Effects of Nitrogen Sources on the Growth and Biochemical Composition of Diatom (Amphora coffeaeformis) Used for Shrimp Larviculture

Amphora coffeaeformis is a benthic diatom and serves as a rich nutritional feed for various aquaculture industries. The objective of this experiment was to compare the effects of different nitrogen sources on the growth and biochemical composition of the diatom (A. coffeaeformis) culture. Sodium nitrate in Guillard’s f medium, used as a control treatment, was compared with sodium nitrite and ammonium sulfate. The results in the 3rd batch of culture showed that all treatments led to the highest growth on Day 6. The highest cell dry weight occurred in the ammonium sulfate treatment with significance (0.78±0.06 mg/mL). The cultures in each treatment were harvested at the exponential phase (Day 3) for biochemical composition analysis. A. coffeaeformis in the ammonium sulfate treatment significantly accumulated the highest protein content, at 44.82 % by dry weight, while the highest lipid content at 29.78 % by dry weight was significantly found in the sodium nitrate treatment. The cell size and structure showed no significant differences among the treatments. The experiment demonstrated the effects of different nitrogen sources on the growth and biochemical composition of A. coffeaeformis. After that, we selected A. coffeaeformis that was cultured with the nitrate and ammonia nitrogen sources for feeding to shrimp larvae. This experiment was conducted to evaluate the effects of A. coffeaeformis on the growth, survival rate, salinity stress test, and ammonia stress test for shrimp. The experiment was designed with four treatments, as follows: 1) the control feed with flake winner (no water exchange for 28 days), 2) Am-NO3 supplement with A. coffeaeformis cultured using nitrates (no water exchange for 28 days), 3) Am-NH3 supplement with A. coffeaeformis cultured using ammonia (no water exchange for 28 days), and 4) the positive control feed with flake winner (daily water exchange at 20 %). The results showed that the growth of shrimp fed with the diet supplemented with A. coffeaeformis cultured using nitrate and ammonia were not significantly different from the negative and positive controls (P > 0.05). However, the survival rate in the negative control was significantly lower than the other groups (P < 0.05). In this study, the stress test for white shrimp postlarvae utilized 2 methods: the ammonia or salinity stress tests. The survival rate of the shrimp after the ammonia stress test was not statistically and significantly different (P > 0.05). However, the results from the salinity stress test indicated that the highest survival rate was observed in the shrimp fed with the diet supplemented with A. coffeaeformis cultured using nitrate. A. coffeaeformis cultured with the sodium nitrate treatment had a positive effect on shrimp tolerance to salinity changes.

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The growth performance and resistance to salinity stress of striped catfish Pangasius sp. juvenile in biofloc system with different feeding rates

Jurnal Akuakultur Indonesia ◽

10.19027/jai.17.2.113-119 ◽

2018 ◽

Vol 17 (2) ◽

pp. 113 ◽

Cited By ~ 1

Author(s):

Wellya Wichi Meritha ◽

Muhammad Agus Suprayudi ◽

Juli Ekasari

Keyword(s):

