Dragon fruit (Hylocereus spp.), also known as Pitaya or Pitahaya belonging to the family Cactaceae, is an most important tropical fruit crop as it is rich in antioxidants (a source of vitamins and minerals, prevent cancer, diabetes, cardiovascular, respiratory, gastrointestinal and urinary diseases), as well as dietry fiber and low in calories. It has drawn worldwide attention owing to its new flavor, color and attractive appearance along with their enormous health benefits. It gained great commercial potential in India by consumer preference for new and exotic phyto-chemically rich nutrient fruits and its adaptability to new environment with abiotic stress tolerance like drought and temperature extremes. Although Hylocereus spp. reported in worldwide, only four species such as H. undatus, H. monocanthus (Syn. H. polyrhizus), H. costariscensis and H. megalanthus (Syn. Selenicereus megalanthus) are mostly cultivated in different parts of the world. Among them, the H. undatus is widely cultivated in Indian States like Tamil Nadu, Andhra Pradesh, Karnataka, Maharashtra, Punjab and West Bengal.
In general, fresh fruits and vegetables are excellent source of antioxidant constituents (phenols and flavonoids) which confer protection against chronic diseases caused by oxidative stress, namely cardio-vascular disorders and some kinds of cancer. Recently, dragon fruit cultivation was introduced in Andaman and Nicobar Islands which is highly dependent on import of common fruits and vegetables from mainland India to meet out nutrient requirement of Islands. This fruits are also known for its richness in antioxidant and antiproliferation properties6–8 with phenolic and polyphenolic compounds
Nowadays, it is very difficult to separate species and varieties of the dragon fruit owing to high intra and inter-specific hybridization which created some taxonomical confusion in worldwide. Morphological and genetic heterogeneity in many fruits characteristics such as sweetness, size, shape, color, and bracts number by this intra and inter-specific hybridization makes it difficult to increase the quality standards for the exportation market because it posed serious problems in determining their performance in handling and shelf life.
A characteristic fruit view of three different Hylocereus species of dragon fruit (1) H. undatus—DGF1 (a); (2) H. costariscensis—DGF2 (b), DGF4 (c) and (3) H. megalanthus—DGF3 (d).
An illustration of important traits of three different Hylocereus species of dragon fruit. Cladode characters: (A) length of segments (cm), (B) number of spines and (C) margin ribs of cladode; Flower characters: (D) flower bud shape and (E) shape of apex; fruit characters: (F) fruit length (cm) and (G) position towards the peel.
Table 1.
Characterization of three dragon fruit (Hylocereus) species with 34 quantitative traits of cladode, flower and fruit in Andaman and Nicobar Islands.
Accession/descriptors | H. undatus | H. costariscensis | H. megalanthus | ||
DGF 1 | DGF 2 | DGF 4 | DGF 3 | ||
Cladode | |||||
Length of segments (cm) | 73.9 | 75.9 | 36.2 | 60.1 | |
Cladode width (mm) | 39 | 38 | 53 | 35 | |
Arch height of cladode (mm) | 6 | 4 | 2 | 2 | |
Distance between areoles (mm) | 38 | 35 | 34 | 40 | |
Number of spines | 4 | 4 | 5 | 3 | |
Length of areoles (mm) | 3 | 4 | 1 | 1 | |
Flower | |||||
Flower bud length (mm) | 25 | 26 | 25 | 21 | |
Flower bud width (mm) | 12 | 14 | 16 | 9 | |
Pericarpel length (mm) | 205 | 243 | 246 | 246 | |
Pericarpel width (mm) | 37 | 36 | 37 | 32 | |
Flower pericarpel: separation of bracts | 7.58 | 8.46 | 7.16 | 8.12 | |
Flower length (cm) | 23.22 | 19.26 | 18.36 | 22.15 | |
Flower: length of style (cm) | 13.42 | 7.34 | 7.02 | 12.89 | |
Flower: number of stigma lobes | 28.2 | 23.4 | 20.3 | 28.1 | |
Flower bifurcation of stigma lobes (cm) | 2.18 | 1.76 | 1.67 | 2.13 | |
Distance of anthers below stigma (mm) | 15 | 15 | 15 | 16 | |
Days to bud initiation (DFT) | 457.8 | 422.5 | 863.8 | 845.6 | |
Days to anthesis | 30.6 | 29.8 | 33.5 | 37.3 | |
Average no. of flowers plant−1 fruiting cycle−1 | 11.3 | 12.5 | 10.3 | 15.8 | |
Fruit | |||||
Fruit length (cm) | 15.2 | 13.9 | 10.1 | 8.9 | |
Fruit diameter (cm) | 10.9 | 9.6 | 9.3 | 4.2 | |
Total fruit weight (g) | 419.3 | 267.4 | 106 | 26.5 | |
Peel weight (g) | 160.5 | 97.3 | 45.6 | 16.3 | |
Pulp weight (g) | 258.8 | 170.1 | 61.9 | 10.3 | |
No. of bracts | 37 | 33 | 27 | 59 | |
Length of the apex bracts (mm) | 62 | 29 | 47 | 21 | |
Width of the base of the bract (mm) | 47 | 32 | 23 | 8 | |
Distance between bract to bract (mm) | 51 | 37 | 41 | 10 | |
TSS ( oB) | 11.2 | 15.9 | 9.1 | 18.3 | |
Titrable acidity (%) | 0.22 | 0.19 | 0.28 | 0.16 | |
Average fruit set fruiting cycle−1 plant−1 (%) | 83.8 | 63.9 | 44.9 | 41.3 | |
Days from anthesis to fruit maturity | 19.3 | 22.5 | 18.7 | 25.6 | |
Number of fruiting cycles | 07 | 08 | 02 | 01 | |
Average fruit yield season−1 plant−1 (Kg) | 6.3 | 5.2 | 1.8 | 1.1 |
Table 2.
