The latter was estimated in comparison to commercial varieties. Cross pollinated species and species reproducing asexually are highly. Various models have been posited to explain heterosis, including dominance, overdominance, and pseudooverdominance. By heterosis new varieties of field crops like maize, sugar beets, sorghum, grasses and sunflower etc. The second is the overdominance hypothesis, in which heterotic traits occur through interactions of favorable alleles at one or more loci shull, 1908. The fundamental principle underlying this success is the phenomenon of heterosis. However in both autogamous or allogamous plants it is difficult to exclude a role of marginal overdominance which could.
Studies conducted at the international rice research institute irri during 1980 and 1981 have shown up to 73% heterosis, 59% heterobeltiosis and 34% standard heterosis for. Combining abilities of sugar beet genotypes for root. Combining ability heterosis maize plant breeding introduction types of hybrids, which exhibit high heterosis. May 23, 2017 heterosis and its manifestation heterosis or hybrid vigour is the superiority of the f1 hybrids over parents in one or more characters. More branches per panicle and more grains per branch. Genetic basis of the evolution of adaptedness in plants. The contribution of epigenetic factors to inbreeding depression and heterosis remains elusive. Heterosis and combing ability studies for yield and yield.
The bonus from heterosis should be approximately 5% for production and 10% for mortality, fertility, health and survival. Heterosis, inbreeding depression, various theories of heterosis heterosis and inbreeding depression cross pollinated species and species reproducing asexually are highly. Pdf recent research on the mechanism of heterosis is important. Pdf heterosis or hybrid vigor is a phenomenon where hybrid progeny have superior. Hybrid breeding facilitates a maximum exploitation of heterosis. When two homozygous inbreeds a true breeding line obtained by continuous inbreeding of genetically unlike constituents are crossed together, the resulting hybrids obtained from. Jul 30, 2017 heterosis is a term used in genetics and breeding and is also known as hybrid vigor.
Department of agriculture, agricultural research service, department of genetics, north carolina state university, raleigh, north. In these proceedings an effort is made to merge modern plant breeding efficiency with ecological aspects of plant breeding, reflected in adaptation. Heterosis exploiting breeding schemes for rapid yield. Heterosis for yield and agronomic attributes in diverse maize. Improving plants using hybrid vigor module agronomy and. To discuss the utilisation of heterosis in plant breeding it is necessary to consider its genetic basis. Heterosis or hybrid vigor, on the other hand, is the tendency of outbred strains to exceed both inbred parents in fitness. Still it is generally held that a tendancy for the expressions of the features of both the parents in the hybrids is the basis of heterosis. If true, it should not be possible to obtain an inbred that performs equally as well as the best hybrid bernardo 2002 breeding for. Predicting arabidopsis freezing tolerance and heterosis in. Breeding value of 2n pollen diploandroids in tetraploid. If true, it should not be possible to obtain an inbred that performs equally as well as the best hybrid bernardo 2002 breeding for quantitative traits in plants pp 243246.
Breeding crops with a high yield and superior adaptability is vital to maintaining global food security. The third is the epistasis hypothesis, which states that heterosis is the epistatic interaction of beneficial nonallelic genes at two. It describes an advantage of the offspring as compared to the two parental lines with respect to physiological traits such as growth. Heterosis and inbreeding depression are considered sis suggests that heterosis may arise from epistasis between alleles at different loci stuber 1994. Heterosis definition types of heterosis heterosis in. However, leng reports that row number is affected in widely different degrees by heterosis, and that number of kernels per row ear length is the only primary yield component in which large positive effects of heterosis are manifested consistently 20. Jul 09, 2010 heterosis associated gene expression in maize embryos 6 days after fertilization exhibits additive, dominant and overdominant pattern. Heterosis exploiting breeding schemes hebs for outbreeding crops ranks among the biggest impacts made by plant breeders to world food supply. Concepts and breeding of heterosis in crop plants, cssa. Abstract heterosis, or hybrid vigor, is one of the most important tools in plant breeding and has previously been demonstrated for plant freezing tolerance.
The global partnership initiative for plant breeding capacity building gipbfao and biodiversity international use the term prebreeding to describe the various activities of plant breeding research that have to precede the stages involved in cultivar development, testing and release biodiversity international and gipbfao, 2008. Plant and animal breeders exploit heterosis by mating two different purebred lines that have certain desirable traits. Studies on heterosis and combining ability in bittergourd. Edwards heterosis is the foundation of modern maize breeding programs.
