Propagation and rootstocks of Mandarin orange

Propagation and rootstocks

     Most of the mandarin cultivars are propagated through seeds except Kinnow and Nagpur mandarins. Usual practice in Coorg, Assam and other north-eastern hills is to use seedlings as planting material. But with concerted efforts made to find out suitable rootstocks for different regions, orchardists have shifted to vegetative methods, particularly T-budding.

By seed

       For quality planting material, select uniformly matured fruits from healthy, true-to-type and heavy-bearing plants to extract seeds. Freshly extracted seeds should be mixed with ash and dried in shade. Seeds should be sown immediately after extraction. Otherwise, they may loose their viability. Seeds are sown at a distance of 2–3cm. Germination may take place within 3–4 weeks. Since the seeds are polyembryonic, the sexual seedlings which are stunted and poor in growth are rogued out and the rest that are produced from the cells of nucellus are allowed to grow. The seedlings, thus, selected are more or less uniform in growth and production. Every care must be exercised to protect the seedlings in the nursery from weeds, insect pests and diseases.

By budding

         Of various vegetative methods, T-budding is by and large the most common method followed. Selection of a suitable rootstock for a particular region and proper mother plant are important steps. Many rootstocks have been used for different mandarin cultivars in different regions. However Rough Lemon (Jatti Khatti and Jambheri), Rangpur Lime, Cleopatra, Troyer Citrange and Karna Khatta are potential rootstocks.

        Seeds of identified rootstock for a particular area should be extracted from fully matured, healthy fruits. They are sown in lines (10–15cm deep) on raised seed-beds inside a polyethylene house. About 1–2 months old seedlings are shifted to secondary beds. These are finally budded when they attain a height of 25–30cm and 1–2cm diameter. Scion should be selected from healthy, vigorous, mature, virus-free and high-yielding trees. They should also be free from water sprouts and chimeras. Further use of dormant scion budwood from past season's growth is used after it has hardened. The budwood should be taken from round or cylindrical green twigs.

           Optimum time for budding varies according to the place. It may be done at a time, when there is free flow of sap and bark slips easily. In Punjab and adjoining areas, budding is practised either in February–March or September–October, whereas in Nagpur and Coorg regions, September–November is the ideal time.