Sweet sorghum and Miscanthus：Two potential dedicated bioenergy crops in China

Among the potential non-food energy crops,the sugar-rich C4 grass sweet sorghum and the biomass-rich Miscanthus are increasingly considered as two leading candidates.Here,we outline the biological traits of these energy crops for largescale production in China.We also review recent progress on understanding of plant cell wall composition and wall polymer features of both plant species from large populations that affect both biomass enzymatic digestibility and ethanol conversion rates under various pretreatment conditions.We finally propose genetic approaches to enhance biomass production,enzymatic digestibility and sugar-ethanol conversion efficiency of the energy crops.

Land Resource Areas and Spatial Analysis of Potential Location of Bioenergy Crops Production in Mississippi

Mississippi State is renowned for its land resource areas (LRA) and production of bioenergy crops which generate both agricultural and economic benefits. Agricultural commodities play a key role in economic growth, therefore the ability to produce more would enhance development. This paper offers an analysis of the production of bioenergy crops in Mississippi. Relative measures, time series graphs and descriptive statistics coupled with geographic information systems (GIS) mapping using ArcMap were employed to generate the outcome of this research. The outcome of the statistical analysis indicated that corn and soybeans were the most produced crops in Agricultural Districts 10 and 40. These districts produced more bioenergy crops than the other districts. GIS mapping results also showed that the potential area for bioenergy crops is in zone 131 of the Mississippi Land Resource Area (MLRA). This zone has an absolute advantage in the production of these crops which includes the diversity of biomass production such as corn, cotton, soybeans, wheat, rice, barley, grain sorghum, canola, camelina, algae, hardwoods, and softwood. The paper recommends a constant GIS mapping and land management systems for each agricultural district in Mississippi to enable researchers and farmers to determine the factors which contribute towards the increasing and decreasing trends in the production of the bioenergy crops.

Bioenergy Crops as a Promising Alternative to Fossil Fuels in Louisiana: A Geographic Information System (GIS) Perspective

Rising greenhouse gas emissions are causing climate change, and the world’s focus has shifted to the need to reduce our reliance on fossil fuels. There has been a rise in the published literature on the utilization of crops for bioenergy production in Louisiana. However, very few scholarly documents have used Geographic Information Systems (GIS) to map the distribution of potential bioenergy crops in Louisiana. This study seeks to fill the void by evaluating the potential of bioenergy crops in Louisiana for energy production using GIS. Given this objective, the agricultural census data for 1999, 2009, 2019, and 2020 obtained from the U.S. Department of Agriculture were used in the analysis. The quantities of various crops produced in the state were loaded into an attribute table and joined to a shapefile using ArcGIS software. The symbology tool’s graduated option was used to create five maps representing each of the bioenergy crops in Louisiana. The findings of the GIS analysis show that some of the parishes, such as Franklin produced the most bushels of corn (13,795,416), Iberia produced the most tons of sugarcane (1,697,980), East Carroll produced the most bushels of soybean (8,237,991), Tensas harvested the most bales of cotton (80,898) and Avoyelles produced the most bushels of sorghum (630,694). The abundance and availability of crops as raw materials for energy production will translate into lower prices in terms of energy use, making bioenergy crops a promising alternative to fossil fuels. In addition, gasoline price data from 1993-2022 was obtained from U.S. Energy Information Administration. A regression model for the average annual gasoline price over the years was constructed. The results show that the average annual gasoline price variation with respect to years is statistically significant (p 0.05). This suggests that gasoline prices will generally rise despite a price drop over the years. The paper concludes by outlining policy recommendations in the form of assessing the availability and viability of other crop types, such as wheat, oats, and rice, for energy production in the state.

A study on the bioenergy crop production function of land use in China

Based on the analysis of the bioenergy crop production function of land use,combined with the status quo of Chinese land use,the cultivation of energy plants and the bioenergy crop production function of land use had been analyzes and discusses in this paper.Results show that there were a lot of unused lands and marginal lands which can be planted bioenergy crops to perform the bioenergy crop production function of land use with great potentials;and currently there were no food production problems.Therefore,it was very important for China to emphasize bioenergy crops planting in order to fully use land resources in our country,moderate the energy crisis and increase peasants' income.

