In maize crops, however, the use of heterosis developed in such a unique way that hybridization was recommended as a valuable breeding method. Heterosis and combing ability studies for yield and yield. Duvick introduction hybrid vigor, or heterosis, usually refers to the increase in size or rate of growth of offspring over parents. Combining ability heterosis maize plant breeding introduction types of hybrids, which exhibit high heterosis. Springer3 1usdaars, plant genetics research unit, and division of plant sciences, university of missouri, columbia, missouri, united states of america, 2usdaars, u. The latter was estimated in comparison to commercial varieties. 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. Yield and leaf area showed highly significant heterosis in f 1 hybrids ranging from 102 to 309% and 46. Concepts and breeding of heterosis in crop plants, the third joint plant breeding. The third is the epistasis hypothesis, which states that heterosis is the epistatic interaction of beneficial nonallelic genes at two. The significantly positive contrast between inbreeding depression and midparent heterosis for grain yield indicated the presence of positive additive x additive epistatic interactions. 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. Sep 07, 2014 ii seminar on molecular basis of heterosis in crop plants manjappa ii ph. Heterosis and inbreeding depression of epigenetic arabidopsis. 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. Ppt heterosis powerpoint presentation free to view id. Heterosis in plant breeding request pdf researchgate. 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.
Heterosis, inbreeding depression, various theories of. Heterosis and hybrid rice breeding sant singh virmani. 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. The fundamental principle underlying this success is the phenomenon of heterosis. To discuss the utilisation of heterosis in plant breeding it is necessary to. 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. Heterosis and combining ability of indigenous and exotic crosses of barley sweta singh, l. 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. Plant breeding is the art and science of changing the traits of plants in order to produce desired characteristics. 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. Study of heterosis for grain yield and its components.
Heterosis or hybrid vigor, on the other hand, is the tendency of outbred strains to exceed both inbred parents in fitness. The exact genetic mechanism behind heterosis is not definitely known. 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. Despite such an extensive use in agriculture, the underlying mechanisms of heterosis are still poorly understood. Plant and animal breeders exploit heterosis by mating two different purebred lines that have certain desirable traits. The bonus from heterosis should be approximately 5% for production and 10% for mortality, fertility, health and survival. The book contains a wealth of useful information for practicing hybrid rice breeders, seed producers, researchers, and students of plant breeding. Heterosis and combing ability studies for yield and yield component traits in sunflower helianthus annuus vikas v. In this article we will discuss about heterosis or hybrid vigour. Mid parent mph and better parent bph heterosis was estimated for plant height ph, ear height eh, anthesis. Sandeep kumar bangarwa the term heterosis was first used by shull in 1914.
Jul 30, 2017 heterosis is a term used in genetics and breeding and is also known as hybrid vigor. Breeding crops with a high yield and superior adaptability is vital to maintaining global food security. 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. The heterosis nature has been exploited in various crop plants for the improvement of different plant varieties. 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. The term heterosis was first used by shull in 1914. Ppt heterosis powerpoint presentation free to download. Overdominant epistatic loci are the primary genetic basis. Heterosis and combining ability analysis in bread wheat. Book of abstracts the genetics and exploitation of heterosis in crops. New technologies on multiple scales are reengineering traditional plant breeding to.
However in both autogamous or allogamous plants it is difficult to exclude a role of marginal overdominance which could. It describes an advantage of the offspring as compared to the two parental lines with respect to physiological traits such as growth. B48 heterosis and combining ability among white maize elite inbred lines. Progress toward understanding heterosis in crop plants. 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.
Zhikang li, plant breeding, genetics, and historically, heterosis. 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. Feeding people and protecting natural resources 1 donald n. Heterosis exploiting breeding schemes hebs for outbreeding crops ranks among the biggest impacts made by plant breeders to world food supply. 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. Hybrids represent a cornerstone in the success story of breeding programs. Breeding value of 2n pollen diploandroids in tetraploid. Heterosis, the increase in such characteristics as size, growth rate, fertility, and yield of a hybrid organism over those of its parents.
Shull 1952 coined the term heterosis and defined it as. Studies on heterosis and combining ability in bittergourd. High yielding cotton hybrids combining early maturity and resistance to leaf curl virus. Dear colleagues, the phenomenon of heterosis was first described by darwin as having a positive effect on plant traits, as displayed. These effects can be due to mendelian or nonmendelian inheritance. Combining ability and heterosis for yield and component. Department of agriculture, agricultural research service, department of genetics, north carolina state university, raleigh, north.
Improving plants using hybrid vigor module agronomy and. In the process of plant breeding, the phenomenon of heterosis has been. 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. A plant breeding phenomena that we very successful exploit commercially, the biological basis of which remains poorly understood. Furthermore, the best hybrid outperformed the best line variety by 1. 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. The objectives of our research were to i examine the magnitude of heterosis over the mid. Recent research on the mechanism of heterosis is important for crop.
