Sugarcane Stalk Research Articles

Crop resilience to climate change: A study of spatio-temporal variability of sugarcane yield in a subtropical region, China

Increasing sugarcane production to meet sugar industry demands is a major challenge facing agricultural sector in a more vulnerable environment to climate change in subtropical China. Numerous studies have shown the impact of climate change on sugarcane production, but most of these studies were conducted in a plot or catchment scale without assessing the impacts at regional scale. In this paper, climatic elements of temperature, rainfall, and radiation data, simulated by 28 global climate models, were evaluated using the Taylor chart. The two greenhouse gas emission scenarios, RCP4.5 and RCP8.5, were used to generate climate changes in the region. Combined with the spatial analysis method, the spatial and temporal variation of temperature, rainfall and radiation in Guangxi region from 2010 to 2100 were studied. A validated APSIM-sugarcane model was selected to simulate sugarcane yield at 22 research stations in Guangxi region under different RCP scenarios in the future, and to analyze the three research stages (2030s: 2021-2040; 2060s: 2051-2070 and 2090s: 2081-2100). The spatio-temporal changes of aboveground biomass weight (DM), sugarcane stalk and sucrose (S) yields of the years 2021-2100 were compared with those in the base years (1961-2010), and the effects of climate change on sugarcane yield were quantified. On average, the DM yields were projected to increase by 3.6 and 4.7 and 5.8 t ha−1 for RCP4.5 and 2.9, 5.4 and 8.5t ha−1 for RCP8.5 in 2030s, 2060s and 2090s as compared to 1961–2010, respectively. Similarly, the projected increase in S yields were 5.2, 7.0, and 8.3 t ha−1for RCP4.5 and 4.3, 7.2 and 10.8 t ha−1 for RCP8.5 in the respective future years in comparison with baseline years. The results showed that sugarcane yield had no significant relationship with changes in solar radiation, but the yield had significant correlations with rainfall and temperature changes. Combine changes in radiation, rainfall, temperature and elevated CO2 might be accounted for 69 and 76% changes in sugarcane DM and S yields, respectively, across the entire location. An increase in temperature caused a little increase in sugarcane yield, while an increase in rainfall increased sugarcane yields significantly, but decreased when it exceeded a certain limit. On the other hand, the S yield increased with increase in temperature at constant radiation, but decreased when the radiation exceeded a certain limit. Temperature changes only caused S yield increase when radiation and temperature increased simultaneously. The effects of temperature and rainfall on S yield were similar to those on biomass yield. The effects of radiation and rainfall on S yield showed that both rainfall and radiation increased S yields, but the amplitude was limited. Therefore, to mitigate climate change in the future, supplemental irrigation can be used to increase soil moisture content to improve sugarcane yield.

DEVELOPMENT OF A MACHINE FOR CUTTING SUGAR CANE BUDS

This research aims to manufacture and test a machine for cutting sugar cane buds to develop mechanization of the stage of preparing sugarcane seedlings in the nursery. The developed machine consists of a frame, cutting unite, electric motor, and power transmission system. This machine will save the time, effort and costs spent on cutting reeds by traditional methods at farmers. The machine cuts the sugarcane stalks that are used as seeds and which contain undamaged buds, the operator cuts the groups of sprouts by the bud cutting machine. The machine has been tested at three transmission ratios to cutting rate of R1 = 22, R2 = 32, and R3 = 40 buds/min. The results of preliminary tests revealed that the machine achieved the skipping, percentage of damaged, cutting efficiency, and productivity was (4.09, 7.19, 11%), (2.37, 5.39, and 8.99%), (97.63, 94.61, 91%), (1266, 1782, 2136 bud/hr.) at the cutting rate R1, R2, and R3 respectively. The total costs for operating the machine are 50.3 L.E./h to at the highest cutting rate R3.