Switchgrass as a bioenergy crop in the Loess Plateau, China：Potential lignocellulosic feedstock production and environmental conservation

A large portion of the Loess Plateau of China is characterized as “marginal” with serious land degradation and desertification problems. Consequently, two policies, Grain for Green and Western Development Action were established by the Chinese government in response to the demand for ecological protection and economic development in the Loess Plateau. These policies are designed to increase forest cover, expand farmlands, and enhance soil and water conservation, while creating sustainable vegetation restoration. Perennial grasses have gained attention as bioenergy feedstocks due to their high biomass yields, low inputs, and greater ecosystem services compared to annual crops. Moreover, perennial grasses limit nutrient runoff and reduce greenhouse gas emissions and soil losses while sequestering carbon. Additionally, perennial grasses can generate economic returns for local farmers through producing bioenergy feedstock or forage on marginal lands. Here, we suggest a United States model energy crop, switchgrass（Panicum virgatum L.） as a model crop to minimize land degradation and desertification and to generate biomass for energy on the Loess Plateau.

Changes in the Regulating Ecosystem Service on the Contaminated Site Used for Energy Purposes

Soil cleaning, the ability of the soil to immobilize the risk elements, belongs to important agroecosystem services in terms of protection of the hydrosphere and plant production from contamination. Dynamic monitoring of selected indicators of soil quality was realized in a special network of site on soil used for planting fast growing willow (Salix viminalis). Monitoring of the study site Kuchyňa (Mollic Fluvisol) is running since 2010 year. The fast-growing willow was planted on an area of about 43 hectares. Study site Kuchyňa belonged to the degraded contaminated sites, at the time of planting (the total contents of the risk elements were as follows: Cd 1.016 mg∙kg−1, Zn 199.000 mg∙kg−1, Ni 51.500 mg∙kg−1) There were positive changes in the total content of cadmium, zinc and nickel (in 2018 year), the zinc content decreased by 27% compared to 2010, the nickel content was lower by 23% and the Cd content by 57% in comparison to 2010 year, these elements have a declining trend during the monitored period. The remediation ability of the willow in relation to the risk elements was manifested by the accumulation of these elements in the wood mass and by their decrease in the soil below the limit value. The regulatory ecosystem service, the potential for the immobilisation of the risk elements, was evaluated based on the sum of the assessment of the contamination potential and the sorption potential of soil. The decrease of the total content of risk elements in the soil below the limit value was manifested in the increase of the potential of the agroecosystem regulatory service, the potential of risk element immobilisation, from very low category to medium category. If willow cultivation continued in the next decade, the value of risk element Zn would most likely reach the value 73 mg∙kg−1, which is less than 50% of the limit value, based on the results of the predictive model. In the case of Cd, the soil would be completely cleaned and in the case of Ni, its total content in the soil would fall to 23 mg∙kg−1, which is less than 40% of the limit value. The overall potential for contamination would fall into the category—very low (forecast for 2021 year). The higher potential of immobilisation reduces the risk of contaminants transport and thus prevents contamination of the other ecosystem components such as biota.

Food Conditioning Affects Expression of Insect Resistance in Diploid Willows(Salix spp.)

The high energy quota and versatility of use make willows (Salix spp.) attractive as bioenergy crops. Insect defoliation constitutes a threat to the profitability of willow growers. Hitherto, the breeding for resistance against the main insect pests has been hampered by the fact that all known resistant willow clones are polyploids, and existing molecular breeding tools work most effectively for diploids. Here, we firstly report diploid willows highly resistant to the main insect defoliator, the leaf beetle (Phratora vulgatissima), offering new opportunities for breeding resistance. Leaf beetles exposed to three resistant clones (two S. purpurea one S. eriocephala) laid three to 27 times fewer eggs than females on a susceptible S. viminalis clone. Secondly, we show that beetles laid significantly more eggs on resistant clones if they were fed the susceptible clone prior to the oviposition monitoring test compared to when they prefed on resistant clones. Nevertheless, the differences observed between resistant and susceptible clones were pronounced in all cases. The food conditioning effect means that small differences in resistance among clones may be undetected.

Net primary production in three bioenergy crop systems following land conversion

Aims Identifying the amount of production and the partitioning to above-and belowground biomass is generally the first step toward select-ing bioenergy systems.There are very few existing studies on the dynamics of production following land conversion.The objectives of this study were to(i)determine the differences in aboveground net primary production(ANPP),belowground net primary produc-tion(BNPP),shoot-to-root ratio(S:R)and leaf area index in three bioenergy crop systems and(ii)evaluate the production of these three systems in two different land use conversions.Methods This investigation included biometric analysis of NPP on three agri-cultural sites converted from conservation reserve program(CRP)management to bioenergy crop production(corn,switchgrass and prairie mix)and three sites converted from traditional agriculture production to bioenergy crop production.Important findings The site converted from conventional agriculture produced smaller ANPP in corn(19.03±1.90 standard error[SE]Mg ha^(−1) year^(−1))than the site converted from CRP to corn(24.54±1.43 SE Mg ha^(−1) year^(−1)).The two land conversions were similar in terms of ANPP for switchgrass(4.88±0.43 SE for CRP and 2.04±0.23 SE Mg ha^(−1) year^(−1) for agriculture)and ANPP for prairie mix(4.70±0.50 SE for CRP and 3.38±0.33 SE Mg ha^(−1) year^(−1) for agriculture).The BNPP at the end of the growing season in all the bioenergy crop systems was not significantly different(P=0.75,N=8).

