Tropical and Subtropical Agroecosystems最新文献

Background. Different forage innovations have been used to alleviate livestock feed shortage in Ethiopia. Napier, Rhodes, and Desho grasses are the most widely cultivated forage grasses in the backyard system. Objective. To evaluate the effect of harvesting age of Urochloa grass cultivar/ accessions on morphology, forage yield, chemical composition at Wolaita Sodo State dairy farm, Ethiopia. Methodology. The experiment involved a 5 × 3 factorial arrangement in a Randomized Complete Block Design with three replications, three harvesting ages (60, 90, and 120 days of age), and five Urochloa grass cultivars/ accessions (Urochloa hybrid 'Mulato II', Urochloa mutica (Forssk.) T.Q. Nguyen, Urochloa brizantha (Hochst. ex A. Rich.) R.D. Webster 'acce. no. DZF13151', Urochloa brizantha (Hochst. ex A. Rich.) R.D. Webster 'Piata' and Urochloa brizantha (Hochst. ex A. Rich.) R.D. Webster 'acce no. DZF16550') during 2020˗2021. Results. Plant height and number of leaves were greater (P<0.05) for U. mutica than for the remaining cultivars across the three harvesting ages. The tillers number was greater (P<0.05) for U. brizantha acce. no. 16550 at120 days of harvesting than the remaining cultivars and harvesting ages over the two years. The greatest leaf length was for Piata at 120 days of harvesting compared to the other cultivars and harvesting ages. The leaf: stem ratio was also the highest (P<0.05) for Piata at early age of harvesting. The dry matter, crude protein and digestible organic matter yields varied significantly among cultivars with the highest (P<0.05) values obtained for U. mutica across the three harvesting ages. The highest (P<0.05) crude protein (CP), in vitro organic matter digestibility (IVOMD) and metabolizable energy concentrations were observed for Mulato II and the lowest (P<0.05) value was recorded in U. brizantha acce. no. 13151 across the three harvesting ages. Most morphological characteristics and yield parameters increased (P<0.05) with increasing harvesting age. However, the CP, IVOMD, and leaf: stem decreased with increasing harvesting ages. Implications. The higher DM yield and forage quality of U. mutica and Mulato II may be an indicator of adaptation to midland climatic condition. Conclusion. Growing the outperforming cultivars, Mulato II and U. mutica, and harvesting at 90 days of age is considered as a suitable practice to improve fodder production and availability in the midland agroecology of Ethiopia.

Background: The genus Xylaria comprises over 300 fungal species distributed worldwide that exhibit adaptability to various ecological roles. Consequently, their potential for the synthesis of bioactive molecules with antibacterial and antivirulence properties has been reported. Objective: To characterize the antibacterial and antivirulence properties of Xylaria sp. (OG-03) strain against phytopathogenic bacteria (Pseudomonas syringae, Pseudomonas syringae pv. tabaci, Pseudomonas putida, and Chryseobacterium sp.) and Chromobacterium violaceum 553, respectively. Methodology: A fungal strain was isolated and characterized morphologically and molecularly, and its evolutionary history was investigated through phylogenetic reconstruction. Mycelial growth was assessed in different culture media with natural substrates, and fungal extracts were obtained to evaluate minimal inhibitory (phytopathogenic bacteria) and antivirulence (biosensor strain) activities. Results: Morphological and molecular characterizations of the fungal strain suggested an indeterminate taxonomic classification at the species level within the genus Xylaria. The highest mycelial growth was observed in the REA culture medium, and the liquid rice extract promoted ectostomes proliferation. Fungal biomass extracts displayed antibacterial activity against P. syringae (MIC 7.81 µg/mL, 88% inhibition), Pseudomonas syringae pv. tabaci (MIC 1.95 µg/mL, 87% inhibition), Pseudomonas putida (MIC 1.95 µg/mL, 79.25% inhibition), and Chryseobacterium sp. (MIC 7.81 µg/mL, 85.03% inhibition), respectively. Antivirulence against C. violaceum reduced biofilm formation (125 µg/mL, 59% inhibition) and violacein production (62.5 µg/mL, 58% inhibition). Implications: Xylaria sp. exhibits antibacterial and antivirulence activity against phytopathogenic bacteria. Conclusions: The strain studied is suggested to be an undetermined taxon within the genus Xylaria. The results of biological assays indicated that the fungus possesses antibiotic properties against phytopathogenic bacteria and can inhibit virulence factors associated with quorum sensing.

