Investigations into the causes of segregation of Ogura male sterility in Bangladeshi cultivars of radish

In a series of three experiments during 1998‐99 and 1999‐2000 at Gazipur, Bangladesh, the causes of segregation of Ogura cytoplasmic genetic male sterility in local cultivars of radish were studied. Male‐sterile populations at the BC₅ and BC₆ generations were grown under a range of field temperatures for 2 years and the results on pollen fertility tests revealed that the expression of male sterility was not affected by temperature. Neither was a genotype‐year interaction found. The unexpected segregation observed in the male‐sterile backcross generations might be due to the presence of restorer alleles in the maintainer parents.     

How to maintain improved cultivars

Improved cultivars loose their identity and healthiness unless maintained properly. Contaminating and degrading forces, such as outcrossing, volunteer plants, mixing, natural selection, mutation and seed-borne diseases, are at the root of this. Maintenance selection can prevent this deterioration. How it is carried out depends on the reproduction system of the crop. Crops are therefore classified into four categories; typical cross-pollinating crops, self-pollinating crops with a substantial amount of outcrossing, typical self-pollinating crops with little outcrossing, and the vegetatively reproduced crops. Generally some of the “breeder seed” is used to plant a small plot with spaced plants. A fair number of healthy plants of the cultivar type is selected and the seed is harvested per plant. The progenies of the selected plants are grown in small plots. Non-uniform or deviating plots and plots with a seed-borne disease are removed. The seed of the progenies that are healthy, uniform and similar (and so of the cultivar type) are harvested per progeny to be tested next season on larger plots. The same selection is applied and only the seed of the progenies that are healthy, uniform and similar are harvested together to produce the “breeder seed”. The details of this maintenance selection vary with the reproduction system, the multiplication rate of the crop and the possibilities available to the breeder. Seven crops, potato, common bean, barley, wheat, faba bean, quinoa and maize are discussed here as they represent the different reproduction systems and multiplication rates, while being important Andean food crops.     

Breeding alfalfa cultivars resistant to the alfalfa weevil

A ten-year study consisting of nine field experiments was conducted to evaluate alfalfa (Medicago sativa L.) for resistance to larval feeding by the alfalfa weevil (Hypera postica Gyllenhal). The results were consistent over years and experiments. Only one source of alfalfa germplasm, designated Starnes, showed resistance to larval feeding in the field under natural infestations of the weevil. The cultivars Team, Arc, and Liberty have been developed from this germplasm source. The only effective method of selection for field resistance to the weevil was field selection under natural weevil infestations. Selection was based on low larval feeding on spaced plants. After six generations of such selection the Starnes germplasm showed only one-third as much defoliation as did the check cultivars. The heritability of the weevil resistance was moderately high. Field resistance was transferred to other strains through hybridization; hybrids were intermediate to the resistant and susceptible parents. Resistance was stable.Laboratory and greenhouse efforts to breed alfalfa weevil resistant alfalfa-using such techniques as adult cotyledon-nonpreference tests, adult leaf-feeding tests, larval-growth and survival tests, oviposition-stimulus tests, and oviposition-nonpreference tests-have failed to produce field resistance.Paper No. 5308 of the Journal series of North Carolina Agricultural Experiment Station, Raleigh, N. C., in cooperation wich ARS, USDA. Received 15 June 1977.     

Suitability of Chinese wheat cultivars for production of northern style Chinese steamed bread