Characterization of three dragon fruit (Hylocereus) species with 26 qualitative traits of cladode, flower and fruit in Andaman and Nicobar Islands.
Accession/descriptors | H. undatus | H. costariscensis | H. megalanthus | |
DGF 1 | DGF 2 | DGF 4 | DGF 3 | |
Cladode | ||||
Margin ribs of cladode | Convex | Convex | Convex | Concave |
Cladode waxiness | Weak | Weak | Strong white wax | Light waxy |
Young cladode colour | Light reddish | Light reddish | Light reddish | Light reddish |
Flower | ||||
Flower bud shape | Elliptic | Ovate | Elliptic | Elliptic |
Shape of apex | Rounded | Acute | Rounded | Rounded |
Flower bud main color | Yellowish green | Yellowish red | Greenish purple | Yellow with pink tinge |
Flower pericarpel: reddish color intensity of bracts | Green with purple edge | Green with dark red edge | Green with dark pink edge | Dark Green with light pink edge |
Sepal pattern | Edged | Edged | Edged | Edged |
Shape of bracts | Ovate | Ovate | Ovate | Ovate |
Flower colour of petals | Milky white | Milky white | Milky white | Milky white |
Flower colour of sepals | Light green | Light green | Light green | Green |
Flower colour pattern of sepals | Greenish with purple edge | Lemon yellow | Greenish with purple edge | Greenish yellow |
Flower colour of stigma lobe | Creamish green | Cream | Cream | Creamish green |
Flower colour of ring at base of reproductive organs | Lemon yellow with purple edge | Lemon yellow with dark red edge | Lemon yellow with red edge | Greenish yellow with pink edge |
Month of bud initiation | April | March | May | May |
Time of anthesis | 11.00 PM | 11.00 PM | 11.30 PM | 10.30 PM |
Duration of anthesis | 4–6 h | 4–6 h | 4–6 h | 4–6 h |
Fruit | ||||
Fruit shape | Moderately elongated | Medium elongated | Moderately rounded | Elongated |
Fruit width | Narrow | Broad | Medium | Narrow |
Position towards the peel | Slightly held out | Strongly held out | Held towards the peel | Slightly held out |
Colour of pulp | White | Pink | Dark Purple | White |
Colour of peel | Pinkish green | Pinkish Red | Pink | Yellow |
Juiciness of flesh | Medium | High | Medium | High |
Seed size | Small | Medium | Medium | Large |
No. of seeds fruit−1 | Many | Many | Many | Medium |
Fruiting season | May to Oct | Apr to Nov | Jun to Sept | Jul to Sept |
Table 3.
Range of variation for 34 quantitative traits of three dragon fruit (Hylocereus) species of cladode, flower and fruit in Andaman and Nicobar Islands.
