Problems in breeding and cytology of sugar cane

Occasion for writing this article was the appearance of two papers of Price, one concerning the occurrence of apomixis in sugar cane, the other dealing with cytological results of intra-and interspecific crosses of Saccharum. Especially in the latter he criticized Bremer's discovery of endo-duplication during megasporogenesis in Saccharum forms.The present author formulates his stand-point by an ample discussion of endoduplication as cause of chromosome increase in Saccharum crosses. The phenomenon of parthenogenesis is treated in relation to hybridization and speciation. The author concludes that Price gives evidence of insufficient understanding of endo-duplication while also about the occurrence of parthenogenesis he cannot agree with him.     

Problems in breeding and cytology of sugar cane

In connection with the increase of chromosome number found in species hybrids of Saccharum the author studied embryo-sac development within several Saccharum froms from early stages of meiosis in the embryo-sac mother cells to stages where fertilization already had taken place.Normally by meiosis within E M C's a row of four haploid megaspores is formed from which the innermost, the chalazal megaspore, develops into an embryo-sac and the other three degenerate.Haploid embryo-sacs, thus formed, may occur in Saccharum. Frequently however, in Saccharum endo-duplication takes place, that is splitting of the chromosomes within the nucleus of the chalazal megaspore, through which the chromosome number is increased.It is described how within Saccharum by this phenomenon embryo-sacs may be formed with diploid and tetraploid chromosome numbers and with numbers between haploid and diploid.The increase of chromosome number, observed in the young megaspore after meiosis, could be confirmed by counting the chromosomes of dividing nuclei within young embryo-sacs.Chromosome numbers found in dividing zygotes and endosperm nuclei within fertilised embryo-sacs also pointed to the occurrence of egg-cells and polar nuclei that must be haploid, diploid and tetraploid.The significance of this research in relation to plant breeding will be discussed in Part V.     

Problems in breeding and cytology of sugar cane

In this article a survey is given on sugar cane breeding, as it was performed in Java during a period of about fifty years. When in the eighties of the nineteenth century sugar cane was heavily affected by the sereh disease it was Soltwedel, the first director of the Sugar Experiment Station Midden Java, who tried to obtain sereh resistant cane varieties by species hybridization, until his early death intervened. The first species hybrids were obtained in 1893 by Wakker, who crossed noble sugar cane, Saccharum officinarum, with Kassoer, considered by him as a wild species. In later years it appeared from morphological investigations by Jeswiet (1916) and from cytological investigations by Bremer (1921) that Kassoer is to be considered as a spontaneous hybrid between S. officinarum and S. spontaneum, the wild glagah. In 1895 Kobus imported the Indian sugar cane Chunnee in Java. Chunnee, not belonging to S. officinarum, was crossed with noble sugar cane (for the first time) in 1897. From this cross many clones were obtained which appeared to be resistant against the sereh disease but were highly susceptible to mosaic. The continued crossing between noble sugar cane and Kassoer, however, was very successful. Many clones were obtained, which as commercial varieties, showed a high degree of resistance against sereh disease and mosaic and moreover gave a much higher sugar production than the susceptible varieties of noble sugar cane.The following terms are introduced: first, second and third nobilisation of the wild S. spontaneum. Kassoer cane itself is a product of the first nobilisation, the direct cross between noble sugar cane and wild cane. The back cross between Kassoer and noble sugar cane is called the second nobilisation. When cane varieties belonging to the second nobilisation are crossed again with noble sugar cane, the third nobilisation of S. spontaneum is said to take place. The well-known sugar cane variety 2878 P.O.J. belongs to the third nobilisation.In all clones investigated Saccharum officinarum has 2n=80 chromosomes. Within S. spontaneum types occur which in chromosome number vary from 2n=48 to 2n=128. The Java glagah has 2n=112 chromosomes.Clones of the first glagah nobilisation S. officinarum (n=40) x S. spontaneum (n=56) did not have 2n=40+56 chromosomes, but 2n=40+40+56=136 chromosomes.In relation to the taxonomy of Saccharum many other cytological details are given. Within S. officinarum the basic chromosome number x=10. About S. spontaneum opinions are divided. The author supposes that x=6,8 and 10 are basic numbers of S. spontaneum.     

