Water relations, growth, and survival of root-wrenched Douglas-fir seedlings

Publisher Website
Google Scholar
Abstract
Root wrenching in the nursery was investigated in relation to Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedling growth and survival under field conditions. Immediately after wrenching, seedlings had lower plant water potential and leaf conductance of water vapor than unwrenched seedlings. At lifting, shoots of wrenched seedlings were shorter, lighter, and of smaller diameter than those of unwrenched seedlings. Seedlings from four of six seed sources tested had significantly lighter taproots after wrenching, but lateral root and total root weights were not significantly different. Mainly because of lighter shoots, wrenched seedlings had smaller shoot–root ratios than controls. After field planting, wrenched and unwrenched seedlings at a droughty site did not differ in leaf conductance or plant water potential, and throughout exposure to a simulated summer drought in pots, all seedlings showed equal plant water potential, leaf relative water content, and seedling condition. However, wrenched seedlings of four seed sources did not set a bud as quickly during drought and had significantly fewer active roots than unwrenched seedlings. In no case did root wrenching improve growth or survival in the field, and among four seed sources shoot growth was significantly less than that of unwrenched seedlings after 3 years.

This publication has 0 references indexed in Scilit: