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The foliar application of plant growth regulators to sugarcane can increase crop growth and yield per cultivated area, improve crop productivity and quality, and mitigate possible abiotic stresses by optimizing photosynthesis. The productive potential of sugarcane has not been fully tapped, and plant growth regulator technology via foliar application could greatly benefit the production of food and renewable energy from the sugarcane production chain. In this study, we conducted 15 sugarcane field trials to evaluate the effects of plant growth regulators (17 ppm GA3 activity, 817 ppm IAA activity and 43 ppm zeatin) via foliar application at the vegetative stage (V) or vegetative and maturation stages (VM) on the photosynthetic and antioxidant enzyme activities, carbohydrate production and yield production of three harvest periods (early, mid-late and late harvest sugarcane). In general, foliar application increased the enzymatic, agronomic, quality and energy parameters of sugarcane. The application of plant growth regulators in V and VM increased the activities of the photosynthetic enzymes phosphoenolpyruvate carboxylase and ribulose-1,5-bisphosphate carboxylase-oxygenase, decreased the contents of malondialdehyde and hydrogen peroxide, and increased superoxide dismutase, catalase, ascorbate peroxidase, and proline content. The average stalk yield over the three harvest times increased by 5.4 and 8.0% in V and VM, respectively, compared to the control (101 Mg ha−1). In addition, V and VM increased the sucrose concentration, theoretical recoverable sugars (TRS), and sugar productivity by averages of 2.9%, 2.6% and 9.3%, respectively compared to the control (13.9% of sucrose, 139 kg sugar stalk−1 of TRS, and 13.9 Mg ha−1 of stalk yield), across all harvest seasons. The best results for straw, bagasse and energy production were observed in VM, with average increases of 8.0%, 7.7% and 8.0% compared with the control (14.1 Mg ha−1, 6.1 Mg ha−1 and 69.8 kWh, respectively). Thus, plant growth regulator application can increase sugarcane metabolism, growth and development. Although single plant growth regulator application in the vegetative stage improved all sugarcane parameters, the double application of plant growth regulators in the vegetative and maturation stages ensured improvements in yield and product quality. [ABSTRACT FROM AUTHOR]

In sugarcane, sequences related to the genus Sphingomonas have been widely detected by microbiome studies. In this work, the presence of bacteria of this genus was confirmed using culture-dependent and independent techniques. A collection of thirty isolates was obtained using semispecific cultivation conditions, and a specific PCR assay was applied to help confirm the isolates as belonging to the genus. A series of laboratory evaluations were carried out to identify potential properties among the isolates in the collection, which consequently allowed the identification of some most promising isolates for the development of new agricultural bioinputs. In a separate analysis, the culture-independent fluorescence in situ hybridization (FISH) methodology was applied to demonstrate the natural occurrence of Sphingomonas in different organs and tissues of sugarcane. The results showed the presence of bacteria of the genus in the spaces between cells (apoplast) of the culm parenchyma, in vessels in the region of the leaf vein, on the adaxial surface of the leaf blade, and on the root surface, sometimes close to the base of root hairs, which suggests extensive colonization on the host plant. In summary, the present study corroborates previous metagenomic amplicon sequencing results that indicated a high occurrence of Sphingomonas associated with sugarcane. This is the first study that uses approaches other than amplicon sequencing to confirm the occurrence of the genus in sugarcane and, at the same time, demonstrates potentially beneficial activities to be explored by sugarcane cultivation. [ABSTRACT FROM AUTHOR]

The water deficit resulting from climate variations limits the profitability and sustainability of sugarcane fields, making water supply through irrigation necessary to sustain the potential production of sugarcane. However, the water used for irrigation purposes must be properly managed, ensuring the conservation of water resources and the reduction of costs with the use of inputs and energy. Pulsed drip irrigation aims to support irrigation management, improving the efficient use of water and mitigating the deleterious effects of water deficit. This study aims to evaluate the growth, productivity, and industrial yield of sugarcane cultivated under continuous and pulsed drip irrigation. A field experiment was conducted at the Experimental Sugarcane Station of Carpina, in Carpina in the State of Pernambuco, Northeast Brazil, from December 2020 to December 2021. The experimental arrangement was randomized blocks in a 2 x 5 factorial design, with two types of irrigation application (pulsed and continuous) and five irrigation levels (40, 60, 80, 100, and 120% of crop evapotranspiration – ETc), with four replications. Pulsed drip irrigation increased the yield of stalks (9%) and sugar (21%) in the sugarcane crop and ethanol (17%) derived from sugar in the juice. Pulsed drip irrigation, when compared to continuous irrigation, improved the performance of sugarcane, providing a reduction in water consumption and increasing growth, stalk yield, sugar and predicted ethanol yield. Thus, based on this study, pulse irrigation is an efficient approach to irrigation management, contributing to the stability of sugarcane production while conserving water relative to continuous irrigation. [ABSTRACT FROM AUTHOR]

This work aimed to carry out an analysis to measure the importance of sugarcane culture for the Brazilian Eastern Amazon, which comprises the States of Amapá, Mato Grosso, Pará, Tocantins and part of the State of Maranhão. For this, data on Planted Area, Productivity and Production, provided by the National Supply Company (CONAB), referring to the 2012/2013 to 2021/2022 harvests in the states of the region in question were used. Data were normalized and submitted to correlation and regression analysis between the considered variables (planted area, productivity and production), to better understand how these variables behaved and related to each other in these last 10 sugarcane harvests in the region. As a result, it was noticed that the data had a normal distribution, with some strong and moderate correlations, whether positive or positive, which coincided with the results also obtained in the regression tests. However, the identified correlations and regressions occur differently in each State, with emphasis on the State of Pará, which presented strong positive correlations for all tests carried out (planted area, productivity and production), as well as regressions considered significant. The evaluations carried out demonstrated the quality of the data used and provided greater robustness in the analysis of the variables considered, allowing a better understanding of the importance of sugarcane for the Eastern Amazon. [ABSTRACT FROM AUTHOR]

