STANDARDIZATION OF MICROPROPAGATION PROTOCOL FOR MASS PRODUCTION OF DRAGON FRUIT (Hylocereus undatus (Haw.) BRITTON AND ROSE)
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Date
2022-04
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University of Horticultural Sciences, Bagalkot. (College of Horticulture, Bagalkot).
Abstract
Dragon fruit (Hylocereus undatus (Haw.) Britton and Rose) or pitaya is an emerging tropical
and subtropical fruit crop belonging to Cactaceae. Due to its attractive colour, high nutritional
composition and luscious taste, commercial cultivation has been picking up in India over the
past decade. However, the supply of planting material is a bottleneck in meeting the increasing
demand. The conventional propagation method through stem cutting is time-intensive due to its
slow growth and seeds doesn‟t assure true to type planting material. The upsurge requirement
for planting material demands tissue culture generated planting material, which ensures the
crop's clonal fidelity and availability of planting material throughout the year. Therefore, we
investigated the standardisation of the micropropagation protocol of dragon fruit in this study.
Different types of explants (in vitro stem, in vitro leaf and in vivo stem) were inoculated onto
Murashige and Skoog's (MS) medium supplemented with different concentrations of 2,4-D and
BAP for their shoot proliferation. A 100.00 % response to shooting induction, the maximum
number of shoots per explant (9.94) and longest shoot length (2.26 cm) were recorded when in
vivo stem (E3) explant was cultured on MS0 + 1.5 ppm BAP. The in vitro stem explant (E1)
cultured on MS0 + 2.0 ppm BAP exhibited the earliest bud break (12.00 days). The in vitro
proliferated shoots were further rooted in MS media supplemented with different concentrations
of NAA and IBA. Among the treatments, cent per cent rooting with the least number of days for
root initiation (6.00 days) and the longest root per shoot (5.24 cm) was recorded in the treatment
MS0 + 0.1 ppm IBA. Average roots per shoot (5.71) were highest in MS0 + 0.5 ppm NAA. The
well-developed shoots and roots were transferred to protrays filled with a different potting
mixture of sand, soil and vermicompost alone or in combination. Sand + vermicompost (1:1)
(v/v) exhibited the maximum survival (100.00 %), the maximum number of shoots/plantlet
(7.66), longest mean shoot length (10.61 cm), the maximum number of roots per plantlet (11.27)
and longest mean root length (10.38 cm). The genetic fidelity of the in vitro regenerated plants
was assessed by using eight ISSR markers on 25 randomly selected seedlings and four sets of
mother plants with their respective regenerants. The per cent polymorphism was highest (57.69
%) in seedlings and lowest (1.92 %) in M3 and M4 populations. Principal coordinate analysis
and dendrogram constructed through neighbour-joining indicated greater genetic diversity in the
seedlings. High genetic proximity was observed among tissue cultured plantlets with their
respective mother plants. The economic analysis revealed that the cost of production of planting
materials through tissue culture was higher by Rs. 5.09 as compared to that of the conventional
method of stem cuttings.