Hasil untuk "Agriculture (General)"

Nur Fariha Amir, Aslizah Mohd-Aris, Tuan Norhafizah Tuan-Zakaria et al.

Background: Volvariella volvacea is a highly nutritious edible mushroom grown mainly in Southeast Asian countries. However, the low yield of V. volvacea has discouraged farmers from engaging in its production. Objective: The study was conducted to observe the improvement of V. volvacea yield depending on various physiochemical parameters of V. volvacea growth. Methods: The parameters tested in this study include the weight of the substrate, i.e., 2 kg (W1) and 6 kg (W2); the surface area of the substrate: A1 (1218 cm2), A2 (1530 cm2) and A3 (2000 cm2); and four different substrate formulations (F1, F2, F3 and F4). Results: Substrate weight and surface area were found to be important, but not critical, factors in determining fruiting bodies formation, total fungal mass, and BE rate. However, the formulation media showed a significant contribution that could help in the induction of fruiting bodies. According to the results, the culture medium with a mixture of EFB substrate and black soil showed the highest BE percentage of 17.75 % (at optimised substrate weights = 2 kg). Conclusion: The results of this study can be used as a reference for further studies to improve the cultivation of V. volvacea, especially when EFB fibres are used as the main substrate. Future studies to identify genes involved in the formation of fruiting bodies are strongly recommended.

Tafesse Kibatu, Sebsebe Demissew, Diriba Muleta et al.

Enset is a staple food for approximately 25% of Ethiopia’s population. It is threatened by a range of biotic and abiotic stress, of which bacterial wilt is the most significant. This study investigated the enset bacterial wilt (EBW) status on farms in Gedeo, Kembata Tembaro, Gurage, Hadiya zones, and the Basketo special woreda of Southern Ethiopia. In addition, infected enset plant samples were collected from Hadiya, Kembata Tembaro, and Gedeo zones to assess bacterial strain diversity using physicochemical and morphological approaches. Representative Kebeles were selected using purposive sampling based on their agroecological conditions. Data was collected through in-depth interviews, questionnaires, group discussions, and field observation. The morphology of bacterial wilt isolates was characterized by color, texture, form, elevation, margin, and motility. In addition, a combination of oxidase, aesculin hydrolysis, catalase, gram reaction, hydrogen sulfide (H2S), gelatin liquefaction, and fructose, lactose, mannitol, and sorbitol utilization tests were conducted to capture physiochemical differences. Tolerance to salt and high temperatures was also evaluated. The bacterial wilt impact varies significantly across enset growing regions, with highlands experiencing the highest. This research emphasizes the importance of assessing both spatial and temporal variation, as well as integrating local knowledge and robust scientific approaches for effective bacterial wilt management and enset landrace conservation efforts. The research also provides valuable insights into the characteristics of bacterial wilt isolates in Southern Ethiopia. Analyses of morphology, potassium hydroxide solubility, catalase activity, and carbohydrate utilization were consistent, however, variations in bacterial isolates response to tests of easculin, oxidase, gelatin liquid, H2S tests and response to osmotic and temperature exposures. This study reveals a strong association between the bacterial wilt effect and the enset growing regions. EBW exhibits seasonal fluctuations. Bacterial wilt isolates displayed consistent morphological characteristics. All isolates similarly utilized sorbitol, mannitol, lactose, and fructose carbohydrates. All isolates exhibited positive potassium hydroxide solubility and catalase activity. However, the isolates displayed variations in responses to easculin, oxidase, gelatin liquefaction, and H2S production. The isolates also displayed variations in tolerance to salt and high temperatures. These variations can be valuable for understanding disease epidemiology and management.

Kecan Chen, Runcheng Zhou, Wenjing Zhang et al.

