Water Relations of Wrenched and Unwrenched P. radiata Seedlings on Being Transplanted into Conditions of Water Stress

Authors: D.A. Rook
Publication: New Zealand Journal of Forestry, Volume N.Z.J.For. 1969, Issue N.Z.J.For. 14(1) 1969, pp 50-58, May 1969
Publisher: New Zealand Institute of Forestry

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Abstract: Internal water deficits and rates of transpiration of seedlings which had been unwrenched (C), root wrenched once (W/l), or wrenched at fortnightly intervals over the previous five months (W/F) were compared for seven days after being transplanted into conditions of water stress in a controlled environment cabinet. Relative turgidities of the needles of the seedling pretreatments were ranked in the order W/F > W/i > C. Rates of transpiration of the W/F seedlings were significantly higher than those of the seedlings of the other two treatments! Differences in rates of transpiration between detached shoots of the three treatments were slight; those of the W/F seedlings had the highest rates. Seven days after the seedlings were transplanted the root systems of only the W/F stock showed, many new roots. Results from this investigation support those from field trials which indicate that well-wrenched transplants survive dry conditions better than W/i plants, and even more so than C plants, owing in part at least to the effect of repeated wrenching in producing a root system more capable of meeting the requirements of the plant after transplanting.

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