芸薹属种子休眠特性的研究——Ⅲ.不同发芽促进剂及热震荡对油菜种子的破眠效果

本文研究了不同发芽促进剂及热震荡对芸薹属的不同种质的破眠效果,结果表明:(1)野生或自生种质的种子与栽培种质相比,均有较深的休眠性,其中尤以云南野生白菜(Brassiacampestris L.)及新疆毛芥(B.xinjiangensis Y.Z.Lan)的休眠性为强。(2)GA_2结合其他发芽促进剂与单独GA_2处理,对种子的萌发都有明显的促进作用,破眠程度(DBE)值在0.78—0.86之间,两者之间不存在显著差异,但是不同种质的DBE变化较大,以较深休眠的自生芥菜(B.juncea L.)效果最差。(3)热震荡对于解除芸薹属自生芥菜种子休眠的效果更差,劣于200ppm GA_3。     

越冬粳稻品种"东野一号"的选育

“东野一号“是由江西省农业科学院水稻研究所选育成的越冬粳稻新品种,该品种的强耐冷性来自东乡野生稻.1992年利用具有强耐冷性的东乡野生稻与栽培梗稻0298品种(02428/029)杂交,回交一次,收获大量BC1F2代种子,把种子播种在装有泥巴器皿中,在恒温箱30℃发芽至生长2叶1心,放在常温下练苗1～2d,再放入冰箱或生物培养箱内0℃低温处理72小时(可见器皿中的水结冰),移出放置常温下5d,其成活苗移栽到大田,成熟时分单株收获,编号挂牌,将收获株系在海南加代,其相应禾蔸在南昌自然越冬(南昌N28.41‘,每年冬天出现0℃以下的下雪结冰天气),次年再入选能越冬的稻株.通过这种“双重低温加压“筛选方法的连续选择,于1998年选育成耐冷性强的“4913-1“稳定越冬株系,1999年进行株系比较试验,表现产量水平好,株叶形态好,后期落色好;2000年在本所进行品比试验,该品系比对照增产显著;2001-2003年在省内外进行多点试验示范,2003年12月通过了江西省农作物品种审定(赣审稻2003027).     

野生二粒小麦种子休眠特性分析

为给野生二粒小麦资源利用提供依据,对分别来自以色列北部湿润山区的Mt.Hermon、北部加利利(Galilee)附近地区的Gamla、Ammiad和Tabigha、中部山地区的Mt.Gerizim以及南部内盖夫沙漠北缘的J'aba地区的6个自然群体野生二粒小麦种子的休眠与萌发特征进行了研究.结果表明,以色列野生二粒小麦成熟的种子均具有明显的休眠习性;高温(40℃)储藏可加快野生二粒小麦种子的后熟过程,从而可以迅速地打破种子的休眠;不同群体野生二粒小麦休眠的程度不相同,由深至浅其休眠顺序为:Mt.Gerizim＜Mt.Hermon＜J'aba＜Ammiad＜Tabigha＜Gamla.进一步的方差分析结果显示,同一小穗上,上、下部两粒种子的休眠和萌发特性也存在着极显著的差异.     

同源四倍体水稻与非洲栽培稻杂交的后效性研究

利用亚洲栽培稻中的4份同源四倍体水稻(O.sativa,2n=4x=48)和相应的4份二倍体水稻(O.sativa,2n=2x=24)为母本,以4份非洲栽培稻(O.glaberrima,2n=2x=24)为花粉供体进行远缘杂交后,对其杂种后代的分离动态进行了研究.结果表明,不同倍性的普通栽培稻与非洲栽培稻之间杂交后代的结实率以二倍体普通栽培稻的较高.在配制的32个杂交组合中,其杂种第1代群体均表现出明显的营养生长优势.从群体的生长势来看,杂种第2代群体比杂种第1代群体要弱一些;在杂种第2代群体中,以同源四倍体水稻为母本的杂交组合的分离现象比以二倍体水稻为母本的杂交组合的分离现象更明显.在各杂交组合的第3代群体中,从植株的株叶形态和生育期来看,株系间的差异和株系内的变异依然很明显,变异频率更宽,变异种类更多.在普通栽培稻与非洲栽培稻的杂交组合中,育性变异、生长势变异、株叶形态变异、染色体变异和结实性变异等是较易发现的变异现象.     