Abstract Streptococcus mutans mediates enamel demineralization through acid production via glycolysis, while Streptococcus salivarius, as a commensal bacterium, promotes caries progression by enhancing biofilm formation. Their synergistic interaction amplifies cariogenicity. Therefore, developing strategies to inhibit both bacterial species is imperative. This study investigated the extraction and characterization of a polysaccharide from mangosteen scarfskin (MSP) and its antimicrobial potential against cariogenic bacteria. Using ultrasonic-assisted extraction, MSP was obtained with a yield of (9.93 ± 0.5696)%, presenting light brown coloration. Antimicrobial assays demonstrated strong anti-efficacy activity against Streptococcus mutans and Streptococcus salivarius, showing a MIC of 1 mg/mL and significant bactericidal effects at 1×MIC and 2×MIC concentrations. Biofilm metabolism analysis showed that MSP caused dose-dependent suppression of bacterial metabolism, while its inhibitory effect on EPS production increased proportionally with concentration. Molecular docking identified specific hydrogen-bond interactions between arabinose (the primary component of MSP) and key residues (THR-315, SER-10, and SER-247) of glucosyltransferase-C (GTF-C), while molecular dynamics simulations demonstrated that arabinose disrupted the structural stability of GTF-C. These findings collectively suggest MSP’s promising application as a novel food additive for caries prevention through oral streptococcal control. Graphical abstract

Daniele Caroline Hörz Engel, Daniela Feltrim, Mayara Rodrigues et al.

Protein hydrolysates are plant biostimulants containing amino acids, oligopeptides, and peptides in their composition. When supplied to plants, protein hydrolysates (HPs) have been identified to improve nitrogen metabolism, enhance the activity of antioxidant enzymes, boost plant defense response to stresses, and positively impact the quantity and quality of products. Soybean is a crucial global commodity, with nitrogen being the primary nutrient for crop development as it directly affects productivity. This study aimed to evaluate the effect of an HP-based biostimulant on the N metabolism in nodulated soybean plants and their productivity. A greenhouse experiment was conducted to test two modes of application of the 0.20% HP-based biostimulant. Soybean plants, growing in pots, were treated with 0.20% HP either via seed treatment or foliar application (at growth stages V3 and V5). Activities of enzymes and compounds related to N metabolism, gene expression, and productivity components were analyzed. It was observed that the mode of application did not significantly influence the results. The application of HPs increased the concentration of nitrate, amino acids, and ureides in soybean leaves. It also positively altered the expression of genes such as nitrate reductase, urease, and asparagine. Additionally, it enhanced productivity, resulting in plants with a greater number and weight of pods and grains. Therefore, it is possible to consider HPs as a stimulator for increasing soybean productivity, even under non-stressing conditions.

Jocimar Costa Rosa, Renan Santos Uhdre, Marcos Ventura Faria et al.

This study aimed to apply, in unprecedented depth, a Bayesian approach to the non-linear regression model developed by Toler for evaluating the stability and adaptability of genotypes. Twenty-five soybean cultivars were evaluated in twenty-one plots across the midwestern of Brazil. A complete block design was employed, with three replications. The evaluated variable was grain yield. The proposed methodology was implemented in the R program by means of the BRugs package. The methodology was capable of differentiating the effect of the environment on soybean cultivars in terms of yield in the different environments, allowing exploration of the response of each genotype to environmental variations. Cultivars 6266RSF, NS6990, GD19I435, GD19I439, GD19C443, RC0496 and IA18661 presented good stability and general adaptability, being the most recommended for future evaluations. The other cultivars presented specific adaptability and high responsiveness to unfavorable environments.

Rafael Mesa Manzano, Javier Esparcia Pérez

The adoption and diffusion of innovations are essential for both the development of production processes and the improvement of agricultural environmental sustainability, at any stage of the value chain. In recent years, social scientists have studied the diffusion and adoption of agricultural innovations from different approaches, such as innovation diffusion theory, behavioral models, econometric models, social capital and social network analysis, among others. In this study we analyze the scientific literature through a bibliometric analysis based on co-citation networks, to explore the theoretical pillars and bibliographic coupling, with which we explore the current methodological research trends of the last 50 years. The conclusions drawn from this analysis are that in recent years agricultural researchers on adoption and diffusion have designed multivariate methods that combine diverse study approaches. This review contributes to a better understanding of theory and practice in the study of the adoption and diffusion of agricultural innovations.

Jin-wen HUANG, Jia-yi WU, Hong-fei CHEN et al.

