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Soil Science Society of America Journal Abstract -

Effect of Soil Temperature on Nodulation of Ceanothus Velutinus Dougl.1


This article in SSSAJ

  1. Vol. 33 No. 5, p. 801-803
    Received: Oct 30, 1968
    Accepted: June 23, 1969

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  1. A. G. Wollum II and
  2. C. T. Youngberg2



The nodulation of snowbrush (Ceanothus velutinus Dougl.) from two seed sources was evaluated at soil temperatures of 10, 15, 22, 26, and 31C. One source was from the east side of the Cascade Mountains in Oregon and one from the west side. Plants in these areas are considered distinct ecotypes. For the east ecotype it was found that more and larger nodules were formed at 26C than at any other temperature tested. However, the number and size of nodules for the west ecotype plants were not significantly different at 22 and 26C. Maximum plant yields for the east and west plants were found to occur at 26 and at 22 and 26C, respectively. Generally, the east ecotype plant required a longer period of time to form nodules than the west plants at comparable temperatures. When the natural variation of soil temperature was characterized, it was found that temperatures were below 20C about 80% of the sampling period and between 20 and 25C for less than 10% of the sampling period.

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