1 Introduction

As global energy demand continues to rise and traditional fossil fuels exacerbate climate change, there is a growing need to explore more sustainable and environmentally friendly energy sources. Bioenergy has emerged as a promising alternative. Derived from biological materials such as plants, bioenergy is renewable and, unlike petroleum, does not deplete finite resources. It also has the potential to achieve carbon neutrality (Xin and Wang, 2011; Appiah-Nkansah et al., 2019; Yang et al., 2023). The use of bioenergy can significantly reduce greenhouse gas emissions, contributing to the mitigation of global warming. Moreover, diversifying energy sources enhances the security of energy supply. The development of bioenergy also supports rural economies by creating new employment opportunities and promoting rural development (Batog et al., 2020; Lamb et al., 2021).

Sorghum (Sorghum bicolor) is a highly promising bioenergy crop due to its unique agronomic characteristics and strong environmental adaptability, making it a versatile resource with excellent development potential. As a C4 plant, sorghum offers several advantages, including a high photosynthetic rate, low water requirement, and efficient nutrient uptake. It can be cultivated on semi-arid or marginal lands and requires relatively low inputs of pesticides and fertilizers (Xin and Wang, 2011; Calvino and Messing, 2012; Yang et al., 2023). Sorghum is suitable for the production of various types of bioenergy. Its grains are rich in starch, its juice contains fermentable sugars, and its biomass is high in cellulose—all of which can be used to produce bioethanol, biogas, and other fuels (Mullet et al., 2014; Appiah-Nkansah et al., 2019; Mathias et al., 2023). Furthermore, sorghum has a deep root system that contributes to the increase of soil organic carbon and reduces fertilizer runoff. This enhances soil health and provides sorghum with a distinct advantage in sustainable agricultural systems (Lamb et al., 2021).

This study investigates the genetic and agronomic traits that make sorghum suitable for use as a bioenergy crop. It introduces various methods and technologies for converting sorghum into different types of biofuels, such as ethanol and biogas. The research also evaluates the feasibility and environmental benefits of using sorghum for bioenergy production. Through this study, we aim to better understand the potential and application prospects of sorghum in the bioenergy sector, identify current challenges and opportunities in sorghum cultivation and bioenergy conversion, and propose practical strategies to enhance the efficiency and sustainability of sorghum-based bioenergy utilization.

2 Characteristics of Sorghum Relevant to Bioenergy

2.1 High biomass production and adaptability

Sorghum is regarded as a very suitable crop for bioenergy due to its high biomass. Even on marginal land with relatively low input, it can grow well and has a relatively high yield. This is one of its major advantages. Sorghum has many types of genes and its genomic structure is relatively simple, so it is more convenient to conduct research and breeding. Especially in terms of improving its traits related to biomass such as plant height, internode shape, and carbohydrate metabolism, the progress has been faster (Figure 1) (Yang et al., 2023). Sorghum has a relatively long growth period, which enables its root system to continuously grow downward and also allows for the sustained accumulation of biomass. This is particularly important for the development of stable and sustainable bioenergy (Lamb et al., 2021).

2.2 Efficient water and nutrient use

Sorghum is particularly efficient in terms of water usage and nutrient absorption, which is very important for areas with limited water resources, especially when it is used to grow bioenergy crops. Studies have found that sorghum has a relatively high nitrogen fertilizer utilization efficiency, and its roots can grow to deeper parts of the soil, thus enabling it to absorb more deep water and nutrients (Lamb et al., 2021). This deep root can also help plants grow better, reduce the loss of nutrients at the same time, and is beneficial to the soil as well. The water use efficiency (WUE) of sorghum is similar to that of corn, which indicates that it is also very suitable for the production of bioenergy in arid areas (Roby et al., 2017).

2.3 Tolerance to abiotic stresses

One of the most famous aspects of sorghum is that it can withstand environmental pressures such as drought and salinity. This mainly comes from its genes and some physiological adaptations. For example, it can regulate water evaporation when the air is dry (with a high vapor pressure difference), and can continue to grow when there is a lack of water (Truong et al., 2017). Sorghum can also adapt to saline-alkali soil, which enables it to be grown on more less favorable land and further expands its planting range as a bioenergy crop (Huang, 2018). Under these difficult circumstances, sorghum can still have a decent yield. Therefore, in some areas with relatively poor conditions, it is also a reliable source of biomass (Spindel et al., 2018).

