Efficiency of application of Trichoderma on the physiological quality and health of cowpea seeds

One of the main causes of low productivity of cowpea crops in Brazil is the use of low quality seeds. Low quality seeds have a high degree of infestation by phytopathogens, mainly fungi. Seed treatment with biological control agents, such as fungi of the genus Trichoderma, is a useful alternative to reduce or inhibit the transmission of diseases via seeds. In view of the above, this study aims to evaluate the physiological and sanitary quality of cowpea seeds treated with conidia of Trichoderma sp. (1.2, 2.4, 4.8 and 9.6 x 108 CFU g-1). We evaluated the germination and the sanity of seeds, length of seedling radicles, and production of indole acetic acid (IAA) by fungi. The experimental design was completely randomized in all experiments. In general, there was a predominance of Fusarium spp. and Rhizoctonia solani. The treatment of seeds with the conidia of Trichoderma sp. was positive for the parameters related to germination and radicle length of cowpea beans up to the concentration 4.8 x 108 CFU g-1. We conclude that the application of Trichoderma sp. was efficient in reducing the incidence of Fusarium spp., and promoted the germination and elongation of the radicle in cowpea.One of the main causes of low productivity of cowpea crops in Brazil is the use of low quality seeds. Low quality seeds have a high degree of infestation by phytopathogens, mainly fungi. Seed treatment with biological control agents, such as fungi of the genus Trichoderma, is a useful alternative to reduce or inhibit the transmission of diseases via seeds. In view of the above, this study aims to evaluate the physiological and sanitary quality of cowpea seeds treated with conidia of Trichoderma sp. (1.2, 2.4, 4.8 and 9.6 x 108 CFU g-1). We evaluated the germination and the sanity of seeds, length of seedling radicles, and production of indole acetic acid (IAA) by fungi. The experimental design was completely randomized in all experiments. In general, there was a predominance of Fusarium spp. and Rhizoctonia solani. The treatment of seeds with the conidia of Trichoderma sp. was positive for the parameters related to germination and radicle length of cowpea beans up to the concentration 4.8 x 108 CFU g-1. We conclude that the application of Trichoderma sp. was efficient in reducing the incidence of Fusarium spp., and promoted the germination and elongation of the radicle in cowpea

Melon fruit quality front mildew incidence and management of nitrogen and potassium topdressing

This work aimed to evaluate the application effect of different dosages of nitrogen and potassium topdressing on mildew severity and on yield and fruit quality of melon. The three cultivars, Jangada, Gaucho Casca de Carvalho and Gaucho Redondo Cone Sul were evaluated in Cerrado (savannah) and floodplain areas. At 34 days after sowing (DAS) the topdressing treatments with different dosages of nitrogen and potassium were applied. The mildew severity estimation started at 56 DAS and was performed in five-days intervals until the harvesting of the fruits. The yield and physicochemical characteristics of the collected fruits were evaluated at harvest. There was no significative interaction among nitrogen and potassium topdressing, the cultivars and cultivated areas. However, there was significative differences when the factors were analyzed in separate. The cultivar Gaucho Redondo Cone Sul showed a significant linear increase in the area under the disease progress curve and higher productivity on cerrado compared to the remaining cultivars. The cultivar Gaucho Casca de Carvalho produced heavier and with higher °Brix fruits on cerrado. It is possible to conclude that the applied topdressings did not reduce the mildew severity in all tested cultivars, but they increased the yield in the floodplain area without modifying the physicochemical characteristics of the pulp on the evaluated melon fruits.This work aimed to evaluate the application effect of different dosages of nitrogen and potassium topdressing on mildew severity and on yield and fruit quality of melon. The three cultivars, Jangada, Gaucho Casca de Carvalho and Gaucho Redondo Cone Sul were evaluated in Cerrado (savannah) and floodplain areas. At 34 days after sowing (DAS) the topdressing treatments with different dosages of nitrogen and potassium were applied. The mildew severity estimation started at 56 DAS and was performed in five-days intervals until the harvesting of the fruits. The yield and physicochemical characteristics of the collected fruits were evaluated at harvest. There was no significative interaction among nitrogen and potassium topdressing, the cultivars and cultivated areas. However, there was significative differences when the factors were analyzed in separate. The cultivar Gaucho Redondo Cone Sul showed a significant linear increase in the area under the disease progress curve and higher productivity on cerrado compared to the remaining cultivars. The cultivar Gaucho Casca de Carvalho produced heavier and with higher °Brix fruits on cerrado. It is possible to conclude that the applied topdressings did not reduce the mildew severity in all tested cultivars, but they increased the yield in the floodplain area without modifying the physicochemical characteristics of the pulp on the evaluated melon fruits