Growth Performance ◽

Salinity Stress ◽

Water Exchange ◽

Feeding Rate ◽

Specific Growth ◽

Average Length ◽

Stress Test ◽

Feeding Rates ◽

Feed Conversion ◽

Striped Catfish

ABSTRACTThis study aimed to evaluate the growth performance and resistance to salinity stress of striped catfish juvenile reared in biofloc with different feeding rate (FR). The treatments applied in this study were rearing the fish in biofloc with FR 5% and 8% of biomass per day, and rearing the fish with a FR of 8% per day without biofloc system as the control. The fish with an initial average length of 1.81 ± 0.20 cm were stocked in 9 units of 50 L aquaria with density of 40 ind/aquaria (800 ind/m3) for 15 days rearing period. In biofloc systems, the addition of tapioca as a source of organic carbon was done every day with an estimated C/N ratio of 10. No water exchange was done in biofloc systems, whereas regular water exchange was applied in the control. Results of the experiment showed that survival was not significantly different amongst treatments (P>0.05). However, the specific growth rate of the fish in biofloc system with a FR of 8% per day showed the highest value and was significantly different from other treatments (P<0.05). Fish reared in biofloc system tend to have lower feed conversion ratios (FCRs) than the control. The lowest FCR was found in fish reared in biofloc system with 5% FR and significantly lower than control (P<0.05). Salinity stress test was conducted by soaking 15 juveniles in water with a salinity of 20 g/L for an hour. The survival of fish after salinity stress test were significantly higher for fish reared in bifloc system than control (P<0.05). These data showed that rearing striped catfish juvenile in biofloc system could reduce FCR, increase the growth, and robustness of fish. Keywords: biofloc, feeding rate, growth, salinity stress test, striped catfish ABSTRAKPenelitian ini bertujuan untuk mengevaluasi kinerja pertumbuhan dan ketahanan benih ikan patin terhadap stres salinitas yang dipelihara dalam sistem bioflok dengan tingkat pemberian pakan (FR) berbeda. Perlakuan yang terdapat dalam penelitian ini adalah benih patin yang dipelihara dalam sistem bioflok dengan FR 5% dan 8% per hari, dan pemeliharaan benih dengan FR 8% per hari tanpa penambahan sumber karbon sebagai kontrol. Benih patin dengan panjang rata-rata awal 1,81 ± 0,20 cm dipelihara dalam 9 unit akuarium dengan volume air 50 L dan kepadatan 40 ekor/akuarium (800 ekor/m3) selama 15 hari. Pada sistem bioflok, penambahan tapioka sebagai sumber karbon dilakukan setiap hari dengan C/N 10. Pada sistem bioflok tidak dilakukan pergantian air, sedangkan pada kontrol dilakukan pergantian air. Kelangsungan hidup ikan tidak berbeda nyata antar perlakuan. Namun, tingkat pertumbuhan spesifik ikan dalam sistem bioflok dengan FR 8% per hari menunjukkan nilai tertinggi dan berbeda nyata antar perlakuan (P<0,05). Benih yang dipelihara pada sistem bioflok memiliki rasio konversi pakan (FCR) yang lebih rendah dibandingkan kontrol, namun tidak terdapat perbedaan yang signifikan antara perlakuan bioflok (P>0,05). Uji stres salinitas dilakukan dengan merendam 15 ekor benih patin pada air dengan salinitas 20 g/L selama satu jam. Kelangsungan hidup setelah uji stres salinitas dari benih yang dipelihara di bioflok secara signifikan lebih tinggi dibandingkan kontrol (P<0,05). Hasil penelitian menunjukkan bahwa pemeliharaan benih patin pada sistem bioflok dapat menurunkan FCR, dan meningkatkan pertumbuhan dan ketahanan ikan terhadap stres salinitas. Kata kunci: bioflok, feeding rate, pertumbuhan, uji stres salinitas, ikan patin

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Protective Effect of Microbubble Aeration and Dietary Probiotics BALSS on Survival and Immunity of White Leg Shrimp (Litopenaeus vannamei) Postlarvae against Acute Low Salinity Stress

Jurnal Perikanan Universitas Gadjah Mada ◽

10.22146/jfs.51258 ◽

2020 ◽

Vol 22 (1) ◽

pp. 1

Author(s):

Shima Bhaskara Ayuningrum ◽

Indah Istiqomah ◽

Rustadi Rustadi ◽

Bambang Triyatmo ◽

Alim Isnansetyo ◽

...

Keyword(s):

Survival Rate ◽

Glucose Level ◽

Salinity Stress ◽

Bactericidal Activity ◽

Litopenaeus Vannamei ◽

Stress Test ◽

Stress Tests ◽

Low Salinity ◽

Before And After ◽

Experimental Trials

Survival rate and immunity of white leg shrimp ((Litopenaeus vannamei) postlarvae against acute salinity stress were evaluated in indoor experimental trials. The research was conducted with 2x2 factorial design with two levels of aeration (microbubble and macro bubble) and two levels of diet (with and without probiotics) resulting four treatments in triplicate: application of microbubble with gut probiotics (MiP), without gut probiotics (MiC), and macro bubble with gut probiotics (MaP) and without probiotics (MaC). White leg shrimps measuring 7.6 g were maintained in the tanks for 60 days and fed five times a day at a dose of 5% biomass. Harvested shrimp were tested for low salinity stress (5 ppt) for 3 hours. Glucose level, total protein, bactericidal activity, natural agglutination, phenoloxidase, respiratory burst, and superoxide dismutase activities in the hemolymph and the shrimp survival rate (SR) were analyzed before and after the stress tests. Although all examined parameters remained the same between groups before the stress test, significant differences were found among them after the stress test. Microbubble aeration obtained stabilization of hemolymph glucose level, best survival rate, bactericidal activity, and agglutination activities. No significant effect was resulted by the dietary probiotic treatments, but the interaction with aeration treatments revealed the importance to compensate shrimp survival rate when microbubble aeration is unavailable.