This study attempted to clarify the carrying-over effect of different nitrogen treatments applied to the main crop on the crop population growth and yield formation of ratoon rice under mechanized cultivation in Southeast China. Based on the constant total nitrogen application amounts (225.00 kg ha−1) in the main crop, an experiment with different ratios of basal and topdressing nitrogen fertilizer (the ratio of basal fertilizer:primary tillering fertilizer:secondary tillering fertilizer:booting fertilizer at 3:1:2:4 (N1), 3:2:1:4 (N2), 3:3:0:4 (N3), and 4:3:0:3 (N4), respectively, and a control without nitrogen treatment (N0)) was set up across two consecutive years in field using hybrid rice variety Yongyou 1540 as the test materials. The results showed that the total tiller number and effective tillering percentage increased in the main crop under the N1 treatment, more nitrogen fertilizer applied in late growth stage of the main crop, and its effective tillering percentage of the main crop was the highest at up to 70.18%, which was 9.15% higher than that of conventional fertilization treatment (N4), more nitrogen fertilizer applied in early growth stage of the main crop. The same tendency was observed in leaf area index (LAI) value of the main crop and its subsequent ratoon rice, which were 16.52 and 29.87% higher, respectively, in the N1 treatment than that in the N4 treatment at the full heading stage. The same was true in the case of the transport rates of stem and sheath dry mater and the canopy light interception rates in both the main and its ratoon crops. The transport rate of stem and sheath in main crop rice under N1 treatment increased by 50.57% compared with N4 treatment. The canopy light interception rate of N1 treatment increased by 5.07% compared with N4 treatment at the full heading stage of the ratoon crop. Therefore, the total actual yield was the highest in the main and its ratoon crops under N1 treatment, averaging 17 351.23 kg ha−1 in two-year trials, which was 23.00% higher than that in the conventional fertilization treatment (N4). The results showed that appropriate nitrogen treatment was able to produce a good crop stand in the main crop, which was essential for producing a good ratoon crop population and high yield especially under mechanized cultivation with low stubble height of the main crop. The study suggested that shifting the proper nitrogen application amounts to the late growth stage of the main crop, such as N1 treatment, not only had a higher productive effect on ensuring the yield of the main crop, but also had a positive effect on the axillary bud sprouts from the stubbles for ratoon rice, resulting in an increased percentage of productive panicles and achieving the goal of one planting with two good harvests under the conditions of our study.

Rama T. Rashad, Khaled A. H. Shaban, Samia H. Ashmaye et al.

Bio-farming is an eco-friendly advance that minimizes the required chemical additives for optimizing the quality of crops that their storage is often accompanied by seeds’ components degradation. Magnetic treatment of seed was considered as a promising tool improves germination and growth. This study aims to evaluate the effect of individual and combined application of bio-fertilizers and the N-P-K mineral fertilizers preceded by magnetic treatment of dry and/or water-soaked seeds before sowing on the yield and quality of soybean cultivated in a saline soil.The field experiment was carried out in a split-split plot design with triplicates. The main two factors (F1) were not bio-fertilized and bio-fertilized plots. The sub-factors (F2) were three application rates (A: 50%, B: 75%, and C: 100%) of recommended doses of the three N, P, K fertilizers. The sub-sub factors (F3) were seeds not magnetically treated (NM) and magnetically treated (M). All factors were studied for dry soybean seeds (without soaking) and soaked seeds in magnetically treated water. After harvesting, soil and plant samples were analyzed. The most significant increase in the soybean seed yield (kg ha-1) was by 49.98% for the bio-fertilized magnetized dry seeds at 75% and 100% mineral N-P-K fertilization compared with the NM soaked seeds at 50% N-P-K (A rate) without bio-fertilization. The 75% mineral fertilization significantly increased the protein (%) by 41.69% and decreased the proline (mg g-1dw) by 46.68%. Magnetic treatment of seeds before cultivation and combined bio/mineral N-P-K fertilization reduced the Proline that alleviats the stress conditions.

Khalieda Zia, Yuliani Aisyah, Zaidiyah Zaidiyah et al.

