Hybridization is one such technique used to breed crops as well as organisms. F1 hybrid exhibit significant heterosis for ph and eh as compared to their parental inbred lines. Concepts and breeding of heterosis in crop plants, volume 25. In 25 chapters, it explores various aspects of conventional and modern means of plant breeding, including. 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. Despite such an extensive use in agriculture, the underlying mechanisms of heterosis are still poorly understood. Apr 17, 2017 plant height ph and ear height eh are two important agronomic traits in maize selection breeding. 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. Heterosis is of utmost economic importance in plant breeding. To understand the genetic basis of heterosis controlling ph and eh, we conducted quantitative trait locus qtl analysis using a recombinant inbreed line ril based design iii. Breeding techniques of crops and organisms have evolved over the past centuries. Heterosis breeding and inbreeding depression authorstream. Plant breeding is the art and science of changing the traits of plants in order to produce desired characteristics. Plant and animal breeders exploit heterosis by mating two different purebred lines that have certain desirable traits.
Concepts and breeding of heterosis in crop plants, cssa. Effects of visible recessive alleles on vigor characteristics in a maize hybrid. In maize hybrid breeding programs, plant breeders usually focus on the utilization of heterosis for grain yield and its related phenotypes 22. 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. Principles of plant breeding icar ecourse pdf book agrimoon.
Vigor can be determined by measurement of a number of traits from seed yield and plant biomass through to biotic and abiotic stress resistance. Ir36 and ir42 yield 45 tha in wet season trials and 78 tha in dry season trials. Strategies for utilizing heterosis in wheat, rice and oil seed brassica in india, pp. This increased productivity or superiority over the parents is known as heterosis or hybrid vigor or. Davenport, bruce and keable, and pellew proposed this theory in 1910. Heterosis is the superior nature of the hybrids over their parents so it is also known as the hybrid vigour. The firstgeneration offspring generally show, in greater measure, the desired characteristics of both parents. The heterosis nature has been exploited in various crop plants for the improvement of different plant varieties.
Selective breeding of plants and animals, including hybridization, began long before there was an understanding of underlying scientific principles. The continuous inbreeding causes loss of heterosis. 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. Hybrid breeding facilitates a maximum exploitation of heterosis. 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. Difference between heterosis and hybrid vigour compare. Plant height ph and ear height eh are two important agronomic traits in maize selection breeding. Hybrid vigor is defined by mechanisms such as dominant complementation, overdominance, and epistasis. 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 breeding is a significant genetic tool that can encourage yield upgrade from between 30 to 400% and improves.
This site is like a library, use search box in the widget to get ebook that you want. 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. The heterosis can be maintained by the crossing of the plants with the inbreed lines. Improving plants using hybrid vigor module agronomy and. Increasing plant density did not affect heterosis for dry matter at maturity, but caused an increase in heterosis for grain yield and hi. Here, we conducted a systematic survey of the degree of heterosis in arabidopsis. Hybrid vigour has been exploited in both self as well as cross pollinated species. Heterosis and combining ability for yield and yield attributing traits in rice. Heterosis is observed in almost every crop species studied, the application of this phenomenon for its commercial exploitation depends on. Types of heterosis there are three main types of heterosis. 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. Breeding vegetable crops download ebook pdf, epub, tuebl. Assessment of heterosis in two arabidopsis thaliana common.
Pdf heterosis and combining ability for yield and yield. By heterosis new varieties of field crops like maize, sugar beets, sorghum, grasses and sunflower etc. An offspring is heterotic if its traits are enhanced as a result of mixing the genetic contributions of its parents. The latter was estimated in comparison to commercial varieties. Fixation of heterosis hybrid biology zygosity free 30. Heterosis in plant breeding request pdf researchgate. Submitted to submitted by derpartment of genetics and plant breeding, college of agriculture, jau, junagadh. Fixation of heterosis hybrid biology zygosity free. Combining ability and heterosis for yield and related traits in chili capsicum annuum l. 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. As biotechnology developed rapidly, modern techniques of breeding with the modern terminology related to them were introduced to identify these breeding methods.
Genotypebyenvironment interactions affecting heterosis in. Sep 24, 2018 today, heterosis is extensively exploited without detailed knowledge of the underlying molecular principles. An international symposium on heterosis in crops, 1722 august, 1997, mexico city, mexico. Difference between heterosis and hybrid vigour compare the. The environment can influence heterosis, the phenomena in which the offspring of two inbred parents exhibits phenotypic performance beyond the inbred parents for specific traits. 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.
Heterosis and hybrid rice breeding sant singh virmani. Ppt heterosis powerpoint presentation free to download. Theoretical and experimental arguments are given demonstrating the superiority of intergroup compared with intragroup crosses under two aspects. Khaleque mian 1, tofayel ahamed 2 1 department of genetics and plant breeding, bangabandhu sheikh mujibur rahman agricultural university bsmrau, gazipur 1706, bangladesh. Heterosis can be defend as the superiority of f hybrid over both the parents in terms of yield and some other character or. Today, heterosis is extensively exploited without detailed knowledge of the underlying molecular principles.