3 Sorghum Biomass Composition and Energy Potential

3.1 Structural components: cellulose, hemicellulose, and lignin

There are three main components in sorghum biomass: cellulose, hemicellulose and lignin. These components are very important in the process of turning plants into energy. Cellulose and hemicellulose are polysaccharides that can be decomposed into sugars and then fermented into bioethanol. Although lignin can make plants more sturdy, due to its complex structure and difficulty in decomposition, it will affect this process. Some studies have pointed out that the content of these components varies greatly among different sorghum varieties. For instance, the combined proportion of cellulose and hemicellulose in some varieties can range from 52.7% to 60%, while lignin is between 11.6% and 17.7% (Deshavath et al., 2018). There are also studies that have found that these lignocellulose materials of sorghum are effective for ethanol production, especially varieties like Sorghum 506 (Batog et al., 2020). If the lignin content in sorghum is reduced through mutations, such as turning the midvein “brown”, the recovery rate of glucose can be increased and the yield of ethanol can also be enhanced (Rivera-Burgos et al., 2019).

3.2 Energy yield comparison with other bioenergy crops

The energy output of sorghum can be compared with that of major bioenergy crops such as corn and sugarcane, and its performance is also quite good. Because it is a C4 plant, its photosynthetic efficiency is high and it produces a large amount of biomass. Even if the environment is not ideal, it can still grow well. Some studies have made comparisons and found that sorghum can produce considerable biomass. For instance, the sweet sorghum grown in Queensland, Australia, can produce 46.9 to 82.3 tons of biomass per hectare, generate 3 059.18 Nm³ of methane, and the total energy value reaches 761.74 MWh per year (Mathias et al., 2023). Although corn and sugarcane are also famous for their high yields, sorghum is more drought-resistant and can be grown on less favorable land. These are all its advantages (Carpita and McCann, 2008). The yield and cellulose content of hybrid sorghum are both higher than those of local varieties and old varieties, which also makes it a better choice for biofuel raw materials (Habyarimana et al., 2016).

3.3 Potential for second-generation biofuels

Sorghum has great potential in the production of second-generation biofuels. The second-generation fuel uses lignocellulose materials, not food crops. Thus, it will not compete for land with food for human consumption and can also utilize the land that cannot be used for growing grain. The lignocellulose components of sorghum - such as cellulose, hemicellulose and lignin - can be converted into bioethanol through some biotransformation methods. For instance, there is a kind of sorghum called “brown vein”, which has a low lignin content, a high theoretical ethanol yield and a good conversion efficiency. It is regarded as a good material for the second-generation biofuels (Rivera-Burgos et al., 2019). Sorghum can also be grown on marginal land and does not compete with food for resources, which makes it more suitable to be a sustainable energy crop (Tang et al., 2018a). The research also found that the genetic diversity of sorghum can help increase yield and quality, thus making the production efficiency of fuel higher. Nowadays, the development of molecular breeding and genetic technology also makes it easier for us to cultivate sorghum varieties suitable for energy (Yang et al., 2023).

4 Genetic Improvement for Enhanced Bioenergy Traits

4.1 Breeding strategies for high-biomass sorghum varieties

In order to breed sorghum varieties with high biomass, the breeding strategies mainly focus on traits that increase yield and enhance stress resistance. Traditional breeding methods have been used to develop some hybrid sorghum varieties. The vegetative growth period of these varieties is longer than that of sorghum used for grain, so they can accumulate more biomass. Their long growth period, high light interception rate and good efficiency in utilizing sunlight all contribute to the continuous increase of biomass. When breeding, introducing germplasm resources from different sources and combining them with multiple tests in a controlled environment throughout 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 “bio-refinery”, which is to convert plant materials such as sorghum into various biofuels and chemical products, making the uses of sorghum more diverse and valuable. Because sorghum can produce a large amount of biomass and has multiple uses, it has become an important crop in the production of biofuels and biochemicals. However, more research is needed to identify which processing methods are the most effective and cost-effective (Stamenković et al., 2020). Using sorghum to produce bioplastics and chemicals can also reduce reliance on fossil fuels such as oil and alleviate environmental pressure.

