Impact of improved sorghum cultivars on genetic diversity and yield stability (original) (raw)

Role and economic importance of crop genetic diversity in food security

International Journal of Agricultural Science and Food Technology, 2021

Determination of genetic diversity and their relationships among breeding materials is very crucial in crop improvement strategies. Characterization and evaluation of germplasm is prerequisite to screen out the desired genetic materials for the genetic improvement programs. The collection of germplasm relies on the several number of accessions it possesses and the genetic materials available in those accessions for yield and yield components. Climate change and geographical isolation are identifi ed as two majors in the formation of new species. The other sources of germplasm diversifi cation and evolution are biotic factors like competition and predation among themselves. Phenotypic characters are the most important conventional tools to analyse variation among the genetic materials and the visible morphological traits are very crucial tools in genetic diversity investigation. Plant breeding is primarily relied on the variation exist in the genetic diversity of cultivated and their wild relatives together for further improvements. Plant phenotyping is defi ned as the investigation of plant characters by researchers for yield, quality and resistance to biotic and abiotic stresses. Genetic variation and selection are the two basic principles of plant breeding. Additive (heritable) and non-additive variance (dominance and epitasis) are the important components of genetic variance of any quantitative traits. Hence, it is important to decompose the visible phenotypic variation into heritable and non-heritable components with suitable genetic components like genotypic coeffi cient of variation, heritability and genetic advance. Genetic diversity is the totality of genetic difference of genetic variation in the genetic make-up of a species. Genetic diversity ha paramount role in the perpetuation of a species through offering adaptation mechanisms to biotic and abiotic environmental stresses and enables change in the genetic composition to cope with changes in the environment. Eventually, plant genetic diversity is playing a key role in the continuation of agricultural development with signifi cant improvement in different morphological and agronomical characteristics. Selection for improvement highly depends on inherent levels of genetic diversity present at the time in the species, rate of evolutionary response and adaptation to the environmental conditions. As the genetic diversity increases the ability to adapt to changing environments also increases within a given species. Especially, when the climate fl uctuation, new pests and diseases are occurred, the species which have huge genetic diversity capable of overcome the challenges. Since crop plant improvement program is integrated with different research disciplines, the availability and accessibility of diverse genetic materials ensure the sustainability of global food production network.

STUDY OF THE GENETIC DIVERSITY OF CROPS IN THE ERA OF MODERN PLANT BREEDING

Modern plant breeding has transformed food production and will be essential to guaranteeing food security on a global scale. Striking a balance between increasing crop output in response to climate change and reducing crop failure in difficult conditions is crucial for sustainable agriculture. A fuller understanding of how plant breeding affects agricultural genetic diversity is necessary to make this trade-off. Molecular marker technology has been applied to research agricultural genetic diversity throughout the past three decades. Our results disproved our hypothesis that current plant breeding diminishes agricultural genetic diversity by revealing temporal patterns of genetic diversity. This review analyzed theoretical and empirical estimates of agricultural genetic variety, focusing on how genetic diversity varies in response to artificial selection through time, in an effort to understand these oscillations. Numerous studies on agricultural genetic diversity lacked sufficient experimental design, including technical biases related to cultivar and genome sampling, and were not intended to look at how certain plant breeding efforts affected diversity. Theoretical research on how plant breeding affects agricultural genetic diversity has received little attention. Computer simulations of five standard breeding strategies show that plant breeding has a considerable impact on the preservation of heterozygosity over generations. It is crucial that additional plant breeding research investigates the geographical and temporal diversity of agricultural genetics in order to achieve sustainable crop output.

Genetic diversity in cultivated plants—loss or stability?

Theoretical and Applied Genetics, 2004

Human activities like urbanisation, the replacement of traditional agriculture systems by modern industrial methods or the introduction of modern high-yielding varieties may pose a danger to the biological diversity. Using microsatellite markers, we analysed samples of cultivated wheat (Triticum aestivum L.) collected over an interval of 40-50 years in four comparable geographical regions of Europe and Asia. No significant differences in both the total number of alleles per locus and in the PIC values were detected when the material collected in the repeated collection missions in all four regions were compared. About two-thirds of the alleles were common to both collection periods, while one-third represented collection mission-specific alleles. These findings demonstrate that an allele flow took place during the adaptation of traditional agriculture to modern systems, whereas the level of genetic diversity was not significantly influenced.

Genetic diversity and interdependent crop choices in agriculture

Resource and Energy Economics, 2004

The extent of genetic diversity in food crops is important as it affects the risk of attack by pathogens. A drop in diversity increases this risk. Farmers may not take this into account when making crop choices, leading to what from a social perspective is an inadequate level of diversity.

Genetic diversity trends in twentieth century crop cultivars: A meta analysis

Theoretical and Applied Genetics, 2010

In recent years, an increasing number of papers has been published on the genetic diversity trends in crop cultivars released in the last century using a variety of molecular techniques. No clear general trends in diversity have emerged from these studies. Meta analytical techniques, using a study weight adapted for use with diversity indices, were applied to analyze these studies. In the meta analysis, 44 published papers were used, addressing diversity trends in released crop varieties in the twentieth century for eight different field crops, wheat being the most represented. The meta analysis demonstrated that overall in the long run no substantial reduction in the regional diversity of crop varieties released by plant breeders has taken place. A significant reduction of 6% in diversity in the 1960s as compared with the diversity in the 1950s was observed. Indications are that after the 1960s and 1970s breeders have been able to again increase the diversity in released varieties. Thus, a gradual narrowing of the genetic base of the varieties released by breeders could not be observed. Separate analyses for wheat and the group of other field crops and separate analyses on the basis of regions all showed similar trends in diversity.

Agriculture germplasm resources: A tool of conserving diversity

Scientific Research and Essays, 2015

Three major physical resources in the world comprise land, water and the biological diversity. Agricultural biodiversity is an important component of biodiversity, which has a more direct link to the well being and livelihood of mankind than other forms of biodiversity. In fact, it is one of our most fundamental and essential resources, one that has enabled farming systems to evolve since the birth of agriculture about 10,000 years ago. Food plant and animal species have been collected, used, domesticated and improved through traditional systems of selection over many generations. The resulting diversity of genetic resources developed by early farmers now forms the basis on which modern high yielding and disease resistant varieties have been produced to feed the growing human population, expected to reach 9.1 billion by 2050. According to the Convention on Biological Diversity (CBD), "agricultural biodiversity includes all components of biological diversity of relevance to food and agriculture, and all components of biological biodiversity that constitute agro-ecosystems: the variety and variability of animals, plants and microorganisms , at the genetic, species and ecosystem levels, which are necessary to sustain key functions of the agricultural ecosystem, its structure and processes". The effective conservation and use of agricultural biodiversity is very important in ensuring sustainable increases in the productivity and production of healthy food by and for mankind as well as contributing to increased resilience of agricultural ecosystems.

Askö 2000: Genetic Diversity and Interdependent Crop Choices in Agriculture

Bringing Ecologists and Economists Together, 2010

The extent of genetic diversity in food crops is important as it affects the risk of attack by pathogens. A drop in diversity increases this risk. Farmers may not take this into account when making crop choices, leading to what from a social perspective is an inadequate level of diversity.