Tropical Conditions Research Articles

Diversidade genética de Eugenia stipitate Mcvaugh. baseada nas características físicas e físico-químicas dos frutos em condições tropicais

Abstract: The objective of this study was to evaluate the genetic diversity between genotypes based on the physical, chemical and physicochemical characteristics of araçá-boi in tropical conditions. The experiment was carried out at the Federal University of Roraima, in the municipality of Boa Vista, Roraima, Brazil. Genotypes were obtained in the F1 generation, through open pollination. Twelve plants were evaluated, with 10 fruits being collected per plant. The physical and physicalchemical characteristics of the fruits were evaluated: fresh mass, length and diameter of the fruits, pulp yield, firmness, mass of the pulp, peel and seeds, number of seeds, soluble solids, tritratable acidity, pH, ratio SS/AT and vitamin C from fruits. The araçá-boi genotypes showed medium to high genetic variability, obtaining averages for the physical and physicalchemical characteristics higher than those observed in the literature. G genotypes A9, A10 and A6 adopted fruits with larger sizes and produced a greater number of fruits genotypes A1 obtained fruits with higher organoleptic quality. Genotypes A3 produced fruits with higher levels of Vitamin C and fruits with greater firmness. Genotypes A3, A6, A9 and A10 were promising with high agronomic potential and could be selected for the genetic improvement program of the species.

Adaptation mechanism of Phan Rang sheep to salinity in drinking water under tropical conditions.

The aims of this study were to determine adaptation mechanism of sheep to salinity in drinking water. A group of 10 male sheep were used in a 6-week of experiment, with 1week for pre-treatment period (Week 1), 4weeks for during treatment period (Week 2 to Week 5), and 1week for posttreatment period (Week 6). During the pre- and posttreatment periods, sheep consumed with fresh water. However, during treatment period, they were given with diluted seawater (DSW) at concentrations of 0.5%, 1.0%, 1.5%, and 2% for Weeks 2, 3, 4, and 5, respectively. Animal was offered 300 g concentrate and corn stover silage for ab libitum. Dry matter intake decreased as DSW increased, whereas sheep drinking DSW showed an increase in water intake and urine volume (p < 0.05). Body weight change decreased in 2% DSW. Sheep consuming 2% DSW exhibited higher plasma electrolyte levels compared to other groups. But plasma levels of AST, ALT, and creatinine were unaffected by DSW (p > 0.05). The elevated levels and excretions of urinary electrolytes were found in DSW groups (p < 0.05). Water balance was unaffected by DSW, except during the recovery period. It concluded that adapted sheep can consume DSW up to 1.5% without harmful effects.

Requirements of metabolisable energy, crude protein and methionine for growing white leghorn chicken under tropical condition

Requirements of metabolisable energy, crude protein and methionine for growing white leghorn chicken under tropical condition

Effect of Fogging Fogging Cooling System on Physiological and Performance Characteristics of Broiler Chicken Under Tropical Hot Conditions

Effect of Fogging Fogging Cooling System on Physiological and Performance Characteristics of Broiler Chicken Under Tropical Hot Conditions

Physiological evaluation of Sonchus oleraceus L. seeds with different pre-germinative treatments under high tropical latitudinal conditions

Sonchus oleraceus L. is an invasive species that negatively affects the quality and yield of different crops. This research aimed to evaluate the physiological behavior of seeds from the weed S. oleraceus L., which were subjected to different treatments in three experiments. In experiment 1, different gibberellic acid (GA) concentrations were applied (0, 200, 400, and 600 mg L-1). In the second experiment, apical, basal, and apical-basal cut treatments were carried out on the seeds. In a third experiment, seeds were placed at different sowing depths (0.5, 1, 2, 5, and 10 cm) in peat as the substrate. The results indicated that GA at concentrations higher than 200 mg L-1 inhibited seed germination and, consequently, seedling growth. Germination was similar between the 200 mg L-1 GA treatment and the control, but germination occurred faster in the control. The apical-basal cut in the seeds generated the highest percentage of germination, the highest average speed of germination, and a significantly lower time of germination than the control; however, the longest shoot was observed in the seeds without a cut, and the longest root was detected in the seeds with the basal cut. Seedling emergence was affected by sowing depth, where it was significantly greater at 0.5, lesser at 2 cm, and, at greater depths, seedlings did not emerge.

