Sugarcane Production Regions Research Articles

Biological development of Saccharicoccus sacchari () (Hemiptera: Pseudococcidae) on sugarcane in different temperatures.

The pink sugarcane mealybug Saccharicoccus sacchari (Cockerell, 1895) (Hemiptera: Pseudococcidae) occurs practically in all sugarcane producing regions Saccharum spp. (Poaceae) causing damage. Little information is available about insect's biology under Brazilian conditions. In this work, biological development of pink sugarcane mealybug was studied at temperatures of 23 °C ± 2 °C and 28 °C ± 2 °C without photophase and relative humidity of 80%. Number and viability of eggs, incubation time, duration of the last oviposition, duration of each nymphal instar, viability of the nymphs, start of oviposition and longevity of the females were recorded. Biological development of insects was stipulated by the SAS University Edition software, version 9.4. There were differences in the life cycle of the pseudococcid at both temperatures evaluated. Females of S. sacchari had three nymphal instars and reproduce asexually. Asexual reproduction occurs in the field and under controlled conditions. By increasing the temperature increases, insect lived longer and the presence of the winged male in Brazil indicates the possibility of sexual reproduction of the species.

Long-term vinasse application enhanced the initial dissipation of atrazine and ametryn in a sugarcane field in Tucumán, Argentina.

The production of sugarcane bioethanol generates large volumes of vinasse, an effluent whose final disposal can produce an environmental impact that is of concern. The long-term disposal of vinasse in sugarcane fields could challenge crop management, such as the performance of traditional herbicides, by changing soil properties. This study aimed to evaluate the effect of long-term vinasse application on the field and the dissipation of atrazine and ametryn herbicides in a subtropical sugarcane agroecosystem, and to discuss the potential processes involved in it. Vinasse affected soil properties by increasing pH (12%), electrical conductivity (160%), and soil organic carbon (25%) at 0-10 cm depth of soil. Differences in the herbicide calculated sorption coefficient (Kd) varied according to the pedotransfer function applied and the herbicide type (atrazine or ametryn). During the first seven days after herbicide application, the soil underwent long-term vinasse application and increased atrazine and ametryn dissipation 45% and 33%, respectively, compared with the conventional fertilization scheme (control). The Pesticide Root Zone Model revealed that dissipation was mediated mainly by the degradation process rather than transport or other processes. The long-term application of vinasse in a typical sugarcane field of Tucumán, Argentina decreased the potential groundwater pollution of triazines and, adversely, reduced their bioavailability for weed control. For this, the present study presents original information about how long-term treatment with vinasse may require an adaptation of conventional management practices such as the application of herbicides in Argentina and other sugarcane-producing regions. Integr Environ Assess Manag 2024;20:1075-1086. © 2023 SETAC.

Predicting Sugarcane Yield via the Use of an Improved Least Squares Support Vector Machine and Water Cycle Optimization Model

As a raw material for sugar, ethanol, and energy, sugarcane plays an important role in China’s strategic material reserves, economic development, and energy production. To guarantee the sustainable growth of the sugarcane industry and boost sustainable energy reserves, it is imperative to forecast the yield in the primary sugarcane production regions. However, due to environmental differences caused by regional differences and changeable climate, the accuracy of traditional models is generally low. In this study, we counted the environmental information and yield of the main sugarcane-producing areas in the past 15 years, adopted the LSSVM algorithm to construct the environmental information and sugarcane yield model, and combined it with WCA to optimize the parameters of LSSVM. To verify the validity of the proposed model, WCA-LSSVM is applied to two instances based on temporal differences and geographical differences and compared with other models. The results show that the accuracy of the WCA-LSSVM model is much better than that of other yield prediction models. The RMSE of the two instances are 5.385 ton/ha and 5.032 ton/ha, respectively, accounting for 7.65% and 6.92% of the average yield. And the other evaluation indicators MAE, R2, MAPE, and SMAPE are also ahead of the other models to varying degrees. We also conducted a sensitivity analysis of environmental variables at different growth stages of sugarcane and found that in addition to the main influencing factors (temperature and precipitation), soil humidity at different depths had a significant impact on crop yield. In conclusion, this study presents a highly precise model for predicting sugarcane yield, a useful tool for planning sugarcane production, enhancing yield, and advancing the field of agricultural production prediction.