In the field of food, coffee waste begins to be developed by processing it as a beverage product. The skin of coffee fruit can also be processed as a food product, one of which is jelly candy. This study aims to study jelly candy making with the addition of gelatin as a gelling agent and the addition of lemon juice to produce coffee fruit skin jelly candy that has physicochemical and sensory characteristics that meet SNI quality requirements. The design used was factorial Completely Randomized Design consisting of 2 (two) factors. Factor I concentration of gelatin (G) and Factor II is the concentration of lemon water (L). Factor I consists of 4 levels, namely G1 = 10%, G2 = 15%, G3 = 20% and G4 = 25%, while factor II consists of 3 levels, namely L1 = 5%, L2 = 10% and L3 = 15%. Each treatment was repeated 2 times to obtain 24 experimental units. The concentration of gelatin and the concentration of lemon have a very significant effect on water content and pH value. The concentration of lemon has a significant effect on the value of hedonic organoleptic taste. Both interactions have a very significant effect on the value of organoleptic hedonic texture. The results of the analysis of coffee fruit peel jelly candy have an average moisture content of 21.25%, 0.95% ash content, pH 4.53, sensory hedonic color (3.50 neutral reception), aroma (3.48 neutral acceptance), taste (3.50 neutral acceptance), texture (3.59 likes reception). The results showed that 10% gelatin concentration and 10% lemon concentration (G1L2) were the best treatments obtained through the ranking test. The jelly candy produced has 21.32% moisture content characteristics, 1.55% ash content, pH 4.71, 14.09% antioxidant activity, 3.03 mg / 100g vitamin C levels, 3.55 sensory colors (likes) , aroma 3.45 (neutral), taste 3.48 (neutral) and texture 3.43 (neutral).

Aline Antas Cordeiro Cavalcanti, Ana Claudia Campos, Aline Guedes Mamede Moraes et al.

Pemphigus foliaceus (PF) is an autoimmune disease of the skin and is the most common form of pemphigus in domestic animals. This work reports a case of pemphigus foliaceus in a Santa Inês hair sheep. The ewe presented with multifocal bilateral crusted alopecic dermatitis affecting the chest, abdomen, and pelvic and thoracic limbs. Parakeratotic hyperkeratosis and acanthosis, in addition to ballooning degeneration of keratinocytes and subcorneal pustules, were observed histologically, and acantholytic cells and neutrophils were observed within the pustules. In the superficial and deep dermal tissues, there was intense eosinophilic infiltration and the presence of rare macrophages. These microscopic findings were characteristic of PF, and treatment with dexamethasone was ineffective. This disease is rare in sheep, and this is the first case report to be published in Brazil.

Stephan Alexander da Silva Alencar, Charles Kiefer, Karina Márcia Ribeiro de Souza Nascimento et al.

ABSTRACT: This study was conducted to evaluate the effects of net energy levels on the lipid profile of adipose tissue and muscle of swines. A total of 90 animals, with initial weight of 71.94±4.43kg, were used, and distributed in a randomized block design in five net energy levels (2,300, 2,425, 2,550, 2,675, and 2,800Kcal kg-1 feed), with nine replicates and two animals per experimental unit. Lipid profiles of adipose tissue and muscle were analyzed using gas chromatography. Increasing the levels of net energy using soybean oil, improved the lipid profile of adipose tissue and muscle, increased linearly (P<0.05) the concentrations of polyunsaturated fatty acids, especially linoleic and α-linolenic acid, reduced linearly (P<0.05) the monounsaturated and saturated fatty acids and omega 6: omega 3. In adipose tissue was observed linear reduction (P<0.05) of atherogenic and thrombogenic indexes. In conclusion, increasing the level of net energy of the diet using soybean oil improved the lipid profile of adipose tissue and muscle.

Davie Mayeso Kadyampakeni, Kelly T. Morgan, Mongi Zekri et al.

Water is a limiting factor in Florida citrus production during the majority of the year because of the low water holding capacity of sandy soils resulting from low clay and the non-uniform distribution of the rainfall. In Florida, the major portion of rainfall comes in June through September. However, rainfall is scarce during the dry period from February through May, which coincides with the critical stages of bloom, leaf expansion, fruit set, and fruit enlargement. Irrigation is practiced to provide water when rainfall is not sufficient or timely to meet water needs. Proper irrigation scheduling is the application of water to crops only when needed and only in the amounts needed; that is, determining when to irrigate and how much water to apply. With proper irrigation scheduling, yield will not be limited by water stress. With citrus greening (HLB), irrigation scheduling is becoming more important and critical and growers cannot afford water stress or water excess. Any degree of water stress or imbalance can produce a deleterious change in physiological activity of growth and production of citrus trees.  The number of fruit, fruit size, and tree canopy are reduced and premature fruit drop is increased with water stress.  Extension growth in shoots and roots and leaf expansion are all negatively impacted by water stress. Other benefits of proper irrigation scheduling include reduced loss of nutrients from leaching as a result of excess water applications and reduced pollution of groundwater or surface waters from the leaching of nutrients. Recent studies have shown that for HLB-affected trees, irrigation frequency should increase and irrigation amounts should decrease to minimize water stress from drought stress or water excess, while ensuring optimal water availability in the rootzone at all times.