Growth and metal uptake of energy sugarcane (Saccharum spp.) in different metal mine tailings with soil amendments

A pot experiment was conducted to investigate the feasibility of growing energy sugarcane （Sac- charum spp.） in three different metal mine railings （Cu, Sn and Pb/Zn tailings） amended with uncontaminated soil at different mixing ratios. The results indicated that sugarcane was highly tolerant to tailing environments. Amendments of 20% soil to Sn tailings and 30% soil to Cu tailings could increase the biomass of cane-stem for use as the raw material for bioethanol production. Heavy metals were mostly retained in roots, which indicated that sugarcane was useful for the stabilization of the tailings. Bagasse and juice, as the most valuable parts to produce bioethanol, only accounted for 0.6%- 3% and 0.6%-7% of the total metal content. Our study supported the potential use of sugarcane for tailing phytostabilization and bioenergy production.

Contribution of arbuscular mycorrhizal fungi and soil amendments to remediation of a heavy metal-contaminated soil using sweet sorghum

Owing to their potential advantages such as waste reduction,recycling,and economic attributes,fast-growing bioenergy crops have the capacity to effectively phytoremediate heavy metal-contaminated soils.However,little is known about the role of microbial and chemical amendments in phytoremediation using bioenergy crops.Here,we studied the contributions of inoculation with the arbuscular mycorrhizal fungus(AMF)Acaulospora mellea ZZ and three soil amendments,i.e.,hydroxyapatite(HAP),manure,and biochar,at doses of 0.1%and 1%(weight:weight)to heavy metal phytoremediation using sweet sorghum grown on an abandoned agricultural soil,with environmentally realistic contamination(2.6 mg kg^(-1) Cd,1796 mg kg^(-1) Pb,and 1603 mg kg^(-1) Zn),in a plant growth chamber.Mycorrhizal colonization,plant biomass and metal accumulation,metal availability,and soil pH were determined in harvested seedlings 12 weeks after sowing.The results showed that root colonization by indigenous AMF decreased by 28%-46%with HAP,but increased after manure and biochar applications as compared to the no amendment control(CK).The AMF inoculation increased root colonization rates by 16%^(-1)28%and in particular,alleviated the inhibition of HAP.The remediation effects were highly dependent on the amendment type and dose.Among the three soil amendments,HAP was the most effective in promoting plant growth and phytostabilization of Cd,Pb,and Zn and phytoextraction of Cd,particularly at a dose of 1%.Compared to CK,1%HAP decreased DTPA-extractable Cd,Pb,and Zn concentrations in soil by 31%-43%,30%-38%,and 22%-23%,respectively.Manure and biochar also exerted positive effects on heavy metal immobilization,as indicated by lower DTPA extractability,but only the 1%manure treatment showed plant growth-promoting effect.The AMF inoculation did not affect plant growth,but increased soil pH and induced synergistic interactions with amendments on the immobilization of Cd and Pb.In conclusion,soil amendments,particularly HAP,produced positive impacts and synergistic interactions with AMF on the phytostabilization of heavy metals using sweet sorghum.Accordingly,sweet sorghum combined with soil amendments and AMF may be an effective strategy for heavy metal phytoremediation.

Sweet sorghum for phytoremediation and bioethanol production

As an energy crop,sweet sorghum(Sorghum bicolor(L.)Moench)receives increasing attention for phytoremedia‑tion and biofuels production due to its good stress tolerance and high biomass with low input requirements.Sweet sorghum possesses wide adaptability,which also has high tolerances to poor soil conditions and drought.Its rapid growth with the large storage of fermentable saccharides in the stalks offers considerable scope for bioethanol pro‑duction.Additionally,sweet sorghum has heavy metal tolerance and the ability to remove cadmium(Cd)in particular.Therefore,sweet sorghum has great potential to build a sustainable phytoremediation system for Cd‑polluted soil remediation and simultaneous ethanol production.To implement this strategy,further efforts are in demand for sweet sorghum in terms of screening superior varieties,improving phytoremediation capacity,and efficient bioetha‑nol production.In this review,current research advances of sweet sorghum including agronomic requirements,phytoremediation of Cd pollution,bioethanol production,and breeding are discussed.Furthermore,crucial problems for future utilization of sweet sorghum stalks after phytoremediation are combed.