I-RAT: A discussion support system to rapidly assess economic and environmental impacts of different sugarcane irrigation practices

Water pollution and climate change are among the greatest threats to the iconic Great Barrier Reef (GBR). To improve the GBR’s long-term outlook, making improvements on these fronts is required. Owing to the complex interactions between soils, climate, and farm management, a tool is needed to guide agricultural land managers about which management practice changes are more likely to deliver improved water quality and climate resilience outcomes whilst maintaining profitability. Using concepts drawn from social studies of science and technology, a ‘discussion’ support system (DSS) named Irrigation Rapid Assessment Tool (i-RAT) was developed through participatory processes designed to enhance co-learning from the development of this DSS. i-RAT is a rapid assessment-visualisation tool in an interactive web application (https://i-rat.net) to visualise the impacts of changed irrigation practices for sugarcane farmers and extension staff. Specifically, i-RAT compares these impacts regarding farm economics, water quality, productivity, carbon and nitrogen cycles, and greenhouse gas emission. The core of i-RAT is the sugarcane module from the Agricultural Production Systems sIMulator (APSIM) modelling platform. i-RAT was first developed for the Burdekin sugarcane growing region in Queensland (Australia’s largest sugarcane producing region). Various soil types and management scenarios representing farming practices in the Burdekin region were used for simulations (1971–2021) to generate a datacube. In this paper, we describe how fundamental learnings about more (drought) resilient farming systems and more sustainable irrigation practices can be extracted from i-RAT. Details of the participatory approach with research and industry partners that informed the design and function of i-RAT and how APSIM was set up and parameterised are described. A ‘what-if’ analysis demonstrated the i-RAT features and application.

Assessing Drought, Flood, and High Temperature Disasters during Sugarcane Growth Stages in Southern China

As a globally important sugarcane-producing region, Southern China (SC) is severely affected by various agrometeorological disasters. This study aimed to comprehensively assess multiple sugarcane agrometeorological disasters with regards to sugarcane yield in SC. The standardized precipitation evapotranspiration index and the heat degree-days were employed to characterize drought, flood, and high temperature (HT) during sugarcane growth stages in three provinces in SC in the period 1970–2020. Moreover, the relationships between sugarcane climatic yield and disaster intensities were investigated. The results indicated that the most recent decade witnessed the most intensive sugarcane agrometeorological disasters; sugarcane drought and HT intensities significantly (p < 0.05) increased in one and two provinces, respectively. Central and western SC was most drought-prone, while eastern SC was most flood-prone; sugarcane HT was concentrated in southwestern SC. The mature stage exhibited the greatest monthly intensities of drought and flood; the most HT-prone growth stage varied with provinces. The relationships between drought/flood intensity and sugarcane climatic yield were significant in seven districts; the yield-reducing effect of sugarcane flood was more obvious than that of drought. In conclusion, this study provides references for agrometeorological disaster risk reduction for sugarcane in SC.

Climate risk scenarios of orange rust for the sugarcane-producing regions of Argentina and Brazil

Risk analysis of climate change on the spatial distribution of sugarcane orange rust (Puccinia kuehnii) is a strategic study for plant protection to minimize future damages. The objective of this work was to evaluate the potential risk of the occurrence of orange rust in Argentina and Brazil under the climate change scenarios. A mapping methodology integrated the data of climate projections and the phytosanitary problem supported by Geographic Information System (GIS). Normal climate (1961-1990) and future climate (2011-2040, 2041-2070, and 2071-2100) from Intergovernmental Panel on Climate Change were considered. The conditions of climatic favorability for the occurrence of the disease were established by means mathematical logic criteria of GIS, based on knowledge of the authors, who incorporated the implicit effects of the interaction of the virulent pathogen, susceptible host, and predisposing environmental characteristics. The favorability for the occurrence of sugarcane orange rust in the main sugarcane producing regions of Argentina and Brazil varied over the months considered of the cultivation cycle. For Argentina, the future climate scenarios predicted a reduction in favorability for the occurrence of sugarcane orange rust from December to February and an increase in April. In Brazil, the climatic favorability decreased from December to March and increased in May.