Evaluating the techno-economic viability of different solar collectors integrated into an adsorption cooling system in tropical climate conditions

The technology and performance of solar adsorption cooling systems have reached maturity, enabling them to meet the growing demand for air conditioning. High upfront and operating costs have, however, hindered the commercial spread of solar adsorption cooling systems. Comparing the solar adsorption cooling system with commercial air conditioners, the solar thermal system offers superior efficiency. In order to enhance the techno-economic potential of solar adsorption cooling in Malaysia, this study developed a combination of analytical and conceptual frameworks in the form of a multilayer computational network to identify the most efficient solar thermal system. TRNSYS, MATLAB, and REFPROP software were used to model and simulate the solar adsorption cooling system. A Particle Swarm Optimization algorithm (PSO) implemented in MATLAB and linked to TRNSYS was then used to determine the optimal components and variables for each solar thermal system. To determine the most efficient solar thermal system, a techno-economic assessment was conducted to evaluate the solar adsorption cooling system incorporating optimized solar thermal systems. The findings reveal that among the various types of collectors investigated, the evacuated tube collectors demonstrated the highest efficiency in providing the necessary heat energy for the adsorption cooling system. In contrast, the linear Fresnel reflector collector and parabolic trough collectors display exceptional performance, mainly under clear sky conditions. Meanwhile, the photovoltaic-thermal collectors exhibit the greatest energy-saving and techno-economic potential. This advantage arises from their ability to simultaneously generate power and heat, taking advantage of the cost disparity between electricity and natural gas in Malaysia.

Data analytics-based evaluation of blood indices and adaptation of medicated and non-medicated broiler chickens under humid tropical conditions.

The growth performance and blood indices of medicated and non-medicated broiler chickens have been the subject of this research coupled with a paucity of comparative information on what can actually happen to broiler chickens if not medicated when reared under humid tropical conditions. One hundred unsexed day-old broilers were randomly and equally allotted into two treatment groups of TM (medicated) and TN (non-medicated) in a completely randomized design each treatment with five replicates having ten birds each. The birds were reared on deep litter system for 56 d which was divided into two phases of 28 d each (starter and finisher), during which data were collected with respect to daily feed intake, final body weight, body weight gained (BWG), mortality rate while blood analysis was carried out on 28th and 56th d for starter and finisher phases, respectively. Non-medicated group served as control. Feed conversion ratio (FCR) and feed conversion efficiency (FCE), were later calculated. Data collected were subjected to analysis of variance statistically. There was no significant difference between the medicated and non-medicated broilers for daily feed intake, final body weight, and BWG and also for the blood parameters investigated at starter phase. However, at finisher phase, no significant difference was observed in the daily feed intake of Tm and Tn but there was significant (P < 0.05) difference in the final body weight, BWG, FCR, FCE, and mortality rate between the two groups. Birds on Tm attained higher weight significantly (P < 0.05) than those on TN. BWG, FCR, and FCE followed the same trend and also the mortality rate. White blood cells count of TN was higher significantly (P < 0.05) than TM while TM birds recorded higher packed cell volume, red blood counts, and hemoglobin concentration (Hb) significantly (P < 0.05) than TM birds. Effect of medication was much noticeable at finisher phase as it improved the growth rate though mortality rate was close to that of TN group. These results suggest that broilers can be produced free of medication with good feeding without loss of birds while the growth rate can be enhanced with the use of prebiotics and prebiotics.

Models to predict nitrogen excretion from beef cattle fed a wide range of diets compiled from South America.

