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Problem statement: Dragon fruit or pitahaya (Hylocereus undatus), is believed to be a healthy source of vitamins, fiber and antioxidants, especially the red-fleshed varieties which contain lycopene. Approach:Compared to green kiwi fruit (Actinidia deliciosa), which already known contain high antioxidant activity. Results:The antioxidant capacity of Hylocereus undatus (H. undatus) and Actinidia deliciosa (A. deliciosa) in three different solvent extraction; ethanol, methanol and aqueous, was estimated by DPPH free radical scavenging assay. The inhibition of free radical by A. deliciosa is almost 90% compared with H. undatus which only 60-10% in different solvents. Additionally, their total phenolic contents were analyzed by folin-ciocalteau method. The result showed that A. deliciosa (533.70 mg L-1 in ethanol, 460.87 mg L-1 in methanol and 420.652 mg L-1 in distilled water) seemed to be better sources of antioxidant compounds then H. undatus (179.35 mg L-1 in ethanol, 160.87 mg L-1 in methanol and 157.61 in distilled water). Conclusion: When compared between the three different solvent, extract in ethanol shown the most highly antioxidant content followed by methanol and water. The experiment showed the potential of dragon fruit and kiwi extracts high rich in antioxidant which can scavenge free radical in human body. Further study on isolation of individual antioxidant in both extracts can be providing for commercialize the extracts in jus form.

A research on in vitro inhibition of fungal antagonists, isolated from dragon fruit plantation in Sembung village, Bali, on Fusarium sp. (the disease causative agent of dragon fruit plant) was conducted with the main objective to investigate the effectiveness of these fungal antagonists to inhibit the in vitro growth of the pathogen. Dual assay method was applied in this experiment. The results showed that three potential fungal antagonists were successfully isolated in this research and they were identified as Trichoderma harzianum, Aspergillus niger, dan Paecilomyces lilacinus. All these fungal antagonists showed antagonistic activity against Fusarium sp. which was statistically significant (p

Red and white dragon fruit (Hylocereus polyrhizus, Hylocereus undatus) are types of climbing cacti that has been developed as exotic fruit crop due to its highly nutritional value. This fruit which is also known as red or white pitaya is enclosed by red peel while the pulp is embedded with small black seeds. However the fruit has limited shelf life in the presence of normal air by two means; the physicochemical effect of atmospheric oxygen and the aerobic microbial growth. These factors either solely or in association with one another cause changes in colour, texture, flavour that eventually lead to postharvest deterioration. Nevertheless, extending the shelf life of many fresh fruit has been made possible by the usage of modified atmosphere packaging. This is because packaging can affect atmospheric conditions within a fresh fruit so as to extend the shelf life by slowing down the respiration rate that influences the physiological and biochemical properties. Generally, modified atmosphere packaging utilizes polymeric films with different permeabilities for O 2 , CO 2 , other gases, and H 2 O to create a modified atmosphere around the packaged fruit. Benefits of film packaging include maintenance of high relative humidity, reduction of water loss, reducing contamination during handling and thus maintaining the postharvest fruit quality. Furthermore, interest has been shown in the use of plastic films mainly polyethylene with various thickness for modified atmosphere packaging. In this study, plastic film were used to investigate the effects on shelf life and fruit quality attributes of dragon fruit.

A espécie de pitaya mais cultivada atualmente é Hylocereus undatus, a pitaya-vermelha-de-polpa-branca. Colômbia e México são os principais produtores mundiais e, devido à sua rusticidade, a pitaya é considerada uma alternativa potencialmente viável também para o aproveitamento de solos pedregosos, arenosos e maciços rochosos. Apesar da crescente demanda, ainda não há uma cultivar lançada no mercado que atenda às necessidades climáticas de produção e às exigências do consumidor brasileiro. O presente trabalho é parte do programa de seleção e melhoramento da pitaya CPAC PY-01 da Embrapa Cerrados. Objetivou-se realizar o estudo da variabilidade genética de 16 acessos de pitayas mantidos na coleção de germoplasma da Embrapa Cerrados, apresentando diferentes características fenotípicas relacionadas especialmente à produção, por meio de marcadores moleculares RAPD (Random Amplified Polymorphic DNA). O DNA genômico de cada acesso foi extraído, e onze iniciadores decâmeros foram utilizados para a obtenção de marcadores moleculares RAPD, que foram convertidos em matriz de dados binários, a partir da qual foram estimadas as distâncias genéticas entre os acessos e realizadas análises de agrupamento e de dispersão gráfica. Foram obtidos 111 marcadores RAPD, perfazendo uma média de 10,1 marcadores por primer, dos quais 45 (40,54%) foram polimórficos. As distâncias genéticas entre os 16 acessos variaram entre 0,006 e 0,148. As maiores distâncias genéticas foram obtidas entre os acessos "52" e "61", sendo que, em 2007, o primeiro produziu mais de 25 frutos, e o segundo, nenhum. Assim, deduz-se que, nesse caso, a próvável causa da variação seja genotípica. As menores distâncias genéticas foram constatadas entre os acessos "63"e "55" e entre "19"e "59". Os dois grupos apresentaram valores de produção próximos. Os marcadores moleculares RAPD mostraram que, mesmo dentro da mesma espécie, há variabilidade genética entre plantas com produções diferentes, ressaltando a importância das técnicas moleculares para subsidiar e auxiliar nos trabalhos de seleção, em programas de melhoramento genético.The most cultivated pitaya species nowadays is Hylocereus undatus, red pitaya with white pulp. Colombia and Mexico are the major world producers and, due to its rusticity, pitaya is considered a potentially viable alternative to make good use of gravel, sandy and compact rocky soils. Although the great demand, there is not yet a variety released on the market that attends production climatic needs and brazilian consumer exigencies. The present work is a part of Embrapa Cerrados pitaya CPAC PY-01 selection and improvement program. We have had the objective to realize genetic variability study of 16 pitaya accesses maintained at Embrapa Cerrados germoplasm collection, showing different phenotypic characteristics with special relation to production, through molecular markers RAPD (Random Amplified Polymorphic DNA). Each access genomic DNA was extracted and eleven decamer primers indicators were used to obtain molecular markers RAPD, that were converted in a binarium data matrix, from where it was estimated genetic distances between accesses and realized grouping analysis and graphic dispersion. One hundred and eleven RAPD markers were obtained, making a 10,1 markers medium per primer, in witch 45 (40,54%) were polymorphic. Genetic distances between 16 accesses varied within 0,006 and 0,148. The biggest genetic distances were obtained between accesses "52" and "61"; in 2007, the first one produced more than 25 fruits and the second one, none. The smallest genetic distances were verified between accesses "63" and "55" and between 19" and "59". Both groups showed close production values. RAPD molecular markers showed that, even inside the same species, there is genetic variability between plants with different productions, standing out molecular techniques importance as auxiliary instruments selection breeding programs.

The tropical Americas produce a wide variety of fruits, many with very good quality characteristics. Most are consumed in the region where they are produced, and many are not well known in the markets of developing countries. In recent years consumers in developed countries have become increasingly interested in trying new and different fruits. This study presents five tropical fruit produced on the Yucatan Peninsula, Mexico, that are not well known in international markets and presents the feasibility of their introduction into and marketing in Europe. Descriptions are given of five fruits: mamey sapote (Calocarpum mammosum), sapota (Achra sapota), custard apple (Annona squamosa), dragon fruit (Hylocereus undatus) and star apple (Chrysophyllum cainito). Their principal uses are listed and important characteristics for their marketing are noted. They are harvested in different seasons, ranging from winter to spring and summer and some are known to Europeans who have traveled to tropical countries. Given their quality characteristics and good acceptance, they are considered as potentially promising for successful introduction into the European tropical fruit market.