Fifty-six bread wheat cultivars and advanced lines from major Chinese wheat growing regions and 10 Australian cultivars were grown in Anyang located in Yellow and Huai Valleys and Chengdu located in Yangtze region. The genotypes were examined for their suitability to produce northern style Chinese steamed bread (CSB) and used to investigate the association between wheat quality traits and performance of northern style CSB under manual and mechanized processing conditions. Anyang-sown wheat samples showed better grain quality characteristics and CSB quality than the Chengdu-sown materials. These differences were largely due to adverse climatic conditions prevailing in Chengdu that resulted in the deterioration of flour whiteness, Farinograph stability, and starch quality. Therefore, Chengdu was generally unfavorable for producing good quality wheat. However, significant variability among cultivars was observed in Chengdu, and Batavia, Dollar bird, and Tasman from Australia and Jing 411, Xiaoyan6, and Shaan 229 from China showed very good CSB quality under manual conditions, and Hartog, Batavia, Tasman, and Vulcan from Australia, and Jing 411 and Dongfeng 1from China were identified to confer good CSB quality under mechanized conditions. The wide range of CSB quality variations indicates that genetic improvement of CSB quality is possible in both environments. Protein content, gluten strength, and extensibility were positively associated with loaf volume and steamed bread elasticity. The relationship between gluten strength, extensibility, and appearance and stickiness were highly dependent on processing methods, i.e., negatively using a manual method and positively or slightly negatively using a mechanized process. Therefore, wheat quality requirement for CSB depends on CSB processing conditions. Medium protein content and medium-to-strong gluten strength with good extensibility is desirable for mechanized methods, but weak-to-medium gluten type for manual methods. High flour whiteness and RVA peak viscosity was found desirable for CSB quality regardless of the processing method used. Flour whiteness, falling number, and peak viscosity appeared to be more crucial in determining CSB quality in Chengdu, although protein content and Farinograph stability also contributed to appearance, elasticity, and stickiness. This revised version was published online in July 2006 with corrections to the Cover Date.     

地黄不同品种物质生产与养分吸收特性的研究

摘要：以8个地黄品种（2个栽培种、3个变异种,3个野生种）为研究对象,通过分析不同生育阶段地黄干物质生产和养分吸收特征,以期为合理施肥,制定地黄高产优质栽培技术提供依据。结果表明：不同地黄品种物质生长和养分吸收表现出较大差异,集中表现在栽培种显著高于野生种。在人工栽培过程中,形成100公斤地黄经济产量的氮磷钾养分需求量平均为2.10 kg (1.6~2.50),0.48 kg (0.29~0.60) 和1.8 kg (1.41~2.16)。氮钾肥吸收高峰期出现在中期,生育后期养分吸收增加较中期有所减少,而磷素吸收高峰则一直延续到收获。依据上述结果,我们认为,必须降低地黄人工栽培过程中基施氮肥的比例,大量的氮肥应施在地黄快速生长期,适当的增加中后期磷钾,特别是钾肥使用有助于增加地黄的生长,提高地黄经济产量。     

Variation in pod production and abortion among chickpea cultivars under terminal drought

The effect of terminal drought on the dry matter production, seed yield and its components including pod production and pod abortion was investigated in chickpea (Cicer arietinum L.). Two desi (with small, angular and dark brown seeds) and two kabuli (with large, rounded and light coloured seeds) chickpea cultivars differing in seed size were grown in a controlled-temperature greenhouse, and water stress was applied by withholding irrigation 1 (early podding water stress, ES), 2 (mid-podding water stress, MS) or 3 (late-podding water stress, LS) weeks after the commencement of pod set. In addition, the pod and seed growth of well-watered plants was followed for the first 19 days after pod set. Growth of the pod wall followed a sigmoid pattern and was faster in the desi than in the kabuli cultivars, while no difference was found in early seed growth among genotypes. Time of pod set affected the yield components in all treatments with the late-initiated pods being smaller, having fewer seeds per pod and smaller seeds, but no significant difference between pods initiated on the same day on the primary and secondary branches was observed. Early stress affected biomass and seed yield more severely than the later stresses, and in all stress treatments secondary branches were more affected than primary ones. Pod production was more affected by early stress than by late stress, regardless of cultivar. Pod abortion was more severe in the kabuli than in the desi cultivars, but final seed size per se did not appear to be a determinant of pod abortion under terminal drought conditions. The data indicated that the production and viability of pods was affected as soon as water deficits began to develop. The results show that pod abortion is one of the key traits impacting on seed yield in chickpeas exposed to terminal drought and that irrespective of differences in phenology, kabuli types have greater pod abortion than desi types when water deficits develop shortly after first pod set.     

加强专用性品种选育 推动大豆生产和加工的发展

1选育和推广加工专用性品种的必要性 我国已有4000多年的大豆栽培历史,直到20世纪60～70年代一直是世界最大的大豆生产和出口国,而后相继被美国、巴西和阿根廷超过,位居第4～5名.在我国大豆食品加工生产已有2千多年的历史,大豆制品以豆腐及其衍生制品为主,在各种传统大豆制品中,酱油、豆腐和豆乳最受欢迎,而且长盛不衰,新型大豆制品的豆乳粉、大豆浓缩蛋白、大豆分离蛋白等产品也得到迅速发展.     