Silicon Application Modulates the Growth, Rhizosphere Soil Characteristics, and Bacterial Community Structure in Sugarcane

Silicon (Si) deficiency, caused by acidic soil and rainy climate, is a major constraint for sugarcane production in southern China. Si application generally improves sugarcane growth; however, there are few studies on the relationships between enhanced plant growth, changes in rhizosphere soil, and bacterial communities. A field experiment was conducted to measure sugarcane agronomic traits, plant nutrient contents, rhizosphere soil enzyme activities and chemical properties, and the rhizosphere bacterial community diversity and structure of three predominant sugarcane varieties under two Si treatments, i.e., 0 and 200 kg of silicon dioxide (SiO2) ha−1 regarded as Si0 and Si200, respectively. Results showed that Si application substantially improved the sugarcane stalk fresh weight and Si, phosphorus (P), and potassium (K) contents comparing to Si0, and had an obvious impact on rhizosphere soil pH, available Si (ASi), available P (AP), available K (AK), total phosphorus (TP), and the activity of acid phosphatase. Furthermore, the relative abundances of Proteobacteria showed a remarkable increase in Si200, which may be the dominant group in sugarcane growth under Si application. Interestingly, the AP was noticed as a major factor that caused bacterial community structure differences between the two Si treatments according to canonical correspondence analysis (CCA). In addition, the association network analysis indicated that Si application enriched the rhizosphere bacterial network, which could be beneficial to sugarcane growth. Overall, appropriate Si application, i.e., 200 kg SiO2 ha−1 promoted sugarcane growth, changed rhizosphere soil enzyme activities and chemical properties, and bacterial community structures.

Rearranging the sugarcane holobiont via plant growth-promoting bacteria and nitrogen input

The development and productivity of plants are governed by their genetic background, nutrient input, and the microbial communities they host, i.e. the holobiont. Accordingly, engineering beneficial root microbiomes has emerged as a novel and sustainable approach to crop production with reduced nutrient input. Here, we tested the effects of six bacterial strains isolated from sugarcane stalks on sugarcane growth and physiology as well as the dynamics of prokaryote community assembly in the rhizosphere and root endosphere under two N fertilization regimes. All six strains, Paraburkholderia caribensis IAC/BECa 88, Kosakonia oryzae IAC/BECa 90, Kosakonia radicincitans IAC/BECa 95, Paraburkholderia tropica IAC/BECa 135, Pseudomonas fluorescens IAC/BECa 141 and Herbaspirillum frisingense IAC/BECa 152, increased in shoot and root dry mass, and influenced the concentration and accumulation of important macro- and micronutrients. However, N input reduced the impact of inoculation by shifting the sugarcane microbiome (rhizosphere and root endosphere) and weakening the co-dependence between soil microbes and sugarcane biomass and nutrients. The results show that these beneficial microbes improved plant nutrient uptake conditioned to a reduced N nutrient input. Therefore, reduced fertilization is not only desirable consequence of bacterial inoculation but essential for higher impact of these beneficial bacteria on the sugarcane microbiome.

A systematic high-throughput phenotyping assay for sugarcane stalk quality characterization by near-infrared spectroscopy

BackgroundSugarcane (Saccharum officinarum L.) is an economically important crop with stalks as the harvest organs. Improvement in stalk quality is deemed a promising strategy for enhancing sugarcane production. However, the lack of efficient approaches for systematic evaluation of sugarcane germplasm largely limits improvements in stalk quality. This study is designed to develop a systematic near-infrared spectroscopy (NIRS) assay for high-throughput phenotyping of sugarcane stalk quality, thereby providing a feasible solution for precise evaluation of sugarcane germplasm.ResultsA total of 628 sugarcane accessions harvested at different growth stages before and after maturity were employed to take a high-throughput assay to determine sugarcane stalk quality. Based on high-performance anion chromatography (HPAEC-PAD), large variations in sugarcane stalk quality were detected in terms of biomass composition and the corresponding fundamental ratios. Online and offline NIRS modeling strategies were applied for multiple purpose calibration with partial least square (PLS) regression analysis. Consequently, 25 equations were generated with excellent determination coefficients (R2) and ratio performance deviation (RPD) values. Notably, for some observations, RPD values as high as 6.3 were observed, which indicated their exceptional performance and predictive capability.ConclusionsThis study provides a feasible method for consistent and high-throughput assessment of stalk quality in terms of moisture, soluble sugar, insoluble residue and the corresponding fundamental ratios. The proposed method permits large-scale screening of optimal sugarcane germplasm for sugarcane stalk quality breeding and beyond.