Background. Estimation of animal body weight (BW) is a fundamental tool in herd management for the development of reproductive, nutritional and health programmes. Objective. To compare the actual BW and its estimation by visual method and measurement of the heart girth (HG) or hip width (HW) for estimating BW in crossbred beef heifers reared under humid tropical conditions in Mexico. Methodology. Data on GH, HW, BW estimated by the visual method (MV) and actual BW were recorded in 105 crossbred replacement heifers (Bos taurus × Bos indicus) Swiss American, Beef Master, Simmental, and Brahman with different degrees of crossbreeding. Heifers ranged in age from three to 20 months and were grazed on star grass (Cynodon nlemfuensis) and humidicola grass (Brachiaria humidicola) pastures without supplementation. BW was recorded using a digital scale, HG was measured using a flexible fibreglass tape and HW was measured using a 65 cm forceps. BW by visual estimation was considered as the average of three observations made by three observers, HG and HW methods using the formula 1) BW (kg): 202.68 - 4.39 × HG + 0.03 × HG²; 2) BW (kg): 0.26 × HW^1.90. The Pearson coefficient and the distribution (density) of each variable, were assessed using a correlation matrix graph. Also, a comparison the measures obtained by each of the different estimation methods with the observed weights, by inspecting the paired Bland-Altman plots, prior to logarithmic transformation. Results. Correlations between observed BW and predicted BW for the HG, HW and visual methods showed a positive and significant relationship (P<0.001), with r values of 0.95, 0.89 and 0.92, respectively. The HG method tended to overestimate the real BW, whereas, in the visual and HW methods, the values are evenly and randomly distributed around the line, indicating that these methods neither underestimated nor overestimated the BW. Implications. Although the HG method showed the highest correlation coefficient between observed and predicted BW, the result of the present study showed that visual assessment highlights the ability of observers to visually estimate the BW of growing heifers. Conclusion. Livestock handlers have a very accurate estimation of BW. The use of alternative methods to scales, such as the HG measuring method, can be useful and practical tools to improve the accuracy of the assessment.

Background. The increasing utilisation of fibre feedstuffs in diets of pigs nowadays calls for concerns not only on the growth but also the health status of the animals and the possibility to eradicate the use of in-feed antibiotics for pigs. Objective. To evaluate the growth performance and gut promoting activity of three fibre feedstuffs (Palm kernel cake (PKC), Brewers’ dried grain (BDG) and Wheat offal (WO)) in diets of growing pigs. Methodology. Three dietary treatments containing 40 % each of PKC, BDG and WO were randomly allotted to 24 growing crossbred (Large White x Hampshire) pigs of average initial weight of 30± 0.50 Kg in an 82 d feeding trial. Results. There was an influence (p<0.05) of sources of fibre feedstuffs for the arabinoxylan- and mannan-oligosaccharide concentrations of the dietary treatments with BDG having comparatively higher values than WO and PKC diets. The short-chain fatty acid (SCFA) concentrations and pH of gut digesta were different (p<0.05) across dietary groups with pigs fed BDG diet having higher SCFA concentration in the foregut and hindgut. In the gut flora, BDG and WO promoted the highest (p<0.05) Lactobacillus population in the small and large intestines respectively. There were significant (p<0.05) effects of fibre sources on the final weight, average daily gain and daily intake of pigs fed the different treatments with those fed WO diets showing superior performance over pigs fed either PKC or BDG diet. Implication. The WO diet promoted the fastest growth and better gut effects but BDG resulted in the most efficient feed to gain conversion. Conclusion. All the diets exhibited prebiotic activity, enhanced the growth of beneficial bacterial in the gut and could reduce the use of in-feed antibiotics for pigs.

Background. Utilization of indigenous browse species have considerable potential to improve the nutritional deficiencies of low quality ruminant feeds under farmers’ condition. However, there is scarcity of scientific information on their nutritive value and ultimate impact on animals’ performance in Southern Tigray, Ethiopia. Objective. To evaluate the chemical composition, in vitro dry matter digestibility (IVDMD) and in sacco degradability of selected indigenous browse species as animal feed in Southern Tigray, Ethiopia. Methodology. Chemical analysis, IVDMD and in sacco degradability evaluation were done, following standard procedures, on leaf samples collected from nine dominantly available browse species (Ziziphus spina-Chiristi, Acacia tortilis, Balanites aegyptiaca, Grewia mollies, Carissa spinarum, Acacia etbaica, Pittosporum viridiflorum, Olea europaea and Dodonaoea angustifolia) during the main rainy season (end of September, 2020). Results. The crude protein (CP) contents of the browse species ranged from 9.96 to 23.32% on dry matter (DM) basis. The fiber components were highest for P. viridiflorum and lowest for D. angustifolia. The highest values of IVDMD (64.75%) and metabolizable energy (9.01 MJ/Kg DM) were recorded for Z. spina –Chiristi. All in vitro digestibility parameters were positively correlated with CP content but negatively correlated with acid detergent lignin (ADL) contents of the browses. The highest in sacco DM disappearance was recorded for Z. spina–Chiristi at 48 and 72 hours. The concentration of calcium (Ca) ranged from 0.69% for O. europaea to 0.98% for G. mollis. The mean Ca to Phosphorus (P) ratio was 2.7:1. Implications. The information generated in this study is useful for efficient utilization of these valuable indigenous browse species in the study area. Conclusions. All studied browse species could be considered as potential feed sources to supplement low quality roughages.