Antracnose foliar e produtividade de sorgo cultivado em áreas de várzea tropical e terras altas

O sorgo é o quinto cereal mais produzido no mundo e um fator limitante à sua produção é a incidência de doenças, tais como a antracnose (Colletotrichum graminicola). Este trabalho teve por objetivo avaliar a incidência e o progresso da antracnose e a produtividade de diferentes genótipos de sorgo em condições de várzea tropical e terras altas. Para tal, foram utilizados três genótipos de sorgo: DOW 1F305, A9735R e BRS 310. Aos 30 dias após o plantio (DAP), o experimento foi implantado com a aplicação da adubação de cobertura (40 e 80 kg ha-1 de nitrogênio). A avaliação da severidade da antracnose foi realizada utilizando uma escala de notas. Na coleta, determinou-se a produtividade dos genótipos com base na massa dos grãos. Foram registrados diferentes padrões de progresso da antracnose nos genótipos avaliados quando comparadas as duas áreas de estudo. Houve diferença na produtividade de grãos em resposta às doses de nitrogênio aplicadas. A suscetibilidade do genótipo BRS 310 pode estar associada principalmente às condições de cultivo, tendo em vista sua maior sensibilidade à antracnose foliar quando cultivado em terras altas. O genótipo DOW 1F305 foi menos sensível à antracnose e apresentou menor produtividade de grãos independente da condição de cultivo

Isolation and Characterization of Plant Growth-Promotion Diazotrophic Endophytic Bacteria Associated to Sugarcane (Saccharum officinarum L.) Grown in Paraíba, Brazil

Sugarcane is an important Brazilian commodity, being usually cultivated in soils with low natural fertility. This study aimed to isolate diazotrophic endophytes from sugarcane tissues and evaluate the morphological and physiological characteristics of their colonies as well as their plant growth-promoting (PGP) traits in select diazotrophic endophytic bacteria. Fifty-six bacterial isolates were identified in the sugarcane tissues, and these isolates presented distinct morphological and physiological traits. A total of thirty-five bacterial isolates were biochemically evaluated. Overall, Bacillus was the dominant genus. Isolates of Methylobacterium spp. and Brevibacillus agri were present only in leaves, while Herbaspirillum seropedicae occurred only in stems. Except to IPA-CF45A, all isolates were nitrogenase positive. All endophytes exhibit production of indol 3-acetic acid. Over 50% of endophytes solubilize phosphate, release N-acyl homoserine lactones, and present the activity of 1-aminocyclopropane-1-carboxylic acid deaminase, catalase, lipase and protease. The network analysis showed that isolates belonged to Burkholderia, Herbaspirillum, and Methylobacterium interact with Bacillus. Bacterial endophytes exhibited distinct morphological, physiological, and PGP traits that are useful for sustainable agriculture, highlighting the isolates IPA-CC33, IPA-CF65, IPA-CC9 and IPA-CF27. Further studies on the effects of these diazotrophic endophytes and their potential for providing microbial inoculants for improving sugarcane fields will provide valuable information to maintain the sustainability and environment quality.National Council for Scientific and Technological Development 426655/2018-

Efficiency of application of Trichoderma on the physiological quality and health of cowpea seeds

One of the main causes of low productivity of cowpea crops in Brazil is the use of low quality seeds. Low quality seeds have a high degree of infestation by phytopathogens, mainly fungi. Seed treatment with biological control agents, such as fungi of the genus Trichoderma, is a useful alternative to reduce or inhibit the transmission of diseases via seeds. In view of the above, this study aims to evaluate the physiological and sanitary quality of cowpea seeds treated with conidia of Trichoderma sp. (1.2, 2.4, 4.8 and 9.6 x 108 CFU g-1). We evaluated the germination and the sanity of seeds, length of seedling radicles, and production of indole acetic acid (IAA) by fungi. The experimental design was completely randomized in all experiments. In general, there was a predominance of Fusarium spp. and Rhizoctonia solani. The treatment of seeds with the conidia of Trichoderma sp. was positive for the parameters related to germination and radicle length of cowpea beans up to the concentration 4.8 x 108 CFU g-1. We conclude that the application of Trichoderma sp. was efficient in reducing the incidence of Fusarium spp., and promoted the germination and elongation of the radicle in cowpea