Artificial intelligence method developed for classifying raw sugarcane in the presence of the solid impurity

An investigation dedicated to evaluating a big issue in biorefineries, solid impurity in raw sugarcane, is presented. This relevant industrial sector requests a high-frequency, low-cost, and noninvasive method. Then, the developed method uses the averaged color values of ten color-scale descriptors: R (red), G (green), B (blue), their relative colors (r, g, and b), H (hue), S (saturation), V (value) and L (luminosity) from digital images acquired from 146 solid mixtures among sugarcane stalks and solid impurity � vegetal parts (green and dry leaves) and soil. The solid mixture of samples was prepared considering desirable and undesirable scenarios for the solid impurity amounts. The outstanding result was revealed by an artificial neural network (ANN), achieving 100% of accurate classifications for two ranges of raw sugarcane in the samples: from 90 to 100 wt% and from 41 to 87 wt%. Low-computational cost and a simple setup for image acquisition method could screen solid impurity in sugarcane shipments as a promising application.

Isolation and identification of the causal pathogen associated with Pokkah Boeng disease on sugarcane in Upper Egypt

Using morphological and molecular methods, this research sought to distinguish, classify, and characterize the pathogen associated with pokkah boeng disease (knife-cut symptoms). During the 2021 growing season, the sugarcane breeding program at El-Mattana Agricultural Research Station, Luxor Governorate, Egypt, the knife-cut symptom was observed on stalks of sugarcane (variety G.2009-99). The causal pathogen was isolated from samples taken from infected stalks with knife-cut lesions. Pathogenicity studies affirmed that the pathogen isolate was pathogenic on cuttings of the commercial sugarcane variety G. T. 54-9. After 7 days from inoculation, disease signs were detected in cane stalks when opened longitudinally. Stalks of sugarcane in control treatments showed no signs of disease. The pathogen was re-isolated and determined to be similar to the causal fungus that triggered knife-cut symptoms in a normal infection in the field. Morphological characteristics of growth rates, colony features, and shapes of macroconidia, microconidia, conidiogenous cells, and chlamydospores were used to identify the isolate. The pathogen internal transcribed spacer (ITS) was sequenced using ITS1 and ITS4 primers to classify and differentiate it. After microscopic morphology and gene sequencing, the fungus isolate was identified as Fusarium verticillioides. The pathogen pure culture was preserved in the Assiut University Mycological Centre as AUMC 14795, and the ITS sequence was uploaded to GenBank as MW692089. More research is required to assess the prevalence of the pathogen, the resistance of various sugarcane varieties, and an effective method for managing the pathogen.

Sugarcane stem cut quality investigated by finite element simulation and experiment

Previous studies on the cut quality of sugarcane stalks have mainly focused on external factors. However, the effects of internal factors on the cut quality have rarely been studied. In this study, the influence of internal and external factors on the cut quality were considered. Numerical finite element simulations and an experimental design were utilised to investigate the influences of the internal and external factors on the cut quality. The numerical model was validated using experimental cutting tests and based on a theoretical analysis. The optimum combination of cutting system parameters was investigated using an orthogonal test. The cut quality of the optimal combination was verified based on experiments. From the results, it was seen that the cutting bevel angle plays a significant role in affecting the cutting force, whereas machine forward speed (within the range 0.4–0.6 m s−1) and rotational speed (within the range 650–750 rpm) had no noticeable influence on cutting force. The optimal combination obtained by the orthogonal experiment was a cutting bevel angle of 30°, forward speed of 0.4 m s−1, and cutter rotational speed of 650 rpm. The optimised parameter combination produced an improved quality of cut in a cutting test. The damage mechanisms of sugarcane arising from internal factors were also investigated. This study provides basic information for the design of a base cutter for sugarcane harvesting.

Education of Hygiene Sanitation Processing Cane Water Traders as a prevention of Food Borne Disease Prevention

The drink of freshly ground sugarcane from sugarcane stalks has a distinctive aoram, is cloudy in color and is sold without special packaging and is sold on the side of the road where the sanitation is very low so that its bacteriological quality is doubtful. Esherichia coli (e.coli) is a bacteria that can contaminate sugarcane juice. This research is about education on hygiene, sanitation, processing and examination of Escherichia coli (E.coli) bacteria in water drinks.,The most common drink in West Aceh is sugarcane water, this drink is very easy to find on the side of the road and is liked by every community.The purpose of this study was to see the effect of education on hygiene and sanitation of sugarcane water treatment and examination of Escherichia coli (E. coli) bacteria in sugarcane water.The research method used quasi-experimental and observational methods. The population in this study were sugar cane traders with a total sample of 20 people. The results showed that there was an effect of education on the sanitation hygiene of sugarcane water treatment and levels of Escherichia Coli (E.coli) in sugarcane water.