Simple Summary: Our research is the first comparative field-based study on (i) the above- and belowground population dynamics and seasonal abundance and (ii) the effectiveness of conventional and innovative sampling methods for two mealybug species, Saccharicoccus sacchari (Cockerell, 1895) (Hemiptera: Coccomorpha, Pseudococcidae) and Heliococcus summervillei (Brookes, 1978) (Hemiptera: Coccomorpha, Pseudococcidae), in commercial sugarcane (Saccharum sp. hybrids) (f. Poaceae) over consecutive growing seasons. The novel description of S. sacchari and H. summervillei on sugarcane in multiple seasons, along with the best sampling techniques, allows for accurate monitoring and comparison within the Pseudococcidae family, thus aiding the ability to monitor the pest status in commercial sugarcane. This research is focused on a comparative field-based study of the population dynamics and sampling methods of two mealybug species, Saccharicoccus sacchari (Cockerell, 1895) (Hemiptera: Coccomorpha, Pseudococcidae) and Heliococcus summervillei (Brookes, 1978) (Hemiptera: Coccomorpha, Pseudococcidae), in sugarcane (Saccharum sp. hybrids) (f. Poaceae) over consecutive growing seasons. The research monitored and compared the above- and belowground populations and seasonal abundance of these two mealybug species in sugarcane fields in Far North Queensland, with non-destructive sampling techniques of yellow sticky traps, pan traps, and stem traps, and destructive sampling of the whole leaf and whole plant. The results indicated that S. sacchari (n = 29,137) was more abundant and detected throughout the growing season, with population peaks in the mid-season, while H. summervillei (n = 2706) showed peaks of the early-season activity. S. sacchari is primarily located on sugarcane stems and roots, compared to H. summervillei, which is located on leaves and roots. The whole-leaf collection and stem trap were the most effective sampling techniques for quantification of H. summervillei and S. sacchari, respectively. This study enhanced the understanding of S. sacchari and the first-ever record of H. summervillei on sugarcane in Australia and will contribute to the development of more effective pest management strategies. [ABSTRACT FROM AUTHOR]

Knowledge of how certain crops respond to water stress is one of the prerequisites for choosing the best variety and best management practices to maximize crop water productivity (WPc). The selection of a more efficient protocol for managing irrigation depths throughout the cultivation cycle and in the maturation process at the end of the growth period for each sugarcane variety can maximize bioethanol productivity and WPc for bioethanol, sugar and biomass, in addition to the total energy captured by the sugarcane canopy in the form of dry biomass. This study aimed to evaluate the effect of four irrigation depths and four water deficit intensities on the maturation phase for eight sugarcane varieties under drip irrigation, analyzing the responses related to WPc for bioethanol, sugar and biomass. These experiments were conducted at the University of São Paulo. The plots were positioned in three randomized blocks, and the treatments were distributed in a factorial scheme (4 × 8 × 4). The treatments involved eight commercial varieties of sugarcane and included four water replacement levels and four water deficits of increasing intensity in the final phase of the crop season. It was found that for each variety of sugarcane, there was an optimal combination of irrigation management strategies throughout the cycle and during the maturation process. The RB966928 variety resulted in the best industrial bioethanol yield (68.7 L·Mg−1), WPc for bioethanol (0.97 L·m−3) and WPc for sugar (1.71 kg·m−3). The energy of the aerial parts partitioned as sugar had a direct positive correlation with the availability of water in the soil for all varieties. The RB931011 variety showed the greatest potential for converting water into shoots with an energy of 1.58 GJ·ha−1·mm−1, while the NCo376 variety had the lowest potential at 1.32 GJ·ha−1·mm−1. The productivity of first-generation bioethanol had the highest values per unit of planted area for the greatest water volumes applied and transpired by each variety; this justifies keeping soil moisture at field capacity until harvesting time only for WR100 water replacement level with a maximum ethanol potential of 13.27 m3·ha−1. [ABSTRACT FROM AUTHOR]

Hymenopteran parasitoids strongly associated with the sugarcane borer [Diatraea saccharalis (Lepidoptera: Crambidae)] may be found both in organic and conventional sugarcane farming systems. This study aimed to sample parasitoids associated with sugarcane borer in organic, organic near a forest fragment and conventional systems. Two colors of Moericke traps were used (yellow and white) to collect insect samples, and faunistic analyses were performed to determine the composition of parasitoids in each management type. A total of 287 insects were collected, with the most abundant families being Diapriidae (44.44 %), Eulophidae (37.5 %) and Braconidae (18.06 %). The most abundant genus in the organic system was Omphale (Eulophidae), Omphale (Eulophidae) in the organic system near the forest fragment, and Omopria and Coptera (Diapriidae) in the conventional system. The parasitoids were more abundant in the organic system (43.06 %), followed by the organic system near the forest fragment (36.81 %) and the conventional system (20.14 %). The yellow trap was the most effective in attracting parasitoids, which were generally more abundant in organic systems, regardless of proximity to forest fragments.

The sugarcane production is vital for the economy of the Triângulo Mineiro region, in Brazil. However, its is likely to be affected by climate change, due to the increase of gases in the atmosphere. This study aimed to classify the climate suitability of sugarcane for the region, considering the current and future climate change scenarios. Historical series of rainfall and air temperature from 1981 to 2021 were employed, and each location was classified as suitable, restricted or unsuitable, according to the average temperature and annual water deficit. The RCP 2.6, RCP 4.5, RCP 6.0 and RCP 8.5 scenarios were considered to analyze the projections for the end of the 21st century (2081-2100). The region presents an average temperature of 23.2 ºC (±1.36 ºC) and annual water deficit of 189 mm (±77.54 mm). Currently, 85 % of the area is considered as suitable. The Ituiutaba microregion, located in the west, shows a pronounced water deficit, which restricts the sugarcane cultivation. The results from the projections indicate a reduction in the suitability for sugarcane production in the tested scenarios, with the effects on the water regime being more pronounced than those on temperature. For example, the area classified as suitable would decrease to 44.35 and 9.87 %, respectively, in the RCP 6.0 and RCP 8.5 scenarios.

Knowledge of how certain crops respond to water stress is one of the prerequisites for choosing the best variety and best management practices to maximize crop water productivity (WPc). The selection of a more efficient protocol for managing irrigation depths throughout the cultivation cycle and in the maturation process at the end of the growth period for each sugarcane variety can maximize bioethanol productivity and WPc for bioethanol, sugar and biomass, in addition to the total energy captured by the sugarcane canopy in the form of dry biomass. This study aimed to evaluate the effect of four irrigation depths and four water deficit intensities on the maturation phase for eight sugarcane varieties under drip irrigation, analyzing the responses related to WPc for bioethanol, sugar and biomass. These experiments were conducted at the University of São Paulo. The plots were positioned in three randomized blocks, and the treatments were distributed in a factorial scheme (4 × 8 × 4). The treatments involved eight commercial varieties of sugarcane and included four water replacement levels and four water deficits of increasing intensity in the final phase of the crop season. It was found that for each variety of sugarcane, there was an optimal combination of irrigation management strategies throughout the cycle and during the maturation process. The RB966928 variety resulted in the best industrial bioethanol yield (68.7 L·Mg−1), WPc for bioethanol (0.97 L·m−3) and WPc for sugar (1.71 kg·m−3). The energy of the aerial parts partitioned as sugar had a direct positive correlation with the availability of water in the soil for all varieties. The RB931011 variety showed the greatest potential for converting water into shoots with an energy of 1.58 GJ·ha−1·mm−1, while the NCo376 variety had the lowest potential at 1.32 GJ·ha−1·mm−1. The productivity of first-generation bioethanol had the highest values per unit of planted area for the greatest water volumes applied and transpired by each variety; this justifies keeping soil moisture at field capacity until harvesting time only for WR100 water replacement level with a maximum ethanol potential of 13.27 m3·ha−1.