FERTILIZAÇÃO SILICATADA E NITROGENADA NO CONTROLE DA BRUSONE DO ARROZ EM SISTEMA IRRIGADO

The silicon fertilization has a beneficial effect in enhancing the resistance of plants to diseases, however, this effect can be reduced in the presence of high levels of nitrogen. Given the above, this study aimed to investigate the effect of silicated and nitrogen fertilization in control of rice blast in irrigated system. Plants were grown in an area of tropical lowland and evaluated as to the severity of leaf blast incidence on pan-1 of calcium and magnesium silicate associated with 45 kg ha - 1 of nitrogen topdressing on had lower severity of leaf blast and higher grain yield compared to plants not supplemented with silicon. The combination of silicated fertilization with 90 kg ha - 1 of nitrogen topdressing resulted in a greater incidence of panicle rice blast. After analyzing the results, it was concluded that supple- mentation with silicon and nitrogen promoted reduction in the severity of blast in rice plants in irrigation sys- tem without affecting the yield

Respostas antioxidativas em nódulos de caupi inoculado com bradyrhizobium

O nitrogênio é considerado elemento essencial para as plantas, pois está presente na composição das mais importantes biomoléculas. As plantas podem obter esse nitrogênio através do processo de fixação biológica pela simbiose entre a planta e as bactérias fixadoras de nitrogênio. A fixação biológica do nitrogênio pode ser afetada por fatores bióticos e abióticos que provocam estresse oxidativo na planta. O sistema antioxidativo enzimático envolve enzimas, como por exemplo dismutase de superóxido (SOD), catalase (CAT), peroxidase de fenóis (POX), que conferem proteção oxidativa às plantas. Desta forma, objetivo deste trabalho foi avaliar o metabolismo antioxidativo em nódulos de plantas de feijão-caupi inoculadas com Bradyrhizobium sp. (estirpe BR 3267). Os resultados mostraram que a inoculação com Bradyrhizobiumsp. foi efetiva e resultou em baixo acúmulo de amônia e diminuição do estresse oxidativo. Concluiu-se que a inoculação de caupi comBradyrhizobium sp. foi efetiva em estimular as enzimas envolvidas no processo oxidativo (SOD, POX e CAT). Estas enzimas foram eficientes na remoção das espécies reativas de oxigênio e promoveram proteção oxidativa para plantas de caupi.  

Severidade de antracnose em folhas de sorgo submetido a doses crescentes de silício

A antracnose foliar é causada pelo fungo Colletotrichum sublineolum Hann. Kabát et Bub. (sin. C. graminicola (Ces.) G.W. Wils.) em plantas de sorgo podendo reduzir a produtividade de grãos e forragem, e o manejo adequado da nutrição mineral desta planta pode se apresentar como um mecanismo de controle sobre a antracnose. Dentre os minerais utilizados para o manejo de doenças, o silício destaca-se por reduzir a severidade das doenças em várias culturas. Diante do exposto, este trabalho teve por objetivo avaliar a severidade da antracnose em diferentes genótipos de sorgo suplementados com doses crescentes de silício. Para tal, realizaram-se experimentos em condições de casa de vegetação e de campo onde os genótipos de sorgo DOW 1F305 e A9735R foram suplementados com doses crescentes de silício (0; 500; 1.000; 1.500; 2.000; e 4.000 kg ha-1) e avaliados quanto à severidade da antracnose. Avaliou-se a severidade da doença por meio de uma escala de notas e, em seguida, amostras foram coletadas para determinação da concentração de silício nas folhas. Após a análise dos resultados, concluiu-se que houve redução na severidade da antracnose em resposta a adubação com silício para ambos os genótipos avaliados. Apesar do genótipo de sorgo DOW 1F305 acumular menores teores de silício em suas folhas, este genótipo foi mais resistente ao ataque da antracnose foliar