The objective of this meta-analysis was to develop and evaluate models for predicting nitrogen (N) excretion in feces, urine, and manure in beef cattle in South America. The study incorporated a total of 1,116 individual observations of N excretion in feces and 939 individual observations of N excretion in feces and in urine (g/d), representing a diverse range of diets, animal genotypes, and management conditions in South America. The datasetalso included data on dry matter intake (DMI; kg/d) and nitrogen intake (NI; g/d), concentrations of dietary components, as well as average daily gain (ADG; g/d) and average body weight (BW; kg). Models were derived using linear mixed-effects regression with a random intercept for the study. Fecal N excretion was positively associated with DMI, NI, nonfibrous carbohydrates, average BW, and ADG and negatively associated with EE and CP concentration in the diet. The univariate model predicting fecal N excretion based on DMI (model 1) performed slightly better than the univariate model, which used NI as a predictor variable (model 2) with a root mean square error (RMSE) of 38.0 vs. 39.2%, the RMSE-observations SD ratio (RSR) of 0.81 vs. 0.84, and concordance correlation coefficient (CCC) of 0.53 vs. 0.50, respectively. Models predicting urinary N excretion were less accurate than those derived to predict fecal N excretion, with an average RMSE of 43.7% vs. 37.0%, respectively. Urinary and manure N excretion were positively associated with DMI, NI, CP, average BW, and ADG and negatively associated with neutral detergent fiber concentration in the diet. As opposed to fecal N excretion, the univariate model predicting urinary N excretion using NI (model 10) performed slightly better than the univariate model using DMI (model 9) as predictor variable with an RMSE of 36.0% vs. 39.7%, RSR 0.85 vs. 0.93, and CCC of 0.43 vs. 0.29, respectively. The models developed in this study are applicable for predicting N excretion in beef cattle across a broad spectrum of dietary compositions and animal genotypes in South America. The univariate model using DMI as a predictor is recommended for fecal N prediction, while the univariate model using NI is recommended for predicting urinary and manure N excretion because the use of more complex models resulted in little to no benefits. However, it may be more useful to consider more complex models that incorporate nutrient intakes and diet composition for decision-making when N excretion is a factor to be considered. Three extant equations evaluated in this study have the potential to be used in tropical conditions typical of South America to predict fecal N excretion with good precision and accuracy. However, none of the extant equations are recommended for predicting urine or manure N excretion because of their high RMSE, and low precision and accuracy.

Detection and characterization of copy number variation in three differentially-selected Nellore cattle populations.

Introduction: Nellore cattle (Bos taurus indicus) is the main beef cattle breed raised in Brazil. This breed is well adapted to tropical conditions and, more recently, has experienced intensive genetic selection for multiple performance traits. Over the past 43years, an experimental breeding program has been developed in the Institute of Animal Science (IZ, Sertaozinho, SP, Brazil), which resulted in three differentially-selected lines known as Nellore Control (NeC), Nellore Selection (NeS), and Nellore Traditional (NeT). The primary goal of this selection experiment was to determine the response to selection for yearling weight (YW) and residual feed intake (RFI) on Nellore cattle. The main objectives of this study were to: 1) identify copy number variation (CNVs) in Nellore cattle from three selection lines; 2) identify and characterize CNV regions (CNVR) on these three lines; and 3) perform functional enrichment analyses of the CNVR identified. Results: A total of 14,914 unique CNVs and 1,884 CNVRs were identified when considering all lines as a single population. The CNVRs were non-uniformly distributed across the chromosomes of the three selection lines included in the study. The NeT line had the highest number of CNVRs (n = 1,493), followed by the NeS (n = 823) and NeC (n = 482) lines. The CNVRs covered 23,449,890 bp (0.94%), 40,175,556 bp (1.61%), and 63,212,273 bp (2.54%) of the genome of the NeC, NeS, and NeT lines, respectively. Two CNVRs were commonly identified between the three lines, and six, two, and four exclusive regions were identified for NeC, NeS, and NeT, respectively. All the exclusive regions overlap with important genes, such as SMARCD3, SLC15A1, and MAPK1. Key biological processes associated with the candidate genes were identified, including pathways related to growth and metabolism. Conclusion: This study revealed large variability in CNVs and CNVRs across three Nellore lines differentially selected for YW and RFI. Gene annotation and gene ontology analyses of the exclusive CNVRs to each line revealed specific genes and biological processes involved in the expression of growth and feed efficiency traits. These findings contribute to the understanding of the genetic mechanisms underlying the phenotypic differences among the three Nellore selection lines.

