Browsing by Author "Carvalho, D. R. A."
Now showing 1 - 4 of 4
Results Per Page
Sort Options
- 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.
- 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.
- Effects of air humidity and air movement on growth, visual quality and post-production stress tolerance of pot Rose ‘Toril’Publication . Carvalho, D. R. A.; Torre, S.; Vasconcelos, Marta; Almeida, Domingos P. F.; Heuvelink, E.; Carvalho, S. M. P.This work aimed at assessing whether a high level of air movement would improve stomatal closure, counteracting the negative effect of high relative air humidity (RH > 85%) on plant growth, visual quality and postharvest stress tolerance to dark and drought (simulating shipping and/or retailing). Pot rose ‘Toril’ was grown at moderate (60%) and high (90%) RH, combined with no additional air movement or with a continuous additional air flow of 0.92 ± 0.03 m s-1 (MOV). At flowering stage, plants were transferred to continuous darkness and without irrigation. Total dry weight and time to flowering were not significantly affected by RH or MOV. MOV did not affect plant height nor flower dry weight, but it significantly increased peduncle diameter by 6%. Plants grown at elevated RH showed a six-fold higher initial transpiration rate at the start of the postharvest period and a reduced longevity (71%) as compared to moderate RH-grown plants. MOV decreased the initial transpiration rate in high RH-grown plants by 23%. In conclusion, high RH had a minimal effect on plant growth and visual quality parameters but it drastically reduced postharvest storability. MOV during growth slightly improved post-production storability in high RH-grown plants, having a minor effect on visual quality.
- 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.Breeding for better keeping quality: validation of the selection method of promising genotypes. Water stress is one of the most important postharvest quality problems, resulting in shorter vase life and reduced consumer‟s satisfaction. This problem is enhanced in plants grown at high RH (RH > 85%) due to stomatal malfunctioning leading to shorter postharvest longevity. Previously, a subset of a segregating tetraploid population (60 genotypes) cultivated in a greenhouse under noncontroled RH was characterized for stomatal responsiveness to water stress (i.e. desiccation). The population screening revealed extreme differences of relative water content (RWC) after 4 h leaf desiccation. This study aims at the validation of a selection method for promising genotypes with good stomatal responsiveness to desiccation (i.e. high RWC after 4 h desiccation) when grown under contrasting HR conditions. Therefore, five genotypes with expected good stomatal response to desiccation were selected for this study. These genotypes were grown under moderate RH (60%) and high RH (90%). The RWC was significantly different within the five studied genotypes. K099 was the most tolerant genotype to desiccation, with a RWC after 4 h desiccation 19% higher than the least tolerant genotype. Genotypes cultivated at high RH had on average only 10% lower RWC, as compared to genotypes grown at moderate RH, confirming a good stomatal response. The postharvest longevity varied between 12 (K119) and 25 (K099) days and it was not significantly affected by the two different RH during growth. It is concluded that the analysis of the stomatal responsiveness in leaves of cut roses is an efficient method that allows, in the early stages of the selection process, to identify tolerant genotypes to high RH.