Two types of pitaya (Hylocereus cacti) seeds (Hylocereus undatus and Hylocereus polyrhizus) were investigated in this study. The fatty acid, phenolic, tocopherol, and sterol contents of the extracted seed oil were analysed. The results showed that the pitaya seeds contained a high amount of oil (18.33–28.37%). The three major fatty acids in the H. undatus seed oil (WFSO) and H. polyrhizus seed oil (RFSO) were linoleic, oleic, and palmitic acids. The total tocopherol contents in the WFSO and RFSO were 36.70 and 43.50 mg/100 g, respectively. The phytosterol compounds identified in the WFSO and RFSO were cholesterol, campesterol, stigmasterol, and β-sitosterol. Seven phenolic acid compounds were identified in the WFSO and RFSO, namely, gallic, vanillic, syringic, protocatechuic, p-hydroxybenzoic, p-coumaric, and caffeic acids. WFSO and RFSO can be differentiated by their Toff and Ton values in the DSC thermal curves. This study reveals that pitaya seed oil has a high level of functional lipids and can be used as a new source of essential oil.

Raw white pitaya (Hylocereus undatus) juice is very cloudy and viscous. These physical properties lead to the use of enzymatic treatment to clarify the juice. The aim of this study was to obtain the optimum process conditions for enzymatic clarification using response surface methodology (RSM). White pitaya juice was treated with pectinase enzyme (Pectinex Ultra SP-L) at different maceration times (20–100 min), reaction temperatures (30–50C) and enzyme concentrations (0.01–0.1%). These three variables were used as independent variables whose effects on yield, viscosity, clarity and color were evaluated. From the RSM analysis, the recommended enzymatic treatment condition from the study was found at 0.06% enzyme concentration at 49C for 40 min. PRACTICAL APPLICATIONS This paper describes an optimization study on enzymatic clarification of white pitaya juice. The aim was to reduce juice viscosity and to increase juice yield, clarity and color via enzymatic degradation of polysaccharides in the white pitaya. This work recommended an optimal enzymatic treatment for clarification of white pitaya juice using Pentinex Ultra SP-L for commercialization.

Pitaya (Hylocereus undatus) is a tropical and subtropical fruit of the family Cactaceae. The enormous economic potential of this fruit has encouraged its cultivation in Hainan Province of China. In June 2016, a stem blight disease was observed affecting over 15% of the plant in the fruit nursery of Lingao (Hainan Province). Symptomatic plants initially had hygrophanous, dark brown to brown spots, developing into sunken lesions on the lower stem near the ground. White, silky mycelium developed on the stem lesions. Later, white, spherical, shiny and smooth sclerotia (1.0 to 1.5 mm in diameter) were observed, which gradually turned tan to dark brown. Finally only the middle of the pith was left in the stem lesions. Sclerotia were aseptically transferred to potato dextrose agar (PDA) and incubated at 28°C. Two days after incubation, fast-growing fungal colonies (70 to 75 mm in diameter) were observed. Subsequently, small round sclerotia developed in the culture. Abundant milky globoid sclerotia were observed ...

This study examined the vegetative and reproductive growth responses of the crassulacean acid metabolism (CAM) vine-cactus fruit crop species Hylocereus undatus and Selenicereus megalanthus to CO 2 enrichment (1000 μmol mol −1 vs. control of 380 μmol mol −1 ). H. undatus plants enriched with CO 2 demonstrated 52%, 22%, 18%, and 175% increases, relative to plants measured in ambient CO 2 , in total daily net CO 2 uptake, shoot elongation, shoot dry mass, and number of reproductive buds, respectively. The responses of S. megalanthus plants exposed to elevated CO 2 were greater than those of H. undatus under the same conditions. Compared to plant responses in ambient CO 2 , under conditions of CO 2 enrichment, S. megalanthus showed 129%, 73%, 68%, and 233% increases in total daily net CO 2 uptake, shoot elongation, shoot dry mass, and number of reproductive buds, respectively. Moreover, for H. undatus , there was no significant change in fruit fresh mass although it showed a slight (7%) upward trend. On the other hand, fruit fresh mass of S. megalanthus significantly increased by 63% in response to elevated CO 2 . These results indicate the high potential of CAM plants to respond to CO 2 enrichment. It is thus apparent that S. megalanthus grown under CO 2 enrichment may benefit from elevated CO 2 to a greater extent than H. undatus grown under sub-optimal growth conditions.

Hylocereus undatus and Hylocereus polyrhizus are two varieties of the commonly called pitaya fruits. The seeds were separated and the oil was extracted and analysed. Essential fatty acids, namely, linoleic acid and linolenic acid form a significant percentage of the unsaturated fatty acids of the seed oil extract. Both pitaya varieties exhibit two oleic acid isomers. Essential fatty acids are important acids that are necessary substrates in animal metabolism and cannot be synthesised in vivo. Both pitaya varieties contain about 50% essential fatty acids (C18:2 (48%) and C18:3 (1.5%)). This paper details the process of recovering the pitaya seeds and determining the composition of the oil extracted from the seeds.

This study examined the response of the crassulacean acid metabolism (CAM) vine-cactus fruit crop species Hylocereus undatus to two CO2 regimes [enrichment (1000 μmol·mol−1) vs. ambient control (380 μmol·mol−1)] and to two fertilization regimes [0.5- vs. 0.1-strength Hoagland's solution (designated high and low, respectively)]. CO2 enrichment increased total daily net CO2 uptake, nocturnal acid accumulation, shoot elongation, and total dry mass by 39%, 24%, 14%, and 6% (averaging the two fertilization regimes) versus ambient CO2 treatment, respectively. Plants exposed to high fertilization demonstrated 36%, 21%, 198%, and 79% (averaging the two CO2 regimes) increases versus those receiving the low fertilization regime in total daily net CO2 uptake, nocturnal acid accumulation, stem elongation, and total dry mass, respectively. Plants exposed to high fertilization and elevated CO2 demonstrated 108%, 77%, 264%, and 111% increases versus those receiving the low fertilization regime at the ambient CO2 concentration in total daily net CO2 uptake, nocturnal acid accumulation, stem elongation, and total dry mass, respectively. This response was 25% to 71% higher than the summed effects of the separate responses to each factor, indicating a synergistic effect of elevated CO2 and high fertilization. Thus, it is apparent that H. undatus crops grown under a high-fertilization agromanagement regime may benefit from elevated CO2 to a greater extent than those grown with low fertilization.

The quality of three dragon fruit clones (Hylocereus spp.) was determined after x-ray irradiation for disinfestation of quarantine pests. Fruit were treated with irradiation doses of 0, 200, 400, 600, or 800 Gy and stored for 12 days at 10 °C. Irradiation did not affect soluble solids content, titratable acidity, or fructose concentrations. Glucose, sucrose, and total sugar concentrations decreased linearly as dose increased. Minimal softening occurred in the outer flesh layers for fruit treated with 400 or 600 Gy irradiation. Surface color, peel injury, and bract appearance differed among the three clones with irradiation stress, but in all cases, visible changes were minor. Fruit decay was absent or minimal, and disease ratings were not affected by irradiation. Irradiation treatment of dragon fruit at doses 800 Gy or less would ensure visual and compositional quality while providing quarantine security.