6 Environmental Benefits and Challenges

6.1 Contribution to carbon sequestration and reduction of greenhouse gases

Sorghum, especially energy sorghum, has great potential in absorbing carbon dioxide and reducing greenhouse gas emissions. The roots of this kind of sorghum grow very deep and can help the soil store more organic carbon, which is very important for achieving carbon sinks (Figure 2). Its root system can penetrate deeper than 2 meters, not only accumulating a large amount of biomass, but also increasing the level of organic carbon in the soil, which helps to reduce greenhouse gas emissions (Lamb et al., 2021). Using sludge and digestion liquid instead of chemical fertilizers to grow sorghum can also reduce carbon emissions. Studies have found that doing so can reduce carbon dioxide equivalent by 14% and 11% respectively, and it is a promising low-carbon agricultural method (Głąb and Sowiński, 2019). The nationwide simulation results also show that growing sorghum in large areas such as the southern and Midwestern United States can achieve net carbon sinks and further illustrate its role in emission reduction (Gautam et al., 2020).

6.2 Role in soil health improvement and erosion control

The root system of sorghum not only helps absorb and store carbon, but also plays a significant role in improving soil health and preventing soil erosion. The roots of sorghum used for bioenergy are deep and strong, which can improve the soil structure, increase the organic carbon in the soil, and enhance the soil fertility and yield (Lamb et al., 2021). Studies have found that when growing sorghum, using the sludge after sewage treatment can improve the physical and chemical properties of the soil, such as loosening the soil, increasing nutrients and organic carbon, which is very important for soil health (Zuo et al., 2019). Planting sorghum together with cover crops can further increase the storage of carbon and nitrogen in the soil, reduce nitrogen loss and greenhouse gas emissions. All these are helpful for protecting the soil and preventing erosion (Sainju et al., 2018).

6.3 Environmental concerns, including land use and biodiversity impacts

Although growing sorghum has many benefits for the environment, there are also some problems. It may compete with food crops for land. This “food and fuel battle” could affect the food supply and increase the cost of living (Calvino and Messing, 2012). If a large amount of natural areas are reclaimed for growing sorghum, it may damage biodiversity. Especially when the original natural habitats are turned into farmland, this problem will be more obvious. However, growing sorghum in some marginal areas, such as newly reclaimed tidal flats, can reduce these conflicts. This approach can provide more sustainable planting options for bioenergy (Zuo et al., 2019). These practices need to be carefully managed and continuously monitored in order to avoid causing new harm to the local ecology and species diversity.

7 Socioeconomic Impacts of Sorghum Bioenergy

7.1 Contribution to rural development and farmer incomes

Sorghum, as a bioenergy crop, has great potential to help rural development and increase farmers' income. In some areas where the profits of traditional crops are not high, growing sorghum can bring additional income to farmers. Because sorghum is suitable for cultivation on marginal land and has low requirements for the input of chemical fertilizers and pesticides, it is particularly suitable for areas with poor soil. This is not only conducive to the sustainable development of agriculture, but also can enhance the economic resilience of rural communities (Appiah-Nkansah et al., 2019; Batog et al., 2020; Lamb et al., 2021). Moreover, after sorghum is made into biofuel, during the process from planting, processing to transportation and sales, it can also drive employment in rural areas and further promote local economic development (Stamenković et al., 2020; Thomas et al., 2021).

7.2 Economic feasibility and market potential

Sorghum, as a bioenergy crop, has economic advantages. This is mainly because it can produce a large amount of biomass, and this biomass can be used for various energy sources, such as bioethanol, biomethane and biochar (Appiah-Nkansah et al., 2019; Batog et al., 2020; Stamenković et al., 2020). Studies also point out that because sorghum has a high sugar content and a good conversion efficiency, it is a cost-effective biofuel raw material (Mathur et al., 2017; Appiah-Nkansah et al., 2019). Nowadays, the global demand for renewable energy is increasing, and people are increasingly eager to reduce their reliance on fossil fuels such as oil. This also makes biofuels made from sorghum more promising in the market (Mullet et al., 2014; Yang et al., 2023). If sorghum is used to build a biorefinery, not only can its biomass be utilized more fully, but also a variety of valuable products can be produced, which further enhances its economic feasibility (Stamenković et al., 2020).