东乡野生稻自然群体内的形态性状变异调查

对东乡野生稻自然群体内植株的形态性状及生态进行调查,发现东乡野生稻完全是靠休眠芽(地下茎节或未枯死的地上茎节处)来进行无性繁殖,没有种子苗的出现,在生活史性状上也表现为多年生普通野生稻的特征,这表明东乡野生稻确为多年生类型的普通野生稻。然而其性状的主成分分析却揭示出它处于多年生—一年生分化的初始阶段,这种分化可能与其生境中的水分变化有关。生境中的水分状况还与植株的生长习性和芒的颜色有密切关系,匍匐、倾斜类型及具红色长芒的野生稻倾向于生长在常年有一定积水的地方。另外,林场和水桃树下两个群落之间在一些性状上存在相当的差异。     

不同花生品种种子休眠特性的研究

休眠性是作物重要的农艺性状之一。本研究对31个刚收获的花生品种(系)进行发芽试验,以评价不同品种的休眠特性。结果表明,发芽率和萌发率都可以作为评价种子休眠性的指标。不同品种种子发芽率的变异范围为0～71.11%,20个品种(系)的发芽率低于10.0%,其中,徐9641等6个品种(系)的发芽率为0,表现为较强的休眠性;启海花生的发芽率为71.11%,休眠性较弱。相关分析表明,种子休眠性强弱与荚果、籽仁形状和小叶长度有关,长粒型种子和小叶较长的品种休眠性较强,而与其他农艺性状相关不显著。     

东乡野生稻育性恢复性的鉴定与遗传分析

以东乡野生稻水桃树、东塘上2个居群与不同细胞质来源的5个水稻不育系(B06S、珍汕97A、协青早A、中97A和粤泰A）配组,根据F1结实率的高低对东乡野生稻育性恢复性进行鉴定。建立了10个组合的P1、F1、P2、F2群体,利用混合模型理论的Akaike信息准则(AIC),在F2代中鉴定影响数量性状的主基因存在与否,主基因存在时通过分离分析估计主基因和微效基因的遗传效应以及所占总变异的分量。F1代的结实率变化范围为45.98%~76.57%,表明东乡野生稻具有一定的育性恢复性。F2代中该性状符合1对主基因+多基因的遗传模式,主基因遗传率为56.63%~88.29%,多基因遗传率为2.74%~30.97%,总基因型遗传率为63.17%~94.01%。中9A /东塘上居群杂交组合的F2代中,主基因是加性遗传,无显性效应,其他9个组合主基因是完全显性遗传。     

东乡野生稻苗期抗寒性QTL的初步定位

以9311/东乡野生稻F2群体为材料,用108对SSR标记构建连锁图谱,以苗期分蘖叶片相对电导率为抗寒性鉴定指标,采用完备区间作图法检测抗寒性QTL.结果在第3号和11号染色体上定位到2个与抗寒性相关的QTL qSCR3和qSCR11,其表型贡献率分别为16.3％和19.2％.     

水稻低温发芽力的QTL定位

以珍汕97B与多年生稻种质AAV002863的DH群体(198个株系)构建了包含140个SSR标记的连锁图谱,检测了影响水稻低温发芽力性状的数量性状座位（QTL）。15℃下处理6 d,两亲本珍汕97B与多年生稻AAV002863的发芽率分别为79.7%和30.1%,DH群体间的发芽率变化在0%~100%。QTL定位分析检测到2个与低温发芽力相关的基因座,分别位于第3和第10染色体上,贡献率分别为12.6%和12.9%,增效等位基因分别来自多年生稻AAV002863和珍汕97B。上位性分析结果显示,第1与第10染色体上存在影响低温发芽力的互作位点,其互作可以提高低温发芽力,参与互作的第10染色体上的位点也具有加性主效应。     

东乡野生稻自然群体内的形态性状变异调查 

对东乡野生稻自然群体内植株的形态性状及生态进行调查，发现东乡野生稻完全是靠休眠芽（地下茎节或未枯死的地上茎节处）来进行无性繁殖，没有种子苗的出现，在生活史性状上也表现为多年生普通野生稻的特征，这表明东乡野生稻确为多年生类型的普通野生稻。然而其性状的主成分分析却揭示出它处于多年生—一年生分化的初始阶段，这种分化可能与其生境中的水分变化有关。生境中的水分状况还与植株的生长习性和芒的颜色有密切关系，匍匐、倾斜类型及具红色长芒的野生稻倾向于生长在常年有一定积水的地方。另外，林场和水桃树下两个群落之间在一些性状上存在相当的差异。     

Comparative Assessment of the Efficacy of Various Nitrogen Fertilizers

Summary

The efficiency of N fertilizers is usually poor; often less than 50% of the applied N is taken up by the crop. This review focuses on various N fertilizers with respect to the significance of different N loss pathways, namely (i) ammonia volatilization, (ii) dinitrogen and nitrogen oxide emissions, and (iii) nitrate leaching. Further, the significance of biological N immobilization, ammonium fixation and, finally, the impact of nitrate vs. ammonium uptake on crop yield are also discussed. The reviewed literature shows that N fertilizers may differ markedly in their susceptibility to losses. There is, however, considerable scope to improve N efficiency of each N source by proper N management practices.     