In maize crops, however, the use of heterosis developed in such a unique way that hybridization was recommended as a valuable breeding method. Studies conducted at the international rice research institute irri during 1980 and 1981 have shown up to 73% heterosis, 59% heterobeltiosis and 34% standard heterosis for yield in rice. Heterosis, inbreeding depression, various theories of. Heterosis describes the superior phenotypes observed in hybrids relative to their inbred parents. Heterosis is prevalent for multiple traits in diverse maize germplasm sherry a. A plant breeding phenomena that we very successful exploit commercially, the biological basis of which remains poorly understood. Ppt heterosis powerpoint presentation free to view. In maize hybrid breeding programs, plant breeders usually focus on the utilization of heterosis for grain yield and its related phenotypes 22.
Plant breeding can be accomplished through many different techniques ranging from simply selecting plants with desirable. General combining ability gca is mainly due to the additive genetic effects in the evaluation of parents, while specific combining ability sca reflects the non. Aims and objectives of plant breeding plant breeding is an art and science, which tells us ways and means to change the genetic architecture of plants so as to attain a particular objective. Theoretical and experimental arguments are given demonstrating the superiority of intergroup compared with intragroup crosses under two aspects. Heterosis is observed in almost every crop species studied, the application of this phenomenon for its commercial exploitation depends on the expression of the degree of heterosis. Dear colleagues, the phenomenon of heterosis was first described by darwin as having a positive effect on plant traits, as displayed. Paul, minnesota, united states of america abstract background. The heterosis nature has been exploited in various crop plants for the improvement of different plant varieties. Heterosis refers to the phenomenon that progeny of diverse varieties of a species or crosses between species exhibit greater biomass, speed of development, and fertility than both parents.
Sep 07, 2014 ii seminar on molecular basis of heterosis in crop plants manjappa ii ph. Mid parent mph and better parent bph heterosis was estimated for plant height ph, ear height eh, anthesis. The exact genetic mechanism behind heterosis is not definitely known. In my opinion, hybrid corn is the most far reaching development in applied biology in this quarter century mangelsdorf, 1951. Now epigenetic arabidopsis hybrids show that epigenetic diversity and regulation contribute to both. Progress toward understanding heterosis in crop plants.
Submitted to submitted by derpartment of genetics and plant breeding, college of agriculture, jau, junagadh. Plant height, biomass, harvest index, number of primary branches, number of pods per plant, number of seeds per plant, 100seed weight and seed yield were recorded for each plant 10. In the process of plant breeding, the phenomenon of heterosis has been. Heterosis, also called hybrid vigour, the increase in such characteristics as size, growth rate, fertility, and yield of a hybrid organism over those of its parents. An offspring is heterotic if its traits are enhanced as a. Heterosis is defined as the superiority of f1 hybrid over both the parents in terms of yield andor some other characters. Plant height, biomass, harvest index, number of primary branches, number of pods per plant, number of seeds per plant, 100seed weight and seed yield were recorded for each plant 10 observation. Heterosis may be defined as the superiority of an f 1, hybrid over both its parents in terms of yield or some other character heterosis. Heterosis and combining ability analysis in cms hybrid.
Ppt heterosis powerpoint presentation free to download. Duvick introduction hybrid vigor, or heterosis, usually refers to the increase in size or rate of growth of offspring over parents. Heterosis and hybrid rice breeding sant singh virmani. Yield and leaf area showed highly significant heterosis in f 1 hybrids ranging from 102 to 309% and 46. Adaptation in plant breeding springer for research. Maize is a model system for studying heterosis due to the high levels of yield heterosis and commercial use of hybrids.
The book contains a wealth of useful information for practicing hybrid rice breeders, seed producers, researchers, and students of plant breeding. Heterosis, hybrid vigor, or outbreeding enhancement is the improved or increased function of any biological quality in a hybrid offspring. The objectives of our research were to i examine the magnitude of heterosis over the mid. Heterosis has been extensively studied in maize maydica 50 2005. Significant heterosis over economic parent and mid parent was observed for almost all the traits studied. Despite such an extensive use in agriculture, the underlying mechanisms of heterosis are still poorly understood. Selective breeding of plants and animals, including hybridization, began long before there was an understanding of underlying scientific principles. Heterosis is prevalent for multiple traits in diverse.
Heterosis and combining ability of indigenous and exotic crosses of barley sweta singh, l. Book of abstracts the genetics and exploitation of heterosis in crops. Zhikang li, plant breeding, genetics, and historically, heterosis. Heterosis can be defend as the superiority of f hybrid over both the parents in terms of yield and some other character or. Heterosis performance in industrial and yield components. Importance of plant breeding, cytological principles of plant breeding, heterosis, inbreeding and its consequences or applications, selfincompatibility in plants, cytoplasmic male sterility, breeding. This increased productivity or superiority over the parents is known as heterosis or hybrid vigor or. Heterosis is an additional gain above the average genetic level of the two parent breeds. Recent research on the mechanism of heterosis is important for crop. Production of hybrids of seedpropagated horticultural crops is one of the most successful plant breeding techniques because it exploits heterosis, promotes homogeneity, and is a way for commercial breeders to control their products without the necessity for legal patents or plant breeders rights. Heterosis or hybrid vigour is a phenomenon in which hybrid progeny exhibit superior yield and biomass to parental lines and has been used to breed f1 hybrid cultivars in many crops. Full text of plant breeding principles and methods see other formats. India yield and its component traits were studied in 10 parents and their 45 f shailesh marker department of genetics and plant breeding, naini agricultural institute sam higginbottom university of.
