Eucalyptus sp. seedling response to potassium fertilization and soil water.

A considerable portion of Brazil‘s commercial eucalypt plantations is located in areas subjected to periods of water deficit and grown in soils with low natural fertility, particularly poor in potassium. Potassium is influential in controlling water relations of plants. The objective of this study was to verify the influence of potassium fertilization and soil water potential (Ψw) on the dry matter production and on water relations of eucalypt seedlings grown under greenhouse conditions. The experimental units were arranged in 4x4x2 randomized blocks factorial design, as follow: four species of Eucalyptus (Eucalyptus grandis, Eucalyptus urophylla, Eucalyptus camaldulensis and hybrid Eucalyptus grandis x Eucalyptus urophylla), four dosages of K (0, 50, 100 and 200 mg dm-3) and two soil water potentials (-0.01MPa and -0.1 MPa). Plastic containers with 15 cm diameter and 18 cm height, with Styrofoam base, containing 3.0 dm3 of soil and two plants per container were used. Soil water potential was kept at –0.01MPa for 40 days after seeding. Afterward, the experimental units were divided into two groups: in one group the potential was kept at -0.01MPa, and in the other one, at -0.10 MPa. Soil water potential was controlled gravimetrically twice a day with water replacement until the desired potential was reestablished. A week before harvesting, the leaf water potential (Ψ), the photosynthetic rate (A), the stomatal conductance (gs) and the transpiration rate were evaluated. The last week before harvesting, the mass of the containers was recorded daily before watering to determine the consumption of water by the plants. After harvesting, total dry matter and leaf area were evaluated. The data were submitted to analysis of variance, to Tukey's tests and regression analyses. The application of K influenced A, gs and the transpiration rate. Plants deficient in K showed lower A and higher gs and transpiration rates. There were no statistical differences in A, gs and transpiration rates in plants with and without water deficit. The addition of K reduced the consumption of water per unit of leaf area and, in general, plants submitted to water deficit presented a lower consumption of water.A considerable portion of Brazil‘s commercial eucalypt plantations is located in areas subjected to periods of water deficit and grown in soils with low natural fertility, particularly poor in potassium. Potassium is influential in controlling water relations of plants. The objective of this study was to verify the influence of potassium fertilization and soil water potential (Ψw) on the dry matter production and on water relations of eucalypt seedlings grown under greenhouse conditions. The experimental units were arranged in 4x4x2 randomized blocks factorial design, as follow: four species of Eucalyptus (Eucalyptus grandis, Eucalyptus urophylla, Eucalyptus camaldulensis and hybrid Eucalyptus grandis x Eucalyptus urophylla), four dosages of K (0, 50, 100 and 200 mg dm-3) and two soil water potentials (-0.01MPa and -0.1 MPa). Plastic containers with 15 cm diameter and 18 cm height, with Styrofoam base, containing 3.0 dm3 of soil and two plants per container were used. Soil water potential was kept at -0.01MPa for 40 days after seeding. Afterward, the experimental units were divided into two groups: in one group the potential was kept at -0.01MPa, and in the other one, at -0.10 MPa. Soil water potential was controlled gravimetrically twice a day with water replacement until the desired potential was reestablished. A week before harvesting, the leaf water potential (Ψ), the photosynthetic rate (A), the stomatal conductance (gs) and the transpiration rate were evaluated. The last week before harvesting, the mass of the containers was recorded daily before watering to determine the consumption of water by the plants. After harvesting, total dry matter and leaf area were evaluated. The data were submitted to analysis of variance, to Tukey's tests and regression analyses. The application of K influenced A, gs and the transpiration rate. Plants deficient in K showed lower A and higher gs and transpiration rates. There were no statistical differences in A, gs and transpiration rates in plants with and without water deficit. The addition of K reduced the consumption of water per unit of leaf area and, in general, plants submitted to water deficit presented a lower consumption of water

Eucalyptus sp. seedling response to potassium fertilization and soil water.

