The response to drought of 20 open-pollinated families from four Pinus pinaster Ait. populations covering a latitudinal cline (France, Central and Southern Spain, and Morocco) was assessed. The seedlings were cultivated in a greenhouse under controlled temperature and vapor pressure deficit for 120 days, and subjected to two watering regimes for 60 days. Different biomass partitioning variables, pre-dawn water potential, and isotopic discrimination of 13 C in needles (Δ) as surrogate of long-term water use efficiency were estimated for each seedling at the end of the experiment. In response to the imposed drought, there was no change in the root biomass partitioning, but the overall Δ values decreased in response to water stress. All the families of the population from Morocco showed the highest investment in roots, regardless of the watering regime imposed. Inter-family differences within populations were also significant for most parameters as confirmed by the heritability values estimated (higher under the well-watered treatment). The studied P. pinaster populations showed different strategies of response to drought. This may represent an important mechanism by local populations in facing future climatic change. The results could be of value in forest conservation and breeding programs of maritime pine in the future.

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-The objective of this study was to evaluate the effect of the growth regulator indole butyric acid (IBA) on the rooting of mini-cuttings of Castanea crenata x C. sativa hybrid clones. Minicuttings were left to root for 60 days in an acclimatized greenhouse and then transferred to a shade house for a further 30 days. The experiment was a random block design with a double factorial arrangement consisting of five IBA concentrations (0, 2,500, 5,000, 7,500 and 10,000 mg L -1 ) and five clones, with three repetitions, composed of eight minicuttings per repetition. The use of IBA significantly affected the rooting and survival of the mini-cuttings, and good rates were achieved. However, at each IBA concentration we found significant differences between clones, thus suggesting that the conditions of the process of mini-cutting propagation should be specifically adapted to each particular clone.

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