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- Melhoramento para elevada qualidade pós-colheita: validação do método de selecção de genótipos promissoresPublication . Carvalho, D.R.A.; Carvalho, S. M. P.; Fanourakis, D.; Heuvelink, E.; Almeida, Domingos P. F.
- Melhoramento para elevada qualidade pós-colheita: validação do método de selecção de genótipos promissoresPublication . Carvalho, D.R.A.; Carvalho, S. M. P.; Fanourakis, D.; Heuvelink, E.; Almeida, Domingos P. F.
- Estimativa da área foliar em diferentes estados fenológicos baseada em descritores alométricos de rosas de corte cv 'Red Naomi'Publication . Costa, P. M.; Poças, I.; Alves, S.; Pereira, M.; Carvalho, S. M. P.; Cunha, M.A área foliar (AF) é uma variável fundamental para a fotossíntese, transpiração, e produtividade. Métodos expeditos e não destrutivos para a estimativa da AF ao longo do ciclo de produção são necessários para o desenvolvimento de modelos ecofisiológicos e apoiar práticas culturais, tais como a aplicação de fitofármacos e gestão da água. Existem diversos modelos para a estimativa da AF, mas por terem sido desenvolvidos para uma fase do ciclo de produção (geralmente a colheita) têm uma aplicabilidade limitada. Neste trabalho, estudamos como a área de folhas compostas da rosa de corte cv 'Red Naomi ' poderia ser estimada, em diferentes fases fenológicas, a partir de medições expeditas e não-destrutivas. A experiência realizou-se numa estufa localizada na região costeira do norte de Portugal, para a produção de roseiras em sistema sem solo, com uma densidade de 8 plantas/m2, em saco plástico com substrato de fibra de coco e turfa. Para estimativa da AF das roseiras, foi desenvolvido um modelo estatístico baseado em descritores alométricos tais como: comprimento da folha (CF), largura da folha (LF), posição da folha na haste (PF), número de folíolos (NF), assim como relações entre estas medições tais como: forma de folha (relação LL vs PV), e a posição relativa da folha na haste - (RF). A estimação do modelo, baseada na técnica de regressão “stepwise”, foi avaliado por diversos testes de qualidade de ajuste e de verificação da colinearidade entre variáveis. Para a estimativa do modelo foram utilizadas 176 folhas de 20 hastes colhidas em diferentes estados fenológicos. A AF, obtida por um método não-destrutivo, variou entre 7,5-111,8 cm2, a CF de 4,7- 18,9 cm, LF de 3,8-12,2 cm, o NF de 3 a 8 e a PF de 1 a 15. O modelo selecionado, baseado nas medidas de CF, LF, PF e NF, explicou 93% (R2 = 0,93; N = 176, p <0,000) da variabilidade da AF ao longo do ciclo de produção e a diferença média relativa entre a AF medida e modelada foi inferior a 9 %. A validação do modelo, realizada com dados independentes provenientes de 24 folhas, permitiu obter testes de ajustamento semelhantes aos obtidos para o modelo da serie de estimação. A precisão e operacionalidade do modelo desenvolvido para a obtenção da AF, justifica o seu uso em estudos de eco-fisiológicos, modelos de simulação do desenvolvimento, bem como para apoiar práticas culturais em rosas de corte.
- Estimativa da área foliar em diferentes estados fenológicos baseada em descritores alométricos de rosas de corte cv 'Red Naomi'Publication . Costa, P. M.; Poças, I.; Alves, S.; Pereira, M.; Carvalho, S. M. P.; Cunha, M.A number of models for estimating leaf area (LA) are available in the literature, but these were frequently developed for a specific phase of the production (generally the harvest). This study aimed at estimating the LA in different phenological stages using non-destructive allometric measurements of cut rose cv 'Red Naomi' grown in soilless system. A statistical model was developed based on the following allometric measures: leaf length (LL), leaf width (LW), leaf position (LP), number of leaflets (NL) and different combinations of these parameters. The estimated model based on 176 leaves obtained from 20 stalks harvested at different developmental stages explained 92% of the LA variance (R2 = 0.92, n = 176, p < 0.000).This model includes the numerical position of the leaf on the stem (PRFn), ln (LL*LW) and NL as parameters, and the mean absolute difference between measured and estimated LA was less than 11%. It is concluded that the obtained model shows a high accuracy and reliability in the LA estimation in very diverse situations of crop phenology.