Background: In Mexico, rice crop production is limited by phytopathogenic fungi that cause diseases, some of which increase their incidence and severity when conditions such as high humidity and nutrient deficiency or excess occur. Objective: Determine the incidence and severity of the damage caused by phytopathogenic fungi in rice lines subjected to conditions of 100 % and 10 % nitrogen and phosphorous fertilization. Methodology: The experiment was carried out in the spring-summer 2021 cycle, at the Ébano-INIFAP Experimental Site, 136 rice lines were used and two treatments (100 % and 10 % nitrogenous and phosphorous chemical fertilization), were morphologically identified. phytopathogenic fungi and the incidence, severity, plant height and fresh biomass were measured. Results: Higher incidence and severity (27.5 % and <4 % respectively) were obtained in the rice lines subjected to the 10 % nitrogenous and phosphorous fertilization treatment. In both treatments Chiclayo 61 was identified as tolerant to damage from Alternaria sp., Curvularia geniculata and Fusarium equiseti, presenting incidence and severity of symptoms between 3.3 to 36.7 % and <1.5 %, respectively. On the other hand, plant height and fresh biomass showed higher values in the treatment with higher fertilization.Implications: High temperature and precipitation and nutritional deficiency increase damage by phytopathogenic fungi. Conclusion: The incidence and severity of the damage caused by Alternaria sp., Curvularia geniculata and Fusarium equiseti, in the crop increases when there are conditions of nutritional deficiency, in addition, nutrient-deficient plants have lower height and fresh biomass.

Background. One of the main pests of sugarcane are spittlebugs Aeneolamia spp. The use of sticky trap yellow and green colored has been proposed as an alternate monitoring method without definitively determining which color is the most effective. Objective. Evaluate the capture efficiency of colored glue plastic traps on spittlebugs during the sampling period and the general capture of arthropods in sugarcane in Panama. Methodology. The efficiency of sticky traps of yellow, green, blue, white and red colors on spittlebugs populations over time and the general capture of arthropods present in sugarcane in Panama were evaluated. For the observation of spittlebugs in time in ten localities, five traps of the colors mentioned above were established, which were reviewed weekly for four weeks. For the general capture of arthropods, work was carried out in five different locations with an equal number of traps and weeks of observation. Results. In the case of catches in traps associated with the capture time, 2675 individuals of Aeneolamia spp. were captured, where 99% corresponded to Aneolamia lepidior (Fowler) and 1% to Aneolamia reducta (Lallemand). The highest captures were given in yellow traps (52%), followed by green traps (43%), without presenting differences between them but rather an effect of observation time in the capture, which increased from the first week to the fourth. With respect to the general capture of arthropods, 2331 species were found mainly in yellow traps (46.6%) and green traps (41.2%), where 88.4% corresponded to phytophagous insects and less than 10% to predators and parasitoids, with no differences between yellow and green traps in the capture of beneficial insects. Implications. This research implies the importance of integrating alternatives such as sticky plastic traps within the integrated management of the spittlebug in sugar cane. Conclusions. The yellow and green sticky plastic traps turned out to be equally efficient for the capture of spittlebugs species at sampling time, representing an alternative within integrated management programs of the spittlebugs in sugar cane.

Background. Rice production is a major economic activity in the department of Tolima, Colombia. However, conventional agronomic practices have led to soil depletion. In contrast, within the same region, traditional Indigenous Pijao systems persist, characterized by a high degree of crop diversification as well as no or reduced use of agrochemicals and mechanization. Objective. To evaluate soil health over time in rice monocultures and traditional Pijao agroecosystems in Colombia. Methodology. Data was collected between May and September 2019 at four municipalities in an Andean valley. Experimental units were arranged in four treatments classified according to a chrono sequence of consecutive rice monoculture: agroecosystems in which rice has never been planted or ‘traditional Pijao agroecosystems’ (TPA); rice monoculture for 5 to 10 years or ‘young rice agroecosystems’ (YRA); for 10 to 20 years or ‘medium rice agroecosystems’ (MRA); and for more than 20 years or ‘old rice agroecosystems’ (ORA). Twelve indicators were evaluated in each experimental unit: physical (penetration resistance, water infiltration, bulk density, and soil structural index), chemical (pH, CEC/CL%, EC, SOC), and biological (microbial respiration, earthworm abundance, and diversity of arthropods and plants) indicators. Results. Physical and chemical indicators did not present significant differences among the four chrono sequences evaluated. However, TPA obtained the highest values for SOC, structural stability index, and microbial respiration in comparison with conventional rice agroecosystems. Diversity of arthropods and plants significantly differed among the four treatments. Implications. Results suggest that traditional Pijao agroecosystems promote arthropod diversity and plant (weed and crop species) diversity, contributing to a greater sustainability of the region’s agroecosystems. Conclusions. The study illustrates the most relevant soil health indicators for the tropical dry forest zone of southern Tolima are those providing information on soil diversity, structural stability, compaction, and microbial respiration.