7.3 Policy frameworks supporting sorghum as a bioenergy crop

To enable sorghum to truly play a role in the field of bioenergy, there still need to be supporting policies to support its cultivation and utilization. Some policies that encourage the development of bioenergy crops, such as planting subsidies, tax cuts or subsidies, can effectively promote the use of sorghum as an energy crop (Jiang et al., 2019; Stamenković et al., 2020). Some regulations that encourage the use of renewable energy and set targets for biofuel production could also create a stable market environment for the promotion of sorghum biofuels (Calvino and Messing, 2012; Mathur et al., 2017). If the government can invest more funds to support the improvement of sorghum varieties and the research and development of fuel production technologies, it can further enhance the market competitiveness and sustainable development capacity of sorghum (Mullet et al., 2014; Yang et al., 2023).

8 Case Study: Successful Deployment of Sorghum in Bioenergy Production

8.1 Background and region-specific context

Sorghum, as a bioenergy crop, has been promoted in many countries, such as the United States, Brazil and India. In the United States, especially in Iowa, people value the high yield and drought resistance of sorghum and study and cultivate it as a specialized bioenergy crop. In Queensland, Australia, sweet sorghum is used to fill the gap in sugarcane cultivation. The research found that it not only has a high biomass, but also has a good methanogenic effect (Mathias et al., 2023). In the North China Plain of China, sweet sorghum is planted after winter wheat, forming a double-cropping rotation. This not only utilizes cultivated land but also enables planting on saline-alkali land, effectively increasing the output of biomass and energy (Tang et al., 2018b).

8.2 Cultivation practices and biomass yields

The cultivation methods of sorghum may vary in different regions, but everyone's goal is similar, which is to increase biomass yield and enhance the ability to resist environmental pressure. For instance, in Iowa, the United States, high-biomass sorghum can still produce more than 20 tons per hectare of above-ground parts under drought conditions, with most of the roots concentrated in the soil surface layer. In Queensland, Australia, sweet sorghum varieties like SE-81 can produce 46.9 to 82.3 tons of biomass per hectare, and the methane yield can also reach 3 059.18 Nm³ CH₄ (Mathias et al., 2023). In the North China Plain of China, the rotation of medium-maturing sweet sorghum (CT2) and winter wheat can produce 24.9 tons of dry matter per hectare in two seasons a year, and the total energy output reaches 394.6 GJ per hectare (Tang et al., 2018b).

8.3 Outcomes: energy production, environmental benefits, and socioeconomic impacts

Sorghum is a versatile crop that can be used to produce various bioenergies, such as bioethanol, biogas and biomethane. In Central and Eastern Europe, sorghum varieties like Sorghum 506 have been effectively used to produce lignocellulosic ethanol, and have performed well whether as the main crop or a rotation crop (Batog et al., 2020). In Queensland, Australia, the methane production of some sweet sorghum varieties is very high, showing their great potential in biogas production (Mathias et al., 2023). Sorghum has another important advantage, which is that its root system is very deep. These roots can increase the organic carbon in the soil, improve the soil structure and also reduce nutrient loss. In the research in the United States, it has been proved that sorghum roots can effectively improve soil health (Lamb et al., 2021). Studies have pointed out that growing sorghum in the United States can also achieve net carbon sinks, which is very helpful for addressing climate change (Gautam et al., 2020). In terms of social economy, the utilization of sorghum has also enhanced the efficiency of land use and energy output. In the North China Plain of China, the double-cropping of sweet sorghum and winter wheat not only increases energy output but also makes full use of land resources (Tang et al., 2018b). In Queensland, planting sweet sorghum during the off-season of sugarcane not only generates renewable energy but also boosts the local economy and reduces reliance on fossil fuels (Mathias et al., 2023).