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Influence of Different Nitrogen Sources on Growth and Pathogenic Capability of Rhizoctonia solani Causing Root Rot of Faba Bean

International Journal of Phytopathology ◽

10.33687/phytopath.007.01.2393 ◽

2018 ◽

Vol 7 (1) ◽

pp. 19-29 ◽

Cited By ~ 1

Author(s):

Mostafa H. Mostafa ◽

Maha H. Mohamed

Keyword(s):

Growth Rate ◽

Rhizoctonia Solani ◽

Ammonium Sulfate ◽

Sodium Nitrate ◽

Basal Medium ◽

Nitrogen Sources ◽

Disease Index ◽

Glucosamine Sulfate ◽

Infection Cushions

The effect of different nitrogen sources (glucosamine sulfate, ammonium sulfate, aspartic acid, phenylalanine and peptone) in comparison to sodium nitrate, the major nitrogen compound in basal agar Czapek’s synthetic medium growth were studied on the linear growth of Rhizoctonia solani and its pathogenicity on faba bean germinated seeds. Ammonium sulfate exhibited faster liner growth and showed the same effect as the basal medium with sodium nitrate while glucosamine sulfate showed less growth rate compared with sodium nitrate. Glucosamine sulfate and ammonium sulfate showed a significant reduction in number of infection cushions which led to significant decrease of disease index in vitro. Under greenhouse conditions, glucosamine sulfate or peptone as a sole nitrogen sources in food requirements of Rhizoctonia solani inoculum depressed the virulence of the fungus. The effect of different amounts of glucosamine sulfate was determined on fungal growth rate, infection cushions, disease index in vitro and polyphenol oxidase activity. Increasing amount of glucosamine sulfate showed significant reduction of growth rate in comparison to the basal medium with sodium nitrate. All seeds subjected to R. solani grown on different amount of glucosamine sulfate showed the lower number of infection cushions, disease index and polyphenol oxidase activity compared with sodium nitrate. Under greenhouse conditions, disease index showed a significantly decreased effect when glucosamine sulfate used as soil applications and showed better effect on shoot weight and root weight compared with control plants treated with sodium nitrate. Our study proposes that glucosamine sulfate may act as controlling factor of pathogenicity genes of R. solani

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Influence of Nitrogen Sources Applied by Fertigation to an Enriched Soil with Organic Compost on Growth, Mineral Nutrition, and Phytochemicals Content of Coriander (Coriandrum sativum L.) in Two Successive Harvests

Plants ◽

10.3390/plants11010022 ◽

2021 ◽

Vol 11 (1) ◽

pp. 22

Author(s):

Rui M. A. Machado ◽

Isabel Alves-Pereira ◽

Yasmin Faty ◽

Sara Perdigão ◽

Rui Ferreira

Keyword(s):

Ammonium Nitrate ◽

Ammonium Sulfate ◽

Mineral Nutrition ◽

Inorganic Nitrogen ◽

Nitrogen Sources ◽

Dry Weight ◽

Nitrogen Addition ◽

Total Phenols ◽

Shoot Dry Weight ◽

Organic Compost

The aim of the present study was to evaluate the effects of nitrogen source applied by fertigation to an enriched soil with organic compost on plant growth, mineral nutrition, and phytochemical contents in two successive harvests in coriander. The treatments were as follows: unfertilized soil, soil enriched with organic compost, and soil enriched with organic compost to which 60 kg N ha−1 as ammonium nitrate and as ammonium sulfate applied by fertigation were added. Ammonium nitrate addition allowed to obtain a high total fresh yield (3.6 kg m−2) with a low inorganic nitrogen input. Ammonium nitrate increased plant shoot dry weight; fresh yield; and shoot N, K, and Ca uptake in the first harvest. Ammonium nitrate relative to organic compost and to ammonium sulfate increased fresh yield by approximately 57 and 25%, respectively. However, ammonium sulfate in the first harvest greatly increased shoot total phenols, from 137 mgGAE/100 g FW in ammonium nitrate to 280.4 mgGAE/100 g FW. Coriander’s fresh yield, in the second harvest, was unaffected by nitrogen addition. However, ammonium nitrate increased shoot total phenols and FRAP activity. Overall, the shoot phytochemical accumulation in the second harvest was lower than in the first. The combined application of ammonium nitrate and organic compost is a strategy to reduce inorganic nitrogen application.

