Heterosis or hybrid vigour is the superiority of a hybrid offspring over the average of both its genetically distinct parents. Heterosis he fact that vigorous growth so frequently. This theory is based on the assumption that hybrid vigour resulting from heterosis hybridization brings the dominant, favorable genes together. Leaves per plant showed low level of heterosis in f 1 hybrids 0. Combining ability heterosis maize plant breeding introduction types of hybrids, which exhibit high heterosis when the maize is the worlds most widely grown cereal and is uniformity. 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. Course seminar on heterosis breeding in rice oryza sativa l. Aug 21, 2019 heterosis and inbreeding depression are complementary phenomena, both important to the establishment of breeding strategies, such as conventional hybrids and population breeding. Hybrid breeding facilitates a maximum exploitation of heterosis. In cross fertilized plants in which the phenomenon of. The expression of heterosis is restricted to the hybrid individual f1 generation and it dissipates in the advanced generations or in the progenies derived from it due to segregation and recombination which disturb the original heterotic combination of genes.
A plant breeding phenomena that we very successful exploit commercially, the biological basis of which remains poorly understood. These breeds must two breeds with desirable genes is called complementarity. These effects can be due to mendelian or nonmendelian inheritance. Overdominant epistatic loci are the primary genetic basis of. The identification of the genetic and epigenetic framework underlying heterosis would be a landmark discovery revolutionizing modern plant breeding by allowing the optimal exploitation of crop productivity and stability. New technologies on multiple scales are reengineering traditional plant breeding to meet. Ppt heterosis powerpoint presentation free to view. Divergent selection and genetic introgression shape the. Genetic analysis of heterosis for yield and yield components.
However in both autogamous or allogamous plants it is difficult to exclude a role of marginal overdominance which could. Heterosis and inbreeding depression are considered sis suggests that heterosis may arise from epistasis between alleles at different loci stuber 1994. Vigor can be determined by measurement of a number of traits from seed yield and plant biomass through to biotic and abiotic stress resistance. Exploring the molecular basis of heterosis for plant breeding liu. When two homozygous inbreeds a true breeding line obtained by continuous inbreeding of genetically unlike constituents are crossed together, the resulting hybrids obtained from the crossed seeds are usually robust, vigorous, productive and taller than the either parents. Plant breeding can be accomplished through many different techniques ranging from simply selecting plants with desirable. Understanding the various mechanisms by which heterosis arises may facilitate the breeding of hybrids with increased vigor for further crop varieties or species. Various models have been posited to explain heterosis, including dominance, overdominance, and pseudooverdominance. Heterosis performance in industrial and yield components of sweet corn. Heterosis history types of heterosis genetic basis of heterosis moecular basis of heterosis 3. Hybrid vigour has been exploited in both self as well as cross pollinated species. Plant breeding dates to the very beginnings of agriculture, though scientific plant breeding began only in the early 20th century. When two homozygous inbreeds a true breeding line obtained by continuous inbreeding of genetically unlike constituents are crossed together, the resulting hybrids.
Breeding crops with a high yield and superior adaptability is vital to maintaining global food security. Heterosis refers to the superior phenotypes observed in hybrids relative to their inbred parents with respect to traits such as growth rate, reproductive success, and yield. In this perspective, we consider that it might be useful to the field to. The sym posia is held every other year and alternately hosted by the two societies. An understanding of heterosis in genetic terms had to await the rediscovery of mendels laws in 1900. Jun 04, 2017 key difference heterosis vs inbreeding depression breeding is a process which is used to create or produce offspring with desired phenotypes. Publisher summary on a worldwide basis, plant breeding has been one of the most successful technologies developed in modern agriculture. Heterosis was discovered in maize about a century ago and has subsequently been found to. In this perspective, we consider that it might be useful to the field to abandon these. It was immediately apparent that hybrids are more heterozygous than their parents. Plant breeding, application of genetic principles to produce plants that are more useful to humans. Physiological basis of heterosis for nitrogen use efficiency. While the practical application of heterosis in plant breeding is quite successful in many crops through the development of hybrid varieties, the basic understanding of the phenomenon is not very advanced. Heterosis breeding and inbreeding depression authorstream.
