Effects of sucrose, carrot juice and culture media on growth and net CO2 exchange rate in Phalaenopsis hybrid ‘Pink’

•We evaluated the effects of sucrose and carrot juice (CJ) in different media on growth and net CO2 exchange rate of Phalaenopsis hybrid ‘Pink’.•The combination of 30 g L−1 sucrose and 10% CJ in MS medium resulted in the highest leaf length, SPAD leaf greenness, total chlorophyll and CO2 uptake.•The combination of 40 g L−1 sucrose and 10% CJ in VW medium resulted in the highest leaf length, SPAD leaf greenness, total chlorophyll and CO2 uptake.

The successfulness of plant tissue culture in terms of propagation is greatly influenced by the nature of the medium used. This experiment was conducted to determine the effects of various sucrose concentrations as carbon source and carrot juice (CJ) in different culture media on growth and net CO2 exchange rate of Phalaenopsis hybrid ‘Pink’. Plantlets were cultured on two media (half-strength Murashige and Skoog [MS] and Vacin and Went [VW]) supplemented with 0, 10, 20, 30 and 40 g L−1 sucrose either with 0, 10 and 20% (v/v) CJ as a natural additive. After four months of culture, plantlets were transferred to a greenhouse under natural environmental condition. The results showed that the combination of 30 and 40 g L−1 sucrose with 10% (v/v) CJ supplemented with half-strength MS and VW medium, respectively, optimally enhanced root length, leaf length, plant height, leaf greenness, total chlorophyll content and CO2 uptake. The combination of 30 g L−1 sucrose and 10% (v/v) CJ supplemented with half-strength MS medium resulted in the highest leaf length (5.00 ± 0.07 cm), plant height (7.20 ± 0.20 cm), SPAD leaf greenness (35.50 ± 0.26), total chlorophyll (15.13 ± 0.25 μg mL−1) and CO2 uptake (1.11 ± 0.15 μmol m−2 s−1). The combination of 40 g L−1 sucrose and 10% (v/v) CJ supplemented with VW medium resulted in the highest leaf length (5.40 ± 0.10 cm), leaf width (2.60 ± 0.10 cm), plant height (6.50 ± 0.22 cm), SPAD leaf greenness (37.43 ± 0.26), total chlorophyll (17.07 ± 0.39 μg mL−1) and CO2 uptake (1.77 ± 0.04 μmol m−2 s−1).