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Effects of Six Sources of Nitrogen on Yields, Soil Acidity, and Leaf Composition of Coffee

The Journal of Agriculture of the University of Puerto Rico ◽

10.46429/jaupr.v47i1.12933 ◽

1969 ◽

Vol 47 (1) ◽

pp. 41-46

Author(s):

Fernando Abruña ◽

José Vicente-Chandler

Keyword(s):

Ammonium Nitrate ◽

Ammonium Sulfate ◽

Sodium Nitrate ◽

Manganese Content ◽

Nitrogen Sources ◽

Potassium Nitrate ◽

Severe Toxicity ◽

Intensively Managed ◽

Leaf Composition ◽

Different Sources

The effects of heavy applications of nitrogen from six different sources on yields and leaf composition of intensively managed coffee, and on acidity of a Los Guineos clay, were determined under typical conditions in the Coffee Region of Puerto Rico. Lowest yields were obtained when nitrogen was applied as sodium nitrate, while applications of ammonium sulfate, ammonium nitrate, potassium nitrate, ammonium nitrate-lime, and urea resulted in the production of similar high yields of coffee. Coffee leaves from plots on which the different sources of nitrogen were used were similar in nitrogen, calcium, potassium, magnesium, and phosphorus contents. However, leaves from the sodium nitrate plots were highest in sodium content and those from the ammonium sulfate plots were highest in manganese content. Soil pH was lowest in the ammonium sulfate, urea, and ammonium nitrate plots, and highest in the sodium nitrate, potassium nitrate, and ammonium nitrate-lime plots. Soil from the sodium nitrate plots was highest in exchangeable sodium. It is evident that sodium nitrate should not be used as a source of nitrogen for coffee. The desirability of using nitrogen sources other than ammonium sulfate on soils with a high content of manganese where this element can cause severe toxicity of coffee is also discussed.

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THE RESPONSE OF SUGARCANE IN PUERTO RICO TO VARIOUS NITROGEN SOURCES

The Journal of Agriculture of the University of Puerto Rico ◽

10.46429/jaupr.v36i3.13788 ◽

1969 ◽

Vol 36 (3) ◽

pp. 230-239

Author(s):

George Samuels ◽

Pablo Landrau, Jr. ◽

Bernando G. Capó

Keyword(s):

Puerto Rico ◽

Ammonium Nitrate ◽

Nitrogen Source ◽

Ammonium Sulfate ◽

Sodium Nitrate ◽

Nitrogen Sources ◽

The Other ◽

Yield Response ◽

Calcium Cyanamide ◽

Significant Difference

1. A survey of the literature of earlier fertilizer trials in Puerto Rico in which the efficiency of ammonium sulfate, sodium nitrate, tankage, and calcium cyanamide were compared revealed that there was no significant difference in the yield response of sugarcane to these nitrogen carriers. 2. Experiments were conducted in which ammonium sulfate and ammonium nitrate were compared as nitrogen sources for sugarcane. The results at Río Piedras and Guánica showed no significant differences in yield of cane or sugar regardless of which was used. At Isabela there was a better response to ammonium sulfate than to ammonium nitrate in the first ratoon, but it was significant only at the 5-percent point. 3. Uramon and cyanamide when tested along with the ammonium sulfate and nitrate experiments at Río Piedras and Isabela, produced no significant responses as compared with the other nitrogen sources. At Río Piedras liquid ammonium nitrate produced the lowest yield of any nitrogen source used. 4. Ammonium sulfate is the chief nitrogen source used in Puerto Rico. Its use is chiefly dictated by economic and manufacturing conditions. Ammonium nitrate, which is cheaper per unit of nitrogen, cannot be used at present because of extremely high transportation costs based on its explosiveness. 5. A discussion of the agro-economic aspect of nitrogen sources is presented.

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Assessment of Morpho-Physiological, Biochemical and Antioxidant Responses of Tomato Landraces to Salinity Stress

Plants ◽

10.3390/plants10040696 ◽

2021 ◽

Vol 10 (4) ◽

pp. 696

Author(s):

Reem H. Alzahib ◽

Hussein M. Migdadi ◽

Abdullah A. Al Ghamdi ◽

Mona S. Alwahibi ◽

Abdullah A. Ibrahim ◽

...