Drought stress is one of the main environmental factors that cause negative impacts on sugarcane (Saccharum spp.) crops. The identification of drought-tolerant varieties is essential to boost the sugar-energy sector in agricultural years with an incidence of drought stress. Two experiments were conducted under greenhouse conditions to evaluate the degree of drought tolerance of 13 sugarcane varieties (CTC2, CTC4, IACSP95-5000, RB825336, RB835054, RB855035, RB855156, RB855453, RB855536, RB867515, RB965902, RB966928 and SP80-1842) when exposed to restrictions of 50% (moderate water deficiency) and 25% (severe water deficiency) of the soil's water retention capacity. Twelve drought tolerance indices were calculated from the production of shoot dry matter without water restriction (YP) and under moderate or severe water deficit (YS). The RB855035, RB855453 and RB 965902 varieties have greater drought tolerance, and are the most suitable to be cultivated in regions with moderate and severe water restriction. The RB855536 and IACSP95-5000 varieties have greater susceptibility to moderate and severe water deficit. Tolerance indices MP, DI, STI, GMP, YI, k1STI, k2STI and HM were the most suitable for identifying the sugarcane varieties with greater drought tolerance and high potential for shoot dry matter production. under conditions of moderate and severe water stress. [ABSTRACT FROM AUTHOR]

Understanding how abiotic stress influences plant development is important for crop development and management. The gravity changes force may reveal the additional details of the interconnected nature of plants' stress-signaling pathways. Sugarcane plants were submitted to gravity-changing forces using the VSB-30 sounding rocket to identify how these plants respond to this abiotic stress using histological, biochemical, and molecular approaches to evaluate this response. The histological analysis allowed us to observe that this alteration culminates in the intense disorganization of vascular bundles and higher lignin accumulation in plant cell walls at the adaxial epidermis and the mesophyll cells. An increase in enzyme activity from superoxide dismutase and guaiacol peroxidase was also observed. Our results indicate that sugarcane's response is similar to other abiotic stress responses, such as oxidative stress. The RNA sequencing data showed that these plantlets had a different expression on pathways associated with signal perception, plant metabolism involving photosynthesis, amino acid synthesis, cell division, DNA repair, and oxidative enzymes for scavenging ROS. These results presented here using sugarcane plantlets expand our knowledge of how plants can respond to the forces of gravity changes. The expression pattern in roots and leaves showed integrated and distinct responses for some known pathways, and both tissues expressed stress-related transcripts. [ABSTRACT FROM AUTHOR]

BACKGROUND: Herbivory risk is mediated by plant traits related to nutrition and defense that can vary within a species by genotype and age. Prior herbivore damage accrued by a plant can also interact with these traits to alter future herbivory potential by changing plant quantity or quality. Sugarcane (Saccharum spp.) is a perennial crop where aboveground biomass is harvested annually and with varieties differing in nutrition and defenses, making it conducive to evaluating varietal resistance mechanisms. Using data from 16 sugarcane varieties and 28 years, we assessed damage from the primary pest in Louisiana, the sugarcane borer (Diatraea saccharalis, SCB), relative to variety, crop year (ratoon), plant traits, and incidence of prior herbivory. RESULTS: SCB damage differed among varieties but not crop year, mostly following previously established classifications of SCB resistance, and correlated with select nutritional and defense traits. Within a crop year, the probability of SCB damage increased with prior conspecific damage on the same stalk. However, the strength of this prior damage effect did not match known resistance patterns but still differed with variety. CONCLUSIONS: Interactions of plant variety, traits, and prior pest damage but not age impacted sugarcane borer risk. Borer damage was associated with nutritional traits of fiber and sugar content, but not consistently with defensive traits like high stalk wax or hair density, indicating there may be additional resistance traits or indirect impacts of these traits on predators. Published 2023. This article is a U.S. Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

Extended periods of water stress negatively affect sugarcane crop production. The foliar application of supplements containing specific nutrients and/or organic molecules such as amino acids can improve sugarcane metabolism, stalk and sugar yields, and the quality of the extracted juice. The present study assessed the effectiveness of the foliar application of an abiotic stress protection complement (ASPC) composed of 18 amino acids and 5 macronutrients. The experiments were carried out in the field with two treatments and twelve replicates. The two treatments were no application of ASPC (control) and foliar application of ASPC. The foliar application of ASPC increased the activity of antioxidant enzymes. The Trolox-equivalent antioxidant capacity (DPPH) was higher in ASPC-treated plants than in control plants, reflecting higher antioxidant enzyme activity and lower malondialdehyde (MDA) levels. The level of H2O2 was 11.27 nM g−1 protein in plants treated with ASPC but 23.71 nM g−1 protein in control plants. Moreover, the application of ASPC increased stalk yield and sucrose accumulation, thus increasing the quality of the raw material. By positively stabilizing the cellular redox balance in sugarcane plants, ASPC application also increased energy generation. Therefore, applying ASPC is an effective strategy for relieving water stress while improving crop productivity. [ABSTRACT FROM AUTHOR]

Sugarcane plays a crucial role in global sugar and ethanol production. Conventionally, sugarcane propagation involves planting billets. However, Brazilian researchers have introduced the innovative pre-sprouted seedlings (PSS) method, widely used in the MEIOSI (Simultaneously Occurring Interrotational Method) system. Although PSS has several advantages over the conventional method, its sensitivity to water scarcity is a challenge. This study aimed to evaluate the survival and growth of PSS inoculated with Bacillus licheniformis and Bacillus subtilis (PGPB) under different water regimes. The experiment was conducted in the field in a randomized block in strips (split-block) using a 2 × 4 factorial scheme consisting of two inoculation conditions (with and without PGPB) and four water regimes (WR) (0%, 33%, 66%, and 100% of the ideal irrigation). PGPB increased PSS survival (4.17%) and water use efficiency (185.10% under the 0% WR). In addition, inoculation increased root (12.5%, 7.7%, and 16.2% for surface area, area projection, and root volume, respectively) and shoot growth. PGPB also increased nutrient uptake, such as N (60.8% and 18.3% under 0% and 66% WR), P (on average 11.7%), Mn (27.6% and 28.7% under 66% and 100% WR), Zn (111.4% under 0% WR), and Cu accumulation (27.17%), which provided a higher number of stalks per meter and, therefore, a higher multiplication rate in the MEIOSI system. Inoculation proved to be a promising alternative for PSS establishing under water restriction. [ABSTRACT FROM AUTHOR]