Effect of juvenility on cutting propagation of red pitaya. Abstract -- Introduction. Pitaya (Hylocereus undatus) is an exotic fruit species little known in Brazil and which needs basic studies about plant nutrition, propagation and physiology. Emphasizing the co-existence of juvenile and adult stages in the pitaya canopy, the plant is gene- rally propagated by cuttings. Materials and methods. A completely randomized design with four treatments and five replications was adopted. Each treatment was represented by the part of the canopy from which the cutting was taken (upper, middle and lower cutting and cuttings from young plants). The following variables were registered: % cuttings with roots, % of live cuttings, root density, root diameter, root area, root length and root dry mass. Results were sub- mitted to variance analyses, Tukey's test at 0.01 probability error and simple correlation analysis. Results and discussion. The results indicated that the position from which the cutting is taken had a quantitative effect on rooting formation of pitaya cuttings. Juvenile cuttings presented 35% more cuttings with roots than adult cuttings. Root density, root area, root length and root dry mass depended on juvenility, the highest results being registered for juvenile cuttings, inde- pendently of the variable. Conclusion. Juvenile and adult stages co-exist in the pitaya canopy. Juvenility is an important rooting factor for red pitaya cuttings. Brazil / Hylocereus undatus / vegetative propagation / propagation by cuttings / plant developmental stages / juvenility of plants / rooting

Two new pentacyclic triterpene taraxast-20-ene-3α-ol (1) and taraxast-12,20(30)-dien-3α-ol (2) were isolated from chloroform extract of leaves of Hylocereus undatus. These triterpenes showed protective activity against the increase of skin vascular permeability in rabbits. The protective effect, measured as the reduction in leakage of Evans blue, was of 53.5% and 70.1% for 1 and 2, respectively, after peritoneal treatment at a dose of 50 mg/kg. Comparison was made between the action of the compounds and a protective microvascular drug known as troxerutin (64.5%) at the same doses.

Nearly 118 cacti species have been used by Mesoamerican people since pre-Columbian times, and about 40 of those species show signs of domestication. Among used and domesticated species, the hemiepiphytic cactus Hylocereus undatus is one of the most appreciated in Mexico because of its ornamental value and its edible fruits which are consumed at both regional and national scales. This study analysed the pollination biology of cultivated plants of H. undatus to determine the role of selfing in fruit production and the relative importance of nocturnal and diurnal flower visitors in cross-pollination. Flowers were open nearly 17 h. Nocturnal visitors produced significantly higher fruit production (76.9%) than diurnal visitors (46.1%). During the night, nectar-feeding bats Leptonycteris curasoae and Choeronycteris mexicana pollinate flowers, whereas during the day the bee, Apis melifera pollinates flowers. Both self-pollination (100% in unmanipulated treatments and 53.8% in hand self-pollination treatments) and hand cross-pollination treatments (40%) set fruit. The capability of selfing in this cultivated plant has not been reported elsewhere and may be a result of intense local cultivation of this plant in Mexico. This self-pollination capability may significantly reduce labor costs associated with cultivation and allow fruit production to become a viable economic option for local people.

Dragon fruit is a tropical fruit with good taste. It can bring health benefits to human body. As one of the major bioactive components in this fruit, the polysaccharides might contribute to the health benefits. However, the precise structure information remains unknown. A leading polysaccharide of dragon fruit pulp, DFPP, was purified and identified by NMR and GC-MS. →4-β-d-GlcpA-1→, →6-β-d-Galp-1→ and →4-α-l-Rhap-1→ constituted the backbone and α-l-Araf-1→5-α-l-Araf-1→ formed the branch chain. The precise structure was putatively identified as below. The molecular weight was 2.2×10(3)kDa. The structure information of polysaccharides will be helpful to understand this fruit.

Knowledge of appropriate conditions of water and temperature is very important for the metabolic activities involved in the germination process. However, the Rules for Testing Seeds do not indicate the volume of water and the ideal temperature for pitaya germination. The study was carried out to evaluate different water volumes in the substrate and temperatures on seeds germination and vigor of pitaya. The experimental design was completely randomized in a factorial 5 x 3, with treatments consisted of five water volumes in the substrate and three temperatures. The used water volumes was equivalent to 1.5; 2.0; 2.5; 3.0 and 3.5 times the dry weight of the substrate. Were tested at constant temperatures of 20, 25 and 30 °C. The parameters evaluated were: germination, first count of germination, emergence speed index, length and dry mass of plantlets. The temperature of 25 °C and a water volume in the range of 2.5 to 3.5 times the weight of substrate is the most suitable combination for doing germination tests and evaluating the vigor of pitaya seeds. The temperature of 20 °C and the volume of water 1.5 times the weight of the substrate inhibited germination of seeds, O conhecimento das condições adequadas de água e temperatura é de fundamental importância, para as atividades metabólicas envolvidas no processo germinativo. Entretanto, as Regras para Análise de Sementes não indicam o volume de água e a temperatura ideais para a germinação de sementes de pitaya. O trabalho foi conduzido com o objetivo de avaliar diferentes volumes de água no substrato e temperaturas na germinação e no vigor de sementes de pitaya. O delineamento experimental utilizado foi inteiramente casualizado em esquema fatorial 5 x 3, com os tratamentos constituídos pela combinação de cinco volumes de água no substrato e três temperaturas. Os volumes de água utilizados foram equivalentes a 1,5; 2,0; 2,5; 3,0 e 3,5 vezes o peso do substrato seco. Foram testadas as temperaturas constantes de 20; 25 e 30 °C. Avaliou-se a germinação, primeira contagem, índice de velocidade de germinação, comprimento e massa seca de plântulas. A temperatura de 25 °C e o volume de água na faixa de 2,5 e 3,5 vezes o peso do substrato é a combinação mais adequada para a condução dos testes de germinação e vigor das sementes de pitaya. A temperatura de 20 °C e o volume de água de 1,5 vezes o peso do substrato inibiu a germinação das sementes.

The aim of this study was to analyze the physical and chemical characteristics of the maturation process of pitaya fruit (Hylocereus undatus) to identify indicators that can be used to determine the point of physiological maturity and establish the optimal timing of physiological maturity for harvesting the fruit. A completely randomized experimental design was employed and four biological repeats were performed. Physiological maturity was assessed using various physical characteristics: longitudinal length (LL), equatorial diameter (ED), pericarp thickness (PeT), pulp thickness (PuT), fruit mass (FM), pulp mass (PuM), pericarp mass (PeM), pericarp percentage (%Pe), pulp percentage (%Pu), pulp/pericarp ratio (Pu/Pe), pericarp color index (CI), hue color angle (h°), lightness index (L*), chroma (C*), blue-yellow variation (b*), and green-red variation (a*). Additionally, chemical characteristics such as soluble solid content (SS), titratable acidity (TA), SS/TA ratio, and pH were screened. The data were statistically analyzed by fitting regression models and computing Pearson's correlation coefficients (P < 0.05). Physiological maturity in pitaya fruits occurred between the 30th and 32nd days after anthesis, and this proved to be the optimal period for harvest. At this time, the fruit was completely red with high SS, and had the recommended values of TA, pH, and SS/TA ratio. During this period, ED, PuT, FM, PuM, %Pu, and Pu/Pe increased while PeT, PeM, and %Pe fell; these changes are considered desirable by producers and/or consumers. PuM was the variable that displayed more strong's association with other variables in the analysis.

