫茎泽兰再生长情况展开调查研究，并在野外观测的基础上设计两项置于样地附近的盆栽实验，研究紫茎泽兰在不同环境条件下的存活情况，以及与不同物种混播的种间竞争情况。 对综合治理1年后的样地中4个紫茎泽兰种群调查、分析结果表明，在不同的生境，采取不同的方法治理紫茎泽兰会导致紫茎泽兰采取不同的生长和繁殖对策进行再生长。紫茎泽兰生长速度为：水分充足的环境大于水分不充足的环境，萌生植株大于实生植株。种植替代物种绞股蓝（Gynostmma pentaphyllum）能够抑制紫茎泽兰的高生长，但在绞股蓝的压迫下紫茎泽兰长成L型，反而增加了冠幅、分蘖数目和单位株高的分枝数。在繁殖方式方面：采用拔除方法治理的区域紫茎泽兰以克隆繁殖为主，而采用喷洒化学除草剂治理的区域则以有性繁殖为主。 固定样方调查显示，紫茎泽兰再生长的1年当中，群落随季节变化而变。群落的盖度、密度和物种丰富度均随着旱季的深入而达到最低，第二年雨季到来后上升，紫茎泽兰在群落中处于绝对优势，尤其是在旱季优势更为明显。一年生紫茎泽兰在旱季部分植株死亡（死亡率为53.38±1.55%），少部分（5.66±0.45%）开花，产生种子的密度约为50 000ind∙m-2。与本地优势灌木物种车桑子（Dodonaea viscosa）、台湾相思（Acacia confuse）和马桑（Coriaria nepalensis）相比，紫茎泽兰具有更快的生长速度，更大的高度、密度和盖度。 紫茎泽兰种子的萌发需要充足的水分和遮荫条件。在盆栽实验当中，浇水或遮荫条件下足量紫茎泽兰的种子能够萌发更多的幼苗，而且幼苗的死亡率也比无浇水或无遮荫的处理低。在遮荫或去除其它物种竞争的条件下，紫茎泽兰幼苗生长速度更快。只要水分充足紫茎泽兰幼苗不会因拥挤而死亡，但是个体平均生物量会因拥挤而减小。 紫茎泽兰幼苗与本地3种草本植物比较结果，在未遮荫条件下，紫茎泽兰幼苗数量极少，且个体也非常小，而相同条件下荩草（Arthraxon hispidus）和含羞草决明（Cassia mimosoides）生长良好;在遮荫条件下荩草、含羞草决明和戟叶酸模（Rumex haxtatus ）与紫茎泽兰相比则几乎没有优势。 成株紫茎泽兰生命力强，难以控制，幼苗时期是采用替代控制方法治理紫茎泽兰的最佳时期。在替代控制物种选择方面，可以在根除后播种本地灌木和草本植物，因为草本植物在早期可以抑制紫茎泽兰幼苗的萌发和生长，而同时播种的灌木种类则可以在植被恢复的后期起到控制紫茎泽兰再生长的重要作用。

同源四倍体水稻雌配子体发育特性及变异胚囊研究

通过秋水仙素诱导获得同源四倍体水稻10个株系，包括6个恢复系、3个保持系和1个不育系，这些株系具有加倍的染色体组。田间观察表明10个株系具有特殊的农艺性状：茎杆变粗壮、植株颜色加深、叶片变厚、叶宽适度增加、分蘖数减少、有效分蘖的比率下降等。根尖有丝分裂鉴定表明，同源四倍体水稻10个株系具有正常的有丝分裂，观察细胞的染色体数目皆为2n=48。花粉母细胞减数分裂鉴定表明10个株系具有比较理想的减数分裂行为，后期I染色体滞后、末期I微核生成和末期II异常小孢子比率较低，能较好的完成减数分裂过程，其中后期I染色体滞后比率约为10%-20%，末期I微核生成比率约为1%-6%，末期II异常小孢子比率约为1%-8%。这提示，染色体联合和分离不规则导致三价体、单价体 和落后染色体等产生，并进一步导致在后期和末期不均横分离产生异常小孢子，这可能是同源四倍体株系结实率不高的原因之一。 同源四倍体水稻正常胚囊为蓼型，变异胚囊具有多种类型，其比率显著高于二倍体对照，变化范围为39.62%－69.85%。按变异胚囊的结构特点和形成方式，分为四种类型：退化型，结构变异型，无融合生殖型和反足细胞增殖型。退化型胚囊的平均比率为29.17%，包括小胚囊（15.04%）和完全退化胚囊（14.13%），前者仍有较小胚囊腔而后者胚囊腔缺失。结构变异胚囊包括结构缺失、结构重复和位置异常，反映了蓼型胚囊八核七细胞结构的变异，其在各株系的平均比率为18.96%。无融合生殖胚囊发生比率极低，平均比率为1.77%，类型包括反足胚和卵细胞胚。反足细胞增殖胚囊是反足细胞团频繁增殖形成，伴随上述三种变异发生使异常胚囊的多样性进一步增加，其在各株系的平均比率为10.62%。相关分析表明，同源四倍体水稻结实可能主要来自三部分：正常胚囊、正常型小胚囊和反足细胞增殖型胚囊。这三种胚囊具有相对完整的蓼型结构，可能具有较好的育性，其对结实率的贡献程度估计值分别为72.44%、15.12%、12.44%。此外，完全退化型胚囊和位置异常型胚囊对结实率分别表现出显著（-0.66）和极显著（-0.92）的负相关，这表明二者可能是结实性的抑制因素。 Ten autotetraploid strains, which include six restoring lines, three maintaining lines and a sterile line, are derived from artificial induction by colchicine treatments. Variations of agronomical traits are observed which include large organs, sturdy plants, long panicle length and deep leaf color and so on. It has been confirmed that autotetraploid strains exhibit normal chromosome behaviors in mitosis and the chromosome numbers are all 48. Moreover, abnormal