During the survey and monitoring, a disease affecting sugarcane arrows was noticed. Sugarcane inflorescence with symptoms was collected from the germplasm maintained at ICAR-SBIRC, Kannur. The disease was observed in 2017, 2018 and 2021. The length of affected grains varied from 3 to 3.5 mm, an average of 3.2 mm and the width varied from 1 to 1.5 mm, while regular grains showed no change in length, and the width was only 0.5 mm. The affected grains were somewhat bulged and black. Conidia of Epicoccum andropogonis and Claviceps purpurea were observed when examined under a light microscope, whereas, in culturing, the affected grains yielded only E. andropogonis. The morphological characteristics of E. andropogonis were studied in vitro. The shape, color and size of the fungus conidia resembled the conidia in vitro culture media. This fungus was identified based on molecular data from the ITS-rDNA sequence, and this is the first report of false floral smut occurrence on germplasm maintained at SBIRC, Kannur. A total of 24 clones were affected, including a clone WL 08-259 of waterlogging trial in 2021. The clones were categorized based on the number of spikelets affected. All the Saccharum species clones, 287 foreign hybrids and 393 Indian hybrids clones were found to be resistant. The 18 clones of Indian hybrids and two foreign hybrids were found to be highly susceptible, and three clones of Indian hybrids were moderately susceptible. [ABSTRACT FROM AUTHOR]

Spittlebugs are known for reducing the quality of sugarcane. However, the sugar process and crystals produced from damaged sugarcane have not been fully characterized. Furthermore, the proper maturation status of sugarcane could influence the results found for sugar production. This paper aimed to evaluate spittlebugs' interference with sugarcane (SP80-1842), clarified juice, and raw sugar quality in two harvest periods with immature and mature sugarcane. A completely randomized factorial design with three replications was conducted. The first factor was spittlebug damage in stalks: healthy (0% damage) and injured stalks (15, 30, and 60%). The second factor was the harvest periods with the same sugarcane plantation: May–June (with immature stalks) and October (with mature stalks). The results also show that for sugarcane, soluble solids, sucrose, and pH decreased, and the fiber increased in samples with a higher quantity of damaged stalks. With immature sugarcane, 30% of pest damage caused by spittlebugs increased by 41% in phenolic compounds, 39% in color, 29% in ash, and 22% in final crystal moisture. The sugar color is higher because of the increasing phenol compounds provided by spittlebug damage to the raw material. These molecules were not removed by clarifying juice from immature stalks. On the other hand, with proper sugarcane maturation conditions, the level of damaged stalks did not interfere with sugar quality. Therefore, choosing the best moment for harvest could reduce the impacts of the pest on the quality of crystals produced. [ABSTRACT FROM AUTHOR]

Energy cane (Saccharum spp.) bagasse, a type of biomass waste, is often underutilized, burned, or left to dispose of itself. This research aimed to evaluate the potential of converting this bagasse into high-value cellulosic microfiber hydrogels (CMH) for water conservation and potted chili (Capsicum annuum) plant growth. CMH offers a biodegradable alternative to synthetic polyacrylamide (PA) hydrogels and provides the dual benefit of improved water use efficiency and reduced environmental impact due to their ability to naturally break down in the soil. In this study, CMH and PA hydrogels were compared for water retention value (WRV), and reswelling kinetics (RK), as well as their effects on plant height, leaf count, root-to-shoot ratios (R:S ratio), and soil moisture retention. Two versions of CMH, CMH65 and CMH60, were prepared with varying cellulose-chitosan ratios: 65:35 and 60:40, respectively. The hydrogels were tested at four concentrations (0, 0.5, 1.0, and 2.0% w/w) by being mixed in Promix® soil. Observations were recorded over a 16-day period without additional water. Also, the WRV of hydrogels at 240 min and RK (10–180 min) were compared over three swelling-deswelling cycles. The PA hydrogel exhibited higher WRV (exceeding 450%) compared to CMH (45%). However, PA led to reduced plant height, leaf count, and R:S ratio when compared to higher concentrations of CMH65 and CMH60. In general, CMH60 (0.5% and 2%) exhibited superior plant growth. All hydrogels exhibited a significant decrease (p

This research is focused on a comparative field-based study of the population dynamics and sampling methods of two mealybug species, Saccharicoccus sacchari (Cockerell, 1895) (Hemiptera: Coccomorpha, Pseudococcidae) and Heliococcus summervillei (Brookes, 1978) (Hemiptera: Coccomorpha, Pseudococcidae), in sugarcane (Saccharum sp. hybrids) (f. Poaceae) over consecutive growing seasons. The research monitored and compared the above- and belowground populations and seasonal abundance of these two mealybug species in sugarcane fields in Far North Queensland, with non-destructive sampling techniques of yellow sticky traps, pan traps, and stem traps, and destructive sampling of the whole leaf and whole plant. The results indicated that S. sacchari (n = 29,137) was more abundant and detected throughout the growing season, with population peaks in the mid-season, while H. summervillei (n = 2706) showed peaks of the early-season activity. S. sacchari is primarily located on sugarcane stems and roots, compared to H. summervillei, which is located on leaves and roots. The whole-leaf collection and stem trap were the most effective sampling techniques for quantification of H. summervillei and S. sacchari, respectively. This study enhanced the understanding of S. sacchari and the first-ever record of H. summervillei on sugarcane in Australia and will contribute to the development of more effective pest management strategies.

Abstract Low density sugarcane plantation (LDSP) has been implemented by some sugarcane producers in Brazil, aiming to save seeds and operational costs. The study was carried out in the municipality of Areia, Paraíba, Brazil. Five planting densities were used, varying from 5 to 25 m-2 of buds arranged in randomized blocks, with four replications. Data were measured annually over three cultivation cycles (2017 to 2020), during which the field was fertilized with NPK and the harvests were carried out manually without prior burning. The lower planting density presents higher productivity only in the cane plant (101.03 t ha-1) due to the higher plant height (2.37 m) and the higher number of stalks (11 stalks m-2), suggesting that these variables are due to the greater availability of light, water and photosynthate. However, there is a drastic reduction in sugarcane yield for this lower population in the 2nd ratoon by up to 65.62%, which is correlated with number of stalks per meter. We demonstrate the agronomic viability of LDSP in the population of 10 buds m-2 in relation to conventional planting of sugarcane until the 2nd ratoon. Data are important for future studies to present additional considerations for other production factors, such as the effects of mechanized harvesting and the management of nutrients and water, assessing the sustainability of this large-scale planting system.