Background: Maize agricultural policy in Mexico has focused on a monofunctional vision of maize as a basic commercial product, through a bimodal vision of production systems (commercial and subsistence). However, the evidence suggests that the challenge of thinking about the multifunctionality of this crop must be faced due to the complexity of its relationship within different strata of society, to more adequately reflect the diversity of systems based on maize, as well as their flexibility to respond to new challenges and opportunities, and to have better public policy designs. Objective: This work seeks to delve into the importance of the multifunctionality of maize within the context of different types of production units in Central and Southern Mexico, which represent families that make use of different production systems based on maize. This diversity is not a simple cultural curiosity, but rather reflects the complex use of maize cultivation as an economic and cultural mechanism that provides stability to Mexican families who depend on maize as their main crop. Methodology: To describe the multifunctionality of maize in Mexico, we adopted a qualitative approach through in-depth interviews with 51 maize producers from different types of production unit (PU) in the states of Oaxaca, Chiapas, Mexico, and Puebla. A study of production units (PU) typologies carried out with information from 16 states of the country was taken as a basis, where five types of PU were characterized according to their available resources, maize management, and their social characteristics. Results: It was found that: (1) there is a clearly distinguishable PU gradient (where, in addition to the existence of commercial and subsistence units, three others were identified, with direct implications for the design of public policy) that use maize with several purposes; (2) multifunctionality is associated with the diversity of uses and genetic materials that PUs have, and; (3) the variety of functions of maize changes according to the importance of maize in each type of unit and trough time. Implications: This work is positioned in favor of an expanded vision of the maize sector in Mexico instead of a dichotomous vision, where maize systems behave as a fluid continuum where the context of the PU’s affects their relationship with maize, and the way in which they use this crop to face social, climatic, and economic changes, as well as their preferences as consumers, traditions, and cultural identities. Conclusions: This complexity calls to thinking about a pluridiverse maize policy that understands the social complexity of this crop through the multifunctional support it offers to different types of UP’s based on maize systems, and how these differences require more sophisticated institutional approaches.

Background. Soil management practices modify the microbial communities and the carbon stocks (organic, inorganic, and total). The increase in microbiological communities’ diversity improves the production of plants; thus, it is essential to understand the predominant bacterial taxa in the soil. Objective. The objective of the present study was to establish the bacterial communities’ alteration by agroecological management in maize crops in arid northern Mexico. Methodology. Bacterial diversity and composition were determined in soils from Coahuila, Mexico, under three different scenarios: i) Agroecological management (AM), ii) Conventional management (CM), and iii) Control (T, with no vegetation). In addition, pH, electrical conductivity (EC), and soil organic matter (SOM) were analyzed using standard methods. Bacterial DNA was extracted from the soil, amplifying the V3-V4 region of the 16S rRNA gene and sequencing with Illumina. The gene sequences were analyzed in QIIME. Results. A total of 20 bacterial phyla and 631 genera were registered. For AM, CM, and T, respectively, the most abundant genera were Tepidisphaera (7.02, 9.29, and 9.93 %), Sphingomonas (6.55, 5.15, and 4.06 %), Microvirga (2.64, 2.39, and 3.63 %), and Blastococcus (2.91, 3.10, and 3.37 %). A significant difference was observed among groups (p = 0.004), where AM was different, which suggests that the type of substrate determines the diversity and abundance of the bacterial community. Significant differences were found for pH and EC, with higher pH in CM (7.87) and T (7.86) soils. The EC was higher in AM (446 μ Scm^-1) and T (419 μ Scm^-1). On the other hand, AM showed the best result in SOM content (21.80 ± 1.10 gC kg^-1). Implication. Therefore, AM in maize crops has the potential to conserve or restore C stock in degraded arid lands, increasing bacterial diversity, favoring the health of the soil. Conclusion. Agroecological management of maize crops soils in arid North of Mexico promotes greater bacterial diversity, which will favor the availability of nutrients for the future development of healthy plants.