打顶留杈技术在烟草种子生产的应用初报

针对湖北省恩施州独特的气候特点,对烤烟、白肋烟杂交种母本系统的进行了打顶时期、留杈数、留果数及配套施肥技术等方面的研究,结果认为：打顶留杈将烟株烟株生育期延长了205-30d,有效地避免7月底强降水对烟株现蕾、开花和杂交授粉影响,充分利用了8月“伏旱”和9月昼夜温差增大的有利气候,在保证种子质量的前提下,种子产量提高3-4倍;初步形成了系统的生产技术。     

Genetic variation in seed production and its components in four cultivars of the pasture grass Setaria sphacelata

Variation in seed production and its components was investigated between and within four cultivars of the pasture grass Setaria sphacelata, in two experiments over two years, as a basis for future cultivar improvement. The study sought to determine the basis for the considerable differences in seed production of the four cultivars Nandi, Narok, Solander and Kazungula, to determine the extent of genetic variation in the four cultivars in attributes which contribute to seed yield, and to investigate genotypic consistency in seed production over years and seasons. Each experiment comprised 50 genotypes of each cultivar. In the first experiment, plants were harvested a set number of days after median flowering date whereas in the second experiment, which was unreplicated, each genotype was harvested a set number of days after it had flowered. In the first experiment, seed yields were generally highest for Kazungula, lowest for Narok and intermediate for Nandi and Solander. All measured attributes contributing to seed yield exhibited a high order of variation between and within cultivars, but the basis for the large difference in seed yield per plant between cultivars was tiller fertility rather that total tiller number. Averaged over the four harvests, there was a six fold to > 100–fold intra-cultivar genetic range in seed production, associated with differences in tiller fertility, which were associated with differences in date of first flowering. Broad sense heritability for seed yield averaged 0.68 for the four cultivars and showed little change over the four harvests. Genotypes which produced high seed yields in summer were also more productive of seed in autumn and the 0ore productive genotypes in the first year were also more productive in the second year. Cultivars differed in the relative importance of factors which contributed to the high seed yield of high-yielding genotypes. In the second experiment, genotypes with a high seed yield also generally had the highest tiller fertility, even though all genotypes were harvested the same number of days after first flowering. Within-cultivar correlations in seed yield between the two experiments were generally significant and the elite 20% of genotypes from this experiment had 1.2–2.9 times the seed yield of the same genotypes with a very different harvesting regime in the first experiment. It is concluded that opportunities exist in all four cultivars for improvement in seed production and that the selection criterion offering the best opportunity for advance would be fertile tiller number. In Narok, Solander and Nandi, this would result in increased tiller fertility, whereas in Kazungula, it would result in an increase in total tiller number. This revised version was published online in July 2006 with corrections to the Cover Date.     

Relation of cotton cultivars to the cotton-pest problem in the Sudan Gezira

Summary Growing of irrigated cotton in the Sudan, in relation to pest control, entered the crisis phase around 1967–68 and the disaster phase in 1980–81. At the cruxes of the pest-control problem lay the uncontrollable whitefly-induced lint stickiness and the American bollworm (ABW). The paper gives the succession of cotton varieties in the Gezira and reviews the reports on higher incidence of the whitefly and ABW on newer varieties.Logical explanations offered for the higher pest incidence on newer varieties lead to the conclusion that as compared with Sakel-type cottons, the Lambert-type cottons would have a greater build-up of the whitefly, while Acala cottons would have not only larger populations of both whitefly and ABW but also increased losses from the latter. Changes in area under different types of cotton are shown graphically in relation to the pest-control situation and a case is made for the hypothesis that varietal changes in the Gezira had profound ecological effects which favoured the whitefly and ABW, but made sprays less effective, leading eventually to the cotton-pest-control predicament. Finally, based on recent experience, a hope is expressed that switching to cultivars less favourable to the pests and more suited for efficient pesticide application would ease the cotton-protection problem.     