chromosome behaviors are investigated in meiosis including univalent, trivalent, quatrivalent, chromosome lagging and microkernel and so on. It evaluates that the percentage of chromosome lagging in anaphase I is about 10%-20%, the percentage of microkernel in telophase I is about 1%-6% and the percentage of abnormal microspore in telophase II is about 1%-8%. In all, abnormal behaviors of chromosomes could induce univalent, trivalent and et al. and subsequently induce infertile microspore. That may be one of the causes of low seed sets in autotetraploid strains. Embryo sacs of autotetraploid strains are formed according to the Polygonum type. However, these strains exhibit variations of abnormal embryo sacs at high frequencies (39.62% - 69.85%). The variations are frequently involved in the spikelets of the main panicles and the first tillers, leading to obvious decreases of the percentages of normal embryo sacs among the strains. Four types of abnormal embryo sacs are classified basing on their different structures and origins: degenerated embryo sac (DES), structure variation (SV), apomixis (Apo) and antipodal cell proliferation (ACP). Embryo sacs of DES (29.17%) exhibit small embryo sacs (15.04%) or no embryo sac (14.13%), the former showing embryo sacs with decreased size and the latter showing no sac. Embryo sacs of AS (18.96%) include three subtypes: structure deletion, structure duplication and location variation, which suggests abnormalities of the eight nuclei, seven celled pattern of the Polygonum type. Embryo sacs of Apo (only 1.77%) include two origins of apomictic embryos: antipodal embryo and egg embryo. Embryo sacs of ACP are observed frequently (10.62%) in autotetraploid strains which subsequently increase the variations of abnormal embryo sacs. It evaluates by the Pearson’s correlation analysis that seed set is probably contributed by three origins of embryo sacs: normal embryo sacs, small embryo sacs (normal pattern) and embryo sacs of ACP. These three origins exhibit comparatively good structure of the Polygonum type and could account for seed set at a percentage of 72.44%, 15.12%, 12.44%, respectively. Moreover, the subtype of no embryo sac (NES) negatively related to seed set at the P>0.01 level (-0.92) and the subtype of location variation (LV) negatively related to seed set at the P>0.05 level (-0.66). Which suggest the two subtypes may have strong stress on seed set.