Problems in breeding and cytology of sugar cane

In Part V the phenomenon endo-duplication of chromosomes within embryo-sac mother cells—cause of the increase in chromosome number within species hybrids of Saccharum—was discussed.Special cases of change in chromosome number by hybridization of sugar cane, which formerly were inconceivable, appeared to be based on endo-duplication.In Saccharum species hybrids with an increased chromosome number equalling twice the haploid number of the female parent plus once the haploid number of the male parent, are of such a frequent occurrence that they may be called normal.Also within other genera interspecific and intergeneric hybrids are known of which the somatic chromosome numbers show the same kind of increase. They are, however, less numerous than in Saccharum. Of agricultural plants we know them for instance in Solanum (potato), in intergeneric hybrids between Lolium and Festuca and in hybrids between Triticum monococcum and T. turgidum. In horticultural plants they occur in Cyclamen. About the mode of origin of such hybrids opinions are not uniform. In this article the possibility is considered whether the chromosome increase in such hybrids may be interpreted in the same way as in Saccharum.     

An economic selection index for sugar cane breeding

Summary For decision-making about varietal release, plant breeders use yield-trial data supplemented by intuitive selection indices based on secondary characters. It is suggested that they could be replaced by explicit economic indices. Profitability is taken as the function to be maximised. An example drawn from sugar cane in Barbados, West Indies shows that secondary characters can indeed reasonably be given weights which turn out to be economically substantial. In principle, similar economic indices could be developed for any crop. All such equations are essentially local in application.     

Inter-relationships among cane yield and commercial cane sugar and their component traits in autumn plant crop of sugarcane

Seventeen diverse clones of sugarcane (Saccharum spp.) (7 early, 6 mid season and 4 late) were planted in October 1991 and 1992 in flooded (FE) and non flooded (NFE) environments for evaluation of cane yield, commercial cane sugar (CCS), internode length, internode number, stalk length, stalk thickness (circumference), stalk number, sugar recovery, and stalk weight. Cane yield showed significant positive phenotypic correlation coefficient (PCC) with stalk number in FE (P ≤ 0.05) and NFE (P ≤ 0.01). Stalk length had a significant positive PCC with stalk weight in both environments, and with internode length in FE (P ≤ 0.05). Commercial cane sugar also expressed significant positive PCC with cane yield in both environments (P ≤ 0.01), but with stalk number only in NFE (P ≤ 0.05). Genotypic correlation coefficients were generally in the same direction as PCC but higher in magnitude. In both environments, stalk number and stalk weight had relatively high positive direct effects on cane yield. However, flooding tended to enhance the direct effect of stalk weight and diminish the direct effect of stalk number on cane yield. Only cane yield and sugar recovery had high direct effects on CCS. Selection for improvement of cane yield can be based on stalk number and stalk weight in both environments. High yielding clones can be further screened for more sugar recovery to improve CCS. This revised version was published online in July 2006 with corrections to the Cover Date.     

Efficiency of border rows in replicated sugar cane variety trials

Summary Each row was weighed separately in 34 sugar-cane variety trials harvested from 1973 to 1976. The efficiency of weighing only the middle row(s) compared with the whole plot was estimated by calculating coefficients of variation and theoretical gains from selection.It was not efficient to weigh only the middle row in trials with 3-row plots. Gain from selection for true yield (that is, yield in the absence of competition from other varieties) was reduced by 7% and the coefficient of variation increased by 4%, this representing an increase of about 33% in the variability of the trials.It was efficient to weigh only the middle two rows of 4-row plots, especially for trials on commercial farms. This gave a 2% increase in gain from selection and the coefficient of variation was increased by only 0.9%. It reduces the weighing time and amount of cane weighed, minimizing the delay to commercial harvesting while trials are being weighed.On Experiment Stations where land is a limiting factor, the most efficient method is to continue the present practice of planting 3-row plots and weighing the whole plots.     