Weight Changes in Bali Cattle During Lactation at Different Seasons in the Cattle-Oil Palm Production System

The season impacts livestock productivity and cattle kept in grazing production systems in tropical conditions. This research aims to determine the effect of season on the weight changes of Bali cows and calves on oil palm plantations. This research used 20 Bali cattle kept semi-intensively in oil palm plantation areas without feed supplementation in 2016–2018. Cows and calves were weighed at calving and every month until weaning (150 days). Season grouping was based on calving time: dry season (DS) May–October and rainy season (RS) November–April. Data were analyzed by independent T-test statistics using the SPSS 20.0 application. The results of observations showed that cows' body weight decreased gradually until the fourth month of lactation in both seasons. Cows' weight changes were only significantly different in the second month, in which cows at DS were better than RS (P&lt;0.05). The pre-weaning average daily gain (ADG) of calves each month was not significantly different between the two seasons, and they could reach a body weight of 60.60 kg (RS) and 61.47 kg (DS) at weaning. Season differences do not impact weight changes in the Bali cows and calves in the cattle-oil palm plantation production system.

Effect of tillage methods and sowing dates on growth, yield and yield attributes of newly released Basmati rice (Oryza sativa L.) varieties under direct seeded

To standardize the tillage methods and dates of direct seeded Jammu Basmati rice varieties under sub tropical condition, a field experiment was conducted at research farm of Agrometeorology Section, Division of Agronomy, SKUAST-J, Chatha, Jammu during kharif season 2020. The experiment was comprised of two tillage methods i.e. zero (T1) and conventional tillage (T2) , two direct sowing dates viz., 10th (D1) and 25th June (D2) along with four newly released Basmati rice varieties viz., Jammu Basmati-370 (V1), Jammu Basmati-118 (V2), Jammu Basmati-138 (V3) and Jammu Basmati-123 (V4) with 16 treatment combinations and three replications in split-split plot design. Various crop growth parameters (plant height, LAI and above ground dry matter accumulation) were recorded at fortnight interval starting from 30 DAS till physiological maturity of crop was attained. Jammu Basmati rice varieties sown under conventional tillage method recorded significantly higher number of tillers/m2 (232.7) and also effective tillers/m2 (222.7) than the zero tillage method. The 10th June sown crop observed significantly higher leaf area index, dry matter accumulation, yield and yield attributes compared to late sown crop. Crop sown under conventional tillage method realized significantly higher grain yield (23.74 q/ha) as compared to zero tillage method (18.03 q/ha). Among the varieties, Jammu Basmati-123 recorded significantly higher leaf area index, dry matter accumulation and grain yield followed by Jammu Basmati-118, Basmati-370 and Jammu Basmati-138.

Cercospora beticola causes leaf and stem spots of New Zealand spinach (Tetragonia tetragonoides) in Brazil

New Zealand (NZ) spinach (Tetragonia tetragonoides) is an important leafy vegetable crop in Brazil and other countries. This plant is used as a substitute for common spinach because it is rustic and tolerant to tropical and subtropical environmental conditions. It is often affected by a leaf and stem spot disease, which increases in severity during the warm climatic periods. Cercospora tetragoniae has been reported as the cause of this disease, but this is based on an early description of a Cercospora-like species on this host in Argentina, first named Cercosporina tetragoniae but later recombined into Cercospora. In the present study, isolates of Cercospora-like fungi were obtained from NZ spinach and beetroot plants in Brazil, and a multigene molecular study including the act, cal, gapdh, his3, ITS, and tef1-α regions was carried out to identify the causative pathogen. Additionally, morphological and cross inoculation studies were conducted with isolates obtained from diseased plants. The pathogen was confirmed as Cercospora beticola, a common and harmful pathogen of beetroot (Beta vulgaris). Cross-inoculations of isolates obtained from NZ spinach and beetroot showed that the isolates are infective to both hosts. This increases knowledge of epidemiology and management of this important disease. Several attempts to re-collect samples from the type locality in Argentina failed. NZ spinach is no longer grown at La Plata (Argentina), the type locality of C. tetragoniae. Therefore, the task of re-collecting the pathogen is still pending, for epitype designation and for a full clarification of the taxonomic status of C. tetragoniae. The possibility of the pathogen being seed-transmitted has been assessed, and evidence obtained justifies further assessment of this aspect.