Effects of Intra-Row Spacing on Yield and Yield Components of Sugarcane (Saccharum spp. hybrid) Varieties at Omo Kuraz, Southern Ethiopia

Sugarcane stalk population is a key determinant of cane yield and knowing the right intra-row spacing is a critical factor in sugarcane production for a given environment. Therefore, a field experiment was conducted at Omo Kuraz Sugar Estate during the 2018/ 2019 cropping season to determine the effect of intra-row spacings (5 cm overlapping, end-to-end, 5 cm spacing between setts and 10 cm spacing between setts) on growth, yield, yield components and quality parameters of sugarcane varieties (N14, Mex54/245 and C86/112). The treatments were arranged in a split-plot design with three replications. Varieties were represented as the main plot whereas setts spacing treatments were assigned to sub-plots. Analysis of variance revealed that the intra-row spacing effect didn’t show a significant difference in the number of tillers, plant population, millable cane, cane yield, sugar yield, and Brix percent whereas significant (P<0.05) differences were observed in stalk height, stalk girth, number of internodes and weight per stalk. Therefore, the 10 cm intra-row spacing of three budded setts can be recommended for better productivity and profitability of N14 and Mex54/245 varieties at the Omo Kuraz Sugar factory.

Untrafficked furrowed seedbed sustains soil physical quality in sugarcane mechanized fields

AbstractManagement strategies that reduce machinery traffic, such as creating seedbeds, could be adopted to preserve soil health and reduce soil physical restriction to sugarcane (Saccharum sp.) growth. Field experiments on clayey and sandy loam soils were conducted along four crop seasons (2013–2017) to investigate the changes in bulk density, soil penetration resistance, macroporosity and microporosity in the row and inter‐row positions, as well as sugarcane biomass production (root and stalk yield) under different machinery traffic treatments. The experimental areas were conducted in randomized block design with two treatments and four repetitions. The evaluated treatments were: (a) regular traffic, in which all operations were performed mechanically using regular machinery traffic; and (b) without traffic, in which all field operations (except those used for sunn hemp management and for opening the sugarcane planting furrow) were performed manually without machinery traffic. No critical values of physical properties were identified in either soil type in plots without machinery traffic, indicating the lowest density and soil penetration resistance values, as well as higher macroporosity, where sugarcane seedbed zones had been established. Our findings show that seedbeds resulted in greater root growth and development in the soil profile, mainly in inter‐row positions. Overall, sugarcane stalk yield was similar between the treatments in both soil types. This study reinforces the importance of the planting furrow in keeping suitable soil conditions for plant growth and concludes that sugarcane production in untrafficked seedbeds is an effective strategy to sustain soil physical conditions over the crop cycle, without the need for tillage operations during the (re)planting period.Highlights The use of seedbeds sustains soil physical quality along the crop cycle Most of root biomass were concentrated in the crop‐row Crop‐row position provides adequate soil physical conditions for root growth and plant development Untrafficked furrowed seedbed sustains soil physical quality and makes no‐tillage viable

High-Speed Photography Analysis on Sugarcane Base Cutting Process of Contra-Rotating Basecutters

In mechanical sugarcane harvesting, the basecutter is a critical component determining the basecutting quality and energy consumption, both of which have a close relationship with basecutting times (number of contacts between sugarcane and basecutting blades to completely cut cane stools). Therefore, the purpose of this study was to investigate the relationship between the influencing factors and basecutting times by employing a high-speed camera. In this paper, the influencing factors were determined to be the rotational speed (RS) and tilt angle (TA) of the cutting disk, sugarcane stalk feeding rate (FR), and sugarcane stool diameter (SD). Four single-factor experiments and an orthogonal experiment (four factors and four levels) were carried out. In addition, two methods were employed to analyze the experimental data: analysis of range (ANOR) and analysis of variance (ANOVA). The results showed that RS, TA, and SD had positive effects on the basecutting times, while FR had a negative effect. In addition, the order of influence of the above four factors on the basecutting times, obtained by ANOR, was FR > SD > RS > TA (2.625 > 1.75 > 1.425 > 1), and the optimal combination (150 rpm of RS, 5° of TA, 60 mm of SD, and 1.3 m/s of FR) to minimize the basecutting times was also determined. Based on the ANOVA results, basecutting times were significantly affected by FR and RS (p = 0.008, 0.047 0.05). The results of this study will provide a reference for engineers to design and optimize sugarcane basecutters.

