Abstract

Plant breeders face multiple global challenges that affect food security, productivity, accessibility and nutritional quality. One major challenge for plant breeders is developing environmentally resilient crop cultivars in response to rapid shifts in cultivation conditions and resources due to climate change. Plant breeders rely on different crop genetic resources, breeding tools, and methods to incorporate genetic diversity into commercialized cultivars. Breeders use genetic diversity to develop new cultivars with improved agronomics, such as higher yield, biotic and abiotic stress tolerance, and to improve the nutritional quality of foods for a growing world population. Genetic variability is the fundamental requirement for any plant-breeding program to develop a superior cultivar. The presence of genetic variation is a key prerequisite for genetic improvement in plant breeding and plays a pivotal role in germplasms usage in breeding programs. Genetic variability is well defined as the formation of individuals varying in the genotype. Genetic diversity is the range of different inherited traits within a species, which is the prerequisite of the breeding program. Genetic diversity leads to the selection of superior cultivars and their traits. Genetic variation is a measure of the genetic differences that exist within a population. Variation in crop plant can come either from environment or from genetic difference. Genetic variability is the occurrence of variation among individual, due the difference in genetic composition. Variability is pre-request for crop improvement in plant breeding. Without variation among individual or species no need of crop improvement. The paper, therefore, aims to reviewing the overview of genetic variability and it is implication in crop improvement. Variation in crop plant can either due to genetic or environmental variation. There are different method of creating variability in crop for breeding purpose like, genetic recombination, mutation, ploidy modification, transposable element, gene transfer and soma-clonal variation. Genetic variation is important in natural selection that allows for increase or decrease in frequency of population. The existence of variation in crop plant enable individual to adapt new or changing environment. Variation in crop plant also important for adaptation of individual to changing or new environment, yield improvement and development of disease resistance. Therefore, exploiting available genetic variation in crop plant or creating variation is corner stone for plant breeding program.