Cotton is very important crop regarding the global trade. It is grown for its fiber and edible oil in Pakistan. It contributes 1.5 percent to GDP and 69 percent in foreign exchange. There is need to enhance the yield per unit area of cotton by developing high yielding and stress tolerant varieties. In breeding program the parents and their crosses are selected on the basis of their combining ability. Combining ability analysis is performed to identify the general and specific combiner for yield attributed traits. This research was performed for evaluation of four lines as female parents (C-1, CIM-616, TIPO-1 and CYTO-608) and three testers as male parents (NIAB-1048, CYTO-124 and CIM-600) of cotton (Gossypium hirsutum L.). The traits such as plant height, first fruiting node, seed cotton yield, monopodial branches, sympodial branches, ginning out turn percentage, number of bolls per plant, height to node ratio and cotton seed yield was tested. The general combining ability of parental lines and specific combining ability of the F1 cross will be determined for yield related traits. The genotypes with good general combining ability and specific combining ability further exploited for hybrid/variety development programs. For most of the traits like number of monopods per plant, boll weight per plant, seed cotton yield, number of nodes per plant, 1st fruiting node, intermodal distance, ginning out turn percentage, cotton seed yield, seed index, plant height, fiber strength, fiber length, fiber uniformity and fiber fineness value had more value for dominance variance. The higher effects of GCA and SCA indicated that there is the role of additive and non-additive gene action for inheritance of traits.

Cotton is Pakistan's most important fiber crop and the country's economic lifeline. It is an important agricultural commodity in Pakistan, providing a source of income for farmers as well as raw materials for the textile industry. Farmers and the textile industry are also looking for ways to improve fiber quality and increase seed cotton production. Given the low yield pattern and growing demand of the textile industry, the breeding programs need to be planned as a breeder to increase cotton production in the region. Knowledge about inheritance mechanisms, heterosis, and the ability of different characters to combine is crucial for this reason. The most challenging task for plant breeders in any hybridization program is finding the best combination of two (or more) parental genotypes to optimize variation within similar breeding populations, and therefore the possibility of detecting superior transgressive segregants in the segregating populations. After its introduction in 1942, the combining capacity has been commonly used in plant breeding to evaluate the performances of lines in hybrid combinations. Heterosis (also known as hybrid vigor) is a natural occurrence in which hybrid offspring of genetically diverse individuals have enhanced physical and functional characteristics compared to their ancestors. For nearly a century, heterosis has been increasingly used in crop development with the aim of producing more vigorous, higher yielding, and better performing cultivars. A short analysis of previous studies on cotton combining ability and heterotic effect estimation has been provided in this paper. This will strengthen our existing understanding of plant breeding's combining ability and heterosis, as well as recent research advances in this field.

Pakistan is the world's fifth-largest cotton producer. It is grown largely for fibre, and its oil is used as a vegetable oil and contributes  significantly to the local oil industry. Cottonseed oil meets 18.1% of Pakistan's edible oil needs. In 2030, there will be 5.5 million tonnes of total demand for this purpose, with 2 million tonnes of local supply. Bt cotton, which was introduced in 2010 to remove three harmful lepidopteran insects, currently accounts for more than 90% of all cotton grown in Pakistan. Pakistan offers a lot of potential for organic cotton cultivation, particularly in unconventional cotton-growing locations with low insect burdens. Climate change-induced high temperatures and water scarcity are a big worry because contemporary agriculture is practiced in areas that already experience very high temperatures. Phenotypic selection in breeding is ineffective in creating stress-tolerant cotton. Marker-assisted selection technologies have considerably increased the effectiveness of traditional breeding. Modern breeding techniques contributed to the development of novel cotton breeding strategies. Furthermore, CRISPR/Cas9 and genome editing can establish a good foundation for improving resistance against biotic and abiotic stresses.

The volatility of the climate, which is characterized by intermittent heavy rainfall, causes flooding. The problem is exacerbated in soils with limited internal drainage by warm weather patterns. Cotton is commonly grown under these conditions, putting it at risk for yield losses due to summer flooding following heavy rainfall. This requires a deeper understanding of cotton's processes for waterlogging tolerance. This research analyses likely reasons of waterlogging-induced yield loss in cotton, as well as ways for boosting waterlogging tolerance, based on the little information available on cotton and recommendations from other species. The yield penalty is impacted by soil type, phenological stage, and the total time roots were exposed to less than 10% air-filled porosity. In addition to other soil-related issues, an oxygen deficiency in the root zone alters the redox state of nutrients, rendering some inaccessible (such as nitrogen) or potentially poisonous to plants. In addition, xylem-transported root hormones have long been linked to oxygen shortage. Reduced root growth, reduced nutrient uptake and transport, and disturbed hormone signaling are examples of subterranean effects on shoots that impact canopy formation, photosynthesis, and radiation utilization efficiency. Cotton has no evident root aerenchyma reaction and low fermentative activity compared to cereals with greater waterlogging tolerance. We believe that these traits have a significant effect on cotton's susceptibility to prolonged waterlogging. These subsurface components' effects on photosynthesis, shoot functionality, and yield components are discussed. Utilizing management techniques such as fertilizer application, soil aeration, and controlled watering helps prevent waterlogging. Reducing the expression of the genes directing ethylene production and introducing anti-ethylene compounds to limit ethylene biosynthesis are effective methods for preventing yield losses in cotton plants that have become waterlogged.

Improvement of crop species has been a fundamental goal of mankind since the dawn of agriculture. The key to increasing agricultural productivity and improving other attributes has been plant breeding. The foundations of conventional breeding are the utilization of diversity, which occurs naturally in the form of land races and wild relatives, and the development of diverse selection and breeding techniques. Selection, which was the first strategy identified and is currently utilized by the majority of breeding programs, is the most fundamental aspect of plant breeding. There is a need to boost global food production in order to meet the rising demand of a growing population as a result of a growing human population and a changing environment, which have both heightened concerns about global food security. Conventional breeding methods are inadequate to supply this rising need. In the past few decades, numerous advancements in genetic engineering and molecular biology have led to the emergence of novel approaches that rely on phenotypic characterization. Now, the wide availability of molecular markers has facilitated the identification of variation sources and selection. Specifically, genomics played a crucial part in the revolution of plant breeding. Because genomics enabled the extended study of genotype and its relationship to phenotype for multigenic characteristics, allowing for a greater understanding of genotype and phenotype. In this overview, we will address conventional breeding methods and contemporary genomics techniques, and their function in crop improvement.