Combining ability and heterosis for yield and component. The application of heterosis hybrid vigor in hybrid rice since the 1970s has tremendously improved rice productivity worldwide. Giora benari, uri lavi, in plant biotechnology and agriculture, 2012. To discuss the utilisation of heterosis in plant breeding it is necessary to consider its genetic basis. Owing to heterosis hybrid vigor in plants, these hybrids often have superior agricultural performances in yield or disease resistance. Heterosis performance in industrial and yield components. A decrease in the number of heterozygotes implied an increase in the number of homozygotes. The utilization potential of heterosis for maize nue. In maize hybrid breeding programs, plant breeders usually focus on the utilization of heterosis for grain yield and its related phenotypes 22. The objectives of our research were to i examine the magnitude of heterosis over the mid. Heterosis, the increase in such characteristics as size, growth rate, fertility, and yield of a hybrid organism over those of its parents. But how breeders construct hybrid parents to obtain hybrid rice heterosis remains unclear. Fixation of heterosis hybrid biology zygosity free. Dec 10, 2019 in maize hybrid breeding programs, plant breeders usually focus on the utilization of heterosis for grain yield and its related phenotypes 22.
Oct 23, 2017 heterosis is a result of two main phenomena. 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. Despite its importance in maize production, we know surprisingly little about the genetic basis of heterosis. In my opinion, hybrid corn is the most far reaching development in applied biology in this quarter century mangelsdorf, 1951. Heterosis definition types of heterosis heterosis in.
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. Overdominant epistatic loci are the primary genetic basis. Jul 01, 2008 heterosis is the superior performance of f 1 hybrids relative to the midparent value mpv or to the better parent. However in both autogamous or allogamous plants it is difficult to exclude a role of marginal overdominance. Cross pollinated species and species reproducing asexually are highly heterozygous. Heterosis can be defend as the superiority of f hybrid over both the parents in terms of yield and some other character or. Edwards heterosis is the foundation of modern maize breeding programs. Heterosis is an additional gain above the average genetic level of the two parent breeds. Zhikang li, plant breeding, genetics, and historically, heterosis and inbreeding depression are. Difference between heterosis and hybrid vigour compare. 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.
Download book pdf plant breeding pp 451472 cite as. The content of the module will address organization of germplasm into heterotic groups, prediction of heterosis and hybrid performance. Heterosis and inbreeding depression are complementary phenomena, both important to the establishment of breeding strategies, such as conventional hybrids and population breeding. Heterosis, hybrid vigor, or outbreeding enhancement is the improved or increased function of any biological quality in a hybrid offspring. Breeding techniques of crops and organisms have evolved over the past centuries.
Difference between heterosis and inbreeding depression. Exploitation of heterosis as a viable option may play a very significant role in breaking yield barrier and substantially increasing the production and productivity of indian mustard meena et al. Pdf recent research on the mechanism of heterosis is important. 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. The term heterosis was first used by shull in 1914. Heterosis is the superior performance of f 1 hybrids relative to the midparent value mpv or to the better parent. Difference between heterosis and hybrid vigour compare the. In the process of plant breeding, the phenomenon of heterosis has been exploited in various crops and vegetables because of its effect on yield or stress. Today, heterosis is extensively exploited without detailed knowledge of the underlying molecular principles. Shull 1952 coined the term heterosis and defined it as.
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. Davenport, bruce and keable, and pellew proposed this theory in 1910. Improving plants using hybrid vigor module agronomy and. More branches per panicle and more grains per branch. Concepts and breeding of heterosis in crop plants, cssa. In this article we will discuss about heterosis or hybrid vigour. The bonus from heterosis should be approximately 5% for production and 10% for mortality, fertility, health and survival. One of the fascinating techniques of plant breeding the heterosis, know about the hypothesis and application in plant breeding. Principles of plant breeding icar ecourse pdf book agrimoon. 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. Here, by genome analysis, we found that breeders introduced different introgressed exogenous genomes of other rice subpopulations to. Salicylic acid, senescence, and heterosis plant physiology.