Remote sensing-based evapotranspiration modeling using geeSEBAL for sugarcane irrigation management in Brazil

Irrigated agriculture requires the implementation of innovative tools to improve irrigation water management and accurate estimation of actual evapotranspiration (ETa) such as remote sensing-based methodology. This study aimed to evaluate the irrigation management and estimating evapotranspiration through the geeSEBAL, a new tool for automated estimation of ETa based on the Surface Energy Balance Algorithm for Land (SEBAL) and a simplified version of the Calibration using Inverse Modeling at Extreme Conditions (CIMEC) process for the endmembers selection, implemented into the Google Earth Engine (GEE) environment. GeeSEBAL has not been used yet in Brazil for irrigation proposes, and in this research, it was applied to estimate ETa using Landsat images and ERA5-Land as meteorological inputs in the largest sugarcane producing region of the world in Brazil for two ratoon seasons by comparing daily ETa with values obtained from eddy covariance (EC) data, Energy balance components using geeSEBAL were consistent with the measured data and daily ETa presenting RMSE of 0.46 mm with R2 = 0.97. Modeled ETa and Kc were similar for the two seasons, although somewhat overestimated for the fifth ratoon when compared to the EC data, mainly during high atmospheric demand (crop mid-stage). Still, the Kc values were similar to the standard values available in the literature and measured flux tower data for the two ratoons seasons. With ETa from geeSEBAL it was possible to identify water stress over the growing seasons using the remote sensing-based soil water balance, which occurred mainly during the phase after the crop reached the peak Kc (full cover stage) when the irrigation depth required was very high. This analysis showed that geeSEBAL has a significant potential for assessment of ETa for irrigation monitoring and management, even in missing climate data areas, allowing important advances in water resources management for sugarcane and other irrigated crops at field or regional scales.

UFSM XIKA FW: sugarcane cultivar for southern Brazil

In Brazil, in view of the different soil and climatic conditions of the sugarcane-producing regions, a strategy of creating small breeding programs for the crop is being used. Since 2008, the sugarcane breeding program of the Federal University of Santa Maria (UFSM), has been developing new, better adapted and higher-yielding sugarcane cultivars for the climate conditions of the southern region of Brazil. Cultivar UFSM XIKA FW was developed at the Laboratories of Agroclimatology and Genetic Breeding and Plant Production of the UFSM, Campus Frederico Westphalen. It is the first mutation-induced sugarcane cultivar that was protected by the Ministry of Agriculture, Livestock and Food Supply, Brazil. The genotype used for mutation induction was cultivar IAC 87-3396, due to its good performance characteristics in the southern region. The mutation mechanism was induced in 2011, by immersing individual buds in a solution of the chemical mutagenic agent methyl methane sulfonate. The best genotypes were selected and tested in plant cane in 2013 and 2018 and in ratoon cane trials in 2014 and 2015. The new cultivar has a higher sugar production potential, and the mean yield of four years was 8.2 t ha-1 higher than that of the control, indicating a high yield potential.

SsPEP1, an Effector with Essential Cellular Functions in Sugarcane Smut Fungus.

Biotrophic fungi have to infect their host to obtain nutrients and must establish an interaction with the host to complete their life cycle. In this process, effectors play important roles in manipulating the host’s immune system to avoid being attacked. Sporisorium scitamineum is the causative agent of sugarcane smut, the most important disease in sugarcane-producing regions worldwide. In this work, we functionally characterized the conserved effector PEP1 in S. scitamineum. The mating process and the expression of genes in the MAPK signaling pathway and the a and b loci were adversely affected in Sspep1-null mutants. The requirement for SsPEP1 in pathogenicity and symptom development was allele dosage-dependent, i.e., deleting one Sspep1 allele in the mating pair turned a normal black whip with abundant teliospores into a white whip with few teliospores; however, deleting both alleles almost abolished infectivity and whip development. ΔSspep1 mutants produced significantly less mycelium mass within infected plants. Additionally, SsPEP1 was identified as a potent inhibitor of sugarcane POD-1a peroxidase activity, implying that SsPEP1 may function to relieve reactive oxygen species-related stress within the host plant. Taken together, our work demonstrated that SsPEP1 is a multifaceted effector essential for S. scitamineum growth, development, and pathogenicity.

