Journal of Energy Bioscience 2024, Vol.15, No.6, 358-367 http://bioscipublisher.com/index.php/jeb 361 the year can also increase the yield of sorghum more quickly and optimize its composition in biofuels (Mullet et al., 2014). The study also identified the key gene regions that affect sorghum plant height, biomass and stem SAP content through quantitative trait locus (QTL) analysis. These traits are very important for the utilization of bioenergy (Mocoeur et al., 2015; Guden et al., 2023). 4.2 Role of molecular markers and genomic selection In the breeding process of high-biomass sorghum, molecular markers and genomic selection play a significant role. These methods can accelerate the breeding speed and improve efficiency. Models like BayesA, BayesB and BayesCπ are often used to predict some important traits of sorghum, such as plant height, freshness and dry matter yield, as well as fiber composition. These models can help breeders select good seedlings at an early stage, thereby shortening the breeding time (Wang et al., 2024). The use of SNP markers can help understand the structure of sorghum populations and also assist in identifying important genes that affect energy traits (De Oliveira et al., 2018). Researchers also constructed high-density genetic maps and identified QTL related to bioenergy, which provides useful tools for marker-assisted selection and combining good traits in the future (Guden et al., 2023). 4.3 Advances in genetic engineering for sorghum Genetic engineering has made considerable progress in improving the bioenergy performance of sorghum. Current transgenic technology can help researchers identify and regulate some important genes, such as those related to carbohydrate metabolism and stress resistance (Ordonio et al., 2016). Some studies have found some genes that control the internode carbohydrate metabolism of sorghum, and these genes can affect the effect of sorghum as a bioenergy raw material (Yang et al., 2023). The genome of sorghum has been sequenced and a genetic diversity population has also been established. These genomic resources provide support for finding new genes and studying gene functions. Studies have identified genes related to cellulose synthesis and vacuole transport, which are crucial for increasing the quantity and quality of biomass (Brenton et al., 2016). If genetic engineering is combined with traditional breeding and molecular marker technology, it is possible to cultivate sorghum varieties that are more suitable for bioenergy in a targeted manner. 5 Sorghum-Based Bioenergy Products 5.1 Bioethanol production from sorghum grain and stalks Sorghum is a crop with wide uses. Because it can produce a lot of biomass and sugar, it is very suitable for the production of bioethanol. Some sorghum varieties, such as Sorghum 506, can be used as the main crop in temperate regions and can also be used for crop rotation. These varieties perform well in ethanol production (Batog et al., 2020). Moreover, using sorghum to produce ethanol does not compete with grain production for land and is a relatively sustainable approach. Especially sweet sorghum, which has a high sugar content and can be directly fermented into ethanol, is a very promising renewable energy crop (Appiah-Nkansah et al., 2019). Studies have found that under the Mediterranean climate, the theoretical ethanol yield of sweet sorghum is approximately between 2 020 and 5 302 L per hectare (Yucel et al., 2022). 5.2 Biomethane and biogas production from sorghum residues The residues left after sorghum harvest, such as stems, leaves and bagasse, can be used to produce biomethane and biogas. Among them, sweet sorghum is regarded as a good choice, especially suitable for fermentation and gas production during the sugarcane fallow season. Studies have found that the methane yield of some sweet sorghum varieties can reach 227.91 NmL CH4/g VS added. Among them, the SE-81 variety performed the best in terms of methane yield per unit area (Mathias et al., 2023). Another study used an improved pretreatment method with organic solvents to convert sweet sorghum stalks into biogas and bioethanol, and the results were also good. The maximum methane yield could reach 271.2 mL CH4/g VS (Nozari et al., 2018). 5.3 Potential for bioplastics and biochemicals The biomass of sorghum can not only be used as fuel, but also to produce bioplastics and some biochemical products, which is of great help to the development of a green economy. Nowadays, there is a concept of a
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