Provenance variation in morphology and leaflet anatomy of Parkia biglobosaand its relation to drought tolerance

Measurements of morphological and anatomical characteristics made on 4-mont h-old seedlings from five provenances of Parkia biglobosa (Jacq.) Benth., g rown in a tropical greenhouse under controlled conditions, showed significa nt differences between the northern provenances, which represented the Suda n savanna zone, and the southern provenances which represented the forest z one of the species distribution. Seedlings of provenances from the savanna zone showed more xerophytic characteristics than those from the forest zone . They were smaller in height, with a greater number of smaller leaflets pe r pinnae, a lower specific leaflet mass, smaller palisade and guard cells a nd a lower ratio of palisade:non-palisade tissue. There were also significa nt differences in the same characteristics, except palisade cell length, be tween provenances from the easterly and westerly extremes of the species ra nge. Stomatal conductance measured after 2 weeks of droughting also showed that provenances from the savanna zone had higher values, indicating greate r physiological activity and reduced stress, compared with provenances from the forest zone. Multivariate discriminant analysis of the morphological a nd anatomical characteristics showed that 98% of the seedlings were classif ied correctly with respect to provenance. The squared distances between pro venances were closely related to the geographical distances between locatio ns. Yet, not all variation in leaf anatomy could be explained by the differ ence in climatic conditions from north to south. Also drought tolerance was not always related to morphological and anatomical features. It is possibl e that clinal variation within the species from east to west may be interac ting with climatic differences from north to south.