Ademir Silva Menezes, Aureliano Albuquerque Ribeiro, Maria Klécia Neves Tavares et al.

Objetivou-se avaliar a influência de diferentes níveis de salinidade no processo de germinação e crescimento inicial na cultura do girassol. O processo foi conduzido em ambiente telado, no IFCE/Campus Sobral, Ceará, em delineamento inteiramente casualizado, 5 X 4, sendo cinco níveis de sais (CEa = 0,27; 1,5; 3,0; 4,5 e 6,0 dS m-1) com quatro repetições, avaliando-se a porcentagem de emergência – %E, índice de velocidade de emergência – IVE, tempo médio de germinação – TMG, alturas das plântulas – AP, número de folhas – NF e potencial osmótico do solo, que, em seguida, foram submetidas à análise de variância. A percentagem de emergência média dos tratamentos mostrou um aumento linear, de 65% para 67,5%, com relação ao IVE. Também houve um aumento linear expressando valores entre 0,95 (CEa = 0,5 dS m-1) a 1,26 (CEa = 6,0 dS m-1). Verificou-se que o incremento dos sais presente na água de irrigação não influenciou na altura das plântulas, mas provocou reduções no número de folhas e do potencial osmótico do solo. Os níveis de sais testados não influenciaram estatisticamente na germinação do girassol.

Naoki Fujiwara Tsujii, Kotone Tokunaga, Toshiharu Akino et al.

The Japanese queenless ponerine ant Diacamma sp. from Japan employs tandem running during nest relocation, in which a leader ant guides nestmate followers one at a time. We replicated this process by presenting one entire abdominal part of a leader, except for the petiole to followers. When the abdominal part had been rinsed with n-hexane, however, it attracted significantlyfewer followers. This suggests that chemicals on the leader’s abdominal part evoke tandem running. Dissection of abdominal major exocrine glands revealed that the Dufour’s gland was the source of this chemical signal. The chemicals were eluted in the hydrocarbon fraction by silica-gel column chromatography, and the quantitatively major component was estimated as heptadecene (C17:1) through gas chromatograph-mass spectrometer (GCMS) analysis. The position of the double bond was estimated to be between the 8th and 9th carbons through analysis of the epoxidized compound. Only (Z)-isomers of 8-heptadecene evoked tandem running in the followers. We identified the tandem running pheromone of this ant species to be (Z)-8- heptadecene. (163)

Monica Cetean

The seed production potential can be improved a lot by applying an optimal technology of growing, starting by locating the seed lot after a good, and well-balanced forerunner fertilization, disease control, weed control, pest, harvesting the ripe, a right storage

Janusz Rowiński

„PROW 2007—2013” jest kolejnym programem wspierającym rozwój polskiego rolnictwa i regionów wiejskich unijnymi i krajowymi środkami publicznymi. Środki unijne wyniosą około 13,2 mld euro, krajowe publiczne blisko 4,0 mld euro, a środki własne otrzymujących pomoc szacuje się na ponad 7,8 mld euro. Środki zaangażowane w realizację programu szacuje się na ponad 25 mld euro. Program nie spełnia postulatu koncentracji środków na działaniach poprawiających konkurencyjność i produkcyjność gospodarki w regionach wiejskich. Charakteryzuje go dość równomierne rozłożenie środków publicznych na działania wspierające rozwój, ochronę środowiska i dochody rolnicze. Środki publiczne są przeznaczone na następujące cele: rozwój gospodarki żywnościowej — 5,0 mld euro (29,0% środków ogółem), rozwój innych działów gospodarki — 2,8 mld euro (16,5%), ochrona środowiska — 3,1 mld euro (18,0%), wsparcie dochodów i celów socjalnych — 4,6 mld euro (26,9%), inne — 1,6 mld euro (9,5%). Tak duża kwota przeznaczona na wsparcie dochodów i cele socjalne jest słabością programu, który powinien być skorygowany w okresie realizacji.

Clyde W. Fraisse, John Bellow, Charles M. Brown

ABE-381, a 7-page illustrated fact sheet by Clyde W. Fraisse, John Bellow, and Charles Brown, discusses how growers can use the AgClimate Web site to find out how to predict Growing Degree Day accumulation for the current season, and to review GDD for past seasons. Includes references. Published by the UF Department of Agricultural and Biological Engineering, October 2007. ABE381/AE428: Degree-Days: Growing, Heating, and Cooling (ufl.edu) Accessibility Summary: In accordance with Title II regulations this content meets all points of exemption as Archived web content and/or Preexisting conventional electronic documents.

