Environmental and Cultural Influences on Flowering of Eucalyptus dunnii

摘要

Eucalyptus dunnii has become one of the preferred species for hardwood plantation establishment in many areas of south-central China and, in Australia, in northern coastal New South Wales and southeastern Queensland. However, it is a particularly shy-flowering species and this has limitations on plantation establishment and genetic improvement programs. Influences of geographic location and climate on flowering were examined in 17 planted stands of E. dunnii in China and Australia. Incidence of flowering is favoured by mean annual temperatures below about 16°C and stockings below 400 trees ha~(-1), but there was no apparent association between age and flowering. Cultural treatments involving applications of high dosage fertiliser and paclobutrazol were tested in China and Australia to examine the potential for enhancing flowering and seed production in established seed orchards. Early results show that paclobutrazol, either alone or in combination with high dosage fertilisation, increased the proportion of trees initiating flower buds and substantially increased the number of flower buds per tree. Fertiliser did not affect initiation of flower buds. Neither treatment had any effect on initiation of flower buds in environments where untreated trees did not produce buds.