No Brasil, uma consider\ue1vel por\ue7\ue3o dos plantios comerciais de eucalipto est\ue1 localizada em regi\uf5es sujeitas a per\uedodos de d\ue9ficits h\ueddrico (DH) e, normalmente, em solos de baixa fertilidade natural, particularmente pobres em K, o que pode comprometer o crescimento e as rela\ue7\uf5es h\ueddricas das plantas. Assim, este trabalho teve como objetivo verificar a influ\ueancia da aduba\ue7\ue3o pot\ue1ssica e do potencial de \ue1gua do solo (\u3a8w) na produ\ue7\ue3o de mat\ue9ria seca e nas rela\ue7\uf5es h\ueddricas de mudas de eucalipto, em casa de vegeta\ue7\ue3o. O experimento foi constitu\ueddo de 32 tratamentos, compreendendo quatro esp\ue9cies de eucalipto ( Eucalyptus grandis , Eucalyptus urophylla , Eucalyptus camaldulensis e o h\uedbrido Eucalyptus grandis x Eucalyptus urophylla), quatro doses de K (0, 50, 100 e 200 mg dm-3 de K) e dois regimes de umidade do solo (-0,01MPa e -0,10 MPa), no delineamento em blocos casualizados, em esquema fatorial, com tr\ueas repeti\ue7\uf5es. Foram utilizados vasos de PVC, com fundo de isopor, contendo 3,0 dm3 de solo, com duas plantas por vaso. O \u3a8w foi mantido em -0,01MPa por 40 dias. Ap\uf3s, as unidades experimentais foram divididas em dois grupos, sendo o \u3a8w, em um deles, mantido a -0,01MPa e, no outro, a -0,10 MPa. O controle da umidade do solo foi feito gravimetricamente. Uma semana antes da colheita do experimento, foram avaliados o potencial da \ue1gua da folha (\u3a8), a taxa fotossint\ue9tica (A), a condut\ue2ncia estom\ue1tica (gs) e a taxa de transpira\ue7\ue3o. Durante a \ufaltima semana de condu\ue7\ue3o do experimento, a massa dos vasos foi anotada diariamente antes da coloca\ue7\ue3o de \ue1gua de modo a se determinar o consumo de \ue1gua pelas plantas. Na colheita, as plantas foram coletadas e determinada a mat\ue9ria seca. Tamb\ue9m, foi determinada a \ue1rea foliar. Os dados foram submetidos \ue0 an\ue1lise de vari\ue2ncia, a testes de Tukey e an\ue1lises de regress\ue3o. A aplica\ue7\ue3o de K influenciou a A, a gs, a transpira\ue7\ue3o e a EUA. Plantas deficientes em K apresentaram menor A e maior gs e taxa de transpira\ue7\ue3o, com consequente menor EUA. N\ue3o houve diferen\ue7as estat\uedsticas na A, gs e taxa de transpira\ue7\ue3o entre plantas com e sem DH. A adi\ue7\ue3o de K diminuiu o consumo de \ue1gua por unidade de \ue1rea foliar e, em geral, plantas submetidas \ue0 DH apresentaram menor consumo de \ue1gua.A considerable portion of Brazil\u2018s commercial eucalypt plantations is located in areas subjected to periods of water deficit and grown in soils with low natural fertility, particularly poor in potassium. Potassium is influential in controlling water relations of plants. The objective of this study was to verify the influence of potassium fertilization and soil water potential (\u3a8w) on the dry matter production and on water relations of eucalypt seedlings grown under greenhouse conditions. The experimental units were arranged in 4x4x2 randomized blocks factorial design, as follow: four species of Eucalyptus ( Eucalyptus grandis , Eucalyptus urophylla , Eucalyptus camaldulensis and hybrid Eucalyptus grandis x Eucalyptus urophylla), four dosages of K (0, 50, 100 and 200 mg dm-3) and two soil water potentials (-0.01MPa and -0.1 MPa). Plastic containers with 15 cm diameter and 18 cm height, with Styrofoam base, containing 3.0 dm3 of soil and two plants per container were used. Soil water potential was kept at \u20130.01MPa for 40 days after seeding. Afterward, the experimental units were divided into two groups: in one group the potential was kept at -0.01MPa, and in the other one, at -0.10 MPa. Soil water potential was controlled gravimetrically twice a day with water replacement until the desired potential was reestablished. A week before harvesting, the leaf water potential (\u3a8), the photosynthetic rate (A), the stomatal conductance (gs) and the transpiration rate were evaluated. The last week before harvesting, the mass of the containers was recorded daily before watering to determine the consumption of water by the plants. After harvesting, total dry matter and leaf area were evaluated. The data were submitted to analysis of variance, to Tukey's tests and regression analyses. The application of K influenced A, gs and the transpiration rate. Plants deficient in K showed lower A and higher gs and transpiration rates. There were no statistical differences in A, gs and transpiration rates in plants with and without water deficit. The addition of K reduced the consumption of water per unit of leaf area and, in general, plants submitted to water deficit presented a lower consumption of water

Development of a semi-selective medium to detection Xanthomonas axonopodis pv. malvacerum from cotton seeds (Gossypium hirsutum L.)