16个糖能兼用甘蔗品种（系）种性比较

为了解不同糖能兼用甘蔗品种（系）的种性和生产性表现,为今后进行能源甘蔗品种选育和推广提供参考,以广西主栽甘蔗品种ROC22、ROC16作对照,对来自国内外的16个品种（系）在2种不同类型土壤蔗区进行2年新植1年宿根种性比较试验。结果表明 B1、B8、GT26、GT02/833、B9、B28、GT02/48、GT97/69、GT02/208等品种（系）在生物产量、蔗茎产量、蔗糖产量和总可发酵糖产量等方面明显超过对照种ROC22、ROC16,具有丰产性好、抗逆性强、适应性广的优良种性,可在广西的旱地和水田蔗区既可作糖料蔗,也可做能源蔗种植利用。YT96/86、GT99/156和FN94/0403综合表现一般,可在桂南的水田蔗区因地制宜种植。其余品种（系）表现较差,不宜在广西扩大种植和推广。     

A family business: Women,children and smallholder sugar cane farming in Fiji

Abstract: This paper highlights the contribution of women and children to the sugar industry in Fiji by examining the importance of family labour in the historical development of the smallholder system and describing the present situation for the study participants. It is based on ethnographic fieldwork conducted during 1996–97, on the island of Vanua Levu in the northern region of Fiji. The twenty smallholder households in the study comprised both Fijian and Fiji Indian respondents who relied primarily on selling sugar cane for their cash income. How inequalities within the household in terms of allocation of labour and resources are legitimated is outlined. Resource distribution within the household in regards to two important issues for the sugar industry, land and trade liberalisation, are examined. In light of global trends in trade liberalisation and probable falls in sugar prices, future strategies for survival identified by Fijian and Fiji Indian smallholders are also discussed. The case study demonstrates that the sugar industry is still largely reliant on family labour and, particularly for low socio‐economic smallholders, the unremunerated labour of family members makes an essential contribution to the production of sugar cane.     

Rubus coreanus as donor of resistance to cane diseases and mildew in red raspberry breeding

Summary Strong resistance to the cane diseases Elsinoë veneta, Didymella applanata and Botrytis cinerea, and to Sphaerotheca macularis, occurred in F₁ and BC₁ derivatives of an accession of Rubus coreanus. Resistance to cane spot (E. veneta) was polygenic.In eight out of ten BC₁ progenies, average grades for cane spot infections were significantly higher in white-flowered (an ₁) than pink-flowered (An ₁) plants and in hairy-caned (H) than in glabrous (h) seedlings. It is postulated that in R. coreanus factors controlling resistance are linked with An ₁ and. probably, with h.Average grades for spur blight (D. applanata) were significantly higher in white-flowered plants in nine out of ten BC₁ progenies. Spininess (S) was associated with greater susceptibility in six out of eight BC₁ families, although this difference was not statistically significant.Plants with the phenotype hAn ₁ on average provided the best source of resistance to both cane spot and spur blight.     

Analysis of sugar cane variety trials. I. Components of variance and genotype-environment interactions

Summary Surgarcane variety trial data from Barbados and Jamaica were analysed by the analysis of variance. From these analyses, components of variance were estimated in an attempt to quantify genotype x environment interactions. Sixteen sets of trials from Barbados and eight from Jamaica were analysed. The results show that GE effects in both countries were small. It is suggested, on the basis of these analyses that variety trials could use resources more efficiently by growing them at fewer sites, since the absence of site x variety interaction makes each site equally effective for identifying the best genotypes.     

甜菜杂交制种关键技术

新疆是我国第3大甜菜主产区,据2001年<中国农业年鉴>资料统计,仅2000年其栽培面积就达55700hm2,单产水平47576kg/hm2,榜居首位,随着新疆甜菜产业的不断壮大,甜菜原材料充足,使得新疆制糖业蓬勃发展,带动了地方经济的效益增值.甜菜业也在不断的研究和生产实践过程中,制种技术和栽培技术有了进一步提高,现将工作中甜菜杂交制种的几个关键技术要点提出,仅与同行参考.     