The cover and management factor (C-factor) of the Universal Soil Loss Equation (USLE) represents the effects of crop cover, weighted by rainfall pattern, on predicted soil erosion rates. This requires an estimate of seasonal rainfall erosivity and soil protection afforded by the crop at different phenological stages, expressed by a soil loss ratio (SLR). However, soil erosion modelers often rely on vegetation-index-based regressions to directly estimate the cover and management factor (C-factor) of the USLE from satellite images. Since this approach is based on a single or very few images, it does not characterize the seasonality of the crop cover or reflect the seasonality of the rainfall erosivity. Here, we evaluated five vegetation indices (NDVI, NDRE, SFDVI, ViGREEN, and MGRVI) in predicting SLRs and the C-factor for a sugarcane plot in Southeast Brazil. We used Sentinel-2 images and orthomosaics obtained by UAV surveys performed at the middle of each phenological stage. We compared the estimates of the C-factor based on the SLRs and rainfall erosivity against direct regressions from the literature. Our results confirmed the expected poor correlation between the C-factor and the vegetation indices. On the other hand, using the proposed vegetation indices proved to be a reliable alternative to predict the SLR in sugarcane areas, especially the NDVI, the NDRE, and MGRVI. In particular, the MGRVI accurately predicted the SLR and classified the UAV-derived orthomosaics.

Due to complex polyploid, sugarcane whole genome sequencing and characterization lag far behind other crops. PCR-based DNA markers are a viable low-cost option to evaluate genetic diversity and verify genotypes. In this study, the 5S ribosomal RNA-intergenic spacer (ITS) of 171 accessions of Saccharum spp. and Tripidium spp. was dissected, including 30 accessions of S. officinarum, 71 of S. spontaneum, 17 of S. robustum, 25 of S. barberi, 13 of S. sinense, 2 of S. edule, 5 sugarcane cultivars (Saccharum spp. hybrids), 6 of Tripidium spp. (formally Erianthus spp.), and 2 of unknown species. The ITS spacers were amplified from 10 ng of the leaf DNA of each accession with the universal PCR primers PI and PII. The PCR-amplified spacers (amplicons) were analyzed by both agarose gel and capillary electrophoresis (CE). While agarose gel electrophoresis revealed five banding patterns, a total of 42 polymorphic amplicons, ranging from 60 to 506 bp, were detected by CE. Three amplicons, 234-, 235-, and 236-bp in size, were amplified from all accessions of six Saccharum species, except for three S. robustum accessions (Molokai 5573, NG 57-054, and NG 77-235) that lacked the 236-bp amplicon. The 234-, 235-, 236-bp banding pattern found in S. spontaneum was less consistent than other Saccharum species, sometimes missing a few but not all the bands in this region. An amplicon of 61-bp was amplified only from the sugarcane hybrid varieties. The PI/PII patterns indicated diversity and subpopulations within Saccharum, which could potentially be used in Breeding. Moreover, all Saccharum-specific amplicons were mostly absent in Tripidium spp. accessions, which produced 405-bp and 406-bp amplicons, and any pattern of the exceptions indicated misidentification. The T. bengalense accession Kalimpong had a unique CE-banding pattern that was different from all other accessions. Although the clustering pattern of the 42 amplicons only discriminated at the genus level, these amplicons helped identify nine misclassified accessions. This study further demonstrates that these PI/PII amplicons could be particularly useful markers for breeders at sugarcane field stations to quickly confirm and discriminate among the accessions of germplasm collections. [ABSTRACT FROM AUTHOR]

Water deficiency is one of the most limiting abiotic factors to sugarcane world production (Saccharum spp.). Data on chlorophyll content and gas exchange are used to select genotypes tolerant to water deficit. However, these variables are influenced by environmental factors, which vary intensely throughout the day. Thus, this research aimed to evaluate the influence of diurnal variation of gas exchange, leaf water potential, chlorophyll content, and SPAD index on the differentiation between genotypes tolerant and susceptible to water deficiency. The greenhouse experiment was conducted in a completely randomized 2 × 2 × 4 factorial scheme, with two varieties (RB867515/RB855453), two soil water tensions [without water deficiency (–D) and with water deficiency (+D)], and four evaluation times (7 am, 10 am, 1 pm, and 4 pm) with four replicates. RB867515 maintained greater CO2 assimilation, stomatal conductance, transpiration rate, intrinsic transpiration efficiency, leaf water potential, total chlorophyll content, and SPAD index under +D, regulating carbon gain about water loss and providing greater shoot biomass under +D compared to RB855453. The best times to perform the measurements for selecting tolerant genotypes based on physiological traits and specifically on the SPAD index are at 10 am and between 7 am and 10 am, respectively. [ABSTRACT FROM AUTHOR]

A deeper understanding of the mechanisms underlying impaired sugarcane performance (Saccharum spp.) under nitrogen (N) deficiency might help select targeted traits for developing N-efficient genotypes. In this regard, we focused on the study of the effects of low-N stress on mesophyll chloroplast integrity and its relationship with shoot growth traits. Plants were grown in sand culture under varying N supply (1.5, 3.0, 6.0 and 12.0 mM of N) for 60 days, when mature leaves were sampled for transmission electron microscopy analysis. Then, the number of tillers was counted and shoot was harvested to estimate leaf area, dry mass production and leaf N concentration. Images of transmission electron microscopy revealed pronounced damages exclusively to the ultrastructure of mesophyll chloroplast in the severely N-deficient plants (1.5 mM of N), including thylakoid membrane disarrangement and poorly stacked grana. Tillering, leaf area, shoot dry mass and leaf N concentration increased as function of nutrient supply. However, maximum values of these parameters were attained at higher N availability (9.1–9.9 mM of N) than that related to the maintenance of mesophyll chloroplast integrity. Our results suggest, hence, that impairments in the ultrastructure of this organelle plays a key role on poor sugarcane biomass production only under severe N deficiency condition. This finding adds insights into the reasons of impaired sugarcane performance under low-N stress and might assist the selection of suitable traits to be sought in N-efficient genotypes. [ABSTRACT FROM AUTHOR]

Using chemical ripeners in the sugarcane favors the increase of sucrose productivity, regulates the effects of adverse weather conditions for ripening, and promotes the anticipation of harvest. However, it can also modify the nutrient absorption, translocation, and accumulation process and, consequently, affect the nutrient cycling of the straw maintained on the soil surface. Thus, this research aimed to evaluate ripeners' effects (glyphosate − 0.5 L ha−1; sulfometuron-methyl − 0.02 kg ha−1, and trinexapac-ethyl − 0.8 L ha−1) on the nutritional status of the sugarcane leaf canopy. Natural ripening maintained the highest levels of P and Zn throughout the time. The highest levels of N, P, and K were provided by trinexapac-ethyl in most of the evaluated periods, as well as contributing to the highest levels of Ca, Mg, and S, along with sulfometuron methyl, from 30 to 60 days after application (DAA). The highest levels of B and Zn were observed under sulfometuron methyl. On the other hand, glyphosate was the ripener responsible for the lowest nutrient concentrations in the leaf canopy, including N, Ca, Mg, and S at 45 DAA and B and Mn at 30 and 45 DAA. Considering the importance of maintaining the straw for nutrient cycling, in addition to being a ripener, trinexapac-ethyl contributed to the maintenance of high levels of nutrients in the leaf canopy in relation to the other ripeners, which suggests a greater possibility of availability of these nutrients for the ratoon development in the upcoming cycles. [ABSTRACT FROM AUTHOR]