Incidence, Geographical Distribution, and Genetic Diversity of Sugarcane Striate Virus in Saccharum Species in China.

A novel virus of the genus Mastrevirus, family Geminivirdae, has been reported in sugarcane germplasm collections in Florida, Guadeloupe, and Réunion, and was named sugarcane striate virus (SStrV). Although the full-length sequence of an SStrV isolate from China was obtained in 2015, the incidence, geographical distribution, and genetic diversity of this virus remained unclear. A single leaf sample from 2,368 sugarcane plants from main sugarcane-producing regions of China and germplasm collections were tested for SStrV by PCR. Average virus incidence was 25.1% for field-collected samples, and SStrV was detected in most Saccharum species and two sugarcane-related species, with the highest incidence in Saccharum officinarum (44.1%) followed by Saccharum spp. local varieties (33.3%) grown for chewing cane for a long time. The virus incidence was much lower (6.8%) in modern commercial cultivars (Saccharum spp. hybrids). Phylogenetic trees based on full-length genomes of 157 SStrV isolates revealed that Chinese isolates comprised strains A and B, but not C and D, that were reported in Florida, U.S.A. SStrV strain A was the most prominent (98.7%) and widespread strain in China and was further divided into eight subgroups. Almost half (45.6%) of the SStrV-positive samples from S. officinarum and Saccharum spp. local varieties were coinfected with sugarcane mosaic disease viruses or sugarcane yellow leaf virus. Interestingly, most of the plants infected by strain A of SStrV were asymptomatic. SStrV appears to be widespread in China, and its influence on chewing cane deserves further investigation.

An Application of Optimal Control to Sugarcane Harvesting in Thailand

The sugar industry is of great importance to the Thai economy. In general, the government sets sugarcane prices at the beginning of each harvesting season based on type (fresh or fired), sweetness (sugar content) and gross weight. The main aim of the present research is to use optimal control to find optimal sugarcane harvesting policies for fresh and fired sugarcane for the four sugarcane producing regions of Thailand, namely North, Central, East and North-east, for harvesting seasons 2012/13, 2013/14, 2014/15, 2017/18 and 2018/19. The optimality problem is to determine the harvesting policy which gives maximum profit to the farmers subject to constraints on the maximum amount that can be cut in each day, where a harvesting policy is defined as the amount of each type of sugarcane harvested and delivered to the sugar factories during each day of a harvesting season. The results from the optimal control methods are also compared with results from three optimization methods, namely bi-objective, linear programming and quasi-Newton. The results suggest that discrete optimal control is the most effective of the five methods considered. The data used in this paper were obtained from the Ministry of Industry and the Ministry of Agriculture and Co-operatives of the Royal Thai government.

Soil health response to sugarcane straw removal in Brazil

Sugarcane straw removal is a promising strategy to increase bioenergy production in Brazil. However, if straw removal is not properly managed, it may lead to soil health degradation, thus threatening sustainability of the entire bioenergy production system. In this context, a comprehensive assessment was conducted in 12 field experiments located in central-southern Brazil, the world’s largest sugarcane-producing region, to investigate the impacts of straw removal scenarios on soil health, using the Soil Management Assessment Framework (SMAF). Two groups of experiments were arranged in this study, consisting of three (no–NR; moderate–MR; and total removal–TR) and four straw removal treatments (NR; low–LR; high–HR; and TR). Soil samples were collected (0–10 and 10−20 cm) to evaluate a selected set of soil health indicators (i.e., pH, available phosphorus, exchangeable potassium, bulk density and soil organic carbon). Indicators were individually scored and then integrated into an overall Soil Health Index (SHI) and its chemical, physical, and biological components. Datasets were analyzed by site, experiment groups and soil texture (clayey and sandy soils) and the relationships among straw removal, soil health, and sugarcane yield were also investigated. Our findings showed that soil health responses to straw removal were properly detected by SMAF scoring curves. Based on SHI, sandy and clayey soils were functioning at 41–56% and 67–86% of their full potential, respectively. Soil health degradation was mostly induced by TR and HR, while LR and MR resulted in minimal detrimental effects on a short-term basis compared with NR. However, sandy soils were more prone to soil health degradation, indicating that straw removal should be avoided on those soils. For clayey soils, decline in soil health was driven by physical degradation. Healthier soils were associated with higher sugarcane stalk yields, and physical degradation was the main driver for crop yield losses. Conclusions drawn from this study suggest that comprehensive soil health assessments by integrating chemical, physical and biological indicators are fundamental to design more sustainable straw management and bioenergy production systems in Brazil.

