Effect of Antioxidants in Controlling Phenol Exudation in Micropropagation of Litchi cv. Purbi

Conventionally litchi is propagated by vegetative means mainly by air layering or marcottage, grafting and budding. Although for large-scale production of elite litchi clones, micropropagation can be used as a potential alternative to conventional means of propagation. The presence of phenolic compounds causing the death of explants has been one of the significant bottlenecks of litchi micropropagation which causes death of explants after turning brown and these exudates appear as a reaction to injury and/or infection. Litchi cultivar Purbi grown at Horticulture Garden of Bihar Agricultural College, Sabour was selected for the investigation and the required planting material used was Leaf and Nodal segment as a source of the explant. Different antioxidants were used as treatments to control the phenol exudation. The results of the study revealed that all the antioxidants supplemented into the media significantly reduced phenolic exudation for both the explants. However, minimum phenolic exudation (+) was observed for both the explants, when media was supplemented with ascorbic acid 300 mg per litre which also results in maximum per cent shoot regeneration (54.0±0.47) for nodal segments and maximum per cent callus induction (60.9±0.61) for leaf explants after (29.0±0.81 days) and (46.4±0.55 days) of culturing, respectively. Phenolic exudation was recorded highest (++++) under control when no antioxidants were supplemented into the media. Though all other antioxidants used in our study including citric acid, PVP and activated charcoal significantly reduced percent oxidative browning, ascorbic acid was found to be the most effective antioxidant in controlling lethal browning during micropropagation of litchi followed by the combination of ascorbic acid with citric acid (150 mg/l each) in the media for both the explants.