9 Challenges and Limitations

9.1 Technical challenges in conversion processes

There are still some technical difficulties in the process of converting sorghum biomass into bioenergy, especially in the pretreatment and fermentation stages. Pretreatment technologies such as saccharification, fermentation, transesterification, hydrothermal liquefaction, pyrolysis and gasification are all rather complex and require continuous optimization to improve efficiency and reduce costs (Stamenković et al., 2020). Because the biomass of sorghum contains a relatively high content of lignocellulose, it is crucial to first break the cell walls through effective pretreatment methods to release fermentable sugars (Appiah-Nkansah et al., 2019). There are also differences in the contents of cellulose, hemicellulose and lignin among different sorghum varieties, which makes the transformation process more complex (Batog et al., 2020). If too much water is used in these conversions, or if a large amount of nitrogen fertilizer (such as ammonia from the energy-intensive Haber-Bosch process) is used, it will increase costs and be detrimental to the environment (Calvino and Messing, 2012).

9.2 Competition with food crops and land use concerns

Sorghum, as a bioenergy crop, also faces an important problem, that is, it may compete with food crops for farmland. The arable land resources are limited. If a portion of it is used to grow sorghum, it may affect food production, thereby raising the cost of living and potentially causing food security problems (Calvino and Messing, 2012). However, sorghum has one advantage, that is, it can grow on marginal land. Marginal land is usually not suitable for growing grain, but it can be used to grow sorghum, which can reduce the competition for high-quality cultivated land. However, it should also be noted that the conditions in marginal areas are generally poor, and the yield of sorghum in these areas may not be high, which will affect the final biomass output and economic benefits (Nenciu et al., 2021).

9.3 Gaps in research and technological advancements

Although sorghum has made a lot of progress in genetic and genomic research, there are still many research gaps to truly realize its bioenergy potential. Some molecular breeding and directed breeding methods have not fully utilized the existing genetic knowledge, especially in improving traits related to biomass, such as flowering time, plant height and carbohydrate metabolism, etc. (Yang et al., 2023). A more comprehensive life cycle analysis is still needed to identify which preprocessing and transformation methods are both effective and cost-effective. To improve the energy economy of sorghum, it is also necessary to establish a complete “biorefining” model to convert its biomass into various fuels and products more efficiently (Stamenković et al., 2020). At present, there is still a lack of detailed technical and economic analyses on the bioenergy path of sorghum, which also limits our understanding of whether it can be applied on a large scale (Appiah-Nkansah et al., 2019).

10 Future Directions and Recommendations

10.1 Development of multi-purpose sorghum cultivars

To maximize the role of sorghum in bioenergy, it is necessary to cultivate multi-purpose sorghum varieties. This type of variety not only needs to have a high biomass yield, but also better quality of energy and raw materials in order to achieve higher comprehensive benefits. In recent years, many important traits that can be improved have been identified in sorghum genetics and genomics studies, such as flowering time, plant height and carbohydrate metabolism (Calvino and Messing, 2012; Mullet et al., 2014; Yang et al., 2023). By taking advantage of the rich genetic diversity of sorghum and modern breeding techniques, it is expected to breed excellent varieties that are both high-yielding and drought-resistant and tolerant to poor soil (Heitman et al., 2018; Batog et al., 2020; Lamb et al., 2021). If the characteristics that are conducive to the efficient conversion into energy sources such as bioethanol, biogas and biochar can also be integrated, the feasibility of sorghum as a multi-purpose crop will be further enhanced (Appiah-Nkansah et al., 2019; Stamenković et al., 2020).

10.2 Integration of sorghum in circular bioeconomy systems

Incorporating sorghum into the circular bioeconomy system is conducive to enhancing the sustainability and economic benefits of bioenergy. Sorghum can be grown on marginal land with less input, so it is very suitable for this system (Lamb et al., 2021; Yang et al., 2023). The core concept of the circular bioeconomy is to maximize the utilization of resources. For instance, the waste from one stage can be used as raw material for another stage. For instance, the residue left after juicing sweet sorghum can be used for power generation or made into biochar to improve the soil (Heitman et al., 2018; Appiah-Nkansah et al., 2019). Moreover, the deep roots of sorghum can store soil organic carbon, enhance soil fertility, and reduce greenhouse gas emissions at the same time (Lamb et al., 2021). Through these practices, a closed-loop system can be established to make resource utilization more efficient and reduce the impact on the environment at the same time.