水稻同源四倍体高代自交系农艺性状分析及遗传差异研究

课题组在不断地创制新的同源四倍体材料的同时，连续多年以提高结实率为目的培育、筛选自交系材料，已获得自交繁殖十二年的高代自交系材料。相对于诱导创制初期，材料表现出的结实率低，同种系单株间的差异较大；高代材料已表现出较显著的结实率提升和较一致的农艺性状表型。 本实验选取课题组多年培育的同源四倍体水稻高代自交系材料，通过形态学、农艺性状和细胞遗传学比较，研究水稻同源四倍体与二倍体之间的异同。结果显示，所有同源四倍体材料的染色体组成均为2N=4X=48，花粉母细胞(PMC)减数分裂行为较正常，99%以上的染色体都能在减数分裂中期I（MI）发生联会、配对，形成四价体和二价体，这与理论染色体组构成相符。在减数分裂过程中，结实率较高的材料染色体异常现象较少而结实率较低的材料染色体异常现象较严重。统计分析表明，二价体和四价体的比例对结实率没有显著影响，但是三价体的数目对结实率有一定影响。这一结果表明了结实率和细胞减数分裂行为可能存在相关性，同源四倍体的减数分裂行为为筛选高结实率的同源四倍体种系提供了依据。 然后，对同源四倍体水稻高代自交系材料进行农艺性状和品质性状的统计与分析。主要针对结实率、每穗实粒数、有效分蘖和穗长等主要农艺性状，以及直链淀粉含量这一重要的品质性状进行统计。将统计结果与1996年诱导加倍的初代材料的数据相对比分析，结果显示所有材料经过多代选育培养，其农艺性状已经有了较显著的提高，同时同源四倍体材料的农艺性状稳定性也有了较显著的提升。如结实率的提高幅度较大，所有材料的平均结实率均显著高于加倍初代，而同种材料不同单株间的结实率差异也显著地减少，变异系数（CV）的平均值由1996年的41.15%减少到了2008年的28.81%。其他重要农艺性状也有不同程度的改良，种内变异系数也相应地降低。此外，实验测量了同源四倍体材料和来源二倍体材料的直链淀粉含量。分析结果显示，部分材料的直链淀粉含量与二倍体亲本产生了较显著的差异，这可能是诱导加倍过程中的遗传变异造成的；同源四倍体材料的种内变异系数（CV）平均值由1996年的6%下降到了2008年的3.88%，显示出在品质性状方面，同源四倍体材料的遗传稳定性也有较显著的增加。同源四倍体材料农艺性状经过多年的选育，表现出一定的提升，同时，经过多年自交纯化，所有材料种系内的性状差异逐渐缩小，说明同源四倍体水稻的遗传稳定性随着自交纯化而增强，这为同源四倍体水稻的进一步选育打下了良好的基础。 最后，通过测量连续两年的自交系材料的遗传多态性，分析材料间遗传差异和种群遗传结构，深入研究连续两代材料间的遗传差异，研究同源四倍体水稻与二倍体材料遗传稳定性之间的差异。实验采用18对SSR微卫星标记对连续两代15个材料，共94份样本进行差异分析。通过扩增条带长度多态性分析，计算不同材料以及同种材料不同世代间的遗传距离，构建同源四倍体和二倍体水稻的分子指纹库，并绘制聚类图。结果显示，同源四倍体和二倍体不同材料间的遗传差异比较大，遗传距离处于0.4757至0.2816之间；而相同品种不同世代材料间的遗传差异较小，但也表现出一定的遗传差异。同种同源四倍体材料不同世代间的遗传差异比二倍体材料更大，两代四倍体材料间遗传距离处于0.1359至0.0485之间；而两代二倍体材料间的遗传距离处于均小于0.0388。结果表明，同源四倍体水稻高代材料具有一定的遗传稳定性，但与来源二倍体材料相比，其世代间的遗传变异性仍然较强。这种结果说明，经过多代的自交纯化培育，同源四倍体水稻材料能够建立起相对稳定的遗传结构，同时，其强于二倍体亲本的变异性有能够为新品种的选育，农艺性状、品质性状的改良提供一定的遗传基础。此外，分析结果表明通过分子标记辅助检验，水稻材料间的遗传多态性能够有效地区分不同的品种，这为水稻品种的分子鉴定提供了一定的依据。 本研究从细胞学鉴定，农艺性状统计分析以及分子标记辅助聚类分析多方面地对同源四倍体水稻高代系进行了研究，对探究同源四倍体水稻的遗传规律，进一步揭示其遗传特性、农艺性状的遗传构成，为进一步选育优质的多倍体水稻提供了一定的理论依据。 This group insists on creating new Autotetraploid Rice (Oryza sativa L.) materials, while improving the seed-setting of them for many years, cultivated and selected the inbred line materials, has obtained the high generation inbred lines after twelve years cultivation. Compared to the early induced materials, which shown the low seed setting, and the large difference between the different plants in the same germ-line; the high generation materials have shown significant improvement in seed setting and more uniform phenotype agronomic traits. The autotetraploid rice high generation inbred lines material, which has been cultivated for more than 12 years, was chose in this experiment. The similarities and differences between autotetraploid and diploid rice was studied through morphological, agronomic and cytogenetic ways. The results showed that all the chromosome of autotetraploid materials are composed of 2N=4X=48, the pollen mother cells (PMC) meiosis behavior is normal, more than 99% chromosomes in metaphase I(MI) were federated and paired to form tetravalents or bivalents, which constitutes a consistent theory of genome. In the meiosis process, the material with a higher seed setting showed less chromosome abnormal than the material whose seed setting is lower. However, statistical analysis showed that the bivalent and tetravalent rate had no significant impact on seed setting, but the number of trivalent had a certain impact on seed setting. The result shows that the seed setting may be related to the meiosis behavior, which provides a basis to cultivate new autotetraploid germ line with high seed setting through the meiotic behavior. Furthermore, the agronomic and quality traits of autotetraploid rice high generation inbred material were statistically analyzed. The statistically analysis was focused on major agronomic traits such as: seed setting, grains per panicle, effective tillers and panicle length, as well as the important quality trait amylose content. The statistic data was compared with the data in 1996, when the first induced generation of autotetraploid material, and the result shows that after a multi-generation breeding, the agronomic traits has been significantly improved in all the materials, while the stability of agronomic traits also significant upgraded. For instant, the seed setting increased significantly, the average seed setting of all materials was significantly higher than the first induced generation, and the differences