Sugarcane yellow leaf disease (YLD) caused by sugarcane yellow leaf virus (ScYLV) is a major threat for the sugarcane industry worldwide, and the aphid Melanaphis sacchari is its main vector. Breeding programs in Brazil have provided cultivars with intermediate resistance to ScYLV, whereas the incidence of ScYLV has been underestimated partly due to the complexity of YLD symptom expression and identification. Here, we evaluated YLD symptoms in a field assay using eight sugarcane genotypes comprising six well-established commercial high-sucrose cultivars, one biomass yield cultivar, and a susceptible reference under greenhouse conditions, along with estimation of virus titer through RT-qPCR from leaf samples. Additionally, a free-choice bioassay was used to determine the number of aphids feeding on the SCYLV-infected cultivars. Most of the cultivars showed some degree of resistance to YLD, while also revealing positive RT-qPCR results for ScYLV and virus titers with non-significant correlation with YLD severity. The cultivars IACSP01-5503 and IACBIO-266 were similar in terms of aphid preference and ScYLV resistance traits, whereas the least preferred cultivar by M. sacchari, IACSP96-7569, showed intermediate symptoms but similar virus titer to the susceptible reference, SP71-6163. We conclude that current genetic resistance incorporated into sugarcane commercial cultivars does not effectively prevent the spread of ScYLV by its main aphid vector. [ABSTRACT FROM AUTHOR]

ABSTRACT: The main method of sugarcane smut (Sporisoriumscitamineum)control is the genetic resistance. This study assessed the reaction of Brazilian sugarcane genotypes to the smut. The design used was randomized blocks, with 41 genotypes and four replications. The experimental unit consisted of five seedlings per genotype. The genotypes were inoculated by immersing the buds in a smut spores’ suspension. For each genotype, it was obtained the disease incidence in percentage of stalk with whip and with the disease incidence data over time the area under the disease progress curve (AUDPC) were calculated for each genotype. Based in the AUDPC, three genotypes were classified as highly resistant (7.3%), eighteen as resistant (43.9%), twelve as moderately resistant (29.3%), three as moderately susceptible (7.3%) and five as susceptible (12.2%). Genotypes with higher levels of resistance to smut sugarcane can be used for integrated disease management and can be used as parents in new crosses in order to obtain progenies with higher proportion of genotypes resistant to smut.

In the state of Veracruz, Mexico, low sugarcane yields are reported despite the high use of inputs. This results in economic losses and environmental pollution. A fertigation system designed at the Colegio de Postgraduados (COLPOS) Campus Veracruz was established to determine the uniformity and stability of fertilizer distribution in the sugarcane crop. This study was carried out in a sugarcane plot with a farmer participant. Three levels of valve openings at the injector inlet (1/3, 2/3, and 3/3) were tested to determine the homogeneity of fertigation at the outlet of the gates and the stability of the system over time. Samples of waterfertilizer mixture were taken at the outlet of the gates. They were analyzed in the laboratory with a UV-visible spectrophotometer at 202 nm for nitrogen. It was found that the 1/3 and 3/3 valve position openings caused instability in the system. For the 2/3 opening with p = 0.359, no statistical difference (a= 0.05) was found during the time of emptying the container of the waterfertilizer mixture. Therefore, the fertigation system proved to be stable with a valve opening close to 2/3. Using the valve openings, the flow rate of water-fertilizer entering the system is uniformly mixed at the outlets of the multi-gate pipeline that pours into the crop furrows (p = 0.474 and a = 0.05). It can be concluded that in fertilization using a low-pressure irrigation system, nitrogen fertilizer is uniformly distributed when a Venturi type injector is used in a sugarcane agroecosystem with a valve opening close to 2/3. [ABSTRACT FROM AUTHOR]

Artificial or synthetic seed consists of a coating that protects plant tissues, being an alternative for commercial propagation of sugarcane. The objective of this study was to develop a system for synthetic seed production of sugarcane. A first experiment determined the optimal nodal segments size (1.0, 2.5, and 5.0 cm long) in bud emergence; a second experiment evaluated different concentrations of sodium alginate (Na-alginate: 1%, 2% and 3% w/v) and calcium chloride (CaCl2: 50, 100 and 200 mM) to determine bead formation and breaking ability. At 30 days of culture were evaluated the percentage of emergence, shoot length, number of leaves and number of roots. In addition, we determined the cutting force associated with the different combinations of the encapsulation matrix. The results showed a higher percentage of emergence and development by using nodal segment measuring 2.5–5.0 cm long. The combination of 1% Na-alginate + 50 or 100 mM CaCl2 allowed an efficient encapsulation for the formation of synthetic seed, without affecting the percentage of emergence and development variables evaluated. We described a system for the production of synthetic seeds of sugarcane, a biotechnological strategy that may be an alternative for the production of basic seed and the modernization of sugarcane cultivation. [ABSTRACT FROM AUTHOR]

Phosphate fertilization in highly weathered soils has been a major challenge for sugarcane production. The objective of this work was to evaluate the foliar levels of phosphorus (P) and nitrogen (N) and the technological quality and productivity of second ratoon cane as a function of inoculation with plant-growth-promoting bacteria (PGPBs) together with the residual effect of phosphate fertilization. The experiment was carried out at the research and extension farm of Ilha Solteira, state of São Paulo, Brazil. The experiment was designed in a randomized block with three replications in a 5 × 8 factorial scheme. The treatments consisted of five residual doses of phosphorus (0, 45, 90, 135 and 180 kg ha−1 of P2O5, 46% P) applied at planting from the source of triple superphosphate and eight inoculations from three species of PGPB (Azospirillum brasilense, Bacillus subtilis and Pseudomonas fluorescens), applied in single or co-inoculation at the base of stems of sugarcane variety RB92579. Inoculation with PGPBs influenced leaf N concentration, while inoculations with Pseudomonas fluorescens and combinations of bacteria together with the highest doses exerted a positive effect on leaf P concentration. Co-inoculation with A. brasilense + Pseudomonas fluorescens associated with a residual dose of 135 kg ha−1 of P2O5 increased stem productivity by 42%. Thus, it was concluded that inoculations with Pseudomonas fluorescens and their combinations are beneficial for the sugarcane crop, reducing phosphate fertilization and increasing productivity. [ABSTRACT FROM AUTHOR]

