**3. Long-term conservation of** *Hevea* **germplasm**

*In situ* and *ex situ* conservations are the two major strategies used in the conservation of plant genetic resources. *In situ* conservation, the conservation of diversity in its natural habitat, involves the designation, management and monitoring of the population at the location where it is currently found and within the community to which it belongs whereas *ex situ* conservation, collection of which the biodiversity is preserved outside its natural habitat, involves the sampling, transfer and storage of a population of a certain species away from the original location (Maxted et al., 1997). Because of a number of advantages, *the ex situ* method has been used to primarily conserve numerous plant genetic resources. In this method, plant diversity is safely preserved and concentrated in a small number of controlled places under consistent environmental conditions and is readily accessible to breeders.

An alternative solution to rubber tree *in situ* genetic conservation is the management of existing *ex situ* collections (Le Guen et al., 2009). Because of the ease of vegetative propagation by grafting, many *ex situ* collections of *Hevea* were established in various rubber producing countries. In Vietnam, the *ex situ* conservation of *Hevea* germplasm was established in 1985. This germplasm included the collection of local *Hevea* accessions, the introduction of *Hevea* clones from other countries. The majority of this germplasm collection was derived from the IRRDB'81 collection expedition in the Amazon forests of Brazil which is the primary center of diversity of the crop and the source of wild rubber trees. This germplasm was introduced into Vietnam in the form of budwood in 1984. All of the materials were sent to Lai Khe experimental station of the Rubber Research Institute of Vietnam (RRIV) in Binh Duong province, which is located in the traditional rubber growing belt. On receipt of the budwood, each accession was first multiplied by bud grafting and

Fig. 2. Distribution of rubber tree (*H. brasiliensis*) in the world where this species has been planted (adapted from Orwa et al. (2009)). Native range: Bolivia, Brazil, Colombia, Peru and Venezuela; Exotic range: Brunei, Cambodia, China, Ethiopia, India, Indonesia, Laos, Liberia,

*In situ* and *ex situ* conservations are the two major strategies used in the conservation of plant genetic resources. *In situ* conservation, the conservation of diversity in its natural habitat, involves the designation, management and monitoring of the population at the location where it is currently found and within the community to which it belongs whereas *ex situ* conservation, collection of which the biodiversity is preserved outside its natural habitat, involves the sampling, transfer and storage of a population of a certain species away from the original location (Maxted et al., 1997). Because of a number of advantages, *the ex situ* method has been used to primarily conserve numerous plant genetic resources. In this method, plant diversity is safely preserved and concentrated in a small number of controlled places under consistent environmental conditions and is readily

An alternative solution to rubber tree *in situ* genetic conservation is the management of existing *ex situ* collections (Le Guen et al., 2009). Because of the ease of vegetative propagation by grafting, many *ex situ* collections of *Hevea* were established in various rubber producing countries. In Vietnam, the *ex situ* conservation of *Hevea* germplasm was established in 1985. This germplasm included the collection of local *Hevea* accessions, the introduction of *Hevea* clones from other countries. The majority of this germplasm collection was derived from the IRRDB'81 collection expedition in the Amazon forests of Brazil which is the primary center of diversity of the crop and the source of wild rubber trees. This germplasm was introduced into Vietnam in the form of budwood in 1984. All of the materials were sent to Lai Khe experimental station of the Rubber Research Institute of Vietnam (RRIV) in Binh Duong province, which is located in the traditional rubber growing belt. On receipt of the budwood, each accession was first multiplied by bud grafting and

Malaysia, Myanmar, Philippines, Singapore, Sri Lanka, Thailand, Uganda, Vietnam, Guatemala, Cameroon, Ivory Coast, Ghana, Gabon, Guinea, Liberia, Nigeria, Congo,

Bangladesh, Papua New Guinea, and Mexico.

accessible to breeders.

**3. Long-term conservation of** *Hevea* **germplasm** 

then planted in the field genebank for conservation in the form of source-bush garden (Fig. 3). This source-bush garden was laid out in randomized complete block design, in which each accession was represented in two replications of five trees with a planting distance of 1.5 m x 1.2 m. The genetic resources of *Hevea* germplasm conserved in Vietnam were showed in Table 1. The source-bush garden is cut back every year to maintain the conservation and also to generate budwood for various evaluation trials. Several preliminary field evaluation trials for most of *Hevea* germplasm accessions have been being established in several representative locations to evaluate their agronomical and morphological characteristics.

Fig. 3. The source-bush garden for *ex situ* conservation of *Hevea* germplasm in Vietnam


Table 1. The genetic resources of *Hevea* germplasm conserved in Vietnam
