Pathogenicity of branched broomrape (Orobanche ramosa) populations on tobacco cultivars

Parasitic weed species of the genus Orobanche are a serious threat for the production of several crops in Europe, Africa and Asia. In contrast to other broomrape species of agronomic importance, O. ramosa (branched broomrape) has a broad host range and in Europe particularly affects hemp, tobacco, tomato and, in recent times, oilseed rape. Two separate sets of experiments investigated the effect of two populations of O. ramosa on nine tobacco cultivars grown in Europe and belonging to the three major tobacco types: Virgin (flue-cured), Burley (light air-cured) and dark air-cured under standardized glasshouse conditions. The two broomrape populations were discriminated by means of polymorphic DNA fragments obtained by PCR of the intersimple sequence repeat regions (ISSRs). The Orobanche populations exhibited different levels of pathogenicity but all various tobacco cultivars were susceptible. Dark air-cured tobacco cultivars were the least susceptible to both broomrape populations. Virgin and Burley tobacco cultivars were more susceptible to one population of O. ramosa .     

小麦品种产量改良的限制因素分析

通过对关中地区 5 0年来不同时期小麦品种在目前栽培条件下产量性状变化与当前推广品种源库关系的研究 ,初步探明 :①在以往品种改良中 ,收获指数的提高起了重要作用 ;②当前种植的品种中 ,源是产量进一步提高的制约因素 ;③引入新的种质 ,以改善源的功效为基础提高生物学产量 ,且不降低收获指数 ,是超高产育种的根本方法。     

Auswirkungen der Züchtung bei Winterweizen in einem landwirtschaftlichen System mit geringer Betriebsmittelzufuhr von außen

Impact of Wheat Breeding in an Agricultural Low External Input System
Low external input systems, e.g. ecological agriculture, are able to solve problems concerning environmental pollution, diminishing ressources, and overproduction. Since growing conditions of winter wheat are very different in ecological agriculture as compared to conventional systems, the impact of genetic improvement of winter wheat in low external input systems is not well known. Investigations were carried out in two years at two ecologically managed farms using 24 genotypes of winter wheat of different periods of release (about 1900 to 1983). The results can be summarized as follows:
1. The tendency towards higher yields among modern varieties as compared to older cultivars in ecological agriculture was highly significant.
2. The rate of yield improvement was smaller under low external input as compared to conventional conditions results. Yield improvement was greatest in recent decades.
3. In ecological agriculture higher yields among modern varieties resulted from an increased harvest index along with an unchanged biomass production, improved resistance properties, and higher ear weight. Reduced plant height probably has negative effects.
4. Baking quality was improved clearly by wheat breeding.
5. Further genetic improvement of winter wheat yields in low external input systems may result from increased biomass production along with a constant or enhanced harvest index, improved resistance properties, increased plant height, and pronounciation of ear weight.     

Effekte der Sorten- (Weizen)und der Arten- (Weizen, Roggen) Mischung auf die Ertragsleistung krankheitsfreier Bestände

Effects of cultivar (wheat) and species (wheat, rye) mixtures on grain yield of desease-free stands
Cultivar mixtures (winter wheat) and species mixtures (winter wheat/winter rye) grown free from pests and diseases in different environments are compared to pure stands and analyzed with respect to inter-component relationships relevant for yield. All mixtures consisted from two components which were planted 1:1. Mixing effects (i.e. deviations from arithmetic mean of respective components grown in pure stands) on grain yield/ha and yield structure were dependent on components and growing conditions, particularly nitrogen availability. Under conditions suboptimal for one component, ontogenetic differences between components resulted in positive mixing effects on grain yield since the yield proportion of the accompanying partner increased more than proportionally. In several instances, yield proportions shitted without leading to mixing effects. In some experiments and/or mixtures mixing effects could not be observed at all.     

