Assessment of manuka provenances for production of high ‘unique manuka factor’ honey

Manuka (Leptospermum scoparium) honey with high methylglyoxal content, commonly expressed as unique manuka factor (UMF®) content, has strong antibacterial and anti-fungal properties. Consequently, there is a strong demand for high UMF manuka honey in the health food industry both in New Zealand and overseas. Currently manuka honey is produced from natural stands of manuka, but UMF content varies among regions. The active ingredient methylglyoxal is produced by natural chemical transformation of dihydroxyacetone (DHA) present in the nectar. Production of high UMF honey is insufficient to meet market demand; this is due to variation in UMF amongst stands causing unpredictability in quality as well as inaccessibility of many manuka stands. The feasibility of increasing production by establishing manuka plantations using plants known to produce nectar with high DHA content is being investigated. This study compared establishment, growth and nectar DHA content of four manuka provenances; two from Northland, and one each from Waikato and Wairarapa in a replicated, randomised complete block trial (Site A). In addition a manuka plantation of a single provenance was monitored for nectar DHA content (Site B). Both sites are in the Whanganui area. Survival of seedlings in the Site A trial at 12 months was high in all provenances. Nectar DHA content ranged from 3666 to 6902 mg/kg 80° Brix and there were no significant differences amongst the provenances. These DHA levels were considerably higher than levels measured in the local manuka (2565 mg/kg 80° Brix). At Site B nectar DHA content of the plantation manuka (5770 mg/kg 80° Brix) was significantly (P=0.05) higher than the indigenous manuka (2565 mg/kg 80° Brix). Early results suggest that manuka provenances can be utilised on different sites to produce high DHA nectar and ultimately high UMF manuka honey, providing landowners with an additional income and help prevent erosion of marginal hill country.fals