Urea- Versus Ammonium Nitrate–Based Fertilizers for Green Sugarcane Cultivation

This study tested the hypothesis that enhanced-efficiency fertilizers, such as urea treated with NBPT, are a feasible substitute for ammonium nitrate–based fertilizers for green sugarcane cultivation. The experimental design included six N sources applied over sugarcane straw at two sites in Central-South Brazil. Treatments included ammonium nitrate, urea, and four urea-based fertilizers treated with different rates of the urease inhibitor N-(n-butyl)thiophosphoric triamide (NBPT) at two rates of N (50 and 100 kg ha−1), plus an additional control. Nitrogen status in the plant, the activity of glutamine synthetase (GS) and nitrate reductase (NR) in the leaves, and sugarcane stalk yield and quality were evaluated. At site 1, N rates increased the SPAD index, stalk yield, N uptake, and sugar yield. At site 2, N rates increased GS activity, N content, the SPAD index, and N uptake, but stalk and sugar yield were not increased due to large variability in these parameters. All N sources resulted in similar yields at both sites. These results were compared with those in the literature. Among 27 studies surveyed, the average sugarcane yield was 97.8 or 97.4 Mg ha−1 under ammonium nitrate or urea fertilization, respectively, and these averages did not differ by the Kruskal-Wallis test. The results of this study demonstrate that enhanced-efficiency fertilizers have the potential to reduce NH3 emissions from urea-based fertilizers in green sugarcane fields without affecting sugarcane yield.

Bacterial communities associated with sugarcane under different agricultural management exhibit a diversity of plant growth-promoting traits and evidence of synergistic effect

Plant-associated microbiomes have been a target of interest for the prospection of microorganisms, which may be acting as effectors to increase agricultural productivity. For years, the search for beneficial microorganisms has been carried out from the characterization of functional traits of growth-promotion using tests with a few isolates. However, eventually, the expectations with positive results may not be realized when the evaluation is performed in association with plants. In our study, we accessed the cultivable sugarcane microbiome under two conditions of agronomic management: organic and conventional. From the use of a new customized culture medium, we recovered 944 endophytic and epiphytic bacterial communities derived from plant roots, stalks, leaves, and rhizospheric soil. This could be accomplished by using a large-scale approach, initially performing an in planta (Cynodon dactylon) screening process of inoculation to avoid early incompatibility. The inoculation was performed using the bacterial communities, considering that in this way, they could act synergistically. This process resulted in 38 candidate communities, 17 of which had higher Indole-3-acetic acid (IAA) production and phosphate solubilization activity and, were submitted to a new in planta test using Brachiaria ruziziensis and quantification of functional traits for growth-promotion and physiological tests. Enrichment analysis of selected communities has shown that they derived mainly from epiphytic populations of sugarcane stalks under conventional management. The sequencing of the V3-V4 region of the 16S rRNA gene revealed 34 genera and 24 species distributed among the phylum Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria. We also observed a network of genera in these communities where the genus Chryseobacterium stands out with a greater degree of interaction, indicating a possible direct or indirect role as a keystone taxon in communities with plant-growth promotion capacities. From the results achieved, we can conclude that the approach is useful in the recovery of a set of sugarcane bacterial communities and that there is, evidence of synergistic action providing benefits to plants, and that they are compatible with plants of the same family (Poaceae). Thus, we are reporting the beneficial bacterial communities identified as suitable candidates with rated potential to be exploited as bioinoculants for crops.

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.

A transcriptomic analysis of sugarcane response to Leifsonia xyli subsp. xyli infection.