10.3 Collaboration between researchers, policymakers, and industry stakeholders

To promote sorghum better as a bioenergy crop, the joint efforts of researchers, policymakers and all parties in the industry are needed. Scientific researchers can provide technical support, such as improving sorghum varieties and optimizing energy production processes (Mullet et al., 2014; Brenton et al., 2016; Yang et al., 2023). The government departments can encourage sorghum cultivation and infrastructure construction by formulating supportive policies, such as subsidies, tax incentives and relevant regulations (Stamenković et al., 2020). Industry participants such as farmers, bioenergy enterprises and equipment technology providers are the key forces promoting the large-scale application and economic feasibility of sorghum (Tang et al., 2018b; Batog et al., 2020). This multi-party cooperation also helps to establish a complete biorefining system, from sorghum cultivation to fuel processing and subsequent product development, achieving multiple uses of sorghum (Stamenković et al., 2020).

Acknowledgments

The author would like to thank two anonymous peer reviewers for their modification suggestions on the manuscript of the study and the team members for their help in collating the literature.

Conflict of Interest Disclosure

The author affirms that this research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest.

References

Appiah-Nkansah N., Li J., Rooney W., and Wang D., 2019, A review of sweet sorghum as a viable renewable bioenergy crop and its techno-economic analysis, Renewable Energy, 143: 1121-1132.

https://doi.org/10.1016/J.RENENE.2019.05.066

Batog J., Frankowski J., Wawro A., and Łacka A., 2020, Bioethanol production from biomass of selected sorghum varieties cultivated as main and second crop, Energies, 13(23): 6291.

https://doi.org/10.3390/en13236291

Brenton Z., Cooper E., Myers M., Boyles R., Shakoor N., Zielinski K., Rauh B., Bridges W., Morris G., and Kresovich S., 2016, A genomic resource for the development, improvement, and exploitation of sorghum for bioenergy, Genetics, 204: 21-33.

https://doi.org/10.1534/genetics.115.183947

Calvino M., and Messing J., 2012, Sweet sorghum as a model system for bioenergy crops, Current Opinion in Biotechnology, 23(3): 323-329.

https://doi.org/10.1016/j.copbio.2011.12.002

Carpita N., and McCann M., 2008, Maize and sorghum: genetic resources for bioenergy grasses, Trends in Plant Science, 13(8): 415-420.

https://doi.org/10.1016/j.tplants.2008.06.002

De Oliveira A., Pastina M., De Souza V., Da Costa Parrella R., Noda R., Simeone M., Schaffert R., De Magalhães J., Damasceno C., and Margarido G., 2018, Genomic prediction applied to high-biomass sorghum for bioenergy production, Molecular Breeding, 38: 49.

https://doi.org/10.1007/s11032-018-0802-5

Deshavath N., Mahanta S., Goud V., Dasu V., and Rao P.S., 2018, Chemical composition analysis of various genetically modified sorghum traits: pretreatment process optimization and bioethanol production from hemicellulosic hydrolyzates without detoxification, Journal of Environmental Chemical Engineering, 6(4): 5625-5634.

https://doi.org/10.1016/J.JECE.2018.08.002

Gautam S., Mishra U., Scown C., and Zhang Y., 2020, Sorghum biomass production in the continental United States and its potential impacts on soil organic carbon and nitrous oxide emissions, GCB Bioenergy, 12: 878-890.

https://doi.org/10.1111/gcbb.12736

Głąb L., and Sowiński J., 2019, Sustainable production of sweet sorghum as a bioenergy crop using biosolids taking into account greenhouse gas emissions, Sustainability, 11(11): 3033.

