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Proceedings of Past Forest Nursery Association Meetings:

Mineral Nutrition and the Target Seedling
Bigg, William L; Schalau, Jeffrey W.
1990: Roseburg, OR
Containerized Douglas -fir seedlings were grown in a
greenhouse for seven months. Treatments were started in
June 1989 by modifying a standard nutrient solution to
give three levels each of nitrogen and phosphorus in a
complete factorial design. Both nutrients were supplied at
one-third of control, control, and three times control.
Foliar nitrogen, phosphorus, potassium, total dry weight,
and root growth capacity after four weeks were measured
in late December 1989. These data were used to compare
three methods of assessing plant nutritional status: critical
concentration, vector diagnosis, and DRIS (diagnosis and
recommendation integrated system). Unlike critical con-
centration, both vector diagnosis and DRIS identify rela-
tive, not absolute, differences between treatments.
Both nitrogen and phosphorus were found to limit growth
when compared to the standard nutrient solution. Dry
weight was most influenced by nitrogen and RGC was
most influenced by phosphorus. Data suggest that the
level portion (luxury consumption) of a critical concentra-
tion curve is caused by deficiencies in other nutrients.
Also, critical concentration was found to be of little value in
making nutrient recommendations. Both vector diagno-
sis and DRIS were more useful in identifying and ranking
limiting nutrients.
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