VARIATION IN GROWTH AND DISEASE RESISTANCE OF EUCALYPTUS SPECIES AND PROVENANCES TESTED IN VIETNAM.

December 26, 2005 by

INTRODUCTION

The genus Eucalyptus L’Herit of the family Myrtaceae includes about 500 Eucalyptus species having natural distribution mainly in Australia (Eldridge et al., 1993). Only Eucalyptus deglupta Blume occurs naturally in the Philippines, Indonesia and Papua New Guinea (PNG) and the species E. urophylla occurs on seven islands of Indonesia namely Adonara, Alor, Flores, Lembata, Pentar, Timor and Wetar. Eucalypts are very important plantation tree species and by the year 2000 their plantations may exceed 10 million ha (Eldridge et al., 1993).

Be re 1970, more than 50 Eucalyptus species have been used in many trials and pilot plantations in Vietnam (Nghia et al., 1993). During the period from 1986 to 1992, out of 913,463 ha plantation established over the whole country, there has been 428,569 ha of Eucalyptus plantation which occupies 46.5% of total plantation area (Science and Technology Department, MOF, 1994). Eucalypts are very important trees for scattered tree planting and tree planting in farms which can provide firewood, wood for house contruction and raw material for paper industry.

The problem is that productivity of plantation in some areas is not high or even low, at the same time fungus disease (leaf blight) seems to be serious in southern Vietnam, therefore species and provenance selection become very important not only for fast growth but also for disease resistance (Nghia, 1992; Old and Yuan, 1995; Sharma, 1994). The ACIAR Project 9441 has been rmulated to solve the problem. This paper will show some main results of species and provenance trials as well as preliminary investigations relating to disease susceptability.

MATERIALS AND METHODS

Fithteen trials including 80 provenances of 12 Eucalyptus species, established on 12 trial sites across the whole country (Table 1 and 2) will be shown in this paper. There are 3 sites in northern, 2 sites in central, 6 sites in southern Vietnam and 1 site in the Western Highland at elevation of 1000 m a.s.l.. The trial sites selected are representative of areas having good potential for large- scale planting of Eucalyptus species in Vietnam. Sowing, site preparation, measurement and other techniques were applied in the same way for each species and provenance in the individual trials. Fertiliser was not applied for most trials except the trial at Xuan Khanh, 1990; Vinh Linh, 1986; Dong Ha, 1990 and Song May, 1990. Most of the trials have used randomised complete block design with 3-4 replications and generally 49 trees per plot except some demonstration plantations. Spacing between trees was 3 x 2 m. The most important growth data collected annually from the trials are height, ground-level diameter or breast-height diameter and survival (Burley and Wood, 1976; Nghia, 1991). The computer programs Datachain and Genstat 5.2 (Williams and Matheson, 1994) have been used r statistical analysis of growth data of those trials established from 1990 onwards. To investigate disease severity in the trials and plantations, the llowing categories have been used :

Disease severity

Disease severity index

Symptoms

Nil

Low

Medium

Severe

Very severe

0

1

2

3

4

· No foliage infection and no dieback of branches.

· Up to 25% of the foliage infected and dieback of up to 25% branches.

· 25-50% of the foliage infected and dieback of 50% branches.

· 50-75% of the foliage infected and dieback of 75% branches.

· >75% of the foliage infected and dieback of >75% branches.

Table 2. Location and site details of trial sites in Vietnam.

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