In July 2013, an unknown fruit internal brown rot disease was observed on white-fleshed pitahaya (Hylocereus undatus) in Zhanjiang, Guangdong province, China. Based on morphological characteristics and phylogenetic analysis of ITS sequences, the pathogen was determined as Neoscytalidium dimidiatum.

Made available in DSpace on 2015-10-21T20:27:54Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-04-01. Added 1 bitstream(s) on 2015-10-22T09:48:09Z : No. of bitstreams: 1 S0103-84782015000400585.pdf: 528001 bytes, checksum: 2c545d2aa06612df5ddbd3d8006988c4 (MD5) Por ser uma cultura de cultivo recente no país, a pitaya (Hylocereus undatus) ainda carece de estudos, de forma a dar suporte aos produtores. Nesse sentido, o trabalho foi desenvolvido visando a caracterizar a fenologia reprodutiva da cultura na região de Jaboticabal - SP. Avaliou-se clone de pitaya conduzido sob duas colorações de tela plástica, branca e preta, ambas com 50% de sombreamento, durante março de 2009 a dezembro de 2010. Observou-se que a emissão de gemas florais tem início no mês de novembro, com emissão constante até o mês de março, enquanto que o florescimento ocorre até meados de abril, sendo que as altas temperaturas associadas ao início da estação chuvosa são fatores fundamentais para a emissão das gemas reprodutivas. A coloração da tela plástica influenciou no total de flores. O tempo compreendido desde a emissão das gemas até a antese é de 18 a 23 dias, enquanto, da antese à colheita é de 34 a 43 dias. O tempo total entre o aparecimento do botão floral até a colheita pode levar de 52 a 66 dias The dragon fruit (Hylocereus undatus) is recent crop cultivation in Brazil and there is still lack of studies to support the farmers. So, this research aimed to characterize the reproductive phenology of the crop in the region of Jaboticabal, Sao Paulo State, Brazil. It was evaluated red dragon fruit clones over two environmental conditions - under plastic screen black and white, with 50% of shady level, from March 2009 to December 2010. It was observed that the issuance of floral buds and the flowering on dragon fruit culture occurs with a combination of high temperatures and rainfall, with constant emission of floral buds from November to March while the flowering on dragon fruit culture occurs until mid-April. The color of plastic screen had influenced on amount of flowers. The time elapsed since the issuance of flower buds to anthesis is from 18 to 23 days, while the harvest occurs from 34 to 43 days after flower opening. At Jaboticabal, the time of appearance of flower bud to fruit harvest is from 52 to 66 days. Agencia Desenvolvimento Agr &Extensao Rural AGRA, BR-79114005 Campo Grande, MS, Brazil Inst Ensino Super Ariquemes, Ariquemes, RO, Brazil Univ Estadual Paulista Julio Mesquita Filho UNESP, Fac Ciencias Agr &Vet Jaboticabal, Dept Prod Vegetal, Jaboticabal, SP, Brazil Universidade Estadual Paulista Julio Mesquita Filho UNESP, Fac Ciencias Agr &Vet Jaboticabal, Departamento Produção Vegetal, Jaboticabal, SP, Brazil

Native of the Americas, pitaya is currently a fruit bearing plant in expansion in the domestic and international market and is an alternative source of revenue for small and large farmers. As some studies show the lack of efficiency of natural pollinators in fructification in pitaya, the purpose of this study was to evaluate the efficiency of manual self-pollination and of manual cross pollination in Hylocereus undatus in two periods of pollination. The experiment was carried out in the orchard of the Universidade Federal de Lavras (Federal University of Lavras) in a completely randomized design with a 2 x 2 factorial arrangement (two types of pollination and two flowering periods) with 15 replications, with one flower per replication. The flowers were bagged, emasculated and pollinated manually. The percentage of fruit set , longitudinal and transversal diameter of the fruit, mass of the fruit, pulp and peel, thickness of the peel, soluble solids contents, pH, titratable acidity, ratio (soluble solids:titratable acidity), number of seeds per fruit and seed germination were evaluated. It may be concluded that pollination in red pitaya with its own pollen allows fructification. Flowers pollinated in Apr. result in fruit with physical characteristics superior to the fruit generated by pollination in Jan.

Pitaya is a cactaceae originally from Tropical and Subtropical America which belongs to the exotic fruit group, little explored to date by the food and pharmaceutical industries. The objective of the present study was to evaluate the chemical and physical-chemical properties, antioxidant activity and the fatty acid profile of the red pitaya fruit (pulp and peel) [Hylocereus undatus (Haw.) Britton & Rose], grown in Brazil. These analyses have shown that pitaya pulp has high moisture content (86.03%) and low lipid (0.16%) and protein (2.27%) content, which ensures a low fruit calorie value (53.68%). Among the highlighted minerals are potassium (3.090 mg / 100 g), manganese (2.230 mg / 100 g), chromium (1.250 mg / 100 g), sodium (0.140 mg / 100 g), calcium (0.040 mg / 100 g) and, at lower concentrations, phosphorus (0.003 mg / 100 g). On the other hand, the antioxidant activity of pitaya pulp (1266.3 μg mL–1) was lower than in the pitaya peel (445.2 μg mL–1). In the fatty portion of the fruit, we verified that the predominant fatty acid is linoleic acid (50.869% of total fatty acids in the fruit), followed by oleic acid (21.551%) and palmitic acid (12.632%). The antioxidant potential and the chemical properties of pitaya fruit can contribute to maintaining a healthy diet.

Objetivou-se com este trabalho avaliar o efeito do tamanho da estaca e a aplicação de ácido indolbutírico (AIB) no enraizamento de Pitaya 'vermelha'. Estacas de Pitaya 'vermelha' foram coletadas de plantas matrizes e padronizadas com 15,0 e 25,0 cm de comprimento, sendo que metade da quantidade das estacas foi imersa em solução de 3000 mg L-1 de AIB por vinte segundos (imersão rápida) e a outra metade não. Posteriormente, as estacas foram colocadas em canteiro contendo mistura de terra + esterco de curral (3:1 v/v) como substrato. Após 60 dias, foram avaliados as porcentagens de estacas enraizadas e de estacas vivas, e o número de raízes emitidas por estaca. Como conclusão observou-se que o AIB aumentou a porcentagem de estacas enraizadas e promoveu a melhoria da qualidade do sistema radicular das estacas de pitaya vermelha. As estacas de 25,0 cm de comprimento foram mais promissoras para a produção de mudas.This work was carried with the objective to evaluate the cutting length and application of IBA in rooting of red pitaya cutting. The pitaya cutting were collected of stock plant and standardized with 15.0 and 25.0 cm of length and half of the amount of the cuttings received treatment with 3000 mg L-1 of IBA for twenty seconds. Later the cuttings were placed in stonemason containing a soil mixture + corral manure (3:1 v/v) as substrate. After 60 days, the rooting and survival percentage and number of roots emitted by cutting were evaluated. As conclusion, were observed that IBA increased the rooting percentage and promoted the improvement of the quality of roots of red pitaya cuttings.