Descriptors | Min | Max | Mean | SE | SD | Skewness | Kurtosis | CV |
Cladode | ||||||||
Length of segments (cm) | 36.2 | 75.9 | 61.5 | 9.1 | 18.3 | − 1.2 | 0.7 | 29.7 |
Cladode width (mm) | 35.0 | 53.0 | 41.3 | 4.0 | 8.0 | 1.7 | 3.2 | 19.4 |
Arch height of stem (mm) | 2.0 | 6.0 | 3.5 | 1.0 | 1.9 | 0.9 | − 1.3 | 54.7 |
Distance between Areoles (mm) | 34.0 | 40.0 | 36.8 | 1.4 | 2.8 | 0.3 | − 3.0 | 7.5 |
Number of spines | 3.0 | 5.0 | 4.0 | 0.4 | 0.8 | − 6.9 | 1.5 | 20.5 |
Length of Areoles (mm) | 1.0 | 4.0 | 2.3 | 0.8 | 1.5 | 0.4 | − 3.9 | 66.7 |
Flower | ||||||||
Flower bud length (mm) | 21.0 | 26.0 | 24.3 | 1.1 | 2.2 | − 1.7 | 3.3 | 9.1 |
Flower bud width (mm) | 9.0 | 16.0 | 12.8 | 1.5 | 3.0 | − 0.4 | − 0.4 | 23.4 |
Pericarpel length (mm) | 205.0 | 246.0 | 235.0 | 10.0 | 20.0 | − 2.0 | 3.9 | 8.5 |
Pericarpel width (mm) | 32.0 | 37.0 | 35.5 | 1.2 | 2.4 | − 1.8 | 3.1 | 6.7 |
Flower pericarpel: separation of bracts | 7.2 | 8.5 | 7.8 | 0.3 | 0.6 | − 0.1 | − 2.2 | 7.3 |
Flower length (cm) | 18.4 | 23.2 | 20.7 | 1.2 | 2.3 | 0.1 | − 4.3 | 11.1 |
Flower: length of style (cm) | 7.0 | 13.4 | 10.2 | 1.7 | 3.5 | 0.0 | − 5.8 | 34.0 |
Flower: number of stigma lobes | 20.3 | 28.2 | 25.0 | 1.9 | 3.9 | − 0.5 | − 3.0 | 15.4 |
Flower bifurcation of stigma lobes (cm) | 1.7 | 2.2 | 1.9 | 0.1 | 0.3 | − 0.1 | − 5.2 | 13.3 |
Distance of anthers below stigma (mm) | 15.0 | 16.0 | 15.3 | 0.3 | 0.5 | 2.0 | 4.0 | 3.3 |
Days to bud initiation (DFT) | 422.5 | 863.8 | 647.4 | 119.9 | 239.9 | 0.0 | − 5.9 | 37.1 |
Days to anthesis | 29.8 | 37.3 | 32.8 | 1.7 | 3.4 | 0.9 | − 0.6 | 10.4 |
Average no. of flowers plant−1 fruiting cycle−1 | 10.3 | 15.8 | 12.5 | 1.2 | 2.4 | 1.2 | 1.4 | 19.2 |
Fruit | ||||||||
Fruit length (cm) | 8.9 | 15.2 | 12.03 | 15.0 | 30.0 | 0.0 | − 4.4 | 25.0 |
Fruit diameter (cm) | 4.2 | 10.9 | 8.5 | 14.7 | 29.5 | − 1.7 | 3.1 | 34.7 |
Total fruit weight (g) | 26.5 | 419.3 | 204.8 | 87.3 | 174.6 | 0.4 | − 1.9 | 85.3 |
Peel weight (g) | 16.3 | 160.5 | 79.9 | 31.6 | 63.3 | 0.6 | − 1.0 | 79.2 |
Pulp weight (g) | 10.3 | 258.8 | 125.3 | 55.6 | 111.2 | 0.3 | − 2.3 | 88.7 |
No. of bracts | 27.0 | 59.0 | 39.0 | 7.0 | 14.0 | 1.5 | 2.5 | 35.8 |
Length of the apex bracts (mm) | 21.0 | 62.0 | 39.8 | 9.2 | 18.4 | 0.4 | − 2.3 | 46.3 |
Width of the base of the bract (mm) | 8.0 | 47.0 | 27.5 | 8.2 | 16.3 | 0.0 | 0.1 | 59.4 |
Distance between bract to bract (mm) | 10.0 | 51.0 | 34.8 | 8.8 | 17.5 | − 1.3 | 2.3 | 50.4 |
TSS ( oB) | 9.1 | 18.3 | 13.6 | 2.1 | 4.2 | 0.1 | − 3.4 | 31.0 |
Titrable acidity (%) | 0.2 | 0.3 | 0.2 | 0.0 | 0.1 | 0.8 | 0.3 | 24.1 |
Average fruit set fruiting cycle−1 plant−1 (%) | 41.3 | 83.8 | 58.5 | 9.8 | 19.6 | 0.8 | − 1.4 | 33.5 |
Days from anthesis to fruit maturity | 18.7 | 25.6 | 21.5 | 1.6 | 3.2 | 0.7 | − 1.7 | 14.8 |
Number of fruiting cycles | 1.0 | 8.0 | 4.5 | 1.8 | 3.5 | 0.0 | − 5.2 | 78.0 |
Average fruit yield season−1 plant−1 (Kg) | 1.1 | 6.3 | 3.6 | 1.3 | 2.5 | 0.1 | − 4.7 | 70.5 |
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