Abstract Background Diseases are the major factor affecting the quality and yield of sugarcane during its growth and development. However, our knowledge about the factors regulating disease responses remain limited. The present study focuses on identifying genes regulating transcriptional mechanisms responsible for resistance to leaf scald caused by Xanthomonas albilineans in S. spontaneum and S. officinarum. Results After inoculation of the two sugarcane varieties SES208 (S. spontaneum) and LA Purple (S. officinarum) with Xanthomonas albilineans, SES208 exhibited significantly greater resistance to leaf scald caused by X. albilineans than did LA Purple. Using transcriptome analysis, we identified a total of 4323 and 1755 differentially expressed genes (DEGs) in inoculated samples of SES208 and LA Purple, respectively. Significantly, 262 DEGs were specifically identified in SES208 that were enriched for KEGG pathway terms such as plant-pathogen interaction, MAPK signaling pathway, and plant hormone signal transduction. Furthermore, we built a transcriptional regulatory co-expression network that specifically identified 16 and 25 hub genes in SES208 that were enriched for putative functions in plant-pathogen interactions, MAPK signaling, and plant hormone signal transduction. All of these essential genes might be significantly involved in resistance-regulating responses in SES208 after X. albilineans inoculation. In addition, we found allele-specific expression in SES208 that was associated with the resistance phenotype of SES208 when infected by X. albilineans. After infection with X. albilineans, a great number of DEGs associated with the KEGG pathways ‘phenylpropanoid biosynthesis’ and ‘flavonoid biosynthesis’ exhibited significant expression changes in SES208 compared to LA Purple that might contribute to superior leaf scald resistance in SES208. Conclusions We provided the first systematical transcriptome map that the higher resistance of SES208 is associated with and elicited by the rapid activation of multiple clusters of defense response genes after infection by X. albilineans and not merely due to changes in the expression of genes generically associated with stress resistance. These results will serve as the foundation for further understanding of the molecular mechanisms of resistance against X. albilineans in S. spontaneum.

ABSTRACT The Least Limiting Water Range (LLWR) is an indicator of soil physical quality, contributing in information to propose soil management systems in agricultural farming process. This work aimed to assess the usage of LLWR and critical soil bulk density for physical-water quality evaluations, as well as its effect on sugarcane farming under no-tillage and reduced-tillage, in Oxisol. Undisturbed soil samples were collected in 0.00-0.10 and 0.10-0.20 m soil layers, to determine the following attributes: soil bulk density, soil penetration resistance (PR), volumetric water content at field capacity and permanent wilting point and minimum aeration porosity. The LLWR proved to be a good soil physical water quality indicator in sugarcane farming under conservation tillage system. No-tillage presented a greater range of the LLWR when compared to the reduced-tillage, regardless to the PR value adopted as restrictive for sugarcane roots development, increasing the yield of stalks and sugars contents. The critical soil bulk density under no-tillage is between 1.48 and 1.53 Mg m-3 at the RP of 2 and 4 MPa, while under reduced-tillage it is between 1.44 and 1.51 Mg m-3.

Ethanol production is expected to increase to 54 billion litres in 2030. Two alternatives from an agronomic point of view could be increasing the amount of area under sugarcane cultivation and/or narrowing the yield gaps. Precision agriculture (PA) approach and technologies for that are a feasible strategy to boost yields without the need for any further expansion of sugarcane areas. Through life cycle assessment (LCA), this study addressed the economic and environmental suitability of production expansion based on four scenarios in South-Central Brazil. Current production, expansion of area and yield, and PA technology adoption (fertiliser management and systematisation) are the scenarios assessed. The results showed that if no yield gain is achieved, an expansion of 4.5 million hectares of cultivated area will be required to reach those targets. To maintain stable cropping areas, the average yield of sugarcane should be increased from 76.2 Mg ha−1 to 122.4 Mg ha−1 in 2030. Such an increase could potentially reduce production costs by 26% and greenhouse gas emissions by 14% compared to those in the current scenario. However, the findings suggest that the adoption of site-specific management alone is not enough to address the necessary production to reach the goals by 2030. So, conclusions drawn from this study suggest that it will be necessary adopting strategies to increase sugarcane production, either through site-specific management or the expansion of cultivated area. The improved management of spatial–temporal variability through PA technologies is a win–win strategy to promote yield gains, reduce production costs and further ensure environmental benefits of sugarcane-based ethanol. • Area and yield increase would be required to reach ethanol goalsby 2030. • Site-specific management alone is not enough to reach Ethanol goals by 2030. • Fertiliser management and field systematisation reduced production costs. • Spatial–temporal variability management is a win–win strategy. [ABSTRACT FROM AUTHOR]

Silicon (Si) has been associated with minimizing water deficit damage in several plants, but its effects on physiological aspects and gas exchange responses for sugarcane during the ripening phase are still scarce. Therefore, this study aimed to determine whether Si fertilization enhances physiological and gas exchange responses, biomass and sugar production in response to water deficit during the ripening phase of sugarcane, and whether these responses are similar in drought-tolerant and drought-sensitive cultivars. A greenhouse experiment was conducted using two sugarcane cultivars (RB855536 is drought-sensitive; RB867515 is drought-tolerant) without and with Si (0 = zero and 1000 kg−1 Si; -Si and + Si) under well-watered or water deficit conditions at the ripening phase. The biometric, physiological, and gas exchange measurements were independently influenced by the water deficit, cultivar, and Si. The leaf Si concentration, chlorophyll a (Chla), carotenoids, net CO2 assimilation rate (A), electron transport rate (ETR), plant transpiration (E), stomatal conductance (gs), and sugar content in stalks increased with Si, and electrolyte leakage (EL), plant length, leaf area (LA), and stalk fresh biomass decreased. Water deficit decreased the leaf water potential (ψW), fresh biomass of leaves, and LA. RB867515 showed higher LA, plant length, and fresh leaves biomass, while RB855536 showed superior leaf Si, Chla, Chlb, carotenoids, A, ETR, E, sugar content, and EL and lower ψW. Si fertilization promotes enhancement in some physiological and gas exchange aspects and increased sugar contents in stalks, independent of the water deficit at ripening phase or the drought tolerance of sugarcane cultivars. [ABSTRACT FROM AUTHOR]

A total of sixteen accessions of Tripidium arundinaceum (Retz.) Welker, Voronts. & E.A. Kellogg (previously known as Erianthus arundinaceus (Retz.) Jeswiet) were evaluated for salinity tolerance at the bud germination stage by irrigating with 175 mM salinized Hoagland solution in perlite-sand hydroponics. Six accessions, IND99-907, IND01-1134, IND01-1136, IK76-48, and Bethuadahari, were germinated with healthy roots as compared to other accessions. These six accessions were further evaluated for morphological, physiological, and root anatomical parameters for different levels of salinity stress at the formative phase. Young leaf elongation was ceased after the fourth and twelfth day in Co 97010 and Co 86032, respectively, at 175 mM of salinity stress. The growth of young leaves in Co 97010 and Co 86032 was observed up to 25 mM of salinity stress only, whereas in T. arundinaceum accessions viz., IND99-907 and Bethuadahari, growth was recorded even at 175 mM. Lignification of cell walls, thickening of protoxylems, and vacuolization of cortex regions were observed in Co 97010, Co 86032, Bethuadahari, and IND01-1134 as compared to the normal anatomical structures in IND99-907. The accession IND99-907 recorded the lowest Na/K ratio, followed by IND99-1136 at 175 mM of salinity stress. The accession IND99-907 was identified as a salinity-tolerant genotype and suitable for utilization in the sugarcane crop improvement programmes. [ABSTRACT FROM AUTHOR]