Keyword(s):

Salt Stress ◽

Salinity Stress ◽

Dry Weight ◽

Proline Content ◽

Enzymatic Antioxidants ◽

Sod Activity ◽

Carotene Content ◽

Antioxidants Activity ◽

Solanum Lycopersicum L ◽

Salinity Levels

Understanding salt tolerance in tomato (Solanum lycopersicum L.) landraces will facilitate their use in genetic improvement. The study assessed the morpho-physiological variability of Hail tomato landraces in response to different salinity levels at seedling stages and recommended a tomato salt-tolerant landrace for future breeding programs. Three tomato landraces, Hail 548, Hail 747, and Hail 1072 were tested under three salinity levels: 75, 150, and 300 mM NaCl. Salinity stress reduced shoots’ fresh and dry weight by 71% and 72%, and roots were 86.5% and 78.6%, respectively. There was 22% reduced chlorophyll content, carotene content by 18.6%, and anthocyanin by 41.1%. Proline content increased for stressed treatments. The 300 mM NaCl treatment recorded the most proline content increases (67.37 mg/g fresh weight), with a percent increase in proline reaching 61.67% in Hail 747. Superoxide dismutase (SOD) activity decreased by 65% in Hail 548, while it relatively increased in Hail 747 and Hail 1072 treated with 300 mM NaCl. Catalase (CAT) activity was enhanced by salt stress in Hail 548 and recorded 7.6%, increasing at 75 and 5.1% at 300 mM NaCl. It revealed a reduction in malondialdehyde (MDA) at the 300 mM NaCl concentration in both Hail 548 and Hail 1072 landraces. Increasing salt concentrations showed a reduction in transpiration rate of 70.55%, 7.13% in stomatal conductance, and 72.34% in photosynthetic rate. K+/Na+ ratios decreased from 56% for 75 mM NaCl to 85% for 300 mM NaCl treatments in all genotypes. The response to salt stress in landraces involved some modifications in morphology, physiology, and metabolism. The landrace Hail 548 may have better protection against salt stress and observed protection against reactive oxygen species (ROS) by increasing enzymatic “antioxidants” activity under salt stress.

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Halotolerant Microbial Consortia for Sustainable Mitigation of Salinity Stress, Growth Promotion, and Mineral Uptake in Tomato Plants and Soil Nutrient Enrichment

Sustainability ◽

10.3390/su13158369 ◽

2021 ◽

Vol 13 (15) ◽

pp. 8369

Author(s):

Chintan Kapadia ◽

R. Z. Sayyed ◽

Hesham Ali El Enshasy ◽

Harihar Vaidya ◽

Deepshika Sharma ◽

...

Keyword(s):

Salt Stress ◽

Salinity Stress ◽

Dry Weight ◽

Stress Factors ◽

Microbial Consortia ◽

Soil Conditions ◽

Mineral Uptake ◽

Shoot Height ◽

Tomato Plants ◽

Secondary Roots

Salinity significantly impacts the growth, development, and reproductive biology of various crops such as vegetables. The cultivable area is reduced due to the accumulation of salts and chemicals currently in use and is not amenable to a large extent to avoid such abiotic stress factors. The addition of microbes enriches the soil without any adverse effects. The effects of microbial consortia comprising Bacillus sp., Delftia sp., Enterobacter sp., Achromobacter sp., was evaluated on the growth and mineral uptake in tomatoes (Solanum Lycopersicum L.) under salt stress and normal soil conditions. Salinity treatments comprising Ec 0, 2, 5, and 8 dS/m were established by mixing soil with seawater until the desired Ec was achieved. The seedlings were transplanted in the pots of the respective pH and were inoculated with microbial consortia. After sufficient growth, these seedlings were transplanted in soil seedling trays. The measurement of soil minerals such as Na, K, Ca, Mg, Cu, Mn, and pH and the Ec were evaluated and compared with the control 0 days, 15 days, and 35 days after inoculation. The results were found to be non-significant for the soil parameters. In the uninoculated seedlings’ (control) seedling trays, salt treatment significantly affected leaf, shoot, root dry weight, shoot height, number of secondary roots, chlorophyll, and mineral contents. While bacterized seedlings sown under saline soil significantly increased leaf (105.17%), shoot (105.62%), root (109.06%) dry weight, leaf number (75.68%), shoot length (92.95%), root length (146.14%), secondary roots (91.23%), and chlorophyll content (−61.49%) as compared to the control (without consortia). The Na and K intake were higher even in the presence of the microbes, but the beneficial effect of the microbe helps plants sustain in the saline environment. The inoculation of microbial consortia produced more secondary roots, which accumulate more minerals and transport substances to the different parts of the plant; thus, it produced higher biomass and growth. Results of the present study revealed that the treatment with microbial consortia could alleviate the deleterious effects of salinity stress and improve the growth of tomato plants under salinity stress. Microbial consortia appear to be the best alternative and cost-effective and sustainable approach for managing soil salinity and improving plant growth under salt stress conditions.