Novel food and non-food uses for sorghum and millets

Sorghum and millets have considerable potential in foods and beverages. As they are gluten-free they are suitable for coeliacs. Sorghum is also a potentially important source of nutraceuticals such antioxidant phenolics and cholesterol-lowering waxes. Cakes, cookies, pasta, a parboiled rice-like product and snack foods have been successfully produced from sorghum and, in some cases, millets. Wheat-free sorghum or millet bread remains the main challenge. Additives such as native and pre-gelatinised starches, hydrocolloids, fat, egg and rye pentosans improve bread quality. However, specific volumes are lower than those for wheat bread or gluten-free breads based on pure starches, and in many cases, breads tend to stale faster. Lager and stout beers with sorghum are brewed commercially. Sorghum's high-starch gelatinisation temperature and low beta-amylase activity remain problems with regard to complete substitution of barley malt with sorghum malt . The role of the sorghum endosperm matrix protein and cell wall components in limiting extract is a research focus. Brewing with millets is still at an experimental stage. Sorghum could be important for bioethanol and other bio-industrial products. Bioethanol research has focused on improving the economics of the process through cultivar selection, method development for low-quality grain and pre-processing to recover valuable by-products. Potential by-products such as the kafirin prolamin proteins and the pericarp wax have potential as bioplastic films and coatings for foods, primarily due to their hydrophobicity.     

Evolutionary aspects of the trade-off between seed size and number in crops

Whereas the concept that availability of resources drives seed production is sound in principle, it is incomplete as there are many solutions to the allocation of resources that derive from the trade-off between number and size. This paper examines evolutionary aspects of this trade-off in annual grain crops. The analysis is centred on the working hypotheses that, for a given species and environment, allocation of resources to reproduction involves (H1) high plasticity in seed number, which allows for variable resource availability, and (H2) a relatively narrow range of seed size that results from evolutionary and agronomic selection. Comparisons between crops and fish are used to highlight common evolutionary elements in taxa where parents provide little or no care to their offspring, with the consequence that both number and early survival of offspring, hence fitness of parents, are partially related to embryo size and reserves.

The plasticity of seed number in relation to availability of resources is analysed against the established relationship between offspring number and parent growth rate during critical stages. The notion that seed size is under stabilising selection is analysed against three conditions: (1) mean seed size is conservative for a given species and environment, (2) seed size affects fitness, and (3) seed size is heritable. Databases from published papers were compiled to analyse the relative variability of seed size and number, and the heritability of seed size. Evidence for and against the link between seed size and parental fitness is revised using the Smith–Fretwell model as framework (Am. Nat., 108, 499–506).

The proposal of high plasticity of seed number and narrow variability of seed size resulting from stabilising natural selection is generally consistent with evolutionary and genetic considerations. Agronomic selection may have reinforced natural selection leading to relatively narrow seed size in species such as wheat and soybean, where cultivated types retained high plasticity for seed number. In contrast, selection for one or few inflorescences in crops like sunflower and maize may have morphologically reduced seed number plasticity and increased variability of seed size and its responsiveness to resource availability in relation to their wild ancestors.     

Citrus Flavonoids in Fruit and Traditional Chinese Medicinal Food Ingredients in China

Flavonoids-enriched tissues of citrus such as peel, immature fruit and flower are consumed as culinary seasonings, tea ingredients in China for centuries. This HPLC quantitative study on the five citrus flavonoids, naringin, hesperidin, neohesperidin, sinensetin and nobiletin on a wide range of Chinese citrus fruits and several Traditional Chinese Medicinal food ingredients in East China, revealed a great diversity in flavonoid composition. Huyou peel (C. paradisi cv. Changshanhuyou) was found to be the best naringin (3.25%) and neohesperidin (2.76%) source; C. aurantium, a major ingredient of several citrus-related TCM, is also a suitable source of naringin and neohesperidin, and a good juice source for flavanone glycosides; the peel of Wenzhoumiju (C. unshiu) is one of the richest local species in hesperidin (up to 6.25%); Zaoju (C. subcompressa) has the highest content of nobiletin (0.59%), a polymethoxylated flavone. LC-ES-MS analysis of Zanthoxylum genus for flavonoids revealed for the first time the presence of significant amounts (0.74%) of hesperidin in the root of Liangmianzhen (Z. nitidum (Roxb.) DC), a relative of Sichuan pepper, which is a spice widely used in China.     

