EUCALYPTUS GENETIC-IMPROVEMENT IN MADAGASCAR

Eucalyptus improvement was initiated 20 years ago in Madagascar and ai med at selecting species and provenances adapted to the very diverse c limatic conditions of the island. The present paper reviews the result s obtained by interspecific, provenance, and progeny tests. The good a daptation of Eucalyptus grandis and Eucalyptus robusta was confirmed b y various experiments. Malagasy provenances of both species exhibited poorer performance than those recently introduced from Australia. This is thought to be the result of a narrow genetic base and inbreeding. The results obtained from tests conducted in diverse environments indi cate that E. grandis provenances are already well performing but exhib it limited variation. Provenances and progenies performances appear to be quite irregular and unpredictable on the basis of site as shown by the results presented here. Significant genetic differences exist amo ng provenances of E robusta tested for growth parameters. The analysis of variance revealed that genetic gain in volume production is possib le through provenance selection. However, it is suggested to introduce a wider range of provenances of E. grandis and E. robusta for further evaluation and to select plus-trees within provenance rather than sea rch for superior provenance. Tremendous variation in growth rate among trees offers great opportunity for further genetic improvement. It ap pears that there are remarkable provenance x site and progeny x site i nteractions. Future reafforested areas need to be planted with genetic ally improved material. Smallholder's ideotypes require that priority should be given to a few major selection criteria: growth rate and vol ume production, juvenile performance, coppicing ability and fire resis tance. The priorities of the Madagascar genetic improvement programme are to pursue provenance introduction and progeny evaluation and to pr oduce genetically improved material to be distributed on a large scale to village communities. It is suggested that these priorities be comb ined for cost efficiency. Evaluation of different provenances and prog enies in diverse ecological areas, individual selection, and large-sca le production of genotypes with a broad base is presently conducted in breeding seedling orchards to satisfy national needs for Eucalyptus s pp. seeds using synthetic varieties.