Tropical and Subtropical Agroecosystems (Jan 2023)
MULTIPLICATION in vitro OF Phalaenopsis sp. USING PLANT GROWTH REGULATORS, HONEY WATER AND FERMENTED SAP (ORGANIC COMPLEXES)
Abstract
Background: Phalaenopsis is an orchid of economic importance worldwide. Its natural reproduction is slow due to its monopodial growth (a single apical meristem). Therefore, it is necessary to make in vitro propagation protocols more efficient. Objectives: 1. To evaluate three concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) in combination with three of 6-Benzyl Adenine (BA) in the in vitro induction of protocormic like bodies (PLBs) at from leaf explants of Phalaenopsis sp. var. Dudu, under three periods of darkness, 2. To test the effect of four concentrations of honey water and fermented sap, as organic complexes (CO), on the in vitro multiplication rate of PLBs. Methodology: Two tests were carried out: Test 1. Three concentrations of 2,4-D (3, 4, 5 mgL-1) and three of BA (1, 2, 3 mgL-1) were evaluated in leaf explants of Phalaenopsis sp., combined with three periods of darkness 14, 21, 28 days in a completely randomized design with a trifactorial arrangement (27x10). Test 2. Four concentrations of honey water and fermented sap (0, 10, 50, 100 mlL-1) were evaluated, arranged in a completely random design (8x10). Results: The best combination of plant growth regulators (PGR) for the formation of PLBs (14 PLBs/explant) was with 5 mgL-1 of 2,4-D and 2 mgL-1 of BA, during 21 days of darkness. Regarding the use of CO, the addition of 10 mlL-1 of fermented sap and 50 mlL-1 of honey water induced the highest rates of multiplication of PLBs/explant (41.4 and 39.6 PLBs). The regeneration of Phalaenopsis sp. from PLBs occurred in 225 days. Implications: The results obtained in the two trials are the basis for establishing a protocol for the multiplication of Phalaenopsis sp. Conclusions: The combination of 5 mgL-1 of 2,4-D and 2 mgL-1 of BA produced the highest number of PLBs/explant (14) at 21 days of darkness and subsequent light exposure for six weeks. On the other hand, the addition of 10 mlL-1 of fermented sap and 50 mlL-1 of honey water as CO induced the highest rates of PLBs multiplication (41.4 and 39.6 PLBs, respectively). 100% survival of seedlings was observed after 21 days of acclimatization, under greenhouse conditions.
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