https://doi.org/10.3390/SU11113033

Guden B., Yol E., Erdurmuş C., Lucas S., and Uzun B., 2023, Construction of a high-density genetic linkage map and QTL mapping for bioenergy-related traits in sweet sorghum [Sorghum bicolor (L.) Moench], Frontiers in Plant Science, 14: 1081931.

https://doi.org/10.3389/fpls.2023.1081931

Habyarimana E., Lorenzoni C., Marudelli M., Redaelli R., and Amaducci S., 2016, A meta-analysis of bioenergy conversion relevant traits in sorghum landraces, lines and hybrids in the Mediterranean region, Industrial Crops and Products, 81: 100-109.

https://doi.org/10.1016/J.INDCROP.2015.11.051

Heitman A., Castillo M., Smyth T., and Crozier C., 2018, Stem, leaf, and panicle yield and nutrient content of biomass and sweet sorghum, Agronomy Journal, 110(5): 1659-1665.

https://doi.org/10.2134/AGRONJ2018.03.0178

Huang R., 2018, Research progress on plant tolerance to soil salinity and alkalinity in sorghum, Journal of Integrative Agriculture, 17: 739-746.

https://doi.org/10.1016/S2095-3119(17)61728-3

Jiang D., Hao M., Fu J., Liu K., and Yan X., 2019, Potential bioethanol production from sweet sorghum on marginal land in China, Journal of Cleaner Production, 220: 225-234.

https://doi.org/10.1016/J.JCLEPRO.2019.01.294

Lamb A., Weers B., McKinley B., Rooney W., Morgan C., Marshall-Colón A., and Mullet J., 2021, Bioenergy sorghum’s deep roots: a key to sustainable biomass production on annual cropland, GCB Bioenergy, 14(2): 132-156.

https://doi.org/10.1111/gcbb.12907

Mathias D., Edwiges T., Ketsub N., Singh R., and Kaparaju P., 2023, Sweet sorghum as a potential fallow crop in sugarcane farming for biomethane production in Queensland, Australia, Energies, 16(18): 6497.

https://doi.org/10.3390/en16186497

Mathur S., Umakanth A., Tonapi V., Sharma R., and Sharma M., 2017, Sweet sorghum as biofuel feedstock: recent advances and available resources, Biotechnology for Biofuels, 10: 146.

https://doi.org/10.1186/s13068-017-0834-9

Mocoeur A., Zhang Y., Liu Z., Shen X., Zhang L., Rasmussen S., and Jing H., 2015, Stability and genetic control of morphological, biomass and biofuel traits under temperate maritime and continental conditions in sweet sorghum (Sorghum bicolour), Theoretical and Applied Genetics, 128: 1685-1701.

https://doi.org/10.1007/s00122-015-2538-5

Mullet J., Morishige D., McCormick R., Truong S., Hilley J., McKinley B., Anderson R., Olson S., and Rooney W., 2014, Energy sorghum-a genetic model for the design of C4 grass bioenergy crops, Journal of Experimental Botany, 65(13): 3479-3489.

https://doi.org/10.1093/jxb/eru229

Nenciu F., Paraschiv M., Kuncser R., Stan C., Cocarta D., and Vlăduț V., 2021, High-grade chemicals and biofuels produced from marginal lands using an integrated approach of alcoholic fermentation and pyrolysis of sweet sorghum biomass residues, Sustainability, 14(1): 402.

https://doi.org/10.3390/su14010402

Nozari B., Mirmohamadsadeghi S., and Karimi K., 2018, Bioenergy production from sweet sorghum stalks via a biorefinery perspective, Applied Microbiology and Biotechnology, 102: 3425-3438.

https://doi.org/10.1007/s00253-018-8833-8

Ordonio R., Ito Y., Morinaka Y., Sazuka T., and Matsuoka M., 2016, Molecular breeding of Sorghum bicolor, a novel energy crop, International Review of Cell and Molecular Biology, 321: 221-257.

https://doi.org/10.1016/bs.ircmb.2015.09.001

Rivera-Burgos L., Volenec J., and Ejeta G., 2019, Biomass and bioenergy potential of brown midrib sweet sorghum germplasm, Frontiers in Plant Science, 10: 1142.

