EFFECT OF ROOT PINCHING ON GROWTH-PATTERNS OF BLUE OAK (QUERCUS-DOUGLASII H-AND-A) SEEDLINGS

The influence of root pinching on growth patterns of seedlings of blue oak (Quercus douglasii H. & A.) was investigated. The immediate respo nses of the seedlings were: a) Increase of root branches in the upper 10 cm of the soil profile, and b) Increase of root dry mass in the upp er 10 cm of the soil profile, and c) Faster root growth rate. The tota l root length and dry mass were not affected. Indirect effects were: a ) Increase in the number of leaves, and b) Increase in the ratio betwe en leaf area and root dry mass. The differentiation of root distributi on in space and time are an important means of partitioning the soil r esources.