- Avaliação do contributo da expressão genética na tolerância à desidratação em Rosa × hybrida cultivada em humidade relativa elevadaPublication . Carvalho, D. R. A.; Vasconcelos, Marta; Koning-Boucoiran, C. F. S.; Krens, F. A.; Heuvelink, E; Carvalho, S. M. P.Cultivation of cut flowers with high postharvest longevity is of extreme importance for consumer’s satisfaction. A negative water balance is indicated as the most important factor reducing longevity. This problem is more severe in plants grown at high relative air humidity (i.e. RH > 85%) mainly due to a poor stomatal functioning associated to lower abscisic acid (ABA) concentrations, leading to higher water loss. In this paper it is analysed whether a sensitive cut rose cultivar to high RH show different gene expression related to ABA metabolism when grown at moderate (60%) or high (90%) RH. RNA was isolated from fully developed leaves, harvested 180 min after the beginning of the dark period (stomatal closing stimulus) and the relative gene expression was evaluated in genes involved in: biosynthesis (AAO3 and NCED1), oxidation (CYP707A1 and CYP707A3) and conjugation (UGT75B2) of ABA. The stomatal conductivity in the dark period was 5.6-fold higher in intact plants developed at high RH compared to moderate RH-grown plants, showing the reduced closure capacity of the stomata during darkness. After 4 h of leaflet desiccation, leaflets grown at high RH showed a relative water content (RWC) 69% lower than the moderate RH-grown leaflets, validating the sensitivity of K023 to high RH during growth. At last, from the five studied genes only the expression of CYP707A3 was significantly reduced by high RH, without significant differences found in the other genes. In conclusion, the sensitivity of the genotype K023 to high RH cannot be explained by the expression of the genes evaluated in this study, using leaves harvested 180 min after the beginning of the dark period (closing stimulus). We expect that after transferring the plants to the postharvest conditions, inducing water stress, a more contrasting gene expression among RH levels will appear.
- Exploring the expression of defence-related genes in Actinidia spp. after infection with Pseudomonas syringae pv. actinidiae and pv. actinidifoliorum: first stepsPublication . Silva, M. Nunes da; Machado, J.; Balestra, G. M.; Mazzaglia, A.; Vasconcelos, M. W.; Carvalho, S. M. P.Kiwifruit bacterial canker (KBC), caused by Pseudomonas syringae pv. actinidiae (PSA), is currently the most destructive disease of kiwifruit worldwide. Conversely, a closely related bacterial strain, P. syringae pv. actinidifoliorum (PFM), only causes necrotic spots and has not been associated with plant mortality. Moreover, there is some evidence on the higher susceptibility of the Actinidia chinensis var. deliciosa kiwifruit species to KBC, compared with A. arguta, but the reasons behind it are still largely unknown. In this work, micropropagated plants of Actinidia chinensis var. deliciosa 'Hayward' and A. arguta var. arguta 'Ken's Red' were inoculated with PSA or with PFM (10(7) CFUs mL(-1)). Disease development was monitored 1, 2 and 5 days post inoculation (dpi) through the determination colony forming units (CFUs) and the expression analysis of six plant defence-related genes (APX, CAT, SOD, LOX1, SAM and TLP1). At 5 dpi, CFUs in plant tissues inoculated with PSA and PFM were, respectively, 17.4-fold and 2.8-fold higher in A. chinensis compared with A. arguta. Expression of antioxidant enzyme-related genes was very distinct between the two kiwifruit species: SOD expression was drastically increased in A. chinensis (up to 2.1-fold, 5 dpi), whereas in A. arguta CAT was the most upregulated gene (up to 1.7-fold, 2 dpi). LOX1, involved in jasmonic acid biosynthesis, was upregulated in both species, however reaching the highest values at 2 dpi in A. chinensis (2.2 fold) and 1 dpi in A. arguta (1.9-fold). It is concluded that A. arguta is much more tolerant to PSA than A. chinensis and that the molecular mechanisms between the two kiwifruit species involve specific defence pathways being triggered at distinct moments after plant infection.