The reappearance of the early shoot borer Chilo infuscatellus in Java’s sugarcane

Chilo infuscatellus is one of the earliest identified and reported borer species from Java’s sugarcane. The study aimed to describe the composition and distribution of the shoot borer species attacking young sugarcane plants. Field surveys were conducted in 19 sampling sites in the sugarcane fields in Malang, Kediri and Pati. The plant samples with dead heart symptoms were taken from fields to the laboratory to be observed the borer’s attacks and identified the species. The finding of C. infuscatellus in all field samples confirmed that this species did not disappear from the sugarcane crop in Java. Along with this borer, other borer species had been discovered, namely C. sacchariphagus, C. auricilius, Tetramoera schistaceana, Scirpophaga excerptalis and Sesamia inferens. Further study needs to be done to investigate the borer distribution across sugarcane producing regions along with its potential loss due to the borer infestation.

Regional wind pattern, a basis for defining the appropriate lapse of time for sugarcane burning in the Cauca Valley (Colombia)

Pre-harvest burning, an activity associated with manual sugarcane cutting, repels poisonous animals and makes harvesting considerably more straightforward and quicker. However, some reports from other countries that associate pre-harvest burning with human illness determined a change in the sugarcane harvest management. New crop management was based on green harvesting and the use of wind data to decide the right moment for burning. This work aimed to know the standard wind patterns to design strategies that allow sugar mills to burn sugarcane crops with minimum human health impacts. This study was based on the elaboration and analysis of 4320 wind rose plots of 30 weather stations located in the Colombian sugarcane production region. The analysis was performed at daily and monthly scales. The analysis considered the wind speed and wind direction values that increase the risk of affecting a settlement with the particulate matter when burning is done. Results showed that this region has local wind patterns that predominate direction and speed changes in response to the daily cycle. The main factor increasing the risk mentioned above is the wind speed. In this area, calm events (wind speed 5 m s−1) determine restrictions for crop burning 66% of the time. In the remaining 34% of the time, risk depends on the wind direction, and this is the ideal lapse of time for seeking the right moment for burning. The results are a tool for decision-making at different levels.

Sugarcane evapotranspiration and irrigation requirements in tropical climates

Irrigation is necessary to help meet the high demand for water by sugarcane in several countries including Brazil and Australia. The crop irrigation requirements are typically estimated using the crop coefficient-reference evapotranspiration (Kc-ETo) procedure. Sugarcane evapotranspiration rates were measured in three different sugarcane-producing regions of the world, and crop coefficients (Kc) were derived for those diverse environments, irrigation methods, and farming systems, therefore representing a robust basis for irrigation management. We also verified the occurrence of the inverse relation between Kc and ETo found in previous studies. Two experiments in Brazil and one in Australia were used for the analysis. Our data showed that Kc for a full canopy cover was lower than 1.0 in the three experimental sites and that sugarcane evapotranspiration (ETc) seems to be limited and exceeds ETo only when this is below 4 mm day−1. In one of the Brazilian experiments, Kc declined at higher rates than in the other two experiments, and for the three sites, average Kc was 0.77 and 0.87, respectively, for initial and full cover phase when ETo > 6 mm day−1. The increase of aerodynamic and other upstream resistances to water transport of plants appears to be one of the reasons for Kc to decrease at high levels of ETo. Based on our data and the literature, the Kc values provided by Allen et al. (1998) could overestimate the irrigation needs of sugarcane under high evaporative demand conditions. Irrigation management based on Kc should use the average ETo from the preceding 3 days before irrigating to save water and energy while maintaining high yield levels.

Determining optimal policies for sugarcane harvesting in Thailand using bi-objective and quasi-Newton optimization methods

In Thailand, the harvesting season for sugarcane usually begins in November and ends the following May. At the beginning of each harvesting season, the Royal Thai government sets the price of two types of sugarcane, namely fresh and fired, based on sweetness (sugar content) and gross weight of sugarcane delivered to the sugar factories. The aim of the present research is to determine optimal harvesting policies for the two types of sugarcane in sugarcane producing regions of Thailand in order to maximize revenue and minimize harvesting cost. In this paper, a harvesting policy is defined as the amount of each type of sugarcane harvested and delivered to the sugar factories during each 15-day period of a harvesting season. Two optimization methods have been used to solve this optimization problem, namely the ε-constraints method and a quasi-Newton optimization method. In the ε-constraints method, the problem is considered as a bi-objective optimization problem with the main objective being to determine harvesting policies that maximize the total revenue subject to upper bounds on the harvesting cost. In the quasi-Newton method, the aim is to determine the harvesting policy which gives maximum profit to the farmers subject to constraints on the maximum amount that can be cut in a 15-day period. The methods are used to determine optimal harvesting policies for the north, central, east, and north-east regions of Thailand for harvesting seasons 2012/13, 2013/14, and 2014/15 based on the data obtained from the Ministry of Industry and the Ministry of Agriculture and Co-operatives of the Royal Thai government.

Simulating scenarios for compost and vinasse use to improve the economics and environmental aspects of representative Colombian sugarcane production systems

AbstractThe Colombian industrial sector is moving toward alternative forms of treatment of industrial waste, considering that the waste can be a source of raw material in the production chain. Thus, aiming at the decrease in mineral fertilizer use, and maintaining or even raising the crop yield, the sugarcane industry has recently advanced in the composting of the industrial waste and application in the field, both of them being potentially sustainable practices. This manuscript reports the economic benefits and the greenhouse gas (GHG) emissions related to the sugarcane production system in Colombia that has been simulated in this study to evaluate the beneficial effects of reusing industrial waste from ethanol production. This study was performed using the Virtual Sugarcane Biorefinery (VSB) modeling software for the simulation of agricultural and industrial parameters on integrated alternatives for the sugarcane industry. Colombian sugarcane sector was modeled using three scenarios representing agricultural systems that do not use composted industrial waste vs a paired scenario for each condition where composted waste is utilized. Regarding compost and vinasse use as fertilizer and soil conditioner, GHG emissions from the biogenic origin are not included as a reported item in the matrix of GHG emissions of the sugarcane sector. Inputs for the economic and environmental assessment models are based on actual operational data from two mill sites, one located in the traditional sugarcane production region of Cauca River Valley and the other one, on the agricultural expansion region of Llanos Orientales. Here, we have found that the reuse of composted industrial waste is beneficial and provides an economic cost savings of 2–6% per year. However, it also results in an annual increase of 10–20% in the GHG emissions.

Microbial biodiesel production: From sucrose-based carbon sources to alkyl esters via enzymatic transesterification

Abstract Sucrose, in contrast to glucose, is a lower-cost carbon source. This manuscript discloses that its use in submerged fungal growth promotes lipids more suitable to biodiesel production due to lower unsaturation indexes. The wild strain of Mucor circinelloides URM 4182, a potential source of microbial lipid, was grown on three sucrose-based carbon sources: commercial brown sugar, sugarcane juice, and sugarcane syrup, achieving biomass accumulation productivities up to 3.62 ± 0.04 g L−1 day−1, and lipid productivities as high as 0.93 ± 0.01 g L−1 day−1. Lipid extraction was performed using ethanol, a green alternative to petroleum-derived solvent, and characterized according to their fatty acid distribution, from which C16:0 and C18:1 stand as the most abundant fatty acids. Extracted lipids were converted to ethyl esters via lipase-catalyzed reactions achieving ester contents up to 97.4% and low contents of mono- and diacylglycerols (1.9% and 1.0%, respectively). The interest in utilizing sucrose-based sources is due to the wide abundance of such feedstock in sugarcane-producing regions, and due to the potential of increasing value to these low-cost carbon sources. The results presented herein demonstrate a simple, yet efficient, process of converting sucrose and its derivatives to microbial biodiesel using green-chemistry processes, such as lipid extraction using ethanol, avoiding the use of harsh and toxic chemicals commonly utilized, and enzyme-catalyzed reactions.

