Browsing by Author "Carvalho, Susana M.P."
Now showing 1 - 10 of 12
Results Per Page
Sort Options
- Avaliação dos efeitos da aplicação de micorrizas ericóides no crescimento de mirtilo (Vaccinium corymbosum L.)Publication . Gonçalves, Patrícia A. F.; Silva, M. A. Nunes da; Machado, Joana; Carvalho, Susana M.P.; Vasconcelos, Marta W.O mirtilo (Vaccinium corymbosum L.) apresenta um sistema radicular muito superficial e compacto, sem pêlos radiculares. Como tal, estas plantas tendem a estabelecer simbiose com fungos ericóides micorrízicos (FEM), o que lhes permite aumentar a absorção de nutrientes e água. Como a colonização natural é frequentemente reduzida e dependente da cultivar e das práticas agronómicas, a inoculação externa com fungos micorrízicos tem vindo a ser utilizada pelos viveiristas para aumentar a taxa de fungos simbiontes. Contudo, a relação planta/fungos ericóides está ainda pouco estudada e o modo como estes microsimbiontes melhoram o crescimento e a nutrição do mirtilo necessita de ser elucidado. Neste estudo, foram inoculadas duas cultivares de mirtilo (‘Aurora’ e ‘Duke’) com uma mistura comercial de FEM. Cerca de 14 meses após inoculação foi avaliada a taxa de colonização das raízes e foram registados vários parâmetros biométricos (peso seco, altura da planta, diâmetro do caule e comprimento da raíz), fisiológicos (teor de clorofila das folhas) e nutricionais (concentração de minerais inorgânicos) em plantas submetidas a tratamento com inóculo e plantas controlo. Os resultados obtidos demonstraram que a percentagem de peso fresco das raízes naturalmente colonizada por fungos ericóides foi aproximadamente 30 % para ambas as cultivares (plantas controlo), aumentando para 56 % na ‘Aurora’ e para 44 % na ‘Duke’ em plantas inoculadas com mistura de FEM. Nas plantas inoculadas da cv. ‘Aurora’, observou-se um aumento significativo do peso seco total das raízes (48 %) e dos caules (31 %) comparativamente às plantas controlo. Paralelamente, também se verificou um aumento significativo da altura das plantas e do comprimento das raízes. Já na cv. ‘Duke’ o efeito da inoculação não foi significativo em nenhum dos parâmetros biométricos estudados. A inoculação induziu a acumulação de Mo nas raízes e de K nos caules e folhas na cv. ‘Aurora’, e aumentou a concentração de Mn, Fe e Cu nas raízes e caules (em alguns casos por 280 %) na cv. ‘Duke’. A inoculação de plantas de mirtilo com fungos ericóides tem um potencial evidente no estímulo do crescimento das plantas e absorção de nutrientes; no entanto, a sua eficácia parece estar dependente da cultivar.
- Breeding cut roses for better keeping quality: first stepsPublication . Fanourakis, D.; Carvalho, D.R.A; Gitonga, V.; Heusden, A.W. van; Almeida, Domingos P. F.; Heuvelink, E.; Carvalho, Susana M.P.
- Effect of tris(3-hydroxy-4-pyridinonate) iron(III) complexes on iron uptake and storage in soybean (Glycine max L.)Publication . Santos, Carla S.; Carvalho, Susana M.P.; Leite, Andreia; Moniz, Tânia; Roriz, Mariana; Rangel, António O. S. S.; Rangel, Maria; Vasconcelos, Marta W.Iron deficiency chlorosis (IDC) is a serious environmental problem affecting the growth of several crops in the world. The application of synthetic Fe(III) chelates is still one of the most common measures to correct IDC and the search for more effective Fe chelates remains an important issue. Herein, we propose a tris(3-hydroxy-4-pyridinonate) iron(III) complex, Fe(mpp)3, as an IDC corrector. Different morphological, biochemical and molecular parameters were assessed as a first step towards understanding its mode of action, compared with that of the commercial fertilizer FeEDDHA. Plants treated with the pyridinone iron(III) complexes were significantly greener and had increased biomass. The total Fe content was measured using ICP-OES and plants treated with pyridinone complexes accumulated about 50% more Fe than those treated with the commercial chelate. In particular, plants supplied with compound Fe(mpp)3 were able to translocate iron from the roots to the shoots and did not elicit the expression of the Fe-stress related genes FRO2 and IRT1. These results suggest that 3,4-HPO iron(III) chelates could be a potential new class of plant fertilizing agents.