Problems involved in breeding for resistance

At the start of a breeding programme mostly a cross is made between the resistant plant and a plant belonging to a commercial variety of the crop in question. If both belong to the same species the exchange of genes can be easily brought about. If, however, the resistance is present only in other more distantly related species, difficulties mostly arise.In consequence of successful breeding work races of the parasite able to break down the resistance can come to the fore. It is of the utmost importance to combine the genes for resistance from all available sources so as to produce barriers that cannot be broken down or at least only with great difficulty. Therefore not only the easy line of intraspecific crossing should be followed but also the much more difficult one of interspecific and even of intergeneric crossing.As in most cases resistance is dominant, the method of repeated backcrossing can be used with great profit. In each step of the backcross programme large numbers of seedlings should be raised, selecting very carefully the parent material that will be used for the next step, even if this selection takes several years. As a consequence the number of subsequent backcrosses can be restricted and the danger of loss of valuable genes for resistance and for other characters is very much reduced.If resistance is recessive the backcross method cannot be applied to its full extent. The F₁ is susceptible and by inbreeding more or less resistant seedlings can be obtained. If the resistant source is a wild species this program of outbreeding followed by inbreeding has to be repeated and progress will be very slow.A point of major importance is the availability of quick methods for mass-testing. These methods need not be more reliable than is demanded by the kind of material that has to be tested.

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Samenvatting Bij de uitvoering van een kweekprogramma wordt altijd begonnen met het kruisen van de resistence plant met een plant uit het ras dat men wil verbeteren.Als beide planten tot dezelfde soort behoren kan de uitwisseling van genen gemakkelijk worden bewerkstelligd. Indien de resistentie echter alleen in andere meer of minder verwante soorten voorkomt, dan treden gewoonlijk complicaties op.Als gevolg van de verbouw van resistente rassen zijn fysio's van de parasiet, welke de resistentie kunnen doorbreken, in staat zich naar verhouding sterk te vermeerderen. Het is daarom van het grootste belang de resistentie-genen uit alle beschikbare bronnen te combineren, teneinde een barrière op te kunnen werpen die niet of slechts met grote moeite te doorbreken is. Men moet derhalve niet alleen de gemakkelijke weg van de raskruising volgen maar ook de veel moeilijker weg van de soortskruising en zelfs die van de geslachtskruising, teneinde ook die genen in het werk te betrekken die buiten de soort voorkomen.Daar de resistentie in de meeste gevallen dominant is kan de methode van de herhaalde terugkruising met voordeel worden toegepast.Bij iedere volgende stap in het terugkruisingsschema moeten grote aantallen zaailingen worden opgekweekt, terwijl het toekomstige oudermateriaal met grote zorg moet worden uitgezocht. Daardoor kan het aantal terugkruisingen worden beperkt en tevens het gevaar voor verlies van waardevolle genen.Als de resistentie recessief overerft kan de methode van de herhaalde terugkruising niet in volle omvang worden toegepast. De F₁ is vatbaar en door inteelt kunnen meer of minder resistente zaailingen worden verkregen. Als de bron van resistentie een wilde soort is dan moet dit programma van kruisen gevolgd door inteelt worden herhaald en zal er slechts langzaam vooruitgang optreden.Van veel belang is de mogelijkheid snelle methoden voor massale toetsing te ontwikkelen. Deze methoden behoeven niet betrouwbaarder te zijn dan door de aard van het te toetsen materiaal wordt geëist.

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Lecture read at the A-course Resistance in agriculture, 12–14 Jan. 1959, organised by the Royal Society of Agricultural Science and the Netherlands Society of Graduates in Agriculture at Wageningen.     