Yield losses in soybeans from frogeye leaf spot caused by Cercospora sojina

Three soybean [Glycine max (L.) Merr.]cultivars (Samsoy 1, TGx 1025-12E and TGx 996-26E) were evaluated for yield losses resulting from frogeye leaf spot caused by Cercospora sojina Hara. Replicated field plots were established at two locations in Nigeria that have a high natural infestation of C. sojina. The cultivars were either not sprayed, sprayed once or sprayed twice during the growing season with the fungicide benomyl. Disease spread early in the season was from border rows of a susceptible soybean cultivar into the plots. Mean disease severity (DS) for unsprayed cultivars ranged from 0.6 to 4.5 on a scale of 0–5. Plots receiving two sprays had lower DS values, ranging from 0.5 to 2.4. Differences between unsprayed and double-sprayed plots for yield and 300-seed weight ranged from 2.5 to 58.8 and 0.6 to 28.6%, respectively. Seed weight was negatively correlated with DS.     

Smut Incidence and Yield Losses of Corn Cultivars under Different Plant Population Densities

Six corn cultivars were grown, under field conditions, at two population densities of 14285 and 22875 plants/ acre. All were subjected to an artificial infection at 6-leaf growth stage to determine their reactions to smut disease and yield losses. Changes in plant chemical composition, including K and N contents of ear-leaf, were performed at silking stage. The results showed that corn cultivars imposed wide variations to smut reaction. Susceptibility to smut disease was less prevalent on D.H 204 and 3-way cross 310 and more abundant on D.H 215, Iskandria 11 and El-Kabera 1. The corn cultivar Giza 2 appeared an intermediate reaction. Smut incidence at high population density was markedly depressed by 6.6 % below the comparable level at low population rate. Differences in yield losses between low and high plant population densities were actually limited for smut resistant cultivars, while the opposite was true for the more susceptible ones. On average, the yield losses at the low population density varied from 2.5 % for D.H 204 to 14.4 % for Iskandria 11. The calculated losses of the respective cultivars declined to 2.3 and 9.2 % at the thicker stand. The overall effect of increasing smut infection on yield losses, as revealed from the regression coefficients of the response curves, was clearly pronounced at the higher plant population, whereas the yield was substantially improved by 9.7 %. Varietal response to smut performance was explained on the basis of vigor growth and K/N ratio of ear-leaf.     

姜荷花的形态特征及在白云禁毒主题公园的花境应用

姜荷花Curcuma alismatifolia要种植在光照充足且排水良好的环境,种植时需消毒土壤及种球,使用缓释复合肥,保持土壤湿润,并及时防治炭疽病及蝗虫等病虫害.参考泰国农业部对姜荷花新品种的测试内容,对广州白云禁毒主题公园中种植的10个姜荷花品种的叶片、花序、株高等进行了观察测量.结果表明,10个品种的株高、冠...     

番茄品种分子指纹的SRAP分析

[目的]利用SRAP技术对3个番茄样品进行品种鉴定。[方法]以3个番茄样品(瓯秀806、瓯秀201和一个待确认品种)的新鲜叶片为试验材料,通过改良的CTAB法提取DNA,对其进行SRAP分析并构建供试样品间的聚类树状图。[结果]利用设计的54对引物扩增出多态性位点103个,分析表明3号番茄品种确认为瓯秀806。[结论]该试验结果表明应用SRAP分析技术可以对番茄品种进行有效的鉴定。     

不同烤烟品种成熟及烘烤过程中类胡萝卜素含量分析

 以K326、云烟85和红花大金元中部烟叶为材料,分析了相同生态条件下不同烤烟品种成熟及烘烤过程中烟叶类胡萝卜素含量的变化。结果表明：在烟叶成熟期和烘烤过程中,不同烤烟品种类胡萝卜素含量及成熟期降解速度均存在很大差异。K326欠熟烟叶中类胡萝卜素含量很高,但是随着叶片衰老变黄,类胡萝卜素含量大幅、快速降低。云烟85和红花大金元欠熟烟叶中类胡萝卜素含量明显低于K326,但红花大金元成熟期类胡萝卜素的降解幅度明显小于K326和云烟85。因此,红花大金元适熟和过熟烟叶中的类胡萝卜素含量均高于K326和云烟85。烘烤过程中3个烤烟品种烟叶的类胡萝卜素含量均呈现下降趋势,但以烘烤温度由25℃升至45℃的变黄期下降幅度最大,并且也呈现K326降解速度最快,红花大金元最慢的变化规律,因此,红花大金元初烤烟叶中的类胡萝卜素含量高于K326和烟85。