Sugarcane ratoon stunting disease (RSD) caused by Leifsonia xyli subsp. xyli (Lxx) is a common destructive disease that occurs around the world. Lxx is an obligate pathogen of sugarcane, and previous studies have reported some physiological responses of RSD-affected sugarcane. However, the molecular understanding of sugarcane response to Lxx infection remains unclear. In the present study, transcriptomes of healthy and Lxx-infected sugarcane stalks and leaves were studied to gain more insights into the gene activity in sugarcane in response to Lxx infection. RNA-Seq analysis of healthy and diseased plants transcriptomes identified 107,750 unigenes. Analysis of these unigenes showed a large number of differentially expressed genes (DEGs) occurring mostly in leaves of infected plants. Sugarcane responds to Lxx infection mainly via alteration of metabolic pathways such as photosynthesis, phytohormone biosynthesis, phytohormone action-mediated regulation, and plant-pathogen interactions. It was also found that cell wall defense pathways and protein phosphorylation/dephosphorylation pathways may play important roles in Lxx pathogeneis. In Lxx-infected plants, significant inhibition in photosynthetic processes through large number of differentially expressed genes involved in energy capture, energy metabolism and chloroplast structure. Also, Lxx infection caused down-regulation of gibberellin response through an increased activity of DELLA and down-regulation of GID1 proteins. This alteration in gibberellic acid response combined with the inhibition of photosynthetic processes may account for the majority of growth retardation occurring in RSD-affected plants. A number of genes associated with plant-pathogen interactions were also differentially expressed in Lxx-infected plants. These include those involved in secondary metabolite biosynthesis, protein phosphorylation/dephosphorylation, cell wall biosynthesis, and phagosomes, implicating an active defense response to Lxx infection. Considering the fact that RSD occurs worldwide and a significant cause of sugarcane productivity, a better understanding of Lxx resistance-related processes may help develop tools and technologies for producing RSD-resistant sugarcane varieties through conventional and/or molecular breeding.

Selection of reference genes for normalization of microRNA expression in sugarcane stalks during its interaction with Colletotrichum falcatum.

The microRNAs role in various cellular and metabolic functions is gaining more limelight in line with second-generation NGS technology. For the validation of candidate miRNA genes, the quantitative real-time PCR is the widely trusted and efficient method to follow. Sugarcane miRNAs are less explored in sugarcane defense response during their interaction with Colletotrichum falcatum inciting red rot. Further, for RT-qPCR experiments involving sugarcane miRNA expression studies, a stable internal reference gene is required. Hence, we have taken a study involving 20 candidate genes to identify stable expressing reference genes using NormFinder, geNorm, BestKeeper, and deltaCt statistical algorithms. The candidate reference genes included miRNAs and protein-coding genes. The results indicated that there is a variation in ranking among the algorithms. We found miR1862c as the stably expressed miRNA reference gene among the candidates and miR444b.2 along miR1862c formed the best reference gene pair combination, which can be used in the experiments aiming to explore sugarcane miRNAs in the defense mechanism against C. falcatum. The stable miRNA reference gene was further validated with other lesser stable reference gene candidates to assess the effect of stable reference genes during normalization. The present study evaluating the sugarcane miRNAs as reference genes for normalizing RT-qPCR expression data involving miRNAs during sugarcane ×C. falcatum interaction is the first of its kind. Further, this systematic approach can be followed to assess the reference gene in various experimental conditions involving sugarcane miRNAs.

Coupling kinetic models and advection–diffusion equations. 2. Sensitivity analysis of an advection–diffusion–reaction model

Abstract The accompanying paper (Uys et al., in silico Plants, 2021: diab013) presented a core model of sucrose accumulation within the advection–diffusion–reaction framework, which is able to capture the spatio-temporal evolution of the system from a set of initial conditions. This paper presents a sensitivity analysis of this model. Because this is a non-steady-state model based on partial differential equations, we performed the sensitivity analysis using two approaches from engineering. The Morris method is based on a one-at-a-time design, perturbing parameters individually and calculating the influence on model output in terms of elementary effects. Fourier amplitude sensitivity test (FAST) is a global sensitivity analysis method, where all parameters are perturbed simultaneously, oscillating at different frequencies, enabling the calculation of the contribution of each parameter through Fourier analysis. Overall, both methods gave similar results. Perturbations in reactions tended to have a large influence on their own rate, as well as on directly connected metabolites. Sensitivities varied both with the time of the simulation and the position along the sugarcane stalk. Our results suggest that vacuolar sucrose concentrations are most sensitive to vacuolar invertase in the centre of the stalk, but that phloem unloading and vacuolar sucrose uptake also contribute, especially towards the stalk edges. Sucrose in the phloem was most sensitive to phloem loading at the nodes, but most sensitive to phloem unloading in the middle of the internodes. Sink concentrations of sucrose in the symplast were most sensitive to phloem unloading in the middle of the internodes, but at the nodes cytosolic invertase had the greatest effect.