Plant breeding, rajmata vijayaraje scindia krishi vishwa vidhyalaya, gwalior, madhya pradesh, india combining ability and heterosis for grain yield and its attributing traits in bread wheat. These effects can be due to mendelian or nonmendelian inheritance. Hybrids represent a cornerstone in the success story of breeding programs. Heterosis and combining ability in soybean heterosis 15 for most of the characters, the desirable heterosis is positive but for some characters negative heterosis is also important in soybean. In this perspective, we consider that it might be useful to the field to abandon these. New technologies on multiple scales are reengineering traditional plant breeding to. Supriya2 1aicrp on sunflower, mars, uas raichur, karnataka, india 2department of genetics and plant breeding.
The module will introduce learners to other concepts such as genetic hypotheses for hybrid vigor, quantitative genetics of heterosis, and new tools to study hybrid vigor. In cross fertilized plants in which the phenomenon of heterosis is very important, such as maize, it appears that a great part can be explained by the mutation load. Shull 1952 coined the term heterosis and defined it as. Heterosis and combing ability studies for yield and yield component traits in sunflower helianthus annuus vikas v.
Combining ability and heterosis for yield and component. Furthermore, the best hybrid outperformed the best line variety by 1. Heterosis in plant breeding request pdf researchgate. Heterosis is the superiority of an f 1 hybrid produced through crossing of two genetically different individuals over the mean of its parents or the better parent. Despite such an extensive use in agriculture, the underlying mechanisms of heterosis. Transcriptomic and proteomic analysis of heterosis various transcriptomic es have been carried out to explore the gene expression changes between hybrid analys and its parents to correlate the changes to heterosis. Heterotic groups and patterns are of fundamental importance in hybrid breeding. High yielding cotton hybrids combining early maturity and resistance to leaf curl virus. Heterosis, or hybrid vigor, is a predominant phenomenon in plant genetics, serving as the basis of crop hybrid breeding, but the causative loci and genes underlying heterosis remain unclear in. The heterosis concept, defined over a century ago, continues to be applied in the production of several hybrids from different vegetable species. Heterosis and inbreeding depression of epigenetic arabidopsis. Combining ability analysis gca enables plant breeders to select parental lines for crossing and provides the opportunity to understand the nature of gene actions involved in the.
Springer3 1usdaars, plant genetics research unit, and division of plant sciences, university of missouri, columbia, missouri, united states of america, 2usdaars, u. The heterosis can be maintained by the crossing of the plants with the inbreed lines. Ppt heterosis powerpoint presentation free to view id. Overdominant epistatic loci are the primary genetic basis. Despite its importance in maize production, we know surprisingly little about the genetic basis of heterosis. Biometrical methods in quantitative genetic analysis.
To discuss the utilisation of heterosis in plant breeding it is necessary to. In this article we will discuss about heterosis or hybrid vigour. The term heterosis was first used by shull in 1914. The content of the module will address organization of germplasm into heterotic groups, prediction of heterosis and hybrid performance. Ir36 and ir42 yield 45 tha in wet season trials and 78 tha in dry season trials.
Plant breeding is the art and science of changing the traits of plants in order to produce desired characteristics. The significantly positive contrast between inbreeding depression and midparent heterosis for grain yield indicated the presence of positive additive x additive epistatic interactions. Concepts and breeding of heterosis in crop plants, the third joint plant breeding. Various models have been posited to explain heterosis. Sandeep kumar bangarwa the term heterosis was first used by shull in 1914. Heterosis breeding and inbreeding depression authorstream. Study of heterosis for grain yield and its components. Breeding of f1 hybrid cultivars based on heterosis is used in many. Heterosis, the increase in such characteristics as size, growth rate, fertility, and yield of a hybrid organism over those of its parents. Heterosis and combining ability analysis in bread wheat.
However, leng reports that row number is affected in widely different degrees by heterosis, and that number of kernels per row ear length is the only primary yield component in which large positive effects of heterosis. B48 heterosis and combining ability among white maize elite inbred lines. An offspring is heterotic if its traits are enhanced as a result of mixing the genetic contributions of its parents. Feeding people and protecting natural resources 1 donald n.
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