Exploitation of the genetic variance in maize (Zea mays L.) populations for the mexican tropic

VS-536, The most used maize variety in the southeast of México, present favorable plant and ear traits and adaptation to the tropical conditions. The objectives of this research were to exploit the genetic variance present in maize populations, particulary in the improved version of VS-536. In mass selection is exploited the additive portion of the genetic variance. In varietal crosses of maize formed and evaluated during 2016 to 2023, there was found int the best hybrids, the presence of the VS-536 variety as parent. It suggest that an important portion of the genetic variance correspond to dominance and overdominance gene action and they can be exploited through varietal crosses as SINT4BxVS-536 and V-537CxVS-536; These crosses registered the highest grain yield across the 10 environments in Veracruz and Tabasco states of 6.84 and 6.34 t ha-1 statistically similar to H-520, used as check, that registered 6.73 t ha-1 ; Heterosis values with respect to the best parent were 15.80 and 11.21% for each cross respectively. The varietal cross SINT4BxVS-536 present short plant and ear height, tolerant to lodging, good plant and ear aspect and sanity, the leaves above the ear are in semierect position, excellent husk cover, the grain is white and present semident texture

Enhancing Pectin Particles with Polymer Additives: Mitigating Rumen Degradation and Minimizing Yellowish Milk Color in Grazed Cows.

The pigments consumed in grazing give the milk from dual-purpose cows raised in tropical conditions a yellowish color, affecting the quality and price of the milk. This study aimed to develop an economical method with supplementary pectin to antagonize the availability of carotenes by designing microparticles with shellac and palm oil as a viable alternative to protect pectin degradation against rumen microbes. Three preparations of microparticles based on citrus pectin were synthesized: unprotected (PnP), protected with palm oil (PwP), and protected with palm oil and shellac (PwPL) microparticles. Samples were roughly characterized by spectroscopy and electron microscopy techniques. The effect of PnP, PwP, and PwPL on blood metabolites and physicochemical characteristics of the milk of grazing lactating cows was evaluated through in vivo assays. The release of citrus pectin from microparticles was determined as uronic acids using solutions with distinct pH, whereas its degradation was studied using in situ tests. Results revealed that PnP, PwP, and PwPL are amorphous structures with sizes that range from 60 to 265 nm or 750 to 3570 µm and have surface charges that range from -11.5 to -50.2 mV. Samples exhibited characteristic peaks during FTIR analyses that corresponded to O-H, C=O, and COOCH3 groups and bands within the UV-vis region that indicated the absorption of pectin. The EDS analysis revealed the presence of carbon, oxygen, or calcium in samples. The release of uronic acids was higher at pH 2-3 with PwPL. The in situ degradability of PnP, PwP, and PwPL was 99, 28.4, and 17.7%, respectively. Moreover, PwPL decreased the blood concentration of glucose, cholesterol, and lactate. In contrast, 100 g of pectin per animal daily during the feed process reduced yellow coloring. In conclusion, designing particles protected with lipids and polymers as shellac is an economical method that resists degradation at pH levels greater than five.