Introduction . To facilitate establishment of pitaya (Hylocereus undatus ) cultivations in new areas, factors affecting its propagation by cuttings and seeds were studied. Materials and methods . Firstly, cuttings of (5, 15 and 25) cm length were tested in three substrates: peat moss (pm), peat moss and sand mix (1:1) (pm/sa) and sand (sa). Indole-3-butyric acid (IBA) solutions were prepared at [0, 5, 10 or 15] mM dissolved in 70% ethanol. After the basal cuttings were dipped for 10 s in these IBA solutions, cuttings were planted in (pm/sa). After (1, 2 or 3) weeks, the cutting rooting, number and length of the developed roots were measured. Moreover, germination was tested at four temperatures [(16, 20, 24 and 28) °C] by placing seeds on wetted filter papers in Petri dishes. Light effect was tested at four white light intensities of (0, 500, 1000 or 2000) lx. Seed viability was tested at 24 °C in darkness with 1000 seeds. The effect of (pm), (pm/sa) and (sa) was tested on germination and seedling growth. The percentage of germination, days to emergence and growth rate of seedlings were measured. Results and discussion . After two weeks, 25-cm pitaya cuttings rooted successfully in the three substrates, but the number and length of the developed roots were affected by the type of substrate. A significant effect of cutting size on root initiation, and number and length of the developed roots was found. IBA consistently improved rooting percentage and root number and length. Overall, 5-cm-long cuttings treated with IBA (10 mM) could be efficient at propagating pitaya. The seed viability was 83%. Germination, which varied between (71 and 83)% depending on the temperature, began after 6 days at (24 and 28) °C. Light intensity at (1000 or 2000) lx reduced seed germination. Potted seedlings grew successfully in the greenhouse.

Dragon fruit ( Hylocereus undatus ) are a host of fruit fly ( Bactrocera spp.), and thus export to many markets will require a disinfestation treatment. This work investigated the potential for disinfestation by heat treatment (HT) of cv. Binh Thuan in order to meet the biosecurity requirements of importing countries. Main-season fruit from Viet Nam were subjected to hot air treatments and stored for 2–4 weeks storage at 5 °C in sealed polypropylene bags, and fruit quality examined during subsequent shelf-life at 20 °C. HTs applied were fruit core temperatures (FCT) of 46.5 °C for durations of 20 and 40 min, and 48.5 °C for 50, 70 and 90 min. Assessments included turgor of the bracts and stem, the appearance of the body of the fruit and presence of rots, skin colour, flesh firmness, soluble solids concentration, fruit acidity, taste, and flesh translucence. ‘Binh Thuan’ Dragon fruit proved to be tolerant of hot air treatment and at the lower HT temperature (FCT 46.5 °C for 20 min) fruit quality was not significantly different from non-heated control fruit, either after treatment at harvest, or after storage for up to 4 weeks. However, metrics quantifying the appearance of both control- and HT-fruit generally deteriorated with storage time at 5 °C, although the internal appearance of the flesh, and taste, remained acceptable throughout. Shelf-life effects were restricted to comparison of the lower HT temperature (FCT 46.5 °C for 20 min) and non-heated control fruit. Shelf-life after any of the storage periods was terminated after only 4 d, as fruit available for study had not been sprayed with fungicides during the season, and developed anthracnose rots readily at 20 °C. No differences in shelf-life characteristics were established between HT fruit and control fruit. Our results provide strong evidence that ‘Binh Thuan’ Dragon fruit are a suitable candidate for fruit fly disinfestation by hot air HTs, and that fruit quality during or after storage does not suffer as a consequence.

Net CO2 uptake rates (PN) were measured for the vine cacti Hylocereus undatus and Selenicereus megalanthus under relatively extreme climatic conditions in Israel. Withholding water decreased rates and the daily amount of CO2 uptake by about 10 % per day. Compared with more moderate climates within environmental chambers, the higher temperatures and lower relative humidity in the field led to a more rapid response to drought. The upper envelopes of scatter diagrams for PN versus temperature for these Crassulacean acid metabolism species, which indicate the maximal rates at a particular temperature, were determined for both night time CO2 uptake in Phase I (mediated by phosphoenolpyruvate carboxylase, PEPC) and early morning uptake in Phase II (mediated by ribulose-1,5-bisphosphate carboxylase/ oxygenase, RuBPCO). As stem temperature increased above 13 °C, the maximal PN increased exponentially, reaching maxima near 27 °C of 12 and 8 μmol m –2 s –1 for Phases I and II, respectively, for H. undatus and 6 and 4 μmol m –2 s –1 , respectively, for S. megalanthus. Based on the Arrhenius equation, the apparent activation energies of PEPC and RuBPCO were 103 and 86 kJ mol –1 , respectively, for H. undatus and 77 and 49 kJ mol –1 , respectively, for S. megalanthus, within the range determined for a diverse group of species using different methodologies. Above 28 °C, PN decreased an average of 58 % per °C in Phase I and 30 % per °C in Phase II for the two species; such steep declines with temperature indicate that irrigation then may lead to only small enhancements in net CO2 uptake ability.

Amino acids and amines are the precursors of betalains. Therefore, the profiles of free amino compounds in juices obtained from cactus pears [Opuntia ficus-indica (L.) Mill. cv. Bianca, cv. Gialla, and cv. Rossa], pitaya fruits [Selenicereus megalanthus (K. Schumann ex Vaupel) Moran, Hylocereus polyrhizus (Weber) Britton & Rose, and Hylocereus undatus (Haworth) Britton & Rose], and in extracts from differently colored Swiss chard [Beta vulgaris L. ssp. cicla (L.) Alef. cv. Bright Lights] petioles and red and yellow beets (B. vulgaris L. ssp. vulgaris var. conditiva Alef. cv. Burpee's Golden) were investigated for the first time. Amino compounds were derivatized with propyl chloroformate. While gas chromatography (GC) with mass spectrometry was used for peak assignment, GC flame ionization detection was applied for quantification of individual compounds. Whereas proline was the major free amino compound of cactus pear and pitaya fruit juices, glutamine dominated in Swiss chard stems and beets, respectively. Interestingly, extremely high concentrations of dopamine were detected in Swiss chard stems and beets. Furthermore, the cleavage of betaxanthins caused by derivatization in alkaline reaction solutions is demonstrated for the first time. Amino acids and amines thus released might increase the actual free amino compound contents of the respective sample. To evaluate the contribution of betaxanthin cleavage to total amino acid and amine concentration, isolated betaxanthins were derivatized according to the "EZ:faast" method prior to quantification of the respective amino compounds released. On a molar basis, betaxanthin contribution to overall amino compound contents was always below 6.4%.

Background and Aims Hylocereus undatus, a hemiepiphytic cactus cultivated in 20 countries for its fruit, hasfleshy stems whose water storage is crucial for surviving drought. Inter-tissue water transfer during drought was therefore analysed based on cell volumes and water potential components. Methods In addition to determining cell dimensions, osmotic pressures and water potentials, a novel but simple procedure leading to an external water potential of zero was devised by which cells in thin sections were perfused with distilled water. The resulting volume changes indicated that the parenchyma‐chlorenchyma water movement was related to more flexible cell walls in the water-storage parenchyma with its lower internal turgor pressure (P) than in the chlorenchyma. Key Results Under wet conditions, P was 045MPa in the chlorenchyma but only 010MPa in the water-storage parenchyma. During 6 weeks of drought, the stems lost one-third of their water content, becoming flaccid. About 95% of the water lost came from cells in the water-storage parenchyma, which decreased by 44% in length and volume, whereas cells in the adjacent chlorenchyma decreased by only 6%; the osmotic pressure concomitantly increased by only 10% in the chlorenchyma but by 75% in the water-storage parenchyma. Conclusions The concentrating effect that occurred as cellular volume decreased indicated no change in cellular solute amounts during 6 weeks of drought. The ability to shift water from the parenchyma to the chlorenchyma allowed the latter tissue to maintain a positive net CO2 uptake rate during such a drought.