- Eficiência energética em crisântemo e tomatePublication . Carvalho, Susana M.P.; Ploeg, Anke van der; Heuvelink, Ep
- Genotypic variation in the response to suboptimal temperature at different plant densities in cut chrysanthemumPublication . Ploeg, Anke van der; Carvalho, Susana M.P.; Heuvelink, EpEnergy efficiency of greenhouse cut chrysanthemum (Chrysanthemum morifolium Ramat.) may be increased by breeding. In addition to breeding for cultivars with a shorter reaction time at suboptimal temperatures, an alternative approach would be to develop cultivars that are heavier at suboptimal temperatures so that they could be grown at a higher plant density, enhancing the production per unit area. Therefore, the combined effect of temperature and plant density on growth and development of four cut chrysanthemum cultivars was investigated in three greenhouse experiments, carried out in different seasons. For growth-related traits, no interactions between temperature and cultivar were found, limiting the possibilities for breeding. At suboptimal temperatures, growth rate early in the cultivation period decreased as a consequence of a lower light interception resulting from a lower specific leaf area. Thus a higher dry mass production at lower temperature could only be explained by a longer cultivation time. Temperature also influenced external quality, but these effects were cultivar dependent. For instance, temperature affected the slope of the positive linear relationship between total dry mass and number of flowers, reducing number of flowers at low temperature for the same plant dry mass. It is concluded that there are possibilities for breeding for suboptimal temperature-tolerant cultivars.
- Iron metabolism in soybean grown in calcareous soil is influenced by plant growth-promoting rhizobacteria: a functional analysisPublication . Roriz, Mariana; Pereira, Sofia I.A.; Castro, Paula M.L.; Carvalho, Susana M.P.; Vasconcelos, Marta W.Iron deficiency results in severe yield losses, particularly in calcareous soils. Recent evidences suggest that biofertilizers with plant growth-promoting rhizobacteria (PGPR) may be an efficient strategy for enhancing iron (Fe) nutrition in legumes. This work aimed at evaluating the capacity of PGPR strains to enhance Fe uptake-related processes in soybean grown in calcareous soil. From the studied 24 PGPR, Sphingobium fuliginis ZR 1–6 and Pseudomonas jessenni ZR 3–8 strains were selected for the inoculation experiment based on their in vitro ability to produce indole-3-acetic acid, 1-aminocyclopropane-1-carboxylic acid deaminase, siderophores, and organic acids, to tolerate high pH, and to reduce Fe3+. The effect of bacterial inoculation on improving Fe uptake was tested using each isolate alone or combined and through the evaluation of several morphological, physiological, and molecular parameters. Inoculation with S. fuliginis showed beneficial effects particularly at the root level by the improvement of ferric chelate activity (111%) and FRO2 expression (646%), resulting in increased Fe root content (62%). Inoculation with P. jessenii increased Zn and Mn concentrations in the trifoliates (463% and 51%, respectively), decreased Zn concentration in the roots (88%), and increased the expression of FER4 in the trifoliates (5260%). Combined inoculation of both strains fostered Fe accumulation in the trifoliates and increased the expression of IRT1 and FER4 genes, indicating an improved capacity of Fe translocation to the shoots. These results suggest that inoculation with selected PGPR strains could be effective in improving Fe uptake and accumulation in soybean grown under Fe-deficient conditions.
- Modelling visual quality of Kalanchoe blossfeldiana: influence of cultivar and pot sizePublication . Carvalho, Susana M.P.; Almeida, Jorge; Eveleens-Clark, Barbara; Bakker, Menno J.; Heuvelink, Ep
- Morphological and physiological responses of strawberry to a biostimulant and calcium applicationPublication . Wang, Maling; Araújo, David; Vasconcelos, Marta; Gomes, M. Helena; Carvalho, Susana M.P.
- Postharvest water relations in cut rose cultivars with contrasting sensitivity to high relative air humidity during growthPublication . Fanourakis, Dimitrios; Carvalho, Susana M.P.; Almeida, Domingos P.F.; Kooten, Olaf van; Doorn, Wouter G. van; Heuvelink, EpA constant highrelativeairhumidity (RH) during cultivation can strongly reduce the vase life in some cutrosecultivars. We studied three contrastingcultivars in their tolerance to high RH in order to analyse in detail the waterrelations during postharvest and better understand this genotypic variation. Plants were grown at moderate (60%) and high (95%) RH, and cut flowers were placed in water immediately after cutting. Flowers of cv. Pink Prophyta grown at high RH did not open throughout vase life, while flower opening of cvs. Frisco and Dream was not affected by preharvest RH. Cultivation at high RH resulted in about 80% shorter vase life in Pink Prophyta, whereas in Dream and Frisco the negative effect was considerably smaller (15 and 9% shorter vase life, respectively). The shorter vase life and reduced flower opening of cutroses grown at high RH was due to a higher rate of transpiration both in the light and dark periods. It was found that the leaves of Pink Prophyta grown at high RH could partly close their stomata upon lowering of the water potential or when flower stalks were fed with abscisic acid, but stomata remained far more open than in leaves grown at moderate RH. The RH during cultivation did not affect stem hydraulic conductivity and its recovery after air emboli induction. Preventing vascular occlusion largely alleviated the high-cultivation-RH effect on vase life and flower opening, showing that the effect of high-cultivation-RH becomes only important if water uptake is limited.
- Qualidade pós-colheita de rosas: efeitos da humidade relativa e da variação genotípicaPublication . Carvalho, Susana M.P.; Fanourakis, D.; Tapia, A.; Almeida, Domingos P. F.; Malcata, F. Xavier; Heuvelink, E.