EQUATIONS FOR BODY WEIGHT ADJUSTMENTS IN BLACK BELLY EWE LAMBS

&lt;p&gt;&lt;strong&gt;Background. &lt;/strong&gt;As body weight (BW) is rarely determined on fasted animals in most production systems, the need to develop accurate mathematical models for adjusting BW has been identified. &lt;strong&gt;Objective.&lt;/strong&gt; To evaluate models for estimating shrunk body weight (SBW) and empty body weight (EBW) in Black Belly growing ewe lambs raised in tropical conditions. &lt;strong&gt;Methodology.&lt;/strong&gt; Data of sixty Black Belly ewe lambs, between four to eight months of age with a mean BW of 26.55± 3.92 kg (± SD) were used. The SBW was estimated based on the BW without fasting (fed) and the EBW based on SBW through three models: 1. Linear; 2.-Linear without intercept and 3.- Exponential. The predictive capacity of the models was evaluated by cross-validation. &lt;strong&gt;Results. &lt;/strong&gt;The correlation coefficients between BW and SBW and SB and EBW were high (r = 0.94; &amp;lt;0.0001). The coefficients of determination (r&lt;sup&gt;2&lt;/sup&gt;) for the equations between BW and SBW were 0.89 (P&amp;lt;0.001); and 0.86 (P&amp;lt;0.001) for the relationship between SBW and EBW. Based on the AIC (26.81) Eq. 2 described the relationship between BW and SBW better than Eq. 1, (AIC = 28.44) and Eq. 3 (AIC =28.35). The final model to estimate SBW as a function of BW was: SBW (kg): 0.96 (±0.001***) × BW. With respect to the SBW and EBW ratio, Equation 5, was better than the linear Eq. 4, (AIC = 33.01) and Eq. 6 (AIC = 33.35). The following model was: EBW (kg): 0.81 (± 0.06***) × SBW. The cross-validation of the equation of the relationship between BW and SBW showed that Eq. 1 had a higher r2 (0.87), and lower RMSEP and MAE than Eq. 2 and Eq. 3. Also, the equation of the relationship between SBW and EBW the cross-validation revealed that Eqs. 4 and 6 had the higher &lt;sup&gt;r2&lt;/sup&gt; (0.82), and lower RMSEP and MAE and tended to be more accurate than Eq. 5. &lt;strong&gt;Implications. &lt;/strong&gt;The results obtained in present study contributes to the development of mathematical models for more accurate body weight adjustments in tropical sheep. &lt;strong&gt;Conclusion. &lt;/strong&gt;The equations developed and evaluated in the present study revealed that the linear relationship between BW and SBW, and the linear and exponential relationship between SBW and EBW can be used to body weight adjustments in growing Black Belly ewe lambs. It's worth noting that this confirms that the SBW can be calculated using an adjustment factor of 0.96 FBW.&lt;/p&gt;

Assessment of body fluid identification and DNA profiling after exposure to tropical weather conditions.

Despite current advances in body fluid identification, there are few studies evaluating the effect of environmental conditions. The present work assessed the detection of body fluids, blood, semen, and saliva, through lateral flow immunochromatographic (LFI) tests, exposed to tropical weather conditions over time, also evaluating the possibility of obtaining STR (short tandem repeat) profiles and identifying mitochondrial DNA (mtDNA) polymorphisms. Blood, semen, saliva samples, and mixtures of these fluids were deposited on polyester clothes and exposed to open-air tropical weather conditions for 1 month. The test versions from LFI (SERATEC®, Germany) Lab and crime scene (CS) used for the detection - one per each body fluid type - demonstrated that it is possible to identify body fluids and their mixtures up to 14 days after deposition. At 30 days, blood and semen were detected but not saliva. Full STR profiles were obtained from 14-day-old blood samples, and partial profiles were obtained from the remaining samples. It was possible to sequence mtDNA in the samples previously analyzed for STR profiling, and haplogroups could be assigned. In conclusion, this study demonstrated for the first time the possibility of body fluid identification and DNA profiling after exposure to tropical weather conditions for 1 month and also demonstrated the value of mtDNA analysis for compromised biological evidence.

Field tests of the efficiency of the corrosion inhibitor IFKhAN-80 for reinforcement steel in concrete under tropical conditions. 1. Contact protection

Field tests of the efficiency of the corrosion inhibitor IFKhAN-80 for reinforcement steel in concrete under tropical conditions. 1. Contact protection

Effect of crop management and climatic factors on weed control in sugarcane intercropping systems

