Development of in vitro technologies for tea improvement in Indonesia

• Biotechnology Research Unit for Estate Crops, Indonesia

Virtually all green tea in Indonesia, and 40% of tea overall, is produced by smallholders. . A program of improvement was needed because the smallholder plantations had only half the productivity of good estates, and also because many of the current varieties planted were susceptible to blister blight. The Indonesian Government planned to increase tea plantings by 20,000 ha annually, mainly on smallholdings, but the production of such a large number of plants using conventional techniques was not economically feasible.

There was however, the potential to produce the very large numbers of superior plants required for this project by application of biotechnological techniques of plant tissue culture. This project was commissioned to investigate state-of-the-art technologies that could help with rapid propagation of superior tea clones.

The project investigated the application of biotechnological techniques for the improvement of the tea industry in Indonesia with the aim of making superior tea clones more readily available to Indonesian smallholders.

Scientists used in-vitro tissue culture techniques to develop new tea varieties. The biotechnology phase was necessary to create both the diversity of superior lines and the large stock plantation within a short time.

The micropropagation research team looked in detail at tissue culture media suited to tea plants. Scientists used a broad spectrum approach where a large number of treatments were used to systematically test the role of different culture nutrients (e.g. inorganic ions, sucrose, vitamins) on the response of the explants. This systematic approach was applied to both multiplication and root initiation.

The program provided training at the Brisbane laboratory of Queensland University of Technology (QUT) for two Indonesian research workers. Scientists at QUT continued with research aiming to regenerate plants from callus tissue. At the Bogor laboratory the researchers attempted through similar technology to develop a somatic embryogenesis method (growing embryos from cells other than germ cells) related to anther culture, and to find ways to propagate potentially higher yielding tetraploid plants.

Superior tissue-cultured material underwent rapid multiplication to establish a stock plantation of about 400 000 plants from which cuttings could be supplied for normal propagation.

Project work undertaken in Indonesia has shown the way forward for the country to replant very large areas of tea. In the first phase of the project the scientists studied the application of tissue culture techniques to the improvement of tea. After some work it was decided that although micropropagation was feasible for both black tea and green tea clones, the best rates of multiplication achieved were about 2-fold per month. Such rates are useful for experimental purposes but not suitable as a basis for a commercial method. Efforts were then made to find ways to produce somatic embryos in tea, since somatic embryos potentially provide the basis of a technique for rapid propagation that can be automated, with very low labour inputs compared to micropropagation.

The project was then extended, and in the second phase the scientists identified factors affecting embryo development in liquid culture systems, which would in turn allowed the process of embryo development to be controlled. As well they investigated the factors involved in the commercialisation of the processes of somatic embryo and propagule production.

Tea production in Indonesia is based on dry land agriculture, which means that tea plants are subject to moisture stress and loss of production in most years. One advantage that seedling tea plants have over the genetically superior plants propagated from cuttings, is a superior root system, which provides better drought tolerance. An attribute of somatic embryos is that they produce plants that resemble the plants produced from zygotic embryos, in having a shoot and root axis, which leads to the development of a strong taproot while having clonal attributes of uniformity and high productivity. This is not found in plants propagated from cuttings or micropropagation and will confer an advantage of greater drought tolerance in plants derived from somatic embryos.

The project has shown how to produce large numbers of the most suitable varieties from somatic embryos that grow into vigorous, fast-growing plantlets with a strong tap root. The chief breeder at the Tea Research Institute in Indonesia believes these embryos will provide easily the best material for the future. The stage is set to provide an advance that will benefit large numbers of Indonesia's smallholder tea producers.