Adaptation of semidwarf wheat cultivars to rainfed conditions

Summary With a view to determining the comparative adaptation of semidwarf wheats to rainfed conditions, adaptation analyses were carried out on grain yield data of the 6th and 7th International Spring Wheat Yield Nurseries of the International Maize and Wheat Improvement Centre. Sites were chosen which had not received irrigation: across a combined total of 44 such sites, yield variation was closely related to growing seasonal rainfall. Using these sites, yields of thirty-three common cultivars. Norin 10-derived semidwarf cultivars plus tall ones, were regressed against site mean yield to give a regression slope (b) and deviations from the regression (s_d ²) for each cultivar.Semidwarf cultivars generally showed higher mean yields and larger regression slopes (b > 0.9) than tall cultivars from lower latitudes. Tall cultivars from higher latitudes showed the lowest mean yields and the lowest b values (< 0.7). No consistent trends in s_d ² were evident. Despite the greater regression slopes of semidwarf wheats, the best yields under all but the lowest yielding (driest) conditions were given by certain semidwarf cultivars; these had high mean yields and b values close to 1.0 (for example Tobari 66, Inia 66, Pato ArGentino and Sonalika). In contrast other semiwdarfs (notably Chenab 70) of similar mean yield, plant height and phenology, were not well adapted to the drier conditions as indicated by b values close to 1.3. The usefulness of the regression technique and the implications of these results for selection of semidwarf wheats adapted to drier conditions are discussed.Joint contribution from the Department of Agronomy, University of Sydney, N.S.W. 2006, Australia and the International Maize and Wheat Improvement Centre (CIMMYT), Londres 40. Mexico 6, D.F.     

Adaptation of wheat rusts to the wheat cultivars in former Czechoslovakia

Summary In former Czechoslovakia virulence of rusts attacking wheat was studied since the sixties. Since the same time genes for resistance in the registered cultivars were identified. The role of Berberis and Thalictrum as alternate hosts for stem rust and leaf rust, respectively, was investigated as well. Determined changes of virulence in rust populations could only partially be ascribed to changes of resistance genes in the grown cultivars. Unnecessary genes for virulence had no negative effect on the fitness of the pathogen. All tested samples of aeciospores from barberries attacked rye, not wheat. None of Thalictrum species occurring in the Czech and Slovak Republics was found to host wheat leaf rust. However, the sexual stage of wheat stem rust and wheat leaf rust could be induced on Berberis vulgaris and Thalictrum speciosissimum, respectively. General epidemiological conclusions are drawn from the results and experience of the last 35 years.     

Response of four winter wheat cultivars to triallate

Summary Genetic variation among four winter wheat cultivars for response to treatment with triallate was examined. The cultivars showed differential tolerance based on stand count, however, differential tolerance was not seen for any of the other traits examined including visual score, and the mature plant traits, tiller count and yield. Significant effects due to increasing the rate of chemical were observed. An increase in yield was seen at the 0.5 and 1.0 kg/ha rates of triallate. This yield increase was paralleled by trends toward increasing seed number/head and tiller number/unit area. The results indicate that the effect of triallate on wheat has two components. The first component, toxicity, is seen on all cultivars, but the extent of damage varies significantly among cultivars. The second component is positive and leads to an increase in yield without interacting significantly with genotype.     

Differential reaction of wheat cultivars to hot environments

Summary Ten to 20 spring wheat (Triticum aestivum L.) cultivars of Israeli origin were grown in three winter (normal) and two summer (abnormal) growing seasons. During the period of emergence to anthesis mean daily temperature was on the average 12°C higher and photoperiod was about 3 h longer in the summer than in the winter. Data was collected on the durations of the periods from emergence to double-ridge (GS1), double ridge to anthesis (GS2) and anthesis to grain maturation (GS3), as well as on yield and yield components.The duration of all developmental stages was reduced by high temperature. While the duration of GS2 was the most thermo-sensitive, it may also have been reduced by the longer summer photoperiod. The effect of photoperiod on GS2 could not be isolated, but the results were interpreted to show that the effect of photoperiod on the duration of GS2 was relatively small.The most heat-affected yield component was number of grains per spikelet and the least affected component was the number of spikes per plant. High temperature reduced grain weight via reduced grain growth duration and not grain growth rate. A general linear regression model of yield on its components revealed that while variation for number of spikes per plant had the greatest effect on yield variation among cultivars in the winter, variation for number of grains per spikelet and spikelets per spike were by far the most important in the summer. Grain weight was the least important component, in this respect, in all seasons. Varieties which sustained the highest yield in hot environments were able to maintain the longest duration of GS2 and the highest number of grain per spike.     

