The influence of varied concentrations of sucrose and ammonical (NH 4 ? ) nitrogen on in vitro induction and expression of anthocyanin pigments from Rosa hybrida cv. 'Pusa Ajay' was investigated. Of two explants (petal and leaf discs) selected and cultured under two different conditions (light and dark), leaf discs were found to be most suitable for callus initiation. Profuse and early callus induction was observed when leaf discs of rose were cultured under total dark conditions on solid Murashige and Skoog (MS) medium supplemented with 4.0 mg l -1 2,4-dichlorophenoxyacetic acid (2,4-D). Early pigment initiation, enhancement and maximum anthocyanin production from calluses were recorded when leaf discs were cultured on Euphorbia millii (EM) medium supplemented with 7% sucrose compared with calluses cultured at 4% sucrose concentration under 16/8 h (light/dark) photoperiod regime. Reducing the concentration of NH 4 ? nitrogen in the solid MS medium led to slight improvement in anthocyanin production in rose leaf calluses.

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The present study reports the usefulness of ascorbic acid for reducing lenticels browning (LB) in mango, which impairs the cosmetic appeal and thereby the export. Postharvest dip treatment of ascorbic acid at different concentrations (100, 150 and 200 ppm) was given to four varieties of mango (Indian-'Dashehari', 'Langra'; Exotic-'Sensation', 'Eldon'). After treatment, fruits were stored at ambient conditions (35 ± 4°C and 65 ± 5 % RH) for 10 days. At the end of storage period, observations were recorded on several parameters. Our results revealed that fruits of 'Langra' mango exhibited 100 % LB, followed by 'Dashehari' (52.8 %), 'Sensation' (42.9 %) and 'Eldon' (38.3 %). All concentrations of ascorbic acid reduced the LB to greater extent and improved the cosmetic appeal of fruits of all the varieties significantly over untreated fruits but the best results were obtained with 200 ppm concentration for LB (4.8, 1.6, 3.7, 3.2 %, respectively) and other attributes, non-significantly followed by 150 ppm concentration. All concentrations of ascorbic also reduced the activities of polyphenol oxidase, peroxidase and lipoxigenase enzymes, and also reduced respiration rate and ethylene evolution rate but without impairing eating quality attributes (soluble solids concentrates and total carotenoids). It can be concluded that postharvest dip application of ascorbic acid at 150 ppm reduced LB and improve face value without impairing fruit quality.

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