between different plants in the same species also significantly reduced, the average of the coefficient of variation (CV) was reduced from 41.15% in 1996 to 28.81% in 2008. Other important agronomic traits had improved in different degrees; the coefficient of variation within species is also reduced accordingly. In addition, the amylose content of autotetraploid and diploid materials was measured in this experiment. The results shows that the amylose content of some of the material differed from diploid parents significantly, it may caused by the genetic change during the inducing, autotetraploid materials intra-specific coefficient of variation (CV) average reduced from 6% in 1996 to 3.88% in 2008, shows that this is a significant increase of quality traits stability in autotetraploid rice. Agronomic traits of autotetraploid material shows some improvement after years of breeding, at the same time, after years of purification, all material within the germ-line gradually narrow the differences in traits indicates that autotetraploid rice genetic stability was enhanced, which laid a good foundation for the further autotetraploid rice breeding. Finally, this experiment studied the genetic differences between materials of two generations and researched the difference of genetic stability between diploid and autotetraploid rice materials through investigating the genetic polymorphism, genetic differences between materials and population genetic structure of inbred line materials of two consecutive years.18 pairs of SSR microsatellite markers for 15 materials of two generations were used in this experiment, and the total of 94 samples were analyzed. Through the amplification length polymorphism analysis of different materials and materials in different generations, the genetic distance between materials and generations was analyzed, a diploid and autotetraploid rice molecular fingerprint database and map rendering cluster were constructed. The result shows that the genetic distance is between 0.4757 to 0.2816 among different autotetraploid and diploid materials; the genetic distance between different generations of same species was less, but also shows a certain degree of genetic differences. The inter-generational genetic differences of autotetraploid materials were greater than of the diploid materials, which are 0.1359 to 0.0485 as the genetic distance; comparing with the 0.0388 of diploid materials. The result shows that high generation inbred autotetraploid rice material has a certain genetic stability, but the genetic variation between generations is still strong comparing with the source diploid materials. It indicates that, after many generations of purification cultivation, autotetraploid rice materials established a relatively stable genetic structure, at the same time, stronger variability than its diploid parents are useful in the breeding of new varieties, provides a genetic foundation to the agronomic and quality traits improvement. In addition, the analysis result shows that the through the molecular marker-assisted testing, rice genetic polymorphism between materials can effectively distinguish different species, provides a certain basis for molecular identification of varieties of rice. A series of investigation such as cytological identification, statistical analysis of agronomic traits, molecular marker-assisted cluster analysis was applied in this experiment to research genetic pattern of autotetraploid rice high generation inbred lines, revealed the genetic characteristics and the genetic composition of agronomic traits, provides a theoretical basis for the further selection of high quality autotetraploid rice.

水肥空间组合对冬小麦生物学性状及生物量的影响

目的】研究水肥空间组合对冬小麦形态指标及生物量的影响,对指导旱地施肥具有一定理论和实践意义。【方法】以肥熟土垫旱耕人为土为供试土壤,在全生育期遮雨和人工控制土壤水分条件下,采用分层隔水土柱试验法研究与田间土层分布相同土柱不同土层水分、氮、磷组合对冬小麦叶面积、株高、分蘖数、生物量、根冠比和收获指数等指标的影响。【结果】与整体湿润水分处理相比,上干下湿水分处理(0～30cm土层干旱胁迫,30～90cm土层湿润)下,抽穗期小麦旗叶面积、株高分别降低7.03%和3.77%;小麦地上部和根系生物量及收获指数也不同程度降低,但根冠比增加。从肥料处理看,单施磷和氮磷配施处理,小麦叶面积、株高、有效分蘖数和总生物量均极显著高于单施氮和CK,这与供试土壤各土层严重缺磷,而氮素供应相对丰富有关。从不同土层施肥看,在两种水分处理下,单施氮时,以均匀施入0～90cm土层小麦叶面积、株高、有效分蘖数、地上部生物量和根系生物量最高,施入0～30cm土层最低;单施磷和氮磷配施时,0～90cm与0～30cm土层施肥间总叶面积、旗叶面积、株高、有效分蘖数以及总生物量差异不显著,但均显著高于30～60cm和60～90cm土层相应施肥处理。【...