Genetic Differences in the Root Regeneration of Radiata Pine

Abstract

The root regeneration capacity of eight open-pollinated families of radiata pine (Pinus radiata D. Don) was compared after transplanting eight month old seedlings to 8, 11 and 14 ° C soil temperature for 32 d. The results confirmed the major influence of soil temperature on root regeneration. Families differed markedly in their ability to initiate and grow new roots. Differences in the number of new root apices produced between the first and last ranking families were ninefold at 8 ° C, threefold at 11 °C and sevenfold at 14 °C. There was significant family × temperature interaction for new root length. The ability of some families to grow new roots at the warmer temperature of 14 °C did not match their ability at 11 ° C and 8 °C. The weights of shoot and root at transplanting had no apparent effect on the root regeneration capacity of the families studied. The important factors which contributed to genetic effects were the renewed growth of the existing first order lateral roots and the production of second order lateral roots on them. The root regeneration characters were highly heritable. The large genetic difference and the high heritabilities in root characters indicate the scope to exploit genetic effects on root configuration in radiata pine to improve survival and early establishment.