Quantitative trait locus analysis of heterosis for plant. 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. In this study we measured 25 traits in a set of 47 maize hybrids and their inbred parents grown in 16 different environments with varying levels of average productivity. Given the numerous advantages of arabidopsis thaliana as a. Vigor can be determined by measurement of a number of traits from seed yield and plant.
The book contains a wealth of useful information for practicing hybrid rice breeders, seed producers, researchers, and students of. 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. Heterosis is retained in the breeding of crossbred animal and is related to the probability of alleles from different parental lines joining together. This theory is based on the assumption that hybrid vigour resulting from heterosis hybridization brings the dominant, favorable genes together. Combining ability and heterosis for quantitative powdery. Heterosis definition types of heterosis heterosis in. Oct 23, 2017 heterosis is a result of two main phenomena.
Various models have been posited to explain heterosis, including dominance, overdominance, and pseudooverdominance. The content of the module will address organization of germplasm into heterotic groups, prediction of. Concepts and breeding of heterosis in crop plants cssa special. This book offers a detailed overview of both conventional and modern approaches to plant breeding. In my opinion, hybrid corn is the most far reaching development in applied biology in this quarter century mangelsdorf, 1951. Al genetic effects of heterosis in maize hybrid yields. Heterosis or hybrid vigor results in a hybrids phenotypic superiority over its founder parents for quantitative and qualitative traits.
Finally, we highlight problems involved in heterosis research and crop. Notwithstanding large efforts to study the phenomenon of heterosis in the last decades, the identification of common molecular mechanisms underlying hybrid vigour remain rare. The content of the module will address organization of germplasm into heterotic groups, prediction of heterosis and hybrid performance. Ppt heterosis powerpoint presentation free to view. Many of the crops widely grown today stem from a very narrow genetic base. The objectives of our research were to i examine the magnitude of heterosis over the mid. Breeding vegetable crops download ebook pdf, epub, tuebl, mobi.
Combining ability and heterosis for yield and related. The offspring of a f1 female will benefit from maternal heterosis 3. Given the numerous advantages of arabidopsis thaliana as a model species. Download book pdf plant breeding pp 451472 cite as. Heterosis and its manifestation heterosis or hybrid vigour is the superiority of the f1 hybrids over parents in one or more characters. Book of abstracts the genetics and exploitation of heterosis in crops. To understand the genetic basis of heterosis controlling ph and eh, we conducted quantitative trait locus qtl analysis using a recombinant inbreed line ril based design iii population derived. Department of agriculture, agricultural research service, department of genetics, north carolina state university, raleigh, north. Plants free fulltext heterosis breeding in eggplant. The estimation of combining abilities and heterosis for quantitative resistance against erysiphe graminis f. Fur this purpose a half diallel cross and its parents were arranged in five latin rectangles, each inoculated with a current mildew isolate. Heterosis is an additional gain above the average genetic level of the two parent breeds. Department of agriculture, agricultural research service, department of genetics, north carolina state university, raleigh, north carolina 27695.
Understanding the various mechanisms by which heterosis arises may facilitate the breeding of hybrids with increased vigor for further crop varieties or species. These effects can be due to mendelian or nonmendelian inheritance. However, its underlying molecular causes are still unknown. Click download or read online button to get breeding vegetable crops book now. More branches per panicle and more grains per branch. The genetics and exploitation of heterosis in crops. 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. Genotypebyenvironment interactions affecting heterosis. A plant breeding phenomena that we very successful exploit commercially, the biological basis of which remains poorly understood. The bonus from heterosis should be approximately 5% for production and 10% for mortality, fertility, health and survival. Jul 30, 2017 heterosis is a term used in genetics and breeding and is also known as hybrid vigor. Importance of plant breeding, cytological principles of plant breeding, heterosis, inbreeding and its consequences or applications, selfincompatibility in plants, cytoplasmic male sterility, breeding. For fruit yield per plant, twelve and five hybrids exhibited significant positive heterosis over the mid parent and better parent, respectively.
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 book contains a wealth of useful information for practicing hybrid rice breeders, seed producers, researchers, and students of plant breeding. The exact genetic mechanism behind heterosis is not definitely known. Heterosis is a multigenic complex trait and can be extrapolated as the sum total of many physiological and phenotypic traits.
Salicylic acid, senescence, and heterosis plant physiology. Fur this purpose a half diallel cross and its parents were arranged in five latin rectangles, each. Ppt heterosis powerpoint presentation free to view id. Heterosis, hybrid vigor, or outbreeding enhancement is the improved or increased function of any biological quality in a hybrid offspring. Heterosis or hybrid vigor, on the other hand, is the tendency of outbred strains to exceed both inbred parents in fitness. In this article we will discuss about heterosis or hybrid vigour. Heterosis, the increase in such characteristics as size, growth rate, fertility, and yield of a hybrid organism over those of its parents. To discuss the utilisation of heterosis in plant breeding it is necessary to consider its genetic basis. Plant breeding can be accomplished through many different techniques ranging. Hybrid vigour, or heterosis, has been of tremendous importance in agriculture for the improvement of both crops and livestock.
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