A regional approach to determine economic, environmental and social impacts of different sugarcane production systems in Brazil

Brazilian sugarcane sector plays a very important role in the economy of the country, considering sugar, ethanol and bioelectricity production. Over the last decade, a variety of economic, social and environmental elements have pushed the sugarcane sector to increasing adoption of mechanically-based agricultural operations, especially in Center-South region of Brazil. Manual and mechanized sugarcane harvesting technologies were evaluated (with and without burning), as well as straw recovery, in three representative sugarcane production regions in Brazil: São Paulo state, the largest national producer, Northeast, a traditional region of sugarcane production, and Center-West region, sugarcane expansion area. Sugarcane production systems were compared using metrics from Engineering Economics, Life Cycle Assessment, and Social Life Cycle Assessment. The mechanized harvesting presented lower production costs in the São Paulo and Center-West regions, whereas manual harvesting had lowest cost in the Northeast region. When considering the verticalized production system (agricultural and industrial phases), mechanized with straw recovery - operating during both season and off-season periods - presented the best techno-economic performances when compared to the other scenarios in all the regions. Manual harvesting presented higher job creation while mechanized sugarcane systems show better working conditions and workers with higher average income, especially in the agricultural phase. Considering environmental impacts, scenarios with mechanized harvesting without burning and straw recovery presented the best comparative balance of environmental impacts.

Assessing the Likelihood of Gene Flow From Sugarcane (Saccharum Hybrids) to Wild Relatives in South Africa.

Pre-commercialization studies on environmental biosafety of genetically modified (GM) crops are necessary to evaluate the potential for sexual hybridization with related plant species that occur in the release area. The aim of the study was a preliminary assessment of factors that may contribute to gene flow from sugarcane (Saccharum hybrids) to indigenous relatives in the sugarcane production regions of Mpumalanga and KwaZulu-Natal provinces, South Africa. In the first instance, an assessment of Saccharum wild relatives was conducted based on existing phylogenies and literature surveys. The prevalence, spatial overlap, proximity, distribution potential, and flowering times of wild relatives in sugarcane production regions based on the above, and on herbaria records and field surveys were conducted for Imperata, Sorghum, Cleistachne, and Miscanthidium species. Eleven species were selected for spatial analyses based on their presence within the sugarcane cultivation region: four species in the Saccharinae and seven in the Sorghinae. Secondly, fragments of the nuclear internal transcribed spacer (ITS) regions of the 5.8s ribosomal gene and two chloroplast genes, ribulose-bisphosphate carboxylase (rbcL), and maturase K (matK) were sequenced or assembled from short read data to confirm relatedness between Saccharum hybrids and its wild relatives. Phylogenetic analyses of the ITS cassette showed that the closest wild relative species to commercial sugarcane were Miscanthidium capense, Miscanthidium junceum, and Narenga porphyrocoma. Sorghum was found to be more distantly related to Saccharum than previously described. Based on the phylogeny described in our study, the only species to highlight in terms of evolutionary divergence times from Saccharum are those within the genus Miscanthidium, most especially M. capense, and M. junceum which are only 3 million years divergent from Saccharum. Field assessment of pollen viability of 13 commercial sugarcane cultivars using two stains, iodine potassium iodide (IKI) and triphenyl tetrazolium chloride, showed decreasing pollen viability (from 85 to 0%) from the north to the south eastern regions of the study area. Future work will include other aspects influencing gene flow such as cytological compatibility and introgression between sugarcane and Miscanthidium species.