Secondary Metabolites of Pseudomonas aeruginosa LV Strain Decrease Asian Soybean Rust Severity in Experimentally Infected Plants.

Asian Soybean Rust (ASR), a disease caused by Phakopsora pachyrhizi, causing yield losses up to 90%. The control is based on the fungicides which may generate resistant fungi. The activation of the plant defense system, should help on ASR control. In this study, secondary metabolites of Pseudomonas aeruginosa LV strain were applied on spore germination and the expression of defense genes in infected soybean plants. The F4A fraction and the pure metabolites were used. In vitro, 10 µg mL-1 of F4A reduced spore germination by 54%, while 100 µg mL-1 completely inhibited. Overexpression of phenylalanine ammonia lyase (PAL), O-methyltransferase (OMT) and pathogenesis related protein-2 (PR-2; glucanases) defense-related genes were detected 24 and 72 h after soybean sprouts were sprayed with an organocopper antimicrobial compound (OAC). Under greenhouse conditions, the best control was observed in plants treated with 60 µg mL-1 of PCA, which reduced ASR severity and lesion frequency by 75% and 43%, respectively. Plants sprayed with 2 and 20 µg mL-1 of F4A also decreased severity (41%) and lesion frequency (32%). The significant reduction in spore germination ASR in plant suggested that the strain of these metabolites are effective against P. pachyrhizi, and they can be used for ASR control.

Arbuscular Mycorrhizal Fungi (Rhizophagus clarus) and Rhizobacteria (Bacillus subtilis) Can Improve the Clonal Propagation and Development of Teak for Commercial Plantings.

The Tectona grandis L.f. (teak) is an important forest species with high economy value in Asia, Africa, and Latin America. In Latin America, Brazil is one of the countries with the most cultivated areas. The cultivation of teak turns out to be challenging because of its high nutritional demand and the need for seedling production by clonal propagation that includes about 90 days in the nursery phase. The optimization of seedling production is necessary for better results in the nursery and to enhance growth in the field. In this way, the well-known advantage of using microorganisms that promote plant development appears as a potential biotechnological approach to be explored and for the implantation of new areas of wood production. In this study, the inoculation of Bacillus subtilis as plant growth-promoting rhizobacteria (PGPR) was evaluated, and Rhizophagus clarus, an arbuscular mycorrhizal fungus (AMF), and the co-inoculation of these microorganisms in the teak seedling production phase can improve the development of commercial plantations under field conditions. Experiments were carried out under greenhouse and field conditions to evaluate four treatments based on the substrate inoculation of the seedlings. Treatments consisted of a non-inoculated control, PGPR inoculation, AMF inoculation, and PGPR + AMF inoculation. The results of the biometric evaluation of seedlings in the greenhouse showed that there was a significant difference in AMF inoculation and PGPR + AMF inoculation in terms of the specific root length and root density treatments, there was also a positive correlation between these two treatments and the absorption of some nutrients, such as P, N, K, Mg, Cu, Mn, and Zn. This response led to an increase between 4.75 and 11.04% in the field growth rate.

Effect of the fertilization and growth promoting microrganisms on Schizolobium parahyba / Efeito da adubação e microrganismos promotores de crescimento sobre Schizolobium parahyba

The objective of this work was to evaluate the effect of the chemical and biological fertilizing on the development of two varieties of Schizolobium parahyba, paricá and guapuruvú. The chemical fertilizer NPK 20-05-20 and the plant growth promoting microorganisms, Rhizobium sp. (Rhi) and Rhizophagus clarus (Arbuscular Mycorrhizal Fungus - AMF). The experimental design was a randomized complete block with five replicates and eight treatments. Forty-six day old seedlings of each variety were planted in pits containing hydroretent gel. Then the treatments were added: 1. Control; 2. Rhi; 3. AMF; 4. NPK; 5. Rhi + NPK; 6. Rhi + AMF; 7. AMF + NPK; 8. Rhi + AMF + NPK. Plant length, stem diameter and survival in the environment were evaluated. The ANOVA followed by the Duncan test (α = 0,05) was used to compare the means of the treatments. In the four evaluated periods (37, 111, 250 and 360 days), both varieties had a positive effect on height, diameter and survival when applied to NPK treatments. The interaction AMF and Rhizobium sp. favored the growth in diameter of the guapuruvú. For paricá variety that same treatment provided higher growth in height, however, AMF impaired development in diameter of this variety. Thus, it was observed that under low fertility conditions, the interaction AMF + Rhi favored a greater resistance of guapuruvú to abiotic stress compared to treatment 3, and the presence of grasses in the experimental area may have contributed to the reduction on the development of S. parahyba.