Analysis of the differences in growth between five lettuce cultivars marking the development in lettuce breeding for winter production

Summary Since 1950 growth of lettuce for winter production has been improved considerably by breeding. It has been investigated whether this improvement must be attributed to a more rapid leaf production, to larger leaves or to both. To this end the differences in growth between the cultivars Meikoningin. Proeftuin's Blackpool, Rapide, Deci-Minor and Valentine were analysed at a range of temperatures (10, 14, 17 and 20°C) under natural light conditions in autumn. The last four cultivars represent successive improvements in growth of lettuce for winter production.From the experiments it can be concluded that the improvement in growth of lettuce for winter production was initially brought about through increasing the rate of leaf production and there-after through increasing leaf size. At the same time the heat requirement for optimal growth has become higher.     

Gene banks and their contribution to the breeding of disease resistant cultivars

Summary Genetic variation in crop species and their wild relatives holds the key to the successful breeding of improved crop cultivars with durable resistance to disease. The importance of the conservation, characterization and utilization of plant genetic resources nationally and internationally has been recognised, though much remains to be done. Gene banks have now been established in many countries and at most of the international crop research centres. Cell and tissue culture techniques and biotechnological aids have done much to ensure the creation and safe transfer of healthy germplasm around the world. Multidisciplinary, international research and collaboration are essential to the successful breeding of improved disease resistant cultivars. Examples are given of the effective use of genetic resources in breeding disease resistant cultivars of a number of crops, including cotton, rice, potatoes and pearl millet.     

豌豆品种的耐瘠性研究

豌豆的耐瘠特性受到诸多性状的影响，特别是那些对豌豆耐瘠性有标识作用和对经济产量有重大影响的性状，应力求找出其主次，以便对品种的耐瘠特性做出准确的评价。豌豆耐瘠性是个综合概念，也具有灰色性。本试验旨在运用灰色关联度理论对豌豆多性状进行综合评价，以期准确地鉴定其耐瘠性，为育种和高产栽培提供指导。１材料与方法１．１材料试验于２０００年１０月至２００１年４月在四川省射洪县农场进行。供试材料为从美国、日本、香港、台湾、江苏等地引进的１２个食荚甜脆豌豆品种。１．２方法田间设两区：耐瘠鉴定区，人工设置瘠薄地，…     

Ethylene production as a possible indicator of wound healing in roots of several sweet potato cultivars

Summary Fleshy roots of 18 sweet potato cultivars were wounded and cured for 12 days. Significant differences were found between cultivars for ethylene production, cell lignification, and wound periderm formation. Average ethylene production, the number of days ethylene was produced, or the day of peak ethylene production showed nonsignificant and low (r²=0.40) correlations with cell lignification or wound periderm formation; however, multiple regression analysis indicated statistically significant and moderate correlations between selected daily ethylene production and cell lignification (r²=0.74) and wound periderm formation (r²=0.73). These observations suggest that measurement of ethylene produced by wounded sweet potato roots may be useful in helping screen large numbers of sweet potato breeding lines and their progeny for the ability to produce lignified and wound periderm cell layers. Wound healing, however, is only one aspect of good storage capability in sweet potato cultivars.     

Measuring field resistance of cabbage cultivars to black rot

Summary Disease progress and gradient curves of black rot on cabbage were evaluated in field plots of the cultivars Bartolo, Erdeno, Perfect Ball, and Roxy in The Netherlands during 1991 and 1992. Plots were inoculated by single sources in the centre of each plot. Individual plants were examined for disease incidence and severity. Disease progress was described by the Gompertz model. The overall measure of absolute rate (disease progress rate r multiplied with maximum disease intensity K) was used to compare cultivar effects on disease progress. Disease gradients were described by the negative exponential model. The percentile distance (distance from the source at which disease intensity reached 1% of the empirical maximum disease intensity) was used to compare cultivar effects on disease spread. Disease severity is more sensitive than disease incidence to calculate the disease progress and spread of black rot. Measures of progress and gradient were about equally effective to screen cultivars for field resistance to black rot. Perfect Ball was the most susceptible, Erdeno and Bartolo were intermediate and Roxy was the most resistant for incidence and severity measures. Increased levels of field resistance reduced the development of black rot in time and in space. Field resistance of black rot is thought to be composed of several mechanisms. Microplots provide a good instrument for the assessment of small differences in field resistance, expressed equally well in disease progress as in disease gradient curves.