SummaryTo obtain out-of-season cropping and flowering of the tropical vine cacti Selenicereus megalanthus and Hylocereus undatus, the following agricultural manipulations were tested: photoperiodic light applied for 3, 6 or 9 h after sunset; shading (to produce 80%, 60% or 40% of sunlight); flower thinning (when buds were 2–5 cm, 15–25 cm or at anthesis, or by not pollinating the flowers); or separate application of the following growth regulators [N-(2-chloro-4-pyridinyl)-N-phenylurea (CPPU); gibberellic acid (GA3); a commercial mixture of gibberellins (GA4 and GA7) with benzyladenine (BA) known as Perlan™; paclobutrazol (PBZ); or ethephon (Ethrel™)]. Photoperiod and radiation did not alter the pattern of flowering. Maximum flower yields were obtained under 60% sunlight for H. undatus and under 60% or 40% sunlight for S. megalanthus. Removal of young flower buds delayed flowering and late cropping in H. undatus, but with no loss in total flower yield. In both species, CPPU promoted precocious flowering a...

SummarySeasonal changes in skin colour, and sugar and acid contents were studied in pitaya (Hylocereus undatus Britt & Rose) fruits pollinated in July (Summer) and October (Autumn) on Ishigaki Island, Japan. Changes in skin colour pattern (a* and b* values), total soluble solids (TSS) and sugar contents exhibited a sigmoid pattern irrespective of the time of pollination, except for skin colour b* values in Autumn-pollinated fruit. In both groups, mature fruit had higher TSS contents in the centre of the fruit compared with other sections. Malic acid was the main acid in the fruit, with no clear seasonal pattern. Changes in glucose and fructose contents exhibited a similar pattern to that of TSS, but the values were higher in mature Autumn fruit than in mature Summer fruit, and differed among fruit sections. The differences tended to converge during late maturation when a* values and TSS contents reached a constant level. These results indicate that each a* value and TSS content could not be applied solely...

Pairs of linearly variable differential transducers, with a sensitivity of 1 μm, were used to compare daily changes in stem thickness with transpiration and net CO2 uptake for the hemiepiphyte Hylocereus undatus and to examine the possible effects of hormonal signals from its roots. Two daily patterns of transpiration were observed for well‐watered H. undatus: solely nocturnal stomatal opening, which can occur for obligate crassulacean acid metabolism (CAM), and CAM with substantial daytime stomatal opening associated with C3 photosynthesis. Each caused different daily patterns of stem thickness, which could be affected by changes in relative humidity within 1 min. Removing possible root signals by severing distal stem segments or by rapidly drying the root system increased the maximal transpiration rate over 4 d, indicating that root hormonal signals influence stomatal opening, even under well‐watered conditions. Rewatering plants that had their root systems air dried for 4 d resulted in rapid water upta...

Introduction. Deux especes de pitaya coexistent a la Reunion : Hylocereus undatus et H. costaricensis. Ces deux especes, introduites, s'y reproduisent vegetativement et, bien qu'elles fleurissent, ne produisent que rarement des fruits. Une etude a donc ete menee pour verifier les causes de l'improductivite de ces especes et apprecier le role d'eventuels agents pollinisateurs. Materiel et methodes. Deux modes de pollinisation libre (nocturne ou diurne) et deux modes de pollinisation controlee (croisement interspecifique manuel et autopollinisation) ont ete compares sur une parcelle plantee avec les deux especes H. undatus et H. costaricensis intercalees. Les observations ont porte sur la viabilite du pollen, la nature des agents pollinisateurs, les conditions de pollinisation et la fructification. Resultats. Nous avons verifie que l'absence de productivite des deux clones d'Hylocereus en conditions naturelles etait due a leur auto-incompatibilite. En effet, aucune fecondation n'a ete observee sur les 200 autopollinisations effectuees en 1999. Cette auto-incompatibilite n'est pas liee a une sterilite du pollen dont la viabilite in vitro s'est revelee satisfaisante. D'autre part, si les abeilles jouent un role dans la fecondation des deux clones, les fruits resultant de ces pollinisations libres sont significativement moins lourds que ceux issus d'une pollinisation manuelle croisee. Discussion et recommandations. Seule une pollinisation croisee et manuelle peut donc permettre aux deux clones d'Hylocereus presents sur l'ile de la Reunion de produire des fruits de qualite. Un itineraire technique de fecondation est propose. (Resume d'auteur)

Hylocereus undatus [(Haworth) Britton and Rose] is a vine cactus from central America that has been established as a new fruit crop (pitaya) in many tropical and subtropical countries. In order to develop improved irrigation practices, the relationships between water parameters and growth were studied in rooted stem cuttings growing in pots with sandy soil under well-watered and drought-stressed conditions, in a controlled environment. Soil water potential rapidly decreased from -0.02 to -1.5 MPa during the first 5 days of drought. However, growth of new stems emerging from the succulent mature stems only decreased significantly after 3 weeks of drought. After 3 weeks of drought, the water content of growing stems decreased by 2% (P < 0.05) and their water potentials by 0.05 MPa (P > 0.05), as compared with the irrigated controls. At the same time, water content in drought-treated mature stems decreased by 4% (P < 0.05) and water potentials by 0.25 MPa (P < 0.05). Several lines of evidence indicated that active phloem supply of assimilates and associated water reserves from mature stems was the mechanism that allowed developing stems of H. undatus to maintain growth under well-watered and drought conditions: 1) Girdling the phloem of growing stems rapidly inhibited stem elongation. 2) Secretion of sucrose-containing nectar by growing stems was maintained during drought. 3) The water potential gradient was in the wrong direction for xylem transport from mature to young growing stems and axial hydraulic conductivity in young stems was either zero or comparatively low.

• Background and Aims Flowers of the vine cacti of the genera Hylocereus and Selenicereus grown in Israel must be hand pollinated due to self‐incompatibility and lack of efficient pollinators. In controlled pollination experiments, it was found that the time elapsed between pollination and ripening depends on the source of the pollen. Therefore a study was made of some effects of the pollen source on fruit development. • Methods Flowers of Hylocereus polyrhizus were pollinated on the same day with different pollen sources and the stigmas were covered. Fruits were collected 4 d after reaching full colour. • Key Results Pollinating flowers of Hylocereus polyrhizus with Selenicereus grandiflorus and S. megalanthus pollen delayed ripening by 1 and 3 weeks, respectively, as compared with ripening of fruits pollinated with Hylocereus undatus pollen. Other fruit characteristics affected by the pollen source were fruit size, pulp dry weight and number of seeds per fruit, all being significantly reduced, while peel dry weight was significantly increased by S. megalanthus pollen. Total soluble sugar content was reduced in H. polyrhizus fruits pollinated with S. grandiflorus pollen. No other major traits were affected. • Conclusions The results are evidence for the existence of metaxenia, i.e. an effect of pollen on maternal tissues, in cacti fruits. This pollen effect on the fruit‐ripening time may be used for extending the marketing period of H. polyrhizus fruits.