Modern sugarcane cultivars have complex polyploid genomes which impose challenges during conventional breeding. Epigenetic resources can be used as supplementary tools to improve cultivars. In this preliminary investigation, we hypothesised that spontaneous epigenetic variation occurred in two cultivars, N41 and NCo376, regarded as 'widely adaptable' and grown in different environments (3 agroclimatic zones and 5 regions) in South Africa. Epigenetic profiling was conducted by evaluating cytosine methylation patterns using methylation-sensitive amplification polymorphism. There was a high epigenetic differentiation among NCo376 and N41 samples with differentiation index values (ɸst) of 61% and 68%, respectively. The Eston region had more influence on the variability of cytosine methylation in NCo376 than the Mount Edgecombe, Empangeni, Pongola and Umzimkhulu regions. Epigenetic distances for NCo376 showed Eston being more distinct than the rest of the regions. The results showed altered DNA methylation patterns in cultivars grown in different agroclimatic zones, perhaps explaining their adaptability. Future work could include investigating the heritability of epigenetic adaptation, because current elite sugarcane genotypes could be "prepared", through epimutagenesis, for changing environments and even climate change. In time, more targeted epimutagenic breeding could supplement sugarcane improvement programmes. [ABSTRACT FROM AUTHOR]

One of the biggest challenges in the sugarcane industry is obtaining raw material of sufficiently high quality to ensure best economic return. The use of technologies such as chemical ripeners to increase sucrose accumulation is highly recommended when natural ripening conditions are unsatisfactory. The insecticide thiamethoxam is also a bioactivator that can stimulate new stalk and leaf growth, and thus the application of thiamethoxam to sugarcane ratoon regrowth in association with ripener may improve sugarcane quality and yields. This study aimed to evaluate the effectiveness of foliar application of thiamethoxam to sugarcane ratoon regrowth alone or in association with the ripener sulfometuron-methyl. The study comprised six experiments carried out in the early and late harvest seasons in three different locations using the sugarcane varieties RB855453 and SP80-3280. The treatments consisted of a control (natural ripening), application of the ripener sulfometuron-methyl or the bioactivator thiamethoxam alone, or application of both ripener and bioactivator. Thus, biometric and technological parameters were evaluated. The use of thiamethoxam increased stalk yield significantly, with gains up to 13 Mg ha−1. When both ripener and bioactivator were applied, sugar yield increased by up to 14.7% compared with the control. As a bioactivator, thiamethoxam has the potential to increase energy cogeneration from sugarcane via higher biomass production. Thus, thiamethoxam application on sugarcane regrowth treated with sulfometuron-methyl promoted desirable effects on the plant physiology without altering the industrial quality of the sugarcane juice. [ABSTRACT FROM AUTHOR]

Extended periods of water stress negatively affect sugarcane crop production. The foliar application of supplements containing specific nutrients and/or organic molecules such as amino acids can improve sugarcane metabolism, stalk and sugar yields, and the quality of the extracted juice. The present study assessed the effectiveness of the foliar application of an abiotic stress protection complement (ASPC) composed of 18 amino acids and 5 macronutrients. The experiments were carried out in the field with two treatments and twelve replicates. The two treatments were no application of ASPC (control) and foliar application of ASPC. The foliar application of ASPC increased the activity of antioxidant enzymes. The Trolox-equivalent antioxidant capacity (DPPH) was higher in ASPC-treated plants than in control plants, reflecting higher antioxidant enzyme activity and lower malondialdehyde (MDA) levels. The level of H2O2 was 11.27 nM g−1 protein in plants treated with ASPC but 23.71 nM g−1 protein in control plants. Moreover, the application of ASPC increased stalk yield and sucrose accumulation, thus increasing the quality of the raw material. By positively stabilizing the cellular redox balance in sugarcane plants, ASPC application also increased energy generation. Therefore, applying ASPC is an effective strategy for relieving water stress while improving crop productivity.

Sugarcane plays a crucial role in global sugar and ethanol production. Conventionally, sugarcane propagation involves planting billets. However, Brazilian researchers have introduced the innovative pre-sprouted seedlings (PSS) method, widely used in the MEIOSI (Simultaneously Occurring Interrotational Method) system. Although PSS has several advantages over the conventional method, its sensitivity to water scarcity is a challenge. This study aimed to evaluate the survival and growth of PSS inoculated with Bacillus licheniformis and Bacillus subtilis (PGPB) under different water regimes. The experiment was conducted in the field in a randomized block in strips (split-block) using a 2 × 4 factorial scheme consisting of two inoculation conditions (with and without PGPB) and four water regimes (WR) (0%, 33%, 66%, and 100% of the ideal irrigation). PGPB increased PSS survival (4.17%) and water use efficiency (185.10% under the 0% WR). In addition, inoculation increased root (12.5%, 7.7%, and 16.2% for surface area, area projection, and root volume, respectively) and shoot growth. PGPB also increased nutrient uptake, such as N (60.8% and 18.3% under 0% and 66% WR), P (on average 11.7%), Mn (27.6% and 28.7% under 66% and 100% WR), Zn (111.4% under 0% WR), and Cu accumulation (27.17%), which provided a higher number of stalks per meter and, therefore, a higher multiplication rate in the MEIOSI system. Inoculation proved to be a promising alternative for PSS establishing under water restriction.

One of the main objectives of sugarcane plantations is to increase their longevity without decreasing agricultural productivity. In the present study, we analyzed the proteome of the axillary buds of ‘RB966928’ to investigate possible changes in the number of proteins at different cutting stages. Using tryptic digestion followed by ultra-performance liquid chromatography coupled with high-resolution time-of-flight mass spectrometry, 122 proteins were identified from the proteome of the axillary buds of ‘RB966928’. Of the 122, respectively 97 and 95 proteins were detected at the first and fifth cutting stages, of which 27 and 25 proteins were unique to the respective stage. Proteins that prevent the misfolding of polypeptides generated under stress were exclusively detected at the first cutting stage. Meanwhile, proteins associated with stress responses and disease resistance were exclusively detected at the fifth cutting stage. The present proteomic analysis in the regrowth cycles and axillary bud development of ‘RB966928’ significantly advanced our understanding of the biological processes linked to the reduction of agricultural productivity of sugarcane with the advancement of cutting age. Absence of proteins to tolerate adverse growth conditions at the fifth cutting stage may be related to reduced agricultural productivity, in addition to environmental stress, soil compaction, nutrient availability, cultural practices, and pests or pathogen attacks at different phenological stages of crops.