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Factorial Design to Optimize Biosurfactant Production byYarrowia lipolytica

Journal of Biomedicine and Biotechnology ◽

10.1155/2010/821306 ◽

2010 ◽

Vol 2010 ◽

pp. 1-8 ◽

Cited By ~ 29

Author(s):

Gizele Cardoso Fontes ◽

Priscilla Filomena Fonseca Amaral ◽

Marcio Nele ◽

Maria Alice Zarur Coelho

Keyword(s):

Surface Tension ◽

Factorial Design ◽

Ammonium Sulfate ◽

Yeast Extract ◽

Carbon Sources ◽

Nitrogen Sources ◽

Biosurfactant Production ◽

Standard Process ◽

Emulsification Index ◽

Full Factorial

In order to improve biosurfactant production byYarrowia lipolyticaIMUFRJ 50682, a factorial design was carried out. A24full factorial design was used to investigate the effects of nitrogen sources (urea, ammonium sulfate, yeast extract, and peptone) on maximum variation of surface tension (ΔST) and emulsification index (EI). The best results (67.7% of EI and 20.9 mNm−1ofΔST) were obtained in a medium composed of 10 g 1−1of ammonium sulfate and 0.5 g 1−1of yeast extract. Then, the effects of carbon sources (glycerol, hexadecane, olive oil, and glucose) were evaluated. The most favorable medium for biosurfactant production was composed of both glucose (4% w/v) and glycerol (2% w/v), which provided an EI of 81.3% and aΔST of 19.5 mN m−1. The experimental design optimization enhancedΔEI by 110.7% andΔST by 108.1% in relation to the standard process.

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Symbiotic capability of calopo rhizobia from an agrisoil with different crops in Pernambuco

Revista Brasileira de Ciência do Solo ◽

10.1590/s0100-06832013000400005 ◽

2013 ◽

Vol 37 (4) ◽

pp. 869-876 ◽

Cited By ~ 4

Author(s):

Altanys Silva Calheiros ◽

Mario de Andrade Lira Junior ◽

Débora Magalhães Soares ◽

Márcia do Vale Barreto Figueiredo

Keyword(s):

Dry Matter ◽

Nitrogen Sources ◽

Dry Weight ◽

Dry Forest ◽

Forest Zone ◽

Symbiotic Efficiency ◽

Total N ◽

Calopogonium Mucunoides ◽

Legume Symbiosis ◽

Biological Nitrogen

Biological nitrogen fixation by rhizobium-legume symbiosis represents one of the most important nitrogen sources for plants and depends strongly on the symbiotic efficiency of the rhizobium strain. This study evaluated the symbiotic capacity of rhizobial isolates from calopo (CALOPOGONIUM MUCUNOIDES) taken from an agrisoil under BRACHIARIA DECUMBENS pasture, sabiá (MIMOSA CAESALPINIIFOLIA) plantations and Atlantic Forest areas of the Dry Forest Zone of Pernambuco. A total of 1,575 isolates were obtained from 398 groups. A single random isolate of each group was authenticated, in randomized blocks with two replications. Each plant was inoculated with 1 mL of a bacterial broth, containing an estimated population of 10(8) rhizobial cells mL-1. Forty-five days after inoculation, the plants were harvested, separated into shoots, roots and nodules, oven-dried to constant mass, and weighed. Next, the symbiotic capability was tested with 1.5 kg of an autoclaved sand:vermiculite (1:1) mixture in polyethylene bags. The treatments consisted of 122 authenticated isolates, selected based on the shoot dry matter, five uninoculated controls (treated with 0, 50, 100, 150, or 200 kg ha-1 N) and a control inoculated with SEMIA 6152 (=BR1602), a strain of BRADYRHIZOBIUM JAPONICUM The test was performed as described above. The shoot dry matter of the plants inoculated with the most effective isolates did not differ from that of plants treated with 150 kg ha-1 N. Shoot dry matter was positively correlated with all other variables. The proportion of effective isolates was highest among isolates from SABIÁ forests. There was great variation in nodule dry weight, as well as in N contents and total N.

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