Summary The climate of the native tropical forest habitats of Hylocereus undatus , a hemiepiphytic cactus cultivated in 20 countries for its fruit, can help explain the response of its net CO 2 uptake to environmental factors. Under wet conditions, about 85% of the total daily net CO 2 uptake occurs at night via Crassulacean acid metabolism, leading to a high water-use efficiency. Total daily net CO 2 uptake is reduced 57% by only 10 days of drought, possibly involving stomatal closure induced by abscisic acid produced in the roots, which typically occupy a small substrate volume. Total daily net CO 2 uptake for H. undatus is maximal at day/night air temperatures of 30/20° C, optimal temperatures that are higher than those for desert cacti but representative of ambient temperatures in the tropics; its total daily net CO 2 uptake becomes zero at day/night air temperatures of 42/32° C. Stem damage occurs at 45° C for H. undatus, whose photosynthetic cells show little acclimation to high temperatures compared with other cacti and are also sensitive to low temperatures, -1.5° C killing half of these cells. Consistent with its shaded habitat, total daily net CO 2 uptake is appreciable at a total daily PPF of only 2 mol m -2 day -1 and is maximal at 20 mol m -2 day -1 , above which photoinhibition reduces net CO 2 uptake. Net CO 2 uptake ability, which is highly correlated with stem nitrogen and chlorophyll contents, changes only gradually (halftimes of 2-3 months) as the concentration of applied N is changed. Doubling the atmospheric CO 2 concentration raises the total daily net CO 2 uptake of H. undatus by 34% under optimal conditions and by even larger percentages under adverse environmental conditions.

The net CO2 uptake ability of a vine-like cactus native to shaded habitats, Hylocereus undatus, was hypothesized to adjust more rapidly to changes in the applied nitrogen concentration, which can have major impacts on fruiting, than the more massive cactus most widely cultivated for fruit, Opuntia ficus-indica. Specific objectives were to examine the effects of applied N on stem N concentrations and chlorophyll levels, which can affect net CO2 uptake ability and hence growth. After 9 weeks, the total daily net CO2 uptake for H. undatus was only 26% less for the relatively low N concentration of 0.32 mM than for 8 mM N (the N concentration in 0.5-strength Hoagland solution; all other nutrients were maintained at their concentration in 0.2-strength Hoagland solution), compared with 2 weeks for major changes for O. ficus-indica in response to changing applied N. Based on the maximal net CO2 uptake rates at night for the Crassulacean acid metabolism H. undatus, the half-time for the shift in response to seven different N concentrations applied for 22 weeks was 12–13 weeks; the half-time for the attainment of the highest net CO2 uptake rate of 10 μmol m−2 s−1 in response to subsequent application of 16 mM N for 11 weeks was 8–9 weeks. After 22 weeks, the stem N level in response to 0.16 mM N was 0.9% by dry mass and the chlorophyll content per unit stem area was 0.30 g m−2 compared with 2.5% and 0.63 g m−2 for 16 mM N. Subsequent application of 16 mM N for 11 weeks reversed the observable stem bleaching and raised the chlorophyll toward the highest levels. Both the chlorophyll content and the N level per unit stem area are highly correlated with the net CO2 uptake ability of H. undatus and either could help assess the physiological status of this cactus.

The cultivation of vine pitayas, a group of new cactus fruit crops originating in tropical America, has spread to tropical and subtropical regions throughout the world. Data are presented on the growth and fruiting of two red pitayas— Hylocereus undatus and Hylocereus polyrhizus —at four sites in Israel differing in the quality of the irrigation water and climate. The sites are Sede Nizzan and Ma’abarot, located on the coast, with recycled water (EC=1.3–1.4 dS m −1 ) and moderate summer temperatures (mean maximum at midsummer of 34 and 32 °C, respectively); Qetura in the Arava Valley, with saline water (EC=3.2–3.4 dS m −1 ) and high summer temperatures (mean maximum at midsummer of 38 °C); Gilgal in the Jordan Valley, with fresh water (EC=0.8–0.9 dS m −1 ) and temperatures as at Qetura. Vegetative growth at Qetura was slower than at the other sites, a result attributed to the water deficit induced by the salinity of the irrigation water there. At the coastal sites flowering occurred in both summer and autumn, with three or four flushes (prolific in the autumn), while at the valley sites it was restricted to autumn, with a single sparse flush (less than five flowers per 1 m row). Five years after planting (all the orchards had reached their full size), annual fruit yields were 34 t ha −1 at Ma’abarot, 28 t ha −1 at Sede Nizzan, and 5 t ha −1 at Qetura (fruits were not harvested at Gilgal). As percent fruit-set and fruit weight were similar in all the plots examined, it follows that yields were a function of the number of flowers produced at each site. Analysis of the results indicates that the high summer temperatures prevailing in the valleys inhibited flower production in the two study species.

Hylocereus undatus is widely distributed naturally and is currently cultivated in 19 countries for fruit. Because of its relatively thin stems, H . undatus was hypothesized to respond to drought more rapidly than other cacti. Stem water potential, water content and thickness were monitored during drought to provide easily measured parameters to be correlated with net CO 2 uptake ability, allowing the development of irrigation schedules to optimize water-use efficiency. H. undatus exhibited Crassulacean acid metabolism, as maximal stomatal opening and net CO 2 uptake occurred at night. Although the soil water potential decreased to −4.2 MPa during 12 days without watering, the stem water status parameters remained near their values under wet conditions ( Ψ stem of −0.67 MPa, water content of 90.8%, thickness of 4.48 mm). The drought was accompanied by a 63% decrease in the maximal water vapor conductance and a 57% decrease in the maximal net CO 2 uptake rate, but when the roots were excised for plants under wet conditions, neither parameter decreased appreciably over a comparable time period. Injection of 100 μM abscisic acid into attached stems and placing cut ends of detached stems in such a solution substantially reduced gas exchange 1 day later; at 2 days after injecting the hormone, the maximal water vapor conductance was similar to the minimal daytime values under wet conditions and the net CO 2 uptake rate was inhibited by 97%. Abscisic acid produced in the roots apparently leads to stomatal closure for this hemiepiphyte—whose roots can occur in very limited soil volumes—as soon as the water supply starts to deplete rather than after a large fraction of its stem water is transpired.

The betalain pattern of Hylocereus polyrhizus (Weber) Britton & Rose is reported for the first time and a highly practicable technique is described for the simultaneous isolation of pigment and mucilage from the mesocarp by extraction with water. Whereas betaxanthins were totally absent, 10 betacyanins could be separated by HPLC-PDA. For eight betacyanins the respective molecular masses could be obtained by positive ion electrospray mass spectrometry. Five of them were unequivocally assigned to bougainvillein-r-I, betanin, isobetanin, phyllocactin, and iso-phyllocactin. The remaining betacyanins were tentatively identified as (6′-O-3-hydroxy-3-methyl-glutaryl)-betanin, its C15-stereoisomer, and (6′-O-3-hydroxy-3–butyryl)-betanin, respectively. Using the β-glucosidase assay, acylated structures could be distinguished from non-acylated betacyanins. Contrary to white-fleshed Hylocereus undatus (Haworth) Britton & Rose with a slightly pink mesocarp, H. polyrhizus most likely possesses the same set of betalain forming enzymes in both pulp and mesocarp as the betacyanin pattern was found to be similar.

