Provenance Productivity of High and Low Elevation Pinus tecunumanii in Zimbabwe

The productivity potential of provenances and families of Pinus tecunumanii were determined across a range of environments in four orthogonal field trials in Zimbabwe. Provenances of P. tecunumanii from altitudes above 1500 m (High Elevation) in natural stands in Mexico and Central America were significantly superior (P < 0.05) to provenances from altitudes below 1500 m (Low Elevation) when planted in Zimbabwe in eightyear mean individual tree volume (1729.2 versus 1588.6 dm³) at 1760 m a.s.l.; were not significantly different (1163.1 versus 1143.9 dm³) at 1450 m a.s.l.; but the latter was significantly superior (1756.4 versus 1468.6 dm³) at 1050 m a.s.l., and (720.7 versus 531.5 dm³) at 780 m a.s.l. The most productive provenances were Juquila (26.1 m³ha^-1yr^-1) at 1760 m, Yucul (17.3 m³ha^-1yr^-1) at 1450 m, San Francisco (24.9 m³ha^-1yr^-1) at 1050 m and Villa Santa (11.1 m³ha^-1yr^-1) at 780 m a.s.l. Improved P. patula was significantly superior to P. tecunumanii at 1760 m a.s.l but the differences were nonsignificant at 1450 m a.s.l. In the warm lower altitude sites, P. tecunumanii was not significantly different from improved P. oocarpa, the commonly planted species, although some provenances of P. tecunumanii were significantly superior by as much as 31%. The top 10 ranked families of the high elevation P. tecunumanii had an eight-year volume advantage of 1% and 23% over P. patula at Stapleford and Cashel, and 40% and 34% over P. oocarpa at Gungunyana and Maswera respectively. Genotype-environment interaction was significant by elevation group, provenance and family level. The interaction at the family level was however largely contributed by families from the high elevation P. tecunumanii. Opportunities exist for immediate deployment of seed of selected provenances of P. tecunumanii in medium and low altitude areas to improve plantation productivity. There is however, no immediate yield advantage of using P. tecunumanii seed in high potential environments currently planted to P. patula. Breeding and selection could also bring about the planting of P. tecunumanii in the higher altitudes in the near future.