- Pre-harvest relative humidity level influences water uptake and transpiration during post-harvest phase of cut rosesPublication . Fanourakis, D.; Matkaris, N.; Heuvelink, E.; Carvalho, S. M. P.
- Conventional and novel approaches for managing “flavescence dorée” in grapevine: knowledge gaps and future prospectsPublication . Oliveira, M. J. R. A.; Roriz, M.; Vasconcelos, M. W.; Bertaccini, A.; Carvalho, S. M. P.“Flavescence dorée” (FD) is a grapevine quarantine disease associated with phytoplasmas and transmitted to healthy plants by insect vectors, mainly Scaphoideus titanus. Development of efficient methods for its control has been hampered by the lack of knowledge about phytoplasma biological properties, linked also to difficulties in its in vitro cultivation. Conventional management strategies rely mainly on the application of insecticide treatments, roguing of infected plants and production of phytoplasma‐free propagation material. However, these strategies are costly and could have undesirable environmental impacts. Novel approaches are being investigated using transcriptomic and proteomic tools that can assist in identifying key regulators expressed by diseased, recovered and healthy plants. These studies allowed the identification of molecular profiles linked to the grapevine cultivar‐diverse susceptibility that are of great interest for the development of FD less susceptible plants by breeding programmes. Other promising FD management strategies include the use of grapevine endophytic microorganisms with known biocontrol properties and endophytes living inside specialized insect cells, which can be potential candidates for FD vector control. Finally, the application of plant defence elicitors might be an interesting tool for FD containment, but more research is needed before it can be implemented. In this review, the methodologies used for detecting and confining FD diffusion are discussed, focusing mainly on conventional tools, current research perspectives and knowledge gaps.
- Genotypic variation of cut chrysanthemum response to high CO2 concentration: growth, time to flowering and visual qualityPublication . Fanourakis, D.; Heuvelink, E.; Maaswinke, R.; Carvalho, S. M. P.In this study sixteen cut chrysanthemum cultivars were used to evaluate the effects of high CO2 concentration (1500 μmol mol-1) on growth, time to flowering and visual quality as compared to the concentration used in commercial greenhouses (600 μmol mol-1). CO2 enrichment increased light use efficiency (11-41%) and total plant dry mass (TDM) (5-40%) in a cultivar dependent manner. This TDM increase was a result of: (i) higher relative growth rate during the long day period (i.e., 0 to 2 weeks; LD); and (ii) higher absolute growth rate both during the period between 2 to 6 weeks (SD1), and 6 weeks to final harvest (SD2). Cultivar differences in TDM at flowering between the two CO2 concentrations could be explained by differences in growth rate during the LD and SD2 periods. Furthermore, growing at high CO2 regime enhanced the number of flowers and flower buds per plant (NoF, 4-48%). Interestingly, the cultivars that showed the highest percentage of TDM increase, with CO2 enrichment, were not the ones that had the highest increase in the percentage of NoF. In contrast, high CO2 concentration had only a minor or no effect on the number of internodes on the main stem and on the reaction time in all the cultivars examined. From this research it is concluded that there is a large variation in the response of cut chrysanthemum cultivars to CO2 enrichment, in terms of TDM and NoF, which gives possibilities for breeding.
- Avaliação do contributo da expressão genética na tolerância à desidratação em Rosa × hybrida cultivada em humidade relativa elevadaPublication . Carvalho, D. R. A.; Vasconcelos, Marta; Koning-Boucoiran, C. F. S.; Krens, F. A.; Heuvelink, E; Carvalho, S. M. P.