https://doi.org/10.3389/fpls.2019.01142

Roby M., Fernandez M., Heaton E., Miguez F., and VanLoocke A., 2017, Biomass sorghum and maize have similar water-use-efficiency under non-drought conditions in the rain-fed Midwest U.S., Agricultural and Forest Meteorology, 247: 434-444.

https://doi.org/10.1016/J.AGRFORMET.2017.08.019

Sainju U., Singh H., Singh B., Whitehead W., Chiluwal A., and Paudel R., 2018, Cover crop and nitrogen fertilization influence soil carbon and nitrogen under bioenergy sweet sorghum, Agronomy Journal, 110: 463-471.

https://doi.org/10.2134/AGRONJ2017.05.0253

Spindel J., Dahlberg J., Colgan M., Hollingsworth J., Sievert J., Staggenborg S., Hutmacher R., Jansson C., and Vogel J., 2018, Association mapping by aerial drone reveals 213 genetic associations for Sorghum bicolor biomass traits under drought, BMC Genomics, 19: 679.

https://doi.org/10.1186/s12864-018-5055-5

Stamenković O., Siliveru K., Veljković V., Bankovic-Ilic I., Tasic M., Ciampitti I., Đalović I., Mitrović P., Sikora V., and Prasad P., 2020, Production of biofuels from sorghum, Renewable & Sustainable Energy Reviews, 124: 109769.

https://doi.org/10.1016/j.rser.2020.109769

Tang C., Li S., Li M., and Xie G., 2018a, Bioethanol potential of energy sorghum grown on marginal and arable lands, Frontiers in Plant Science, 9: 440.

https://doi.org/10.3389/fpls.2018.00440

Tang C., Yang X., and Xie G., 2018b, Establishing sustainable sweet sorghum-based cropping systems for forage and bioenergy feedstock in North China Plain, Field Crops Research, 227: 144-154.

https://doi.org/10.1016/J.FCR.2018.08.011

Thomas H., Pot D., Jaffuel S., Verdeil J., Baptiste C., Bonnal L., Trouche G., Bastianelli D., Latrille É., Berger A., Calatayud C., Chauvergne C., Rossard V., Jeanson P., Alcouffe J., and Carrère H., 2021, Mobilizing sorghum genetic diversity: biochemical and histological‐assisted design of a stem ideotype for biomethane production, GCB Bioenergy, 13: 1874-1893.

https://doi.org/10.1111/gcbb.12886

Truong S., McCormick R., and Mullet J., 2017, Bioenergy sorghum crop model predicts VPD-limited transpiration traits enhance biomass yield in water-limited environments, Frontiers in Plant Science, 8: 335.

https://doi.org/10.3389/fpls.2017.00335

Wang R.R., Wang L., and Zhao D.G., 2024, Integrating QTL mapping and genomic selection in Eucommia ulmoides breeding, Molecular Plant Breeding, 15(5): 247-258.

https://doi.org/10.5376/mpb.2024.15.0024

Xin Z., and Wang M., 2011, Sorghum as a versatile feedstock for bioenergy production, Biofuels, 2: 577-588.

https://doi.org/10.4155/bfs.11.125

Yang L., Zhou Q., Sheng X., Chen X., Hua Y., Lin S., Luo Q., Yu B., Shao T., Wu Y., Chang J., Li Y., and Tu M., 2023, Harnessing the genetic basis of sorghum biomass-related traits to facilitate bioenergy applications, International Journal of Molecular Sciences, 24(19): 14549.

https://doi.org/10.3390/ijms241914549

Yücel C., Yücel D., Hatipoğlu R., and Dweikat I., 2022, Research on the potential of some sweet sorghum genotypes as bioethanol source underMediterranean conditions, Turkish Journal of Agriculture and Forestry, 46(2): 141-151.

https://doi.org/10.55730/1300-011x.2966

Zuo W., Gu C., Zhang W., Xu K., Wang Y., Bai Y., Shan Y., and Dai Q., 2019, Sewage sludge amendment improved soil properties and sweet sorghum yield and quality in a newly reclaimed mudflat land, The Science of the Total Environment, 654: 541-549.

https://doi.org/10.1016/j.scitotenv.2018.11.127