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Seasonal course of height and needle growth in Pinus nigra grown in summer-dry Central Anatolia

Isik, Kani
Terminal buds of 8–10-year-old Pinus nigra Arnold, planted near Ankara in Central Anatolia, started to break in late March and early April. Leader growth accelerated as the season proceeded, reaching its peak in late May. Trees completed 80–85% of their shoot elongation by early June, and ceased growth by late July. Extra elongation in July was mainly the result of bud maturation. The average terminal shoot growth was 18–20 cm/year. Leader length in P. nigra in year n + 1 showed significant positive correlation with April rainfall of year n, and with bud length formed in year n. These relationships suggest that the amount of shoot growth is largely predetermined by the environmental conditions prevailing during bud formation in the previous year. Needle growth began 6–7 weeks later than leader growth and appeared to be more sensitive than shoot elongation to changes in the physical environment within the current growing-seasons. Needles stopped growing about 9 weeks later than shoots if temperature and other environmental conditions were favorable. The average needle length was 65–85 mm at the time when needle growth ceased.