Base Cutting Energy Consumption for Sugarcane Stools Using Contra-Rotating Basecutters

HighlightsThis study focused on the base cutting energy consumption for sugarcane stools instead of single stalks, thus being more consistent with actual field harvesting.The energy consumption increased with increasing rotational speed (RS) and stool diameter (SD), while it decreased with increasing tilt angle (TA) and feed rate (FR).Each pair of levels of each factor was compared using Duncan’s multiple range test. Three factors (RS, SD, and FR) had significant effects on energy consumption at 95% confidence level, while one factor (TA) had no significant effect.The order of influence and the optimal combination of the four factors to minimize the energy consumed during base cutting were determined.Abstract. Previous studies on contra-rotating basecutter designs based on supported cutting have mainly focused on the base cutting energy consumption for single sugarcane stalks instead of sugarcane stools. However, in the actual base cutting process, a basecutter typically cuts multiple sugarcane stalks (in one sugarcane stool) simultaneously. Therefore, this study investigated how the rotational speed (RS) and tilt angle (TA) of the cutting discs, the sugarcane stool diameter (SD), and the feed rate (FR) affected the energy consumed when cutting cane stools using a contra-rotating cutting platform. Four single-factor experiments and an orthogonal experiment were performed using a Taguchi orthogonal experimental design, and each group was replicated five times. The results of the single-factor experiments showed that the energy consumption was proportional to RS and SD, while it was negatively correlated with TA and FR. The significance of the difference between each pair of levels of each factor was investigated using Duncan’s multiple range test. According to the results of the orthogonal experiment, RS, SD, and FR had significant influences on the base cutting energy consumption at the 95% confidence level; however, TA had no significant influence. The order of influence of the four factors was SD > FR > RS > TA (18.45 > 18.39 > 12.91 > 9.06), and the optimal factor-level combination for minimizing the cutting energy was RS2, TA4, SD1, and FR3 (200 rpm disc RS, 20° disc TA, 60 mm SD, and 1.0 m s-1 FR). An understanding of the relationships between energy consumption and its influencing factors can serve as a valuable reference for researchers seeking to optimize the design of contra-rotating basecutters, which could lead to increased energy efficiency and a reduction in energy consumption during sugarcane harvesting. Keywords: Contra-rotating basecutter, Energy consumption, Orthogonal experiment, Single-factor experiment, Sugarcane stools, Supported cutting.

Experimental Study on Tensile Properties of Sugarcane Leaves

Highlights This article focuses on the tensile properties of sugarcane leaves. The moisture content and sheath diameter were selected as test factors, and the test index was the stalk-leaf connecting force. The load-displacement curves of stalks and leaves were plotted. Two-way ANOVA was also discussed. Abstract . The tensile properties of sugarcane leaves are critical factors affecting the harvesting quality of sugarcane harvesters. Thus, it is important to investigate the tensile properties of sugarcane stalks and leaves. The selected test factors were leaf moisture content and sheath diameter, and the stalk-leaf connecting force was selected as test index. The tests were conducted with two moisture content levels of 15% and 20%, and three sheath diameters of 22, 26, and 30 mm. The stress-strain curves of stalks and leaves were plotted to show how the tensile force varied during the tensile test. The results showed that there was a strong linear correlation between the stalk-leaf connecting force and diameter of leaf sheath, and the connecting force also increased with the increasing moisture content. In addition, leaf tensile forces in longitudinal direction were much larger than in transverse direction. Two-way ANOVA revealed that both of the moisture contents (A) and sheath diameters (B) had significant effects on the stalk-leaf connecting force (p < 0.01), however, the interaction between A and B was not significant (p > 0.1). This study provides a theoretical reference for the design and improvement of crop dividers of sugarcane harvester. Keywords: Moisture content, Sheath diameter, Stalk-leaf connecting force, Sugarcane leaves, Universal testing machine, Tensile properties.