Effects of G a3 dosis associated with organosilicone on sweet oranges in Brazil

GA3 was tested in sweet oranges 'Pera' and 'Hamlin' for delay the picking time without loosening of fruit quality for processing. Hamlin is the firths cv processed in Brazil and Pera is a mid season cv and extending their period of processing is important. Two experiments were made at the Citrus Experimental Station during 1996 season. The treatments are 5 ppm of GA 3 + 0,05% Silwett L-77® (organosilicone), 10 ppm of GA 3 + 0,05% of Silwet L-77®, 20 ppm of GA3 + 0,1% Herbitensil® (Noniphenoloxietilate 40%m/v + isopropilic alcohol 15% m/v) and control, repeated 7 times for Hamlin and 8 times for Pera, with one tree each parcel. The treatments were applied in May 1996, at the stage of greenish yellow colour of the fruits. Evaluations were made each 20 days interval till the final picking, It was analysed fruit quality and retention force for picking and puncture resistance. The results showed no differences for fruit quality of Hamlin from July to mid September and for Pera till September. After some differences occurred. The GA3 treatments were effectives in maintain the fruit retention force for both cvs for 120 days after application. In relation to fruit puncture resistance the treatments with GA3 differed of the control for both cvs, accordingly with the doses and mixtures. The colour index was better maintained with 5ppm of GA3 plus 0,05% of Silwet L-77®. The total fruit production did not differ for both cultivars.

Distribution of Xylella fastidiosa in citrus rootstocks and transmission of citrus variegated chlorosis between sweet orange plants through natural root grafts

To study translocation of Xylella fastidiosa to citrus rootstocks, budsticks from citrus variegated chlorosis (CVC)-affected cv. Pera sweet orange (Citrus sinenesis (L.) Osb.) were top grafted on 15 citrus rootstocks. Disease symptoms were conspicuous 3 months later on all 15 rootstocks tested. The presence of X. fastidiosa was confirmed by light microscopy, double-antibody sandwich enzyme-linked immunosorbent assays, and polymerase chain reaction in rootlets and main roots of CVC-symptomatic Pera sweet orange in 11 of the 15 rootstocks tested. These results suggest that bacterial translocation from the aerial plant parts to the root system occurs but is not essential for X. fastidiosa to induce symptoms in the aerial parts. Bacterial translocation to the roots was not correlated with CVC leaf-symptom severity in the Pera scion. To determine if CVC disease could be transmitted by natural root grafts, two matched seedlings of each of four sweet orange cultivars (Pera, Natal, Valencia, and Caipira) were transplanted into single pots. One seedling rootstock of each pair was inoculated by top grafting with a CVC-contaminated budstick while the other seedling rootstock was cut but not graft inoculated. Transmission of X. fastidiosa from an inoculated plant to a noninoculated plant sharing the same pot was observed in all four sweet orange cultivars tested. Transmission was confirmed by observation of natural roots grafts between the two plants, presence of X. fastidiosa in the root grafts, and disease development in the uninoculated plants. This is the first report of transmission of CVC disease through natural root grafts.

Evaluation of microsatellite markers in cultivars of sweet orange (Citrus sinensis [L.] Osbeck)

Sweet orange is considered a very important species in the citrus world market and presents wide morphological variability. However, its characterization at the molecular level by random amplified polymorphic DNA (RAPD) and isozyme markers is not appropriate. Microsatellite or simple sequence repeats (SSRs) have been suggested as ideal for studies in cultures of vegetative propagation and as value markers for mapping in several species. However, information on microsatellite polymorphism in citrus species is scarce. In this work, microsatellite markers (AG-repeats) were developed from an enrichment library of genomic DNA of sweet orange cv. Pera (Citrus sinensis [L.] Osbeck), and 31 cultivars of sweet orange were evaluated. Evaluation of 18 microsatellite primers did not permit differentiation of the varieties studied. New microsatellite primers are being evaluated with the aim of detecting polymorphisms among the cultivars and closely related species to be used in genetic mapping programs.

Presence of Xylella fastidiosa in sweet orange fruit and seeds and its transmission to seedlings

Xylella fastidiosa, a xylem-limited bacterium, causes several economically important diseases in North, Central, and South America. These diseases are transmitted by sharpshooter insects, contaminated budwood, and natural root-grafts. X. fastidiosa extensively colonizes the xylem vessels of susceptible plants. Citrus fruit have a well-developed vascular system, which is continuous with the vascular system of the plant. Citrus seeds develop very prominent vascular bundles, which are attached through ovular and seed bundles to the xylem system of the fruit. Sweet orange (Citrus sinensis) fruit of cvs. Pera, Natal, and Valencia with characteristic symptoms of citrus variegated chlorosis disease were collected for analysis. X. fastidiosa was detected by polymerase chain reaction (PCR) in all main fruit vascular bundles, as well as in the seed and in dissected seed parts. No visual abnormalities were observed in seeds infected with the bacterium. However, the embryos of the infected seeds weighed 25% less than those of healthy seeds, and their germination rate was lower than uninfected seeds. There were about 2,500 cells of X. fastidiosa per infected seed of sweet orange, as quantified using real-time PCR techniques. The identification of X. fastidiosa in the infected seeds was confirmed by cloning and sequencing the specific amplification product, obtained by standard PCR with specific primers. X. fastidiosa was also detected in and recovered from seedlings by isolation in vitro. Our results show that X. fastidiosa can infect and colonize fruit tissues including the seed. We also have shown that X. fastidiosa can be transmitted from seeds to seedlings of sweet orange. To our knowledge, this is the first report of the presence of X. fastidiosa in seeds and its transmission to seedlings.