The second is the overdominance hypothesis, in which heterotic traits occur through interactions of favorable alleles at one or more loci shull, 1908. The contribution of epigenetic factors to inbreeding depression and heterosis remains elusive. Importance of plant breeding, cytological principles of plant breeding, heterosis, inbreeding and its consequences or applications, selfincompatibility in plants, cytoplasmic male sterility, breeding. Selective breeding of plants and animals, including hybridization, began long before there was an understanding of underlying scientific principles.
More branches per panicle and more grains per branch. Plant breeding can be accomplished through many different techniques ranging from simply selecting plants with desirable. Despite its importance in maize production, we know surprisingly little about the genetic basis of heterosis. Significant heterosis over economic parent and mid parent was observed for almost all the traits studied. Breeding of f1 hybrid cultivars based on heterosis is used in many. The heterosis concept, defined over a century ago, continues to be applied in the production of several hybrids from different vegetable species. Heterosis, hybrid vigor, or outbreeding enhancement is the improved or increased function of any biological quality in a hybrid offspring. Concepts and breeding of heterosis in crop plants, cssa.
If true, it should not be possible to obtain an inbred that performs equally as well as the best hybrid bernardo 2002 breeding for. 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. Various models have been posited to explain heterosis, including dominance, overdominance, and pseudooverdominance. 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. Biometrical methods in quantitative genetic analysis. An offspring is heterotic if its traits are enhanced as a result of mixing the genetic contributions of its parents. The heterosis can be maintained by the crossing of the plants with the inbreed lines. 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. Genetic basis of the evolution of adaptedness in plants. Heterosis is prevalent for multiple traits in diverse. In maize hybrid breeding programs, plant breeders usually focus on the utilization of heterosis for grain yield and its related phenotypes 22.
Heterosis describes the superior phenotypes observed in hybrids relative to their inbred parents. Heterosis and inbreeding depression are considered sis suggests that heterosis may arise from epistasis between alleles at different loci stuber 1994. To discuss the utilisation of heterosis in plant breeding it is necessary to consider its genetic basis. Now epigenetic arabidopsis hybrids show that epigenetic diversity and regulation contribute to both. Heterosis is an additional gain above the average genetic level of the two parent breeds. 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. Submitted to submitted by derpartment of genetics and plant breeding, college of agriculture, jau, junagadh. Combining abilities of sugar beet genotypes for root. Supriya2 1aicrp on sunflower, mars, uas raichur, karnataka, india 2department of genetics and plant breeding. Pdf recent research on the mechanism of heterosis is important. 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.
In my opinion, hybrid corn is the most far reaching development in applied biology in this quarter century mangelsdorf, 1951. Edwards heterosis is the foundation of modern maize breeding programs. Heterosis is defined as the superiority of f1 hybrid over both the parents in terms of yield andor some other characters. 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. Heterosis exploiting breeding schemes for rapid yield.
Heterosis has been extensively studied in maize maydica 50 2005. Theoretical and experimental arguments are given demonstrating the superiority of intergroup compared with intragroup crosses under two aspects. This increased productivity or superiority over the parents is known as heterosis or hybrid vigor or. Heterosis is prevalent for multiple traits in diverse maize germplasm sherry a. Heterotic groups and patterns are of fundamental importance in hybrid breeding. 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. Heterosis breeding and inbreeding depression authorstream. In these proceedings an effort is made to merge modern plant breeding efficiency with ecological aspects of plant breeding, reflected in adaptation. Predicting arabidopsis freezing tolerance and heterosis in.
Heterosis can be defend as the superiority of f hybrid over both the parents in terms of yield and some other character or. 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. Paul, minnesota, united states of america abstract background. Heterosis performance in industrial and yield components. Maize is a model system for studying heterosis due to the high levels of yield heterosis and commercial use of hybrids. When two homozygous inbreeds a true breeding line obtained by continuous inbreeding of genetically unlike constituents are crossed together, the resulting hybrids obtained from. Hybrid breeding facilitates a maximum exploitation of heterosis. Heterosis and combining ability analysis in cms hybrid.
Various models have been posited to explain heterosis. The content of the module will address organization of germplasm into heterotic groups, prediction of heterosis and hybrid performance. Jul 09, 2010 heterosis associated gene expression in maize embryos 6 days after fertilization exhibits additive, dominant and overdominant pattern. 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. Adaptation in plant breeding springer for research. In this perspective, we consider that it might be useful to the field to abandon these. Ppt heterosis powerpoint presentation free to view. Full text of plant breeding principles and methods see other formats. An offspring is heterotic if its traits are enhanced as a. Heterosis definition types of heterosis heterosis in. By heterosis new varieties of field crops like maize, sugar beets, sorghum, grasses and sunflower etc. 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. Ir36 and ir42 yield 45 tha in wet season trials and 78 tha in dry season trials.
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