O objetivo deste trabalho foi avaliar o efeito da adubação química e biológica no desenvolvimento de duas variedades de Schizolobium parahyba, paricá e guapuruvú. O adubo químico NPK 20-05-20 e os microrganismos promotores de crescimento de plantas, Rhizobium sp. (Rhi) e Rhizophagus clarus (fungo micorrízico arbuscular - FMA). O delineamento experimental utilizado foi de blocos casualizados, com cinco repetições e oito tratamentos. Plântulas com 46 dias de idade de cada variedade foram plantadas em covas contendo gel hidratante. Em seguida, os tratamentos foram adicionados: 1. Controle; 2. Rhi; 3. FMA; 4. NPK; 5. FMA + Rhi; 6. Rhi + NPK; 7. FMA + NPK; 8. FMA + Rhi + NPK. O comprimento das plantas, o diâmetro do caule e a sobrevivência no ambiente foram avaliados. A ANOVA seguida do teste de Duncan (α = 0,05) foi utilizada para comparar as médias dos tratamentos. Nos quatro períodos avaliados (37, 111, 250 e 360 dias), ambas as variedades tiveram efeito positivo na altura, diâmetro e sobrevivência quando aplicadas aos tratamentos com NPK. A interação FMA e Rhizobium sp. favoreceu o crescimento em diâmetro do guapuruvú. Para a variedade paricá, o mesmo tratamento proporcionou maior crescimento em altura, entretanto, o FMA prejudicou o desenvolvimento em diâmetro dessa variedade. Assim, observou-se que sob condições de baixa fertilidade, a interação FMA + Rhi favoreceu uma maior resistência do guapuruvú ao estresse abiótico comparado ao tratamento 3, e a presença de gramíneas na área experimental pode ter contribuído para a redução no desenvolvimento de S parahyba.

Effect of the fertilization and growth promoting microrganisms on Schizolobium parahyba / Efeito da adubação e microrganismos promotores de crescimento sobre Schizolobium parahyba

The objective of this work was to evaluate the effect of the chemical and biological fertilizing on the development of two varieties of Schizolobium parahyba, paricá and guapuruvú. The chemical fertilizer NPK 20-05-20 and the plant growth promoting microorganisms, Rhizobium sp. (Rhi) and Rhizophagus clarus (Arbuscular Mycorrhizal Fungus - AMF). The experimental design was a randomized complete block with five replicates and eight treatments. Forty-six day old seedlings of each variety were planted in pits containing hydroretent gel. Then the treatments were added: 1. Control; 2. Rhi; 3. AMF; 4. NPK; 5. Rhi + NPK; 6. Rhi + AMF; 7. AMF + NPK; 8. Rhi + AMF + NPK. Plant length, stem diameter and survival in the environment were evaluated. The ANOVA followed by the Duncan test (α = 0,05) was used to compare the means of the treatments. In the four evaluated periods (37, 111, 250 and 360 days), both varieties had a positive effect on height, diameter and survival when applied to NPK treatments. The interaction AMF and Rhizobium sp. favored the growth in diameter of the guapuruvú. For paricá variety that same treatment provided higher growth in height, however, AMF impaired development in diameter of this variety. Thus, it was observed that under low fertility conditions, the interaction AMF + Rhi favored a greater resistance of guapuruvú to abiotic stress compared to treatment 3, and the presence of grasses in the experimental area may have contributed to the reduction on the development of S. parahyba.(AU)

O objetivo deste trabalho foi avaliar o efeito da adubação química e biológica no desenvolvimento de duas variedades de Schizolobium parahyba, paricá e guapuruvú. O adubo químico NPK 20-05-20 e os microrganismos promotores de crescimento de plantas, Rhizobium sp. (Rhi) e Rhizophagus clarus (fungo micorrízico arbuscular - FMA). O delineamento experimental utilizado foi de blocos casualizados, com cinco repetições e oito tratamentos. Plântulas com 46 dias de idade de cada variedade foram plantadas em covas contendo gel hidratante. Em seguida, os tratamentos foram adicionados: 1. Controle; 2. Rhi; 3. FMA; 4. NPK; 5. FMA + Rhi; 6. Rhi + NPK; 7. FMA + NPK; 8. FMA + Rhi + NPK. O comprimento das plantas, o diâmetro do caule e a sobrevivência no ambiente foram avaliados. A ANOVA seguida do teste de Duncan (α = 0,05) foi utilizada para comparar as médias dos tratamentos. Nos quatro períodos avaliados (37, 111, 250 e 360 dias), ambas as variedades tiveram efeito positivo na altura, diâmetro e sobrevivência quando aplicadas aos tratamentos com NPK. A interação FMA e Rhizobium sp. favoreceu o crescimento em diâmetro do guapuruvú. Para a variedade paricá, o mesmo tratamento proporcionou maior crescimento em altura, entretanto, o FMA prejudicou o desenvolvimento em diâmetro dessa variedade. Assim, observou-se que sob condições de baixa fertilidade, a interação FMA + Rhi favoreceu uma maior resistência do guapuruvú ao estresse abiótico comparado ao tratamento 3, e a presença de gramíneas na área experimental pode ter contribuído para a redução no desenvolvimento de S parahyba.(AU)