Both trials are relatively young, 5 and 8 years respectively at the time of assessment, and it may be too early for specific conclusions and detailed provenance recommendations. The results of the analysis should therefore be interpreted with caution.
Apart from the early age of the trials, care is required in interpretation for another reason, in particular for the Lang Hanh trial. Here the results in many cases are very surprising and differ from what would be expected both when compared with the results of the Ba Vi trial, and when compared with the 8 other P. kesiya trials in the same series that have been analysed. It is, for example, surprising that the Vietnamese sources, which generally have been doing well in the international series, have a rather poor performance at Lang Hanh, under growing conditions they should be well adapted to. Furthermore, the Myanmar provenances Aungban and Zokhua, which in other trials are ranked lower, are above average in the Lang Hanh trial. Finally, many other trials have expressed clear geographical patterns of variation (sources from a country/area within country have similar performance), but, again, this is not the case in the Lang Hanh trial.
The results may of course be real, but could also indicate mistakes in the identification of seedlots at the nursery or in the planting stage. Nothing can be said for sure, but – as mentioned above - the results should be interpreted with special caution. It is recommended that files (establishment report, nursery data) be re-checked for possible errors.
Further, the Lang Hanh trial has problems with encroachment (establishment of a dirt road) in blocks 2 and 4, which are leaving few trees in many plots, and are enhancing the within-block variation. This has also influence on the results.
Because of the potential problems with the Lang Hanh trial, the discussion of results is based on the results of the Ba Vi trial. As mentioned above, this trial is pre-mature, only five years of age, so again, results have to be interpreted with care and preferably compared with results from later assessments.
Based on the results of the Ba Vi trial, the best performing source is the Doi Inthanon source of Thailand. Also the Vietnamese sources are above average together with Simao (China) and Nam Now (Thailand). The Philippine sources, which in other trials have been above average, are average to below average in this trial. The Coto Mines source has a particularly poor performance.
The results of the Ba Vi trial confirm the results from other trials that the Burmese sources are very poor growth performers.
As the Ba Vi trial is too young for an assessment of flowering/fruiting and foxtailing, adaptation can only be discussed based on the analysis of survival. Especially the Doi Inthanon and Nong Krating sources from Thailand have high survival, but also other Thai sources, and Simao of China is above average. Vietnamese sources are intermediate.
With regard to quality, and in particular stemform and branch diameter, the same picture appears. The Vietnamese sources are above average together with Doi Inthanon and Nam Now of Thailand and Tarlac of the Philippines. Simao (China) also has good stemform, but has relatively large branches.