Growth of roots of different Pinus radiata genotypes in soil at different strength and aeration

Summary The penetration and growth of roots of different genotypes of Pinus radiata into Stockdale loamy sand (it has a clay layer at 55–70 cm depth) at different soil strength and aeration were investigated. Soil aeration below 10% air-filled pore space significantly retarded root growth. There were significant differences between Pinus radiata families in root growth in the clay layer at high soil strength and low aeration. Families also differed in their sensitivity towards high soil strength and low aeration conditions in the clay layer. The results of this investigation suggest that there is scope for selecting genotypes that can penetrate and grow in clay layers of high strength or low aeration.