G151 departmentof genetics and plant breeding institute of agricultural sciences bhu, varanasi. Key difference heterosis vs inbreeding depression breeding is a process which is used to create or produce offspring with desired phenotypes. Jul 30, 2017 heterosis is a term used in genetics and breeding and is also known as hybrid vigor. Another aspect in which model systems will remain invaluable is to understand genetic phenomena that are relevant for plant breeding. Heterosis is the foundation of modern maize breeding programs. Concepts and breeding of heterosis in crop plants, the third joint plant breeding symposia, was held on sunday, 3 november 1996 in indianapolis at the.
Selection of parents for the generation of heterosis. However, in practical plant breeding the superiority of f1 over mid parent is of no use since it does not offer the hybrid any advantage over the better parent. Despite such an extensive use in agriculture, the underlying mechanisms of heterosis are still poorly understood. New technologies on multiple scales are reengineering traditional plant breeding to. Submitted to submitted by derpartment of genetics and plant breeding, college of agriculture, jau. Agriculture university jobner303329, jaipur, rajasthan, india email.
We feel that the quantitative genetics of heterosis must be tied to plant improvement and that any theory of heterosis must explain and be consistent with the increase in yield of. Hybridization is one such technique used to breed crops as well as. An offspring is heterotic if its traits are enhanced as a result of mixing the genetic contributions of its parents. This increased productivity or superiority over the parents is known as heterosis or hybrid vigor or. Effective crossbreeding begins with two superior breeds. Heterosis is defined as the superiority of f1 hybrid over both the parents in terms of yield andor some other characters.
As biotechnology developed rapidly, modern techniques of breeding with the modern terminology related to them were introduced to identify these breeding methods. Quantitative genetics and selection in plant breeding. Heterosis will be an additional benefit on top of the parent breed advantage and is especially valuable for traits such as vitality, fertility, disease resistance and health. Ppt heterosis powerpoint presentation free to view id.
Ii seminar on molecular basis of heterosis in crop plants manjappa ii ph. More generally, heterosis is estimated over the superior parent such heterosis is referred as heterosis. When these species are subjected to selfing or inbreeding they show severe reduction in vigour and fertility. Plant and animal breeders exploit heterosis by mating two different purebred lines that have certain desirable traits. Heterosis is a multigenic complex trait and can be extrapolated as the sum total of many physiological and phenotypic. Sep 24, 2018 today, heterosis is extensively exploited without detailed knowledge of the underlying molecular principles.
Submitted to submitted by derpartment of genetics and plant breeding, college of agriculture, jau, junagadh. Yield and leaf area showed highly significant heterosis in f 1 hybrids ranging from 102 to 309% and 46. Therefore, average heterosis is of little or no use to the plant breeder. Reports on the availability of heterosis in this crop dates back to 1943 which had generated interest of plant breeders to harness hybrid vigour. Fixation of heterosis hybrid biology zygosity free 30. 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. The content of the module will address organization of germplasm into heterotic groups, prediction of. Heterosis in plant breeding request pdf researchgate.
The firstgeneration offspring generally show, in greater measure, the desired characteristics of both. Department of agriculture, agricultural research service, department of genetics, north carolina state university, raleigh, north carolina 27695. Feb 28, 2017 one of the fascinating techniques of plant breeding the heterosis, know about the hypothesis and application in plant breeding. Plant breeding is a common practice to develop new varieties and cultivar with beneficial characteristics. Dear colleagues, the phenomenon of heterosis was first described by darwin as having a positive effect on plant traits, as displayed by crossfertilized over selffertilized progenies in the vegetable kingdom.