Peroxidase enzyme (EC.1.11.1.7) activity as an indicator of water stress in sweet pepper plants

The present work was carried out at the Faculdade de Ciências Agronômicas - UNESP, Botucatu, SP. The purpose of the study was to evaluate the physiological and biochemical behavior of sweet pepper (Capsicum annuum L.) plants under different soil water availability conditions and the efficiency of the peroxidase (EC. 1.11.1.7) activity as an indicator of water stress in plants. Sweet pepper plants were grown for 230 days after transplanting of seedlings. The experiment was arranged in a completely randomized experimental design with 4 treatments, two irrigation managements (50 and 1500 kPa) and two soil surface managements (presence or absence of black polyethylene covering), and six replications. Physiological activities, such as stomatal transpiration and resistance to water vapor diffusion, were evaluated, as well as biochemical activities, such as peroxidase activity and total soluble protein in foliar tissues. It was observed that soil water availability may lead to physiological and biochemical alterations in plants. Successive water stress cycles may promote the development of characteristics responsible for improving the plant tolerance to periods of low water availability. The peroxidase enzyme activity showed to be an efficient indicator of water stress in sweet pepper plants.

Peroxidase activity as an indicator of water stress in sweet pepper plants

The purpose of the study was to evaluate the physiological and biochemical behavior of sweet pepper (Capsicum annuum L.) plants under different soil water availability conditions and the efficiency of the peroxidase (EC. 1.11. 1.7) activity as an indicator of water stress in plants. The experiment was carried out at the Faculdade de Ciências Agronômicas UNESP, Botucatu, SP. Sweet pepper plants were grown for 230 days after transplanting of seedlings and arranged in a completely randomized experimental design with 4 treatments, two irrigation managements (50 and 1500 kPa) and two soil surface managements (presence or absence of black polyethylene covering), and six replications. Physiological activities, such as stomatal transpiration and resistance to water vapor diffusion, were evaluated as well as biochemical activities, such as peroxidase activity and total soluble protein in foliar tissues. It was observed that soil water availability may lead to physiological and biochemical alterations in plants. Successive water stress cycles may promote the development of characteristics responsible for improving plant tolerance to periods of low water availability. The peroxidase enzyme activity showed to be an efficient indicator of water stress in sweet pepper plants.

Beta-carotene stability during drying and storage of cassava and sweet potato

The effect of blanching on the β-carotene stability during drying and storage of cassava and sweet potato was evaluated. The orange-fleshed sweet potato showed good retention of β-carotene during the blanching and drying (100% and 96%, respectively), but lower retention (84% and 91%) was observed in cassava. Cassava also showed lower β-carotene stability than sweet potato during the storage of unblanched dried samples. β-Carotene content of dried cassava was reduced from 8.6 μg/g to traces in 20 days of storage while the initial amount of dried sweet potato (463 μg/g) was reduced by about 45% (210 μg/g). Blanching did not affect the β-carotene retention during the drying, but enhanced the stability of this carotenoid during the storage of dried samples at room temperature, especially in cassava. The initial levels of blanched-dried cassava and sweet potato (7.8 and 513 μg/g, respectively) took 70 days to fall by around 50%.

The use of the carbon-13 in the partitioning of photosynthate in vegetative and reproductive twigs of 'Sweet' passion fruit

This study's objective is to evaluate the photosynthates partitioning and source-sink relationships, in vegetative and reproductive twigs of sweet passion fruit, using the carbon-13, stable isotope of carbon. The leaves of vegetative and reproductive twigs were placed in a sealed chamber and 13CO 2 were injected for 30 minutes. After six hours, the different organs of the twig were collected and immersed in liquid nitrogen (-196°C). All plant samples were oven-dried, powdered and combusted in an elemental analyzer. The results showed that the methodology was efficient to evaluate the partitioning of photosynthates. In the vegetative twigs, the new open leaves, the closed leaves and growth meristem were the principal sink for the source leaves enriched with 13CO 2. In the reproductive twigs with only flowers buds, the source-sink relationship was changed and the flowers buds turn to be the principal sink and the growing leaves were secondary sinks. The presence of young fruits changed again the source-sink relationship of the twig, and they were the principal sinks. The apical leaves, with 60% of final leaf area were also a sink for photosynthates.

Optimization of the immobilization of sweet potato amylase using glutaraldehyde-agarose support. Characterization of the immobilized enzyme

A simplified procedure for the preparation of immobilized beta-amylase using non-purified extract from fresh sweet potato tubers is established in this paper, using differently activated agarose supports. Beta-amylase glutaraldehyde derivative was the preparation with best features, presenting improved temperature and pH stability and activity. The possibility of reusing the amylase was also shown, when this immobilized enzyme was fully active for five cycles of use. However, immobilization decreased enzyme activity to around 15%. This seems to be mainly due to diffusion limitations of the starch inside the pores of the biocatalyst particles. A fifteen-fold increase in the Km was noticed, while the decrease of Vmax was only 30% (10.1 U mg-1 protein and 7.03 U mg-1 protein for free and immobilized preparations, respectively). © 2013 Elsevier Ltd.

Relação da higiene bucal com a sensibilidade gustativa e nutrição em idosos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Produtividade e qualidade da cebola em função de doses de enxofre

Pós-graduação em Agronomia (Ciência do Solo) - FCAV

Processamento mínimo de melão tipo Orange Flesh e de melancia 'Crimson Sweet'

Pós-graduação em Agronomia (Produção Vegetal) - FCAV

Compostos bioativos em frutas cítricas: quantificação, avaliação da atividade antioxidante, parâmetros de cor e efeito da pasteurização

Pós-graduação em Alimentos e Nutrição - FCFAR

Efeitos de abelhas na frutificação e qualidade de melancia (cv. Crimson Sweet) na região Central do estado do Piauí

Pós-graduação em Agronomia (Produção Vegetal) - FCAV