Um dos principais fatores limitantes da produção de algodão é a ocorrência de doenças e, entre os patógenos mais importantes estão às bactérias, que causam danos significativos à cultura. A doença conhecida como mancha angular, causada pela bactéria Xanthomonas axonopodis pv. malvacearum (Xam), é uma doença grave, que tem gerado grande preocupação dos produtores. Porém, muitos cultivares com boas características agronômicas apresentam suscetibilidade ao patógeno e, poucos são aqueles que apresentam resistência à doença. O controle da mancha angular é realizado basicamente com uso de resistência genética ao patógeno. Uma das principais fontes de inóculo para esta bactéria é a semente infectada. Este trabalho objetivou o desenvolvimento de um meio semi-seletivo para o isolamento de Xam em sementes de algodão, visando a utilização em análises de rotina em laboratórios de patologia de sementes. O meio de cultura semi-seletivo possuí a seguinte constituição: 3 g de extrato de carne; 5 g de peptona; 10 g de amido solúvel; 10 mL de Tween 80; 0,25 g de cloreto de cálcio; 150 µL de solução de cristal violeta a 1%; 50 mg de cefalexina; 10 mg de clorothalonil; 10 mg de tiofanato metílico e água destilada por 1000 mL. Este meio de cultura possui baixa repressividade a Xam e permite isolar este patógeno de sementes de algodão.One of the main limiting factors of the cotton production is the occurrence of diseases. The bacteria are among the most important pathogens causing significant losses in the production. Cotton bacterial blight is caused by the bacterium Xanthomonas axonopodis pv. malvacearum (Xam). Is a serious disease that affects cotton and has worried world producers. The main source of inoculum for this bacterium is the infected seed. This work had as objective the development of a semi-selective medium to detect Xanthomonas axonopodis pv malvacearum in cotton seeds for routine tests in seed pathology laboratories. By fungitoxicity tests, basead on qualitative and quantitative antibiograms, it was idealized a semi-selective medium with the folloing composition: peptone (5.0 g/L); agar (15.0 g/L); meat extract (3.0 g); starch (10.0 g/L); violet crystal (150.0 µL violet crystal solution at 1%); water (1,000 mL); CaCl2 (0.25 g); Tween 80 (10.0 mL/L). This medium has small effect on Xam and allows to isolate cotton seeds pathogens

Semi-selective culture medium for Xanthomonas axonopodis pv. malvacearum detection in cotton seeds (Gossypium hirsutum L.)

The cotton disease known as angular leaf spot, caused by Xanthomonas axonopodis pv. malvacearum (Xam) has been causing cotton losses in several producing regions around the world. Xam is transmitted by seeds, which may be infected both externally and internally. Infected seeds constitute the main long-distance dissemination mode of the pathogen. In view of this, the use of healthy seeds is a must. To accomplish that, detection methodologies for the bacteria must be developed be used in seed health analysis laboratories. This study aimed to develop a semi-selective medium for Xam detection in cotton seeds. The semi-selective culture medium was named MSSXAN and it was consisted of peptone (5.0 g), beef extract (3 g), sucrose (5 g), soluble starch (10 g), agar (15 g), CaCl 2 (0.25 g), Tween 80 (10 mL), distilled water (1,000 mL), crystal violet solution at 1% (150 μL), cephalexin (50 mg 1*), methyl thyophanate (10 mg*) and chlorothalonil (10 mg*) - *added after culture medium autoclaving. This MSSXAN medium shows low repressiveness to Xam and it be used for isolation of this bacteria in cotton seeds health analysis. © 2009 Academic Journals Inc

Eucalyptus sp. seedling response to potassium fertilization and soil water.