Effect of a continuous hot water treatment of potato tubers on seed-borne fungal pathogens

Summary The viability of five pathogens was decreased by treatment with hot water when tested in vitro.Polyscytalum pustulans was most sensitive andRhizoctonia solani least sensitive. Potato tubers were exposed to 55°C for 5 min in a commercial continuous hot water treatment plant using naturally contaminated seed tubers and tubers which had been inoculated by dipping in comminuted cultures. The frequency of eyes colonised byP. pustulans, Helminthosporium solani, andR. solani was reduced to virtually zero and the effect persisted on tubers subsequently stored at 4°C and at 15°C for up to 16 wk. Results withColletotrichum coccodes were inconclusive. Treatment suppressedPenicillium spp. which, however, rapidly recolonised the eyes during storage, leading to higher contamination levels in the treated than in the untreated tubers. With tubers inoculated withPhoma foveata, good control was achieved when the incubation period before treatment was 10 d but not when the period was 42 d.     

Role of Benzoxazinones in Cereals

Summary

Heterocyclic 1,4-benzoxazin-3-ones and related benzox-azolinones are important natural products of the cereal crops maize, wheat and rye. Much research has focused on the role of these compounds as defensive agents against plant diseases and pests. Studies of a wide variety of biological effects on herbivores and nematodes, plant pathogenic fungi and bacteria are reviewed in this article. Phytotoxic activity of the compounds is also considered with respect to allelopathic interaction with higher plants. Recent investigations of molecular aspects of interactions of cyclic hydroxamic acids and related benzoxazo-linones with acceptor organisms have demonstrated different effective detoxification strategies and tolerance mechanisms. This research has greatly advanced our knowledge about the multiple roles that these allelochemicals play in ecological systems.     

Potential of dry fractionation of wheat bran for the development of food ingredients,part I: Influence of ultra-fine grinding

Wheat bran is an undervalued by-product of white flour and has great nutritional potential due to its high content in fibres and bioactive compounds. Micronized bran could be used as a food ingredient to improve the nutritional potential of cereal products, or be used as a starting material for other processes (bioactive compound extraction or bran fractionation). The aim of this work was to find a way to efficiently decrease the particle size of bran. The influence of the grinding temperature (ambient or cryogenic grinding) on the granulometric distribution of particles, their composition, and their microstructure was studied, at lab-scale and pilot-scale. It showed that the intrinsic characteristics of bran (glass transition within intermediate layers at −46 °C) had more influence on its grinding behaviour than the type of grinding device used: the particles size distributions obtained after grinding at lab-scale and pilot-scale were very similar. At both scales, the granulometric curves were narrow for cryogenic grinding, while for ambient grinding they were spread over the whole particle size range. Ultrafine particles were obtained in both ambient and cryogenic conditions. Negative temperatures, by increasing the material’s brittleness, favoured a fast fragmentation of bran: one step of cryogenic grinding allowed a median particle size of nearly 50 μm to be reached, whereas three successive steps of ambient grinding were needed for the same result. On the other hand, ambient temperature favoured the dissociation of the different constituent layers of wheat bran, and produced less composite particles than cryogenic grinding.     

Multiple use of plants: Studies on selenium incorporation in some agricultural species for the production of organic selenium compounds

The technique of spraying plants with inorganic forms of selenium can be employed for phytochemical production of organic selenium compounds. Fractionation of the plant material makes it possible to produce a highly concentrated and well defined selenium supplement with potential use in animal and human nutrition. The fractionation also gives opportunities to combine production of organic selenium compounds with other products, for example plant fibres. Multiple use of plants can contribute to a more efficient utilization of land area (in comparison to monocultures solely adapted to food production). It also gives the opportunity to develop systems suitable for long term fixation of carbon, as long as the plant material is not reoxidised to carbon dioxide. Plant fibres could provide raw material for the production of paper or building materials in combination with the production of organic selenium compounds preferentially accumulated in another fraction of the processed plant.     

Biological factors influencing the transmission of potato leafroll virus by different aphid species

Summary Macrosiphum euphorbiae, collected in the field from potato plants infected with potato leafroll virus (PLRV), transmitted the virus to fewer potato plants in a field trial than did laboratory-rearedMyzus persicae. In the laboratory,M. persicae was the only efficient vector of PLRV fromPhysalis floridana seedlings, potato sprouts or excised leaves toP. floridana. Two clones ofM. euphorbiae and one clone ofAulacorthum solani transmitted PLRV from infected potato plants toNicotiana clevelandii as effeciently asM. persicae but a clone ofAphis gossypii was an inefficient PLRV vector. An isolate of PLRV, whichM. persicae transmitted inefficiently from potato toN. clevelandii, was also transmitted inefficiently byM. euphorbiae andA. solani.