Dragon fruit (Hylocereus undatus (Haw.)) experiments carried out during 1998-2000 indicated that harvesting was optimal 28-30 days after flowering, on the basis of the indices of colour, total soluble solids (TSS), titratable acidity and colour. Best practice also included spraying the fruit with a mixture of gibberellic acid, α-naphthalene acetic acid (NAA) and β-NAA at a formulation of 8, 150 and 400 ppm, respectively, on the 11th day after flowering. This treatment increased fruit weight, TSS and flesh and bract firmness.

Dragon fruit (pitaya) fruit blotch and stem rot, caused by Bipolaris cactivora, is reported for the first time in Israel. Different symptoms of fruit blotch appear on two different cultivars.

Abiotic stresses usually cause H2O2 accumulation, with harmful effects, in plants. Catalase may play a key protective role in plant cells by detoxifying this excess H2O2. Pitaya (Hylocereus undatus) shows broad ecological adaptation due to its high tolerance to abiotic stresses, e.g. drought, heat and poor soil. However, involvement of the pitaya catalase gene (HuCAT) in tolerance to abiotic stresses is unknown. In the present study, a full-length HuCAT3 cDNA (1870 bp) was isolated from pitaya based on our previous microarray data and RACE method. The cDNA sequence and deduced amino acid sequence shared 73-77% and 75-80% identity with other plant catalases, respectively. HuCAT3 contains conserved catalase family domain and catalytic sites. Pairwise comparison and phylogenetic analysis indicated that HuCAT3 is most similar to Eriobotrya japonica CAT, followed by Dimocarpus longan CAT and Nicotiana tabacum CAT1. Expression profile analysis demonstrated that HuCAT3 is mainly expressed in green cotyledons and mature stems, and was regulated by H2O2, drought, cold and salt stress, whereas, its expression patterns and maximum expression levels varied with stress types. HuCAT activity increased as exposure to the tested stresses, and the fluctuation of HuCAT activity was consistent with HuCAT3 mRNA abundance (except for 0.5 days upon drought stress). HuCAT3 mRNA elevations and HuCAT activities changes under cold stress were also in conformity with the cold tolerances among the four genotypes. The obtained results confirmed a major role of HuCAT3 in abiotic stress response of pitaya. This may prove useful in understanding pitaya's high tolerance to abiotic stresses at molecular level.

Metabolite profiling of red and white pitayas (Hylocereus polyrhizus and Hylocereus undatus) was performed using gas chromatography-time-of-flight-mass spectrometry and ultraperformance liquid chromatography-quadrupole-time-of-flight-mass spectrometry with multivariate analysis. Different species and parts of pitayas (red peel, RP; white peel, WP; red flesh, RF; and white flesh, WF) were clearly separated by partial least-squares discriminate analysis. Furthermore, betalain-related metabolites, such as betacyanins and betaxanthins, or their precursors were described on the basis of their metabolites. The results of antioxidant activity tests [1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), and ferric reducing ability of plasma (FRAP)], total phenolic contents (TPC), total flavonoid contents (TFC), and total betacyanin contents (TBC) showed the following: RP ≥ WP > RF > WF. TPC, TFC, TBC, and betalain-related metabolites were higher in the peel than in the flesh and suggested to be the main contributors to antioxidant activity in pitayas. Therefore, peels as well as pulp of pitaya could beneficially help in the food industry.

O objetivo deste trabalho foi avaliar características físico-químicas dos frutos de 21 acessos de duas espécies de pitaya, Hylocereus undatus e Selenicereus setaceus. Foi utilizado um delineamento inteiramente ao acaso, com quatro repetições, sendo cada repetição a média de três frutos. Foram analisados comprimento e diâmetro dos frutos, sólidos solúveis, massa total da casca e da polpa dos frutos. As análises de variância foram realizadas por meio do programa Genes e as médias foram comparadas pelo teste Scott e Knott, a 5% de significância. Foram determinados os coeficientes de correlação de Pearson entre as diferentes características analisadas. Os acessos 02 e 05 da espécie H. undatus destacam-se por apresentarem maiores comprimento, diâmetro e massa dos frutos, comparando com os dos demais acessos. A espécie S. setaceus apresenta maior teor de sólidos solúveis da polpa dos frutos, diferenciando-se significativamente da espécie H. undatus. Altos valores foram encontrados para herdabilidade e CVg, para as características físicas dos frutos de pitaya, estimativas importantes para se determinarem estratégias de seleção e para se estimar o ganho genético. Os resultados das correlações indicam que quanto maior o tamanho e a massa, menor é o teor de sólidos solúveis na polpa dos frutos de pitaya. The objective of this study was to evaluate physical and chemical characteristics of the fruits of 21 accessions of two pitaya species, Hylocereus undatus and Selenicereus setaceus. The experiments were arranged in a completely randomized design with four replications. Each replication consisted of 3 fruits. The characteristics length, diameter, soluble solids, skin and pulp total mass were analyzed. Soluble solids were determined in the homogenized pulp and at three different points inside the pulp. Analyses of variance were performed with the Genes software and means were compared using the Scott and Knott test. Pearson correlation coefficients between different traits were determined. H. undatus genotypes 02 and 05 stand out due to their larger length, diameter and fruit weight compared with the other genotypes. The species S. setaceus had higher soluble solids content in fruit pulp, differing significantly from H. undatus. High heritability and CVg values were found for the physical characteristics of pitaya fruit. These parameters are important to determine selection strategies and to estimate the genetic gain. The correlations indicated that genotypes with larger fruit size and mass have less soluble solid content in the pulp.

Recentemente, algumas espécies de cactáceas têm-se destacado quanto ao potencial como frutíferas, sendo suas frutas utilizadas como alimento para o homem. dentre essas, a pitaia tem despertado grande interesse. O presente trabalho teve como objetivo estudar a floração e a frutificação em diferentes tipos de cladódios (tamanho e presença ou ausência de frutificação em safras anteriores) de pitaia-vermelha em Lavras-MG. As observações foram realizadas em plantas de pitaia-vermelha [Hylocereus undatus (haw.) Britton & Rose], com quatro anos de idade, tutoradas em mourões de eucalipto com 1,80 m de altura, no espaçamento de 3 x 3 m. Do surgimento do botäo floral até a abertura da flor, decorreram cerca de 21 dias, e da antese até a colheita do fruto, cerca de 35 dias. Cladódios que já haviam produzido frutos em anos anteriores e com tamanho entre 40 e 60 cm de comprimento apresentaram maior porcentagem de cladódios com frutos e maior número de frutos por cladódio. Recently some species of cacti have been detached for their potential as fructiferous, as their fruit used as food for man. Among these, pitaya has received great interest. The present work aimed to study the flowering and fruiting cladodes of different types (size and presence or absence of fructification in previous harvests) of red pitaya in Lavras. The observations were made in plants of red pitaya [Hylocereus undatus (haw.) Britton & Rose], with four years of age, conducted in stakes of eucalyptus with 1.80 m high, spaced 3 x 3m. The appearing of the flower buds till the flower opening took place about 21 days and from the anthesis till the harvest the fruit about 35 days. Cladodes that had already borne fruit in previous years and with size between 40 and 60 cm in length had a higher percentage of fruits and cladodes with higher number of fruits per cladodes.