No Brasil, uma considerável porção dos plantios comerciais de eucalipto está localizada em regiões sujeitas a períodos de déficits hídrico (DH) e, normalmente, em solos de baixa fertilidade natural, particularmente pobres em K, o que pode comprometer o crescimento e as relações hídricas das plantas. Assim, este trabalho teve como objetivo verificar a influência da adubação potássica e do potencial de água do solo (Ψw) na produção de matéria seca e nas relações hídricas de mudas de eucalipto, em casa de vegetação. O experimento foi constituído de 32 tratamentos, compreendendo quatro espécies de eucalipto ( Eucalyptus grandis , Eucalyptus urophylla , Eucalyptus camaldulensis e o híbrido Eucalyptus grandis x Eucalyptus urophylla), quatro doses de K (0, 50, 100 e 200 mg dm-3 de K) e dois regimes de umidade do solo (-0,01MPa e -0,10 MPa), no delineamento em blocos casualizados, em esquema fatorial, com três repetições. Foram utilizados vasos de PVC, com fundo de isopor, contendo 3,0 dm3 de solo, com duas plantas por vaso. O Ψw foi mantido em -0,01MPa por 40 dias. Após, as unidades experimentais foram divididas em dois grupos, sendo o Ψw, em um deles, mantido a -0,01MPa e, no outro, a -0,10 MPa. O controle da umidade do solo foi feito gravimetricamente. Uma semana antes da colheita do experimento, foram avaliados o potencial da água da folha (Ψ), a taxa fotossintética (A), a condutância estomática (gs) e a taxa de transpiração. Durante a última semana de condução do experimento, a massa dos vasos foi anotada diariamente antes da colocação de água de modo a se determinar o consumo de água pelas plantas. Na colheita, as plantas foram coletadas e determinada a matéria seca. Também, foi determinada a área foliar. Os dados foram submetidos à análise de variância, a testes de Tukey e análises de regressão. A aplicação de K influenciou a A, a gs, a transpiração e a EUA. Plantas deficientes em K apresentaram menor A e maior gs e taxa de transpiração, com consequente menor EUA. Não houve diferenças estatísticas na A, gs e taxa de transpiração entre plantas com e sem DH. A adição de K diminuiu o consumo de água por unidade de área foliar e, em geral, plantas submetidas à DH apresentaram menor consumo de água.A considerable portion of Brazil‘s commercial eucalypt plantations is located in areas subjected to periods of water deficit and grown in soils with low natural fertility, particularly poor in potassium. Potassium is influential in controlling water relations of plants. The objective of this study was to verify the influence of potassium fertilization and soil water potential (Ψw) on the dry matter production and on water relations of eucalypt seedlings grown under greenhouse conditions. The experimental units were arranged in 4x4x2 randomized blocks factorial design, as follow: four species of Eucalyptus ( Eucalyptus grandis , Eucalyptus urophylla , Eucalyptus camaldulensis and hybrid Eucalyptus grandis x Eucalyptus urophylla), four dosages of K (0, 50, 100 and 200 mg dm-3) and two soil water potentials (-0.01MPa and -0.1 MPa). Plastic containers with 15 cm diameter and 18 cm height, with Styrofoam base, containing 3.0 dm3 of soil and two plants per container were used. Soil water potential was kept at –0.01MPa for 40 days after seeding. Afterward, the experimental units were divided into two groups: in one group the potential was kept at -0.01MPa, and in the other one, at -0.10 MPa. Soil water potential was controlled gravimetrically twice a day with water replacement until the desired potential was reestablished. A week before harvesting, the leaf water potential (Ψ), the photosynthetic rate (A), the stomatal conductance (gs) and the transpiration rate were evaluated. The last week before harvesting, the mass of the containers was recorded daily before watering to determine the consumption of water by the plants. After harvesting, total dry matter and leaf area were evaluated. The data were submitted to analysis of variance, to Tukey's tests and regression analyses. The application of K influenced A, gs and the transpiration rate. Plants deficient in K showed lower A and higher gs and transpiration rates. There were no statistical differences in A, gs and transpiration rates in plants with and without water deficit. The addition of K reduced the consumption of water per unit of leaf area and, in general, plants submitted to water deficit presented a lower consumption of water