Valdinei Sofiatti, Luis Osmar Braga Schuch, Jonas Farias Pinto et al.

O objetivo foi avaliar o efeito da aplicação do regulador de crescimento ethephon visando à uniformidade de floração e maturação e o controle de doenças de final de ciclo da cultura do arroz. Foi utilizado o fungicida tebuconazole e a avaliou-se a qualidade industrial de grãos das cultivares IRGA 417 e El Paso L 144, em duas densidades de semeadura. O experimento consistiu de uma combinação fatorial (2x2x4) de duas cultivares (IRGA 417 e El Paso L 144), duas densidades de semeadura (50 e 150kg ha-1), e quatro tratamentos foliares (1-testemunha, 2-ethephon, 3-fungicida, 4-ethephon + fungicida), em um delineamento experimental de blocos ao acaso com três repetições. Foi avaliado o percentual de grãos inteiros, e de grãos com gessamento parcial. O percentual de grãos inteiros foi similar em todos os tratamentos, exceto para o tratamento químico com ethephon + fungicida na cultivar IRGA 417, que apresentou menor percentagem de grãos inteiros. Para a percentagem de grãos com gessamento parcial, houve interação entre cultivares, densidades de semeadura e tratamentos foliares. A incidência de gessamento foi maior na cultivar El Paso L 144, porém, nesta cultivar, a pulverização de ethephon na densidade de semeadura de 150kg ha-1, proporcionou redução considerável do percentual de grãos com gessamento.

David L. Wright, P. J. Wiatrak, James J. Marois et al.

Cotton was planted with a cone planter at the seeding rate of 85 seeds/20 ft of row with 36” row spacing on 5 May, 2003 after strip tilling into tilled small grain cover crops. Thimet 20 G was applied in furrow at 6.5 lb/A. This document is SS-AGR-222, a publication of the Agronomy Department, Florida Cooperative Extension Services, Institute of Food and Agricultural Sciences, Univeristy of Florida. Publication date April 2004. https://edis.ifas.ufl.edu/ag229

Liamara Perin, José Ivo Baldani, Veronica Massena Reis

O objetivo deste trabalho foi avaliar a diversidade da população de Gluconacetobacter diazotrophicus oriunda de cultivares de cana-de-açúcar (Saccharum spp.) de diferentes regiões e bancos de germoplasma. O estudo foi realizado com 123 isolados, obtidos de folhas, colmos e raízes de 80 espécies e híbridos de cana-de-açúcar, procedentes de diferentes países e mantidos em coleções de germoplasma nos Estados da Bahia e Rio de Janeiro. Foram utilizados cinco isolados obtidos de plantas de café (Coffea arabica), dois de abacaxi (Ananas comosus) e um de Pennisetum purpureum e mais 10 estirpes com padrões eletroforéticos distintos, após o uso de enzimas comuns do metabolismo microbiano (MLEE). O agrupamento obtido por meio da técnica de imunoadsorção com enzima acoplada (ELISA) sugere que as variações expressas pelos isolados não estão relacionadas com a espécie de planta, a variedade de cana-de-açúcar, a origem geográfica, a parte da planta de onde os isolados foram obtidos e o tempo de amostragem. Altas doses de nitrogênio levaram à diminuição da diversidade de G. diazotrophicus.<br>The objective of this study was to evaluate the diversity of Gluconacetobacter diazotrophicus isolates from different sugarcane (Saccharum spp.) varieties. This study was developed using 123 strains from the internal tissues of stems and roots, isolated from 80 species and hybrids of sugarcane, originated from different countries and maintained in two germoplasm collections localized in Bahia and Rio de Janeiro States. Five isolates obtained from coffee plants (Coffea arabica), two from pineapple (Ananas comosus), one from Pennisetum purpureum and 10 strains, which present different electrophoretic patterns, were used in the comparison. Cluster analysis of enzyme-linked immunosorbent assay (ELISA) results suggested that variations were not correlated with the plant species, sugarcane variety, geographic origin, parts of plants nor with sampling time. High nitrogen doses lowered the diversity of G. diazotrophicus.