几种因素对去皮果蔗保水影响的研究

果蔗是一类专供鲜食的甘蔗,口味甘美,风味独特,具有解渴、解酒、解毒、清热、利尿等保健功能是深受群众喜爱的果品之一。本实验以鲜切去皮的果蔗为原料,通过控制温度,保鲜材料,湿度开展三因素三水平延长果蔗贮藏期研究。结果表明将鲜切果蔗去皮后贮藏在温度为2℃,湿度为90%,并用保鲜膜B包装具有最好的保水性和保藏效果。但易冻伤。     

甘肃省玉米育种问题与对策探讨

分析了甘肃玉米育种的现状和存在的问题。种质创新能力不足、育种技术、育种方法、抗逆性育种重视不够,是目前品种产量潜力不大、适应性和抗逆性不强的主要原因。提出了加强协作攻关、调整育种目标、提高适应性,加强种质扩增、改良和创新,改进育种选择方式,推进新技术应用,密切新品种与栽培技术相结合等对策。育种思路以增强玉米品种适应性和高产优质为目标,以本土化的种质为基础,构建杂种优势群为核心,强化逆境人工选择、采用密植育种策略,探索高配合力的玉米生理生态育种技术。     

The effect of accidental selfing on the analysis of a diallel cross with sugar cane

Summary The diallel cross was found to be an unsuitable design for quantitative genetic analyses with sugar cane.Accidental selfing caused substantial inbreeding depression for most characters. Consequently, analysis of a diallel cross without regard to the effect of accidental selfing would be subject to bias, if accidental selfing were common. A selfing model proposed by Dudley (1963) was extended to include differential selfing, and was tested in an experiment in which the percentage of selfing in each cross was estimated visually.Variance components had large standard errors, which prevented firm conclusions from being drawn, but selfing appeared to cause substantial bias in the estimates. Estimates of genetic variance components from a p(p-1) diallel set, using the extended selfing model, were compared with estimates obtained from the standard analyses in which reciprocal or maternal effects should account for the effect of selfing. The estimates were comparable, but the standard analyses were simpler and produced estimates with lower standard errors.When the effects of selfing were minimized, general combining ability (g.c.a.) effects appeared to be much more important than specific combining ability (s.c.a.) effects for most characters.     

我国棉花育种存在的问题及发展对策

重点分析了当前我国棉花育种中存在的主要问题,并针对问题和今后加快我国棉花育种应关注的方向,提出我国棉花育种技术发展对策和建议。     

关于发展黄淮海地区大豆生产和育种问题

大豆的重要性：据FAO统计：大豆粉占世界８种主要作物蛋白粉的６５．４８％，居各作物的首位。大豆油占世界１４种作物生产的食用油的２５．１０％，最近报道，大豆油已占食用油的３０％，居植物油首位。大豆在大宗农产品国际贸易的地位，居前列，近年来，我国大豆总产量达１４     

Molecular progress in sugar beet breeding for resistance to biotic stresses in sub-arid conditions-current status and perspectives

The yield of sugar beet depends mainly on the effective protection to a number of pests and diseases affecting the crop. In the absence of actual methods of management, as in the case of viral diseases, the availability of genetic resistance sometimes allows the survival of the crop in the affected areas. Integration of molecular markers in conventional breeding procedures has provided a reliable means for improving the efficiency of selection methods. The present review summarizes the evolution, thanks to the application of molecular techniques, of traditional breeding for resistance to some biotic stresses in sub-arid environments.     

Assessment of breeding progress in sugar beet by testing old and new varieties under greenhouse and field conditions

Breeding has led to a continuous increase of the performance of sugar beet varieties and thereby contributes to meet the global needs for food and biomass. This study aimed to analyze the extent of the breeding progress in sugar beet and to determine which parameters and traits were modified by breeding. In 2007 and 2008 sugar beet varieties registered between 1964 and 2003 were cultivated in field trials and in greenhouse experiments to exclude effects from changes in agronomic operations and climatic conditions. Differences in white sugar yield related to the reference variety registered in 1964 were regarded as breeding progress. The results showed an increase in the white sugar yield of 0.6–0.9% a⁻¹ from 1964 to 2003 due to breeding. This was achieved by an improved biomass partitioning (higher root to leaf ratio and higher sugar to marc ratio), better technical quality (decreased concentration of K, Na, and amino N combined as standard molasses loss) and enhanced assimilation (higher chlorophyll content, higher assimilation rates). No changes were observed in leaf development and cambium ring formation. A principle component analysis pointed out that breeding targets have shifted with time from “yield” to “biomass quality”. To continue the breeding progress in future it is essential to integrate multiple resistances and tolerances against biotic and abiotic stress.