ContextCover crops in intercropping systems have a high potential to manage weeds in tropical agroecosystems as an herbicide alternative. However, it still needs to be better investigated in sugarcane cropping systems. ObjectiveThis study assesses the weed control ability of cover crops in sugarcane intercropping systems depending on crop management and climate in tropical conditions. MethodsThis study was based on a set of eight experiments, including ten cover crop species, performed from 2012 to 2021 in three areas in Reunion Island (France) and comparing three inter-row management treatments: i) chemical weed control, ii) cover crops sown in the inter-row, and iii) low weed control. Mean weed and cover crop ground cover were measured during the entire crop cycle, and the complementary weed management practices (herbicide, manual weeding) were also recorded. Sugarcane yield and crop management were evaluated to assess the economic impact of a change in practice. ResultsMean weed ground cover was reduced by 51 % in the cover crop and chemical treatments compared to low control. Additionally, the cover crop treatment had an herbicide treatment frequency index lower by 37 % compared to chemical treatment but a higher number of manual weedings. In all treatments, weed cover increased with rainfall and temperature. In the cover crop treatment, a structural equation modeling approach allowed us to highlight the influence of cover crop (sowing date and species) and sugarcane management (crop cycle - plant or ratoon crop) on weed cover. Weed cover decreased with an increase in cover crop ground cover, which was higher for the early sowing date. Additionally, weed cover was lower in ratoon crops than plant crops but increased over time since intercropping was implemented. Finally, sugarcane yield was lower by 6 % in cover crop treatment compared to chemical treatment. The change in operating costs and revenues between these crop management induced a decrease in profits in intercropping compared to chemical cropping systems, variable according to the degree of mechanization. ConclusionsThis study highlights the predominance of management factors, compared with climate, to explain the effectiveness of weed control in sugarcane intercropping systems. ImplicationsDue to the change in weed cover over time, there is a need to assess the long-term sustainability of this practice and the potential change in weed communities.

Improved tropical cyclone wind speed estimation for microwave altimeter using machine learning

Satellite altimeters can provide excellent global wind speed at 10 m above the sea surface (U10), however, the U10 becomes inaccurate and difficult to measure in tropical cyclone conditions. The violent wind, rough waves and torrential rain manifest an exceptionally complex ocean-atmospheric environment for wind estimation. Although the backscatter signal is measured equally well in normal condition, the interpretation is not straightforward in tropical cyclones that requires complex associations with ocean-atmospheric geophysical variables. Typical U10 regression model developed in normal atmospheric conditions would inevitably reduce the estimation quality and encounter high modelling uncertainties from high dimensional input data that provide ill-posed solutions in extreme U10 estimation. However, other secondary parameters simultaneously measured by the altimeter have properties that convey additional atmospheric information to enhance U10 estimation accuracy in storm condition. Therefore, the present study proposes machine learning (ML) approaches based on artificial neural network (ANN), support vector machine (SVM), and Gaussian process regression (GPR) to integrate the multi-dimensional parameters and provide accurate U10 estimates for different parameter combination. Results suggest that the GPR method, considering atmospheric and sea surface related parameters, can provide the highest accuracy of U10 up to 35 ms−1 with quality perseverance against rain contamination. This study highlights the quality improvement of altimeter U10 estimation and the assessment method of ML in dealing with complex ocean-atmospheric interactions.

Breeding pure and crossbreeds of European cattle breeds for milk production improvement under tropical climate conditions-a review.

The aim of this review was to present the breeding status of pure or crossbreeds of European cattle with African indigenous cattle in order to improve milk yield in African tropical conditions. As the African indigenous breeds are characterized by small size, low body weight (300-450 kg) and low production performances (less than 1000 kg per lactation), short lactation length (205-240 days), etc., the crossbreeding with pure European cattle was done in order to ameliorate production performances especially milk and beef production. As results, it was seen that F1 offspring improved output productions than their parents of tropical origin. Also, it was seen that F1 offspring showed disease and heat resistance than their parents of temperate climate origin. However, at different degrees of crossbreeding, it was seen that the offspring can demonstrate bad production performances than their parents and therefore, the crossbreeding has to respect a certain degree. Other consequences are that the crossbreeding of local and pure European cattle breeds has resulted in calving complications in African local cattle. In African indigenous cattle, the selection as an improvement tool was given less emphasis as a solution to improve output production. That is why, the implementation of a well-prepared selection programs could be practiced in African indigenous cattle in order to preserve African